White privilege

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https://en.wikipedia.org/wiki/White_privilege 

White privilege, or white skin privilege, is the societal privilege that benefits white people over non-white people in some societies, particularly if they are otherwise under the same social, political, or economic circumstances. With roots in European colonialism and imperialism, and the Atlantic slave trade, white privilege has developed in circumstances that have broadly sought to protect white racial privileges, various national citizenships and other rights or special benefits.

In the study of white privilege and its broader field of whiteness studies, both pioneered in the United States, academic perspectives such as critical race theory use the concept to analyze how racism and racialized societies affect the lives of white or white-skinned people. For example, American academic Peggy McIntosh described the advantages that whites in Western societies enjoy and non-whites do not experience, as "an invisible package of unearned assets". White privilege denotes both obvious and less obvious passive advantages that white people may not recognize they have, which distinguishes it from overt bias or prejudice. These include cultural affirmations of one's own worth; presumed greater social status; and freedom to move, buy, work, play, and speak freely. The effects can be seen in professional, educational, and personal contexts. The concept of white privilege also implies the right to assume the universality of one's own experiences, marking others as different or exceptional while perceiving oneself as normal.

Some scholars say that the term uses the concept of "whiteness" as a proxy for class or other social privilege or as a distraction from deeper underlying problems of inequality. Others state that it is not that whiteness is a proxy but that many other social privileges are interconnected with it, requiring complex and careful analysis to identify how whiteness contributes to privilege. Other commentators propose alternative definitions of whiteness and exceptions to or limits of white identity, arguing that the concept of white privilege ignores important differences between white subpopulations and individuals and suggesting that the notion of whiteness cannot be inclusive of all white people. They note the problem of acknowledging the diversity of people of color and ethnicity within these groups.

Some commentators have observed that the "academic-sounding concept of white privilege" sometimes elicits defensiveness and misunderstanding among white people, in part due to how the concept of white privilege was rapidly brought into the mainstream spotlight through social media campaigns such as Black Lives Matter. As an academic concept that was only recently brought into the mainstream, the concept of white privilege is frequently misinterpreted by non-academics; some academics, having studied white privilege undisturbed for decades, have been surprised by the seemingly sudden hostility from right-wing critics since approximately 2014.

Definition

White privilege is a social phenomenon. Although the definition of "white privilege" has been somewhat fluid, it is generally agreed to refer to the implicit or systemic advantages that people who are deemed white have relative to people who are not deemed white; it is the absence of suspicion and other negative reactions that white people experience.

The term is used in discussions focused on the mostly hidden benefits that white people possess in a society where racism is prevalent and whiteness is considered normal, rather than on the detriments to people who are the objects of racism. As such, most definitions and discussions of the concept use as a starting point McIntosh's metaphor of the "invisible backpack" that white people unconsciously "wear" in a society where racism is prevalent.

History

European colonialism

European colonialism, involving some of the earliest significant contacts of Europeans with indigenous peoples, was crucial in the foundation and development of white privilege. Academics, such as Charles V. Hamilton, have explored how modern-era European-organized slavery, beginning with Portugal in the 15th century and culminating in the British Empire and slavery in the United States, began a centuries-long progression of white privilege, and non-white subjugation. Sociologist Bob Blauner has proposed that this era of European colonialism was the height, or most extreme version, of white privilege in history.

In British abolitionist and MP James Stephen's 1824 The Slavery of the British West Indies, while examining the racist colonial laws denying African slaves the ability to give evidence in West Indian jury trials; Stephen makes a clarifying distinction between masters, slaves and "free persons not possessing the privilege of a white skin".

In historian William Miller Macmillan's 1929 The Frontier and the Kaffir Wars, 1792–1836, he describes the motivations of Afrikaner settlers to embark upon the Great Trek as an attempt to preserve their racial privilege over indigenous Khoisan people; "It was primarily land hunger and a determination to uphold white privilege that drove the Trekkers out of the colony in their hundreds". Cape Colony was administered by the British Empire and their increasingly anti-slavery policies were seen as a threat by the Dutch-speaking settlers, who were afraid of losing their African and Asian slaves, as well as their superior status as people of European descent. In 1932, Zaire Church News, a missionary publication in the Zaire area, confronted white privilege's impact from the European colonization of central and southern Africa, and its impact on black people's progress in the region:

In these respects the ambitions of profit-seeking Europeans, individually and especially corporately, may become prejudicial to the educational advance of the Congo people, just as white privilege and ambition have militated against Bantu progress on more than one occasion in South Africa.

Scholar João Ferreira Duarte, in his jointedly written Europe in Black and White, has examined colonialism in relation to white privilege, suggesting its legacy continues "to imprint the privilege of whiteness onto the new map of Europe", but also "sustain the political fortification of Europe as a hegemonic white space".

Early 20th-century

A nicer water fountain for whites next to one for colored people in North Carolina (exhibited in Levine Museum of the New South).

An address on Social Equities, from a 1910 National Council of the Congregational Churches of the United States publication, demonstrates some of the earliest terminology developing in the concept of white skin privilege:

What infinite cruelties and injustices have been practiced by men who believed that to have a white skin constituted special privilege and who reckoned along with the divine rights of kings the divine rights of the white! We are all glad to take up the white man's burden if that burden carries with it the privilege of asserting the white man's superiority, of exploiting the man of lesser breed, and making him know and keep his place.

In his 1935 Black Reconstruction in America, W. E. B. Du Bois introduced the concept of a "psychological wage" for white laborers. This special status, he wrote, divided the labor movement by leading low-wage white workers to feel superior to low-wage black workers. Du Bois identified white supremacy as a global phenomenon, affecting the social conditions across the world by means of colonialism. For instance, Du Bois wrote:

It must be remembered that the white group of laborers, while they received a low wage, were compensated in part by a sort of public and psychological wage. They were given public deference and titles of courtesy because they were white. They were admitted freely with all classes of white people to public functions, public parks, and the best schools. The police were drawn from their ranks, and the courts, dependent on their votes, treated them with such leniency as to encourage lawlessness. Their vote selected public officials, and while this had small effect upon the economic situation, it had great effect upon their personal treatment and the deference shown them. White schoolhouses were the best in the community, and conspicuously placed, and they cost anywhere from twice to ten times as much per capita as the colored schools. The newspapers specialized on news that flattered the poor whites and almost utterly ignored the Negro except in crime and ridicule.

In a 1942 edition of Modern Review magazine, Ramananda Chatterjee accused Winston Churchill of hypocritical policy positions, in his support, as Chatterjee viewed it, of racial equality in the UK and US but not in British India; "Mr Churchill can support white privilege and monopoly in India whilst opposing privilege and monopoly on both sides of the Atlantic." In 1943, during World War II, sociologist Alfred McClung Lee's Race Riot, Detroit 1943 addressed the "Nazi-like guarantee of white privilege" in American society:

White Americans might well ask themselves: Why do whites need so many special advantages in their competition with Negroes? Similar tactics for the elimination of Jewish competition in Nazi Germany brought the shocked condemnation of the civilized world.

US civil rights movement

In the United States, inspired by the civil rights movement, Theodore W. Allen began a 40-year analysis of "white skin privilege", "white race" privilege, and "white" privilege in a call he drafted for a "John Brown Commemoration Committee" that urged "White Americans who want government of the people" and "by the people" to "begin by first repudiating their white skin privileges". The pamphlet "White Blindspot", containing one essay by Allen and one by historian Noel Ignatiev, was published in the late 1960s. It focused on the struggle against "white skin privilege" and significantly influenced the Students for a Democratic Society (SDS) and sectors of the New Left. By June 15, 1969, the New York Times was reporting that the National Office of Students for a Democratic Society (SDS) was calling "for an all-out fight against 'white skin privileges'". From 1974 to 1975, Allen extended his analysis to the colonial period, leading to the publication of "Class Struggle and the Origin of Racial Slavery: The Invention of the White Race" (1975), which ultimately grew into his two-volume The Invention of the White Race in 1994 and 1997.

In his work, Allen maintained several points: that the "white race" was invented as a ruling class social control formation in the late seventeenth and early eighteenth century Anglo-American plantation colonies (principally Virginia and Maryland); that central to this process was the ruling-class plantation bourgeoisie conferring "white race" privileges on European-American working people; that these privileges were not only against the interests of African-Americans, they were also "poison", "ruinous", a baited hook, to the class interests of working people; that white supremacy, reinforced by the "white skin privilege", has been the main retardant of working-class consciousness in the US; and that struggle for radical social change should direct principal efforts at challenging white supremacy and "white skin privileges". Though Allen's work influenced Students for a Democratic Society (SDS) and sectors of the "new left" and paved the way for "white privilege" and "race as social construct" study, and though he appreciated much of the work that followed, he also raised important questions about developments in those areas.

In newspapers and public discourse across the United States in the 1960s, the term "white privilege" was often used to describe white areas under conditions of residential segregation. These and other uses grew out of the era of legal discrimination against Black Americans, and reflected the idea that white status could continue despite formal equality. In the 1990s, the term came back into public discourse, such as in Robert Jensen's 1998 opinion piece in the Baltimore Sun, titled "White privilege shapes the U.S."

Study of the concept

The concept of white privilege also came to be used within radical circles for purposes of self-criticism by anti-racist whites. For instance, a 1975 article in Lesbian Tide criticized the American feminist movement for exhibiting "class privilege" and "white privilege". Weather Underground leader Bernardine Dohrn, in a 1977 Lesbian Tide article, wrote: "... by assuming that I was beyond white privilege or allying with male privilege because I understood it, I prepared and led the way for a totally opportunist direction which infected all of our work and betrayed revolutionary principles."

In the late 1980s, the term gained new popularity in academic circles and public discourse after Peggy McIntosh's 1987 essay "White Privilege: Unpacking the Invisible Knapsack". In this essay, McIntosh described white privilege as "an invisible weightless knapsack of assurances, tools, maps, guides, codebooks, passports, visas, clothes, compass, emergency gear, and blank checks", and also discussed the relationships between different social hierarchies in which experiencing oppression in one hierarchy did not negate unearned privilege experienced in another. In later years, the theory of intersectionality also gained prominence, with black feminists like Kimberlé Williams Crenshaw arguing that black women experienced a different type of oppression from male privilege distinct from that experienced by white women because of white privilege. The essay is still routinely cited as a key influence by later generations of academics and journalists.

In 2003, Ella Bell and Stella Nkomo noted that "most scholars of race relations embrace the use of [the concept] white privilege". The same year, sociologists in the American Mosaic Project at the University of Minnesota reported that in the United States there was a widespread belief that "prejudice and discrimination [in favor of whites] create a form of white privilege." According to their poll, this view was affirmed by 59% of white respondents, 83% of Blacks, and 84% of Hispanics.

21st-century popular culture

White privilege as a concept marked its transition from academia to more mainstream prominence through social media in the early 2010s, especially in 2014, a year in which Black Lives Matter formed into a major movement and the word "hashtag" itself was added to Merriam-Webster. Brandt and Kizer, in their article "From Street to Tweet" (2015), discuss the American public's perception of the concept of privilege in mainstream culture, including white privilege, as being influenced by social media.

Hua Hsu, a Vassar College professor of English, opened his The New Yorker review of the 2015 MTV film White People with the remark: "like the robot in a movie slowly discovering that it is, indeed, a robot, it feels as though we are living in the moment when white people, on a generational scale, have become self-aware". Noting that "white people have begun to understand themselves in the explicit terms of identity politics, long the province of those on the margins", Hsu ascribes this change in self-awareness to a generational change, "one of strange byproducts of the Obama era". Hsu writes that discourse on the nature of whiteness "isn't a new discussion, by any means, but it has never seemed quite so animated".

The film White People itself, produced and directed by Pulitzer Prize winner Jose Antonio Vargas, is a documentary that follows a variety of white teenagers who express their honest thoughts and feelings about their whiteness on-camera, as well as their opinions on white privilege. During one moment of the film, Vargas interviews a white community college student, Katy, who attributes her inability to land a college scholarship to reverse racism against white people, before Vargas points out that white students are "40 percent more likely to receive merit-based funding". In one review of the film, a Daily Beast writer interviews Ronnie Cho, the head of MTV Public Affairs, who acknowledges "young people as the engine behind social change and awareness", and therefore would be more likely to talk about white privilege, but also notes that at the same time, millennials (with some overlap with Generation Z) form "a generation that maybe were raised with noble aspirations to be color blind". Ronnie Cho then asserts these aspirations "may not be very helpful if we ignore difference. The color of our skin does matter, and impacts how the world interacts with us." Later in the same review, writer Amy Zimmerman notes that "white people often don't feel a pressing need to talk about race, because they don't experience it as racism and oppression, and therefore hardly experience it at all. Checking privilege is an act of self-policing for white Americans; comparatively, black Americans are routinely over-checked by the literal police."

In January 2016, hip-hop group Macklemore and Ryan Lewis released "White Privilege II", a single from their album This Unruly Mess I've Made, in which Macklemore raps about his struggle to find his place in the Black Lives Matter protest movement, conscious that his commercial success in hip hop is at least partially a product of white privilege, and his criticism of defensive responses to white privilege. He also says that other white performers have profited immensely from cultural appropriation of black culture, such as Iggy Azalea, though Forrest Wickman, writing for Slate, observes that the line supposedly accusing Azalea of "heisting the magic" is really a self-criticism: The Heist was Macklemore and Ryan Lewis' debut album. Wickman states that "White Privilege II" is not "a great song, but as a think piece it's not terrible" and praises Macklemore for "giving Black Lives Matter protesters (along with up-and-coming singer Jamila Woods) the last word." Spencer Kornhaber, a reviewer for The Atlantic, calls the song "brave" and "both a statement ... and a demonstration" and writes that Macklemore "spotlights the voices of actual black activists". He also criticizes the song for "forgoing metaphor or ambiguity or impressionism". More critically, Kris Ex of Pitchfork Media called the song a "mess", saying that it's "too much to work as hit and not enough to work as a piece of agitprop."

According to Fredrik deBoer, it is a popular trend for white people to willingly claim self-acknowledgement of their white privilege online. deBoer criticized this practice as promoting self-regard and not solving any actual inequalities. Michael J. Monahana argues that the rhetoric of privilege "obscures as much as it illuminates" and that we "would be better served by beginning with a more sophisticated understanding of racist oppression as systemic, and of individual agents as constitutively implicated in that system."

Applications in critical theory

Critical race theory

The concept of white privilege has been studied by theorists of whiteness studies seeking to examine the construction and moral implications of 'whiteness'. There is often overlap between critical whiteness and race theories, as demonstrated by focus on the legal and historical construction of white identity, and the use of narratives (whether legal discourse, testimony or fiction) as a tool for exposing systems of racial power. Fields such as history and cultural studies are primarily responsible for the formative scholarship of critical whiteness studies.

Critical race theorists such as Cheryl Harris and George Lipsitz have said that "whiteness" has historically been treated more as a form of property than as a racial characteristic: in other words, as an object which has intrinsic value that must be protected by social and legal institutions. Laws and mores concerning race (from apartheid and Jim Crow constructions that legally separate different races to social prejudices against interracial relationships or mixed communities) serve the purpose of retaining certain advantages and privileges for whites. Because of this, academic and societal ideas about race have tended to focus solely on the disadvantages suffered by racial minorities, overlooking the advantageous effects that accrue to whites.

Eric Arnesen, an American labor historian, reviewed papers from a whiteness studies perspective published in his field in the 1990s, and found that the concept of whiteness was used so broadly during that time period that it wasn't useful.

Whiteness unspoken

From another perspective, white privilege is a way of conceptualizing racial inequalities that focuses on advantages that white people accrue from their position in society as well as the disadvantages that non-white people experience. This same idea is brought to light by Peggy McIntosh, who wrote about white privilege from the perspective of a white individual. McIntosh states in her writing that, "as a white person, I realized I had been taught about racism as something which puts others at a disadvantage, but had been taught not to see one of its corollary aspects, white privilege which puts me at an advantage". To back this assertion, McIntosh notes a myriad of conditions in her article in which racial inequalities occur to favor whites, from renting or buying a home in a given area without suspicion of one's financial standing, to purchasing bandages in "flesh" color that closely matches a white person's skin tone. She further asserts that she sees

a pattern running through the matrix of white privilege, a pattern of assumptions which were passed on to me as a white person. There was one main piece of cultural turf; it was my own turf, and I was among those who could control the turf. My skin color was an asset for any move I was educated to want to make. I could think of myself as belonging in major ways, and of making social systems work for me. I could freely disparage, fear, neglect, or be oblivious to anything outside of the dominant cultural forms. Being of the main culture, I could also criticize it fairly freely.

Unjust enrichment

Lawrence Blum refers to advantages for white people as "unjust enrichment" privileges, in which white people benefit from the injustices done to people of color, and he articulates that such privileges are deeply rooted in the U.S. culture and lifestyle:

When Blacks are denied access to desirable homes, for example, this is not just an injustice to Blacks but a positive benefit to Whites who now have a wider range of domicile options than they would have if Blacks had equal access to housing. When urban schools do a poor job of educating their Latino/a and Black students, this benefits Whites in the sense that it unjustly advantages them in the competition for higher levels of education and jobs. Whites in general cannot avoid benefiting from the historical legacy of racial discrimination and oppression. So unjust enrichment is almost never absent from the life situation of Whites.

Spared injustice

A protester holds a sign reading "They don't shoot white women like me" at a Black Lives Matter protest in the wake of the non-indictment of a New York City police officer for the death of Eric Garner

In Blum's analysis of the underlying structure of white privilege, "spared injustice" is when a person of color suffers an unjust treatment while a white person does not. His example of this is when "a Black person is stopped by the police without due cause but a White person is not". He identifies "unjust enrichment" privileges as those for which whites are spared the injustice of a situation, and in turn, are benefiting from the injustice of others. For instance, "if police are too focused on looking for Black lawbreakers, they might be less vigilant toward White ones, conferring an unjust enrichment benefit on Whites who do break the laws but escape detection for this reason."

Privileges not related to injustice

Blum describes "non-injustice-related" privileges as those which are not associated with injustices experienced by people of color, but relate to a majority group's advantages over a minority group. Those who are in the majority, usually white people, gain "unearned privileges not founded on injustice." According to Blum, in workplace cultures there tends to be a partly ethnocultural character, so that some ethnic or racial groups' members find them more comfortable than do others.

Framing racial inequality

Dan J. Pence and J. Arthur Fields have observed resistance in the context of education to the idea that white privilege of this type exists, and suggest this resistance stems from a tendency to see inequality as a black or Latino issue. One report noted that white students often react to in-class discussions about white privilege with a continuum of behaviors ranging from outright hostility to a "wall of silence". A pair of studies on a broader population by Branscombe et al. found that framing racial issues in terms of white privilege as opposed to non-white disadvantages can produce a greater degree of racially biased responses from whites who have higher levels of racial identification. Branscombe et al. demonstrate that framing racial inequality in terms of the privileges of whites increased levels of white guilt among white respondents. Those with high racial identification were more likely to give responses which concurred with modern racist attitudes than those with low racial identification. According to the studies' authors, these findings suggest that representing inequality in terms of outgroup disadvantage allows privileged group members to avoid the negative implications of inequality.

A 2019 study published in the Journal of Experimental Psychology had socially liberal people read about white privilege, and then read about a poor person who was either black or white. They found that reading about white privilege did not increase empathy for either, and decreased it if the person was white. One of the study's authors said that this demonstrates the importance of nuance, and recognizing individual differences, when teaching about white privilege.

White privilege pedagogy

White privilege pedagogy has been influential in multicultural education, teacher training, ethnic and gender studies, sociology, psychology, political science, American studies, and social work education.

Several scholars have raised questions about the focus on white privilege in efforts to combat racism in educational settings. Lawrence Blum says that the approach suffers from a failure to distinguish between factors such as "spared injustice" and "unjust enrichment".

White fragility

Robin DiAngelo coined the term "white fragility" in the early 2010s, later releasing her 2018 book White Fragility. She has said that "white privilege can be thought of as unstable racial equilibrium", and that when this equilibrium is challenged, the resulting racial stress can become intolerable and trigger a range of defensive responses. DiAngelo defines these behaviors as white fragility. For example, DiAngelo observed in her studies that some white people, when confronted with racial issues concerning white privilege, may respond with dismissal, distress, or other defensive responses because they may feel personally implicated in white supremacy. Elsewhere, it has been summarized as "the trademark inability of white Americans to meaningfully own their unearned privilege".

DiAngelo also writes that white privilege is very rarely discussed and that even multicultural education courses tend to use vocabulary that further obfuscates racial privilege and defines race as something that only concerns blacks. She suggests using loaded terminology with negative connotations to people of color adds to the cycle of white privilege.

It is far more the norm for these courses and programs to use racially coded language such as 'urban,' 'inner city,' and 'disadvantaged' but to rarely use 'white' or 'overadvantaged' or 'privileged.' This racially coded language reproduces racist images and perspectives while it simultaneously reproduces the comfortable illusion that race and its problems are what 'they' have, not us.

She does say, however, that defensiveness and discomfort from white people in response to being confronted with racial issues is not irrational but rather is often driven by subconscious, sometimes even well-meaning, attitudes toward racism. In a book review, Washington Post critic Carlos Lozada said that the book presents self-fulfilling and oversimplified arguments, and "flattens people of any ancestry into two-dimensional beings fitting predetermined narratives".

White backlash

White backlash, the negative reaction of some white people to the advancement of non-whites, has been described as a possible response to the societal examination of white privilege, or to the perceived actual or hypothetical loss of that racial privilege.

A 2015 Valparaiso University journal article by DePaul University professor Terry Smith titled "White Backlash in a Brown Country" suggests that backlash results from threats to white privilege: "White backlash—the adverse reaction of whites to the progress of members of a non-dominant group—is symptomatic of a condition created by the gestalt of white privilege". Drawing on political scientist Danielle Allen's analysis that demographic shifts "provoke resistance from those whose well-being, status and self-esteem are connected to historical privileges of 'whiteness'", Smith explored the interconnectivity of the concepts:

The hallmark of addiction is "protection of one's source." The same is true of backlash. The linear model of equality drastically underestimates the lengths to which people accustomed to certain privileges will go to protect them. It assigns to white Americans a preternatural ability to adapt to change and see their fellow citizens of color as equal.

In Backlash: What Happens When We Talk Honestly about Racism in America, philosopher George Yancy expands on the concept of white backlash as an extreme response to loss of privilege, suggesting that DiAngelo's white fragility is a subtle form of defensiveness in comparison to the visceral racism and threats of violence that Yancy has examined.

Global

White privilege functions differently in different places. A person's white skin will not be an asset to them in every conceivable place or situation. White people are also a global minority, and this fact affects the experiences they have outside of their home areas. Nevertheless, some people who use the term "white privilege" describe it as a worldwide phenomenon, resulting from the history of colonialism by white Western Europeans. One author states that American white men are privileged almost everywhere in the world, even though many countries have never been colonized by Western Europeans.

In some accounts, global white privilege is related to American exceptionalism and hegemony.

Africa

Namibia

The apartheid system in Namibia created the legal environment for establishing and maintaining white privilege. The segregation of peoples both preserved racial privileges and hindered unitary nation building. In the period of years during the negotiation of Namibian independence, the country's administration, which was dominated by white Namibians, held control of power. In a 1981 NYT analysis, Joseph Lelyveld reported how measures which would challenge white privilege in the country were disregarded, and how politicians, such as Dirk Mudge, ignoring the policy of racial privilege, faced electoral threats from the black majority. In 1988, two years before the country's independence, Frene Ginwala suggested that there was a general refusal to acknowledge the oppression of black women in the country, by the white women who, according to Ginwala, had enjoyed the white privilege of apartheid.

Research conducted by the Journal of Southern African Studies in 2008 has investigated how white privilege is generationally passed on, with particular focus on the descendants of German Namibians, who arrived in the 1950s and 1960s. In 2010, the Journal of Ethnic and Migration Studies further analyzed white privilege in post-colonial Namibia.

South Africa

Registration certificate identifies a person as white

White privilege was legally enshrined in South Africa through apartheid. Apartheid was institutionalized in 1948 and lasted formally into the early 1990s. Under apartheid, racial privilege was not only socially meaningful—it became bureaucratically regulated. Laws such as the 1950 Population Registration Act established criteria to officially classify South Africans by race: White, Indian, Coloured (mixed), or Black.

Many scholars say that 'whiteness' still corresponds to a set of social advantages in South Africa, and conventionally refer to these advantages as "white privilege". The system of white privilege applies both to the way a person is treated by others and to a set of behaviors, affects, and thoughts, which can be learned and reinforced. These elements of "whiteness" establish social status and guarantee advantages for some people, without directly relying on skin color or other aspects of a person's appearance. White privilege in South Africa has small-scale effects, such as preferential treatment for people who appear white in public, and large-scale effects, such as the over five-fold difference in average per-capita income for people identified as white or black.

"Afrikaner whiteness" has also been described as a partially subordinate identity, relative to the British Empire and Boerehaat (a type of prejudice towards Afrikaners), "disgraced" further by the end of apartheid. Some fear that white South Africans suffer from "reverse racism" at the hands of the country's newly empowered majority, "Unfair" racial discrimination is prohibited by Section Nine of the Constitution of South Africa, and this section also allows for laws to be made to address "unfair discrimination". "Fair discrimination" is tolerated by subsection 5.

Asia

Japan

Academic Scott Kiesling's co-edited The Handbook of Intercultural Discourse and Communication suggested that white English speakers are privileged in their ability to gain employment teaching English at Eikaiwa schools in Japan, regardless of Japanese language skills or professional qualifications.

South Korea

White privilege has been analyzed in South Korea, and has been discussed as pervasive in Korean society. White residents, and tourists to the country, have been observed to be given special treatment, and, in particular, white Americans have been, at times, culturally venerated.

A 2006 study found that 40 percent of females in the country used skin whitening products, which professor Charles A. Gallagher described as serving as "a mark of beauty for women, a tangible asset that privileges those with lighter skin". Professor Helene K. Lee has noted that possessing mixed white and Korean heritage, or, specifically, its physical appearance, can afford a biracial individual white privilege in the country. In 2009, writer Jane Jeong Trenka wrote that, as an adoptee to a white family from the United States, it was easier for her to recognize its function in Korean culture.

The culture of US military camptowns in South Korea (a remnant of the Korean War) have been studied as a setting for white privilege, and an exacerbation of racial divides between white American and African American soldiers located on bases, as well as with local Korean people.

North America

Canada

In 2014, the Elementary Teachers' Federation of Ontario received media coverage when it publicly advertised a workshop for educators about methods of teaching white privilege to students. "White Privilege: Unpacking the Invisible Knapsack" had become one of its most recommended teaching tools. During the 2014 Toronto mayoral election, then-candidate John Tory denied the existence of white privilege in a debate.

In 2019, the Canadian Federation for the Humanities and Social Sciences suspended a man from attending their annual meeting for three years for racially profiling a black Canadian scholar. The federation stated that it required the offender to demonstrate that he had taken measures to increase his awareness of white privilege before he would be allowed to attend any future congress.

Later in the year, a former First Nations in Manitoba grand chief stated how many indigenous Canadians perceived the court system of Canada to discriminate against them under the structure of white skin privilege. Journalist Gary Mason has suggested that the phenomenon is embedded within the culture of fraternities and sororities in Canada.

United States

Some scholars attribute white privilege, which they describe as informal racism, to the formal racism (i.e. slavery followed by Jim Crow) that existed for much of American history. In her book Privilege Revealed: How Invisible Preference Undermines America, Stephanie M. Wildman writes that many Americans who advocate a merit-based, race-free worldview do not acknowledge the systems of privilege which have benefited them. For example, many Americans rely on a social or financial inheritance from previous generations, an inheritance unlikely to be forthcoming if one's ancestors were slaves. Whites were sometimes afforded opportunities and benefits that were unavailable to others. In the middle of the 20th century, the government subsidized white homeownership through the Federal Housing Administration, but not homeownership by minorities. Some social scientists also suggest that the historical processes of suburbanization and decentralization are instances of white privilege that have contributed to contemporary patterns of environmental racism.

Wealth

According to Roderick Harrison "wealth is a measure of cumulative advantage or disadvantage" and "the fact that black and Hispanic wealth is a fraction of white wealth also reflects a history of discrimination". Whites have historically had more opportunities to accumulate wealth. Some of the institutions of wealth creation amongst American citizens were open exclusively to whites. Similar differentials applied to the Social Security Act (which excluded agricultural and domestic workers, sectors that then included most black workers), rewards to military officers, and the educational benefits offered to returning soldiers after World War II. An analyst of the phenomenon, Thomas Shapiro, professor of law and social policy at Brandeis University, says, "The wealth gap is not just a story of merit and achievement, it's also a story of the historical legacy of race in the United States."

Over the past 40 years, there has been less formal discrimination in America; the inequality in wealth between racial groups however, is still extant. George Lipsitz asserts that because wealthy whites were able to pass along their wealth in the form of inheritances and transformative assets (inherited wealth which lifts a family beyond their own achievements), white Americans on average continually accrue advantages. Pre-existing disparities in wealth are exacerbated by tax policies that reward investment over waged income, subsidize mortgages, and subsidize private sector developers.

Thomas Shapiro wrote that wealth is passed along from generation to generation, giving whites a better "starting point" in life than other races. According to Shapiro, many whites receive financial assistance from their parents allowing them to live beyond their income. This, in turn, enables them to buy houses and major assets which aid in the accumulation of wealth. Since houses in white neighborhoods appreciate faster, even African Americans who are able to overcome their "starting point" are unlikely to accumulate wealth as fast as whites. Shapiro asserts this is a continual cycle from which whites consistently benefit. These benefits also have effects on schooling and other life opportunities.

Employment and economics

Median weekly earnings of full-time wage and salary workers, by sex, race, and ethnicity, U.S., 2009.

Racialized employment networks can benefit whites at the expense of non-white minorities. Asian-Americans, for example, although lauded as a "model minority", rarely rise to positions high in the workplace: only 8 of the Fortune 500 companies have Asian-American CEOs, making up 1.6% of CEO positions while Asian-Americans are 4.8% of the population. In a study published in 2003, sociologist Deirdre A. Royster compared black and white males who graduated from the same school with the same skills. In looking at their success with school-to-work transition and working experiences, she found that white graduates were more often employed in skilled trades, earned more, held higher status positions, received more promotions and experienced shorter periods of unemployment. Since all other factors were similar, the differences in employment experiences were attributed to race. Royster concluded that the primary cause of these racial differences was due to social networking. The concept of "who you know" seemed just as important to these graduates as "what you know".

According to the distinctiveness theory, posited by University of Kentucky professor Ajay Mehra and colleagues, people identify with other people who share similar characteristics which are otherwise rare in their environment; women identify more with women, whites with other whites. Because of this, Mehra finds that white males tend to be highly central in their social networks due to their numbers. Royster says that this assistance, disproportionately available to whites, is an advantage that often puts black men at a disadvantage in the employment sector. According to Royster, "these ideologies provide a contemporary deathblow to working-class black men's chances of establishing a foothold in the traditional trades."

This concept is similar to the theory created by Mark Granovetter which analyzes the importance of social networking and interpersonal ties with his paper "The Strength of Weak Ties" and his other economic sociology work.

Other research shows that there is a correlation between a person's name and his or her likelihood of receiving a call back for a job interview. Marianne Bertrand and Sendhil Mullainathan found in field experiment in Boston and Chicago that people with "white-sounding" names are 50% more likely to receive a call back than people with "black-sounding" names, despite equal résumé quality between the two racial groups. White Americans are more likely than black Americans to have their business loan applications approved, even when other factors such as credit records are comparable.

Black and Latino college graduates are less likely than white graduates to end up in a management position even when other factors such as age, experience, and academic records are similar.

Cheryl Harris relates whiteness to the idea of "racialized privilege" in the article "Whiteness as Property": she describes it as "a type of status in which white racial identity provided the basis for allocating societal benefits both private and public and character".

Daniel A. Farber and Suzanne Sherry argue that the proportion of Jews and Asians who are successful relative to the white male population poses an intractable puzzle for proponents of what they call "radical multiculturism", who they say overemphasize the role of sex and race in American society.

Housing

Discrimination in housing policies was formalized in 1934 under the Federal Housing Act which provided government credit to private lending for home buyers. Within the Act, the Federal Housing Agency had the authority to channel all the money to white home buyers instead of minorities. The FHA also channeled money away from inner-city neighborhoods after World War II and instead placed it in the hands of white home buyers who would move into segregated suburbs. These, and other, practices intensified attitudes of segregation and inequality.

The "single greatest source of wealth" for white Americans is the growth in value in their owner-occupied homes. The family wealth so generated is the most important contribution to wealth disparity between black and white Americans. It has been said that continuing discrimination in the mortgage industry perpetuates this inequality, not only for black homeowners who pay higher mortgage rates than their white counterparts, but also for those excluded entirely from the housing market by these factors, who are thus excluded from the financial benefits of both capital appreciation and the tax deductions associated with home ownership.

Brown, Carnoey and Oppenheimer, in "Whitewashing Race: The Myth of a Color-Blind Society", write that the financial inequities created by discriminatory housing practices also have an ongoing effect on young black families, since the net worth of one's parents is the best predictor of one's own net worth, so discriminatory financial policies of the past contribute to race-correlated financial inequities of today. For instance, it is said that even when income is controlled for, whites have significantly more wealth than blacks, and that this present fact is partially attributable to past federal financial policies that favored whites over blacks.

Education

According to Stephanie Wildman and Ruth Olson, education policies in the US have contributed to the construction and reinforcement of white privilege. Wildman says that even schools that appear to be integrated often segregate students based on abilities. This can increase white students' initial educational advantage, magnifying the "unequal classroom experience of African American students" and minorities.

Williams and Rivers (1972b) showed that test instructions in Standard English disadvantaged the black child and that if the language of the test is put in familiar labels without training or coaching, the child's performances on the tests increase significantly. According to Cadzen a child's language development should be evaluated in terms of his progress toward the norms for his particular speech community. Other studies using sentence repetition tasks found that, at both third and fifth grades, white subjects repeated Standard English sentences significantly more accurately than black subjects, while black subjects repeated nonstandard English sentences significantly more accurately than white subjects.

According to Janet E. Helms traditional psychological and academic assessment is based on skills that are considered important within white, western, middle-class culture, but which may not be salient or valued within African-American culture. When tests' stimuli are more culturally pertinent to the experiences of African Americans, performance improves. Critics of the concept of white privilege say that in K–12 education, students' academic progress is measured on nationwide standardized tests which reflect national standards.

African Americans are disproportionately sent to special education classes in their schools, and identified as being disruptive or suffering from a learning disability. These students are segregated for the majority of the school day, taught by uncertified teachers, and do not receive high school diplomas. Wanda Blanchett has said that white students have consistently privileged interactions with the special education system, which provides 'non-normal' whites with the resources they need to benefit from the mainline white educational structure.

Educational inequality is also a consequence of housing. Since most states determine school funding based on property taxes, schools in wealthier neighborhoods receive more funding per student. As home values in white neighborhoods are higher than minority neighborhoods, local schools receive more funding via property taxes. This will ensure better technology in predominantly white schools, smaller class sizes and better quality teachers, giving white students opportunities for a better education. The vast majority of schools placed on academic probation as part of district accountability efforts are majority African-American and low-income.

Inequalities in wealth and housing allow a higher proportion of white parents the option to move to better school districts or afford to put their children in private schools if they do not approve of the neighborhood's schools.

Some studies have claimed that minority students are less likely to be placed in honors classes, even when justified by test scores. Various studies have also claimed that visible minority students are more likely than white students to be suspended or expelled from school, even though rates of serious school rule violations do not differ significantly by race. Adult education specialist Elaine Manglitz says the educational system in America has deeply entrenched biases in favor of the white majority in evaluation, curricula, and power relations.

In discussing unequal test scores between public school students, opinion columnist Matt Rosenberg laments the Seattle Public Schools' emphasis on "institutional racism" and "white privilege":

The disparity is not simply a matter of color: School District data indicate income, English-language proficiency and home stability are also important correlates to achievement ... By promoting the "white privilege" canard and by designing a student indoctrination plan, the Seattle School District is putting retrograde, leftist politics ahead of academics, while the perpetrators of "white privilege" are minimizing the capabilities of minorities.

Conservative author Shelby Steele believes that the effects of white privilege are exaggerated, saying that blacks may incorrectly blame their personal failures on white oppression, and that there are many "minority privileges": "If I'm a black high school student today ... there are white American institutions, universities, hovering over me to offer me opportunities: Almost every institution has a diversity committee ... There is a hunger in this society to do right racially, to not be racist."

Anthony P. Carnevale and Jeff Strohl show that whites have a better opportunity at getting into selective schools, while African Americans and Hispanics usually end up going to open access schools and have a lower chance of receiving a bachelor's degree. In 2019, a National Bureau of Economic Research study found white privilege bias in Harvard University's application process for legacy admission.

Military

In a 2013 news story, Fox News reported, "A controversial 600-plus page manual used by the military to train its Equal Opportunity officers teaches that 'healthy, white, heterosexual, Christian' men hold an unfair advantage over other races, and warns in great detail about a so-called 'White Male Club.' ... The manual, which was obtained by Fox News, also instructs troops to 'support the leadership of non-white people. Do this consistently, but not uncritically,' the manual states." The manual was prepared by the Defense Equal Opportunity Management Institute, which is an official unit of the Department of Defense under the control of the Secretary of Defense.

Oceania

Australia

Indigenous Australians were historically excluded from the process that lead to the federation of Australia, and the White Australia policy restricted the freedoms for non-white people, particularly with respect to immigration. Indigenous people were governed by the Aborigines Protection Board and treated as a separate underclass of non-citizens. Prior to a referendum conducted in 1967, it was unconstitutional for Indigenous Australians to be counted in population statistics.

Holly Randell-Moon has said that news media are geared towards white people and their interests and that this is an example of white privilege. Michele Lobo claims that white neighborhoods are normally identified as "good quality", while "ethnic" neighborhoods may become stigmatized, degraded, and neglected.

Some scholars claim white people are seen presumptively as "Australian", and as prototypical citizens. Catherine Koerner has claimed that a major part of white Australian privilege is the ability to be in Australia itself, and that this is reinforced by, discourses on non-white outsiders including asylum seekers and undocumented immigrants.

Some scholars have suggested that public displays of multiculturalism, such as the celebration of artwork and stories of Indigenous Australians, amount to tokenism, since indigenous Australians voices are largely excluded from the cultural discourse surrounding the history of colonialism and the narrative of European colonizers as peaceful settlers. These scholars suggest that white privilege in Australia, like white privilege elsewhere, involves the ability to define the limits of what can be included in a "multicultural" society. Indigenous studies in Australian universities remains largely controlled by white people, hires many white professors, and does not always embrace political changes that benefit indigenous people. Scholars also say that prevailing modes of Western epistemology and pedagogy, associated with the dominant white culture, are treated as universal while Indigenous perspectives are excluded or treated only as objects of study. One Australian university professor reports that white students may perceive indigenous academics as beneficiaries of reverse racism.

Some scholars have claimed that for Australian whites, another aspect of privilege is the ability to identify with a global diaspora of other white people in the United States, Europe, and elsewhere. This privilege contrasts with the separation of Indigenous Australians from other indigenous peoples in southeast Asia. They also claim that global political issues such as climate change are framed in terms of white actors and effects on countries that are predominantly white.

White privilege varies across places and situations. Ray Minniecon, director of Crossroads Aboriginal Ministries, described the city of Sydney specifically as "the most alien and inhospitable place of all to Aboriginal culture and people". At the other end of the spectrum, anti-racist white Australians working with Indigenous people may experience their privilege as painful "stigma".

Studies of white privilege in Australia have increased since the late 1990s, with several books published on the history of how whiteness became a dominant identity. Aileen Moreton-Robinson's Talkin' Up to the White Woman is a critique of unexamined white privilege in the Australian feminist movement. The Australian Critical Race and Whiteness Studies Association formed in 2005 to study racial privilege and promote respect for Indigenous sovereignties; it publishes an online journal called Critical Race and Whiteness Studies.

New Zealand

In New Zealand, a localized relationship to the concept, frequently termed Pakeha privilege, due to the legacy of the colonizing Pākehā settlers, has developed.

In the country's colonial era, Pakeha privilege was enforced in school classrooms by strict time periods, European symbols such as the English alphabet and Western Numerals, and exclusion of Te Reo (the Māori language). All of which would have been alienating and disadvantaging for Māori children.

Academic Huia Jahnke's Mana Tangata: Politics of Empowerment has explored how European New Zealanders rejecting the 'one people' national narrative, naming themselves 'other' by embracing the label Pākehā, has allowed space to examine white privilege and the societal marginalization of Māori people. Massey University scholar Malcolm Mulholland has stated that "studying inequalities between Maori and non-Maori outcomes allows us to identify Pakeha privilege and name it."

In 2016, on the 65th anniversary of Te Rōpū Wāhine Māori Toko I te Ora, the League's president criticized the "dominant Pakeha culture" in New Zealand, and embedded Pakeha privilege.

White guilt

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/White_guilt

White guilt is the individual or collective guilt felt by some white people for harm resulting from racist treatment of ethnic minorities such as African Americans and indigenous peoples by other white people, most specifically in the context of the Atlantic slave trade, European colonialism, genocide of indigenous peoples, The Holocaust and the legacy of these eras.

In certain regions of the Western world, it can be called white settler guilt, white colonial guilt, and other variations, which refer to the guilt more pointedly in relation to European settlement and colonization, such as in Australia and New Zealand. The concept of white guilt has examples both historically and currently in the United States and to a lesser extent in Canada, South Africa, France and the United Kingdom. White guilt has been described by psychologists such as Lisa B. Spanierman and Mary J. Heppner as one of the psychosocial costs of racism for white individuals along with empathy (sadness and anger) for victims of racism and fear of non-white people.

History

Early use

Judith Katz, the author of the 1978 publication White Awareness: Handbook for Anti-Racism Training, is critical of what she calls self-indulgent white guilt fixations. Her concerns about white guilt led her to move from black-white group encounters to all-white groups in her anti-racism training. She also avoided using non-white people to re-educate white people, she said, because she found this led white people to focus on getting acceptance and forgiveness rather than changing their own actions or beliefs.

A report in The Washington Post from 1978 describes the exploitation of white guilt by con artists: "Telephone and mail solicitors, trading on 'white guilt' and on government pressure to advertise in minority-oriented publications, are inducing thousands of businessmen to buy ads in phony publications."

Academic research

In 1999, academic research conducted at the University of Pennsylvania examined the extent of societal feeling of white guilt, possible guilt-based antecedents, and white guilt's relationship to attitudes towards affirmative action. The four studies revealed that "Even though mean White guilt tended to be low, with the mean being just below the midpoint of the scale, the range and variability confirms the existence of feelings of White guilt for some". The findings also showed that white guilt was directly linked to "more negative personal evaluations" of white people generally, and the extent of an individual's feelings of white guilt independently predicted attitudes towards white privilege, racial discrimination and affirmative action.

2003 research at the University of California, Santa Cruz, in its first study, replicated the link between white guilt and strength of belief in white privilege. The second study revealed that white guilt "resulted from seeing European Americans as perpetrators of racial discrimination", and was also predictive of support for compensatory efforts for African Americans.

One academic paper suggests in France, white guilt may be a common feature of management of race relations – in contrast to other European countries.

Rumy Hasan, in his book Multiculturalism: some inconvenient truths (2010), examines "the liberal postcolonial sense of guilt".

Regions

In the United States

American civil rights activist Bayard Rustin wrote that reparations for slavery would be an exploitation of white guilt and damage the "integrity of blacks". In 2006, then-Senator Barack Obama wrote in his book The Audacity of Hope that "rightly or wrongly, white guilt has largely exhausted itself in America". His view on the subject was based on an interaction in the US Senate, where he witnessed a white legislator complain about being made to "feel more white" when a black colleague discussed systemic racism with them.

Shelby Steele, a conservative black political writer, discussed the concept in his 2006 book White Guilt: How Blacks and Whites Together Destroyed the Promise of the Civil Rights Era. Steele criticizes "white guilt" saying that it is nothing more than an alternative interpretation of the concept of "black power":

Whites (and American institutions) must acknowledge historical racism to show themselves redeemed by it, but once they acknowledge it, they lose moral authority over everything having to do with race, equality, social justice, poverty and so on. [...] The authority they lose transfers to the 'victims' of historical racism and becomes their great power in society. This is why white guilt is quite literally the same thing as Black power.

George F. Will, a conservative American political columnist, wrote: "[White guilt is] a form of self-congratulation, where whites initiate 'compassionate policies' toward people of color, to showcase their innocence to racism."

In 2015, when it came to light American civil rights activist Rachel Dolezal had been posing as African American, Washington Post journalist Krissah Thompson described her as "an archetype of white guilt played to its end". Thompson discussed the issue with psychologist Derald Wing Sue, an expert on racial identity, who suggested that Dolezal had become so fascinated by racism and racial justice issues she "over-identified" with black people. In 2016, the school district of Henrico County, Virginia ceased future use of an educational video, Structural Discrimination: The Unequal Opportunity Race, which visualized white privilege and structural racism. Parents complained, calling it a white guilt video, which led to a ban by the county's superintendent.

Since 2016, white liberals rate non-white groups more positively than they do whites. Every other racial group feels more positive about their own race than they do about other races.

In October 2018, The Economist proposed that an increase in Americans claiming Native American ancestry, often incorrectly, may be explained by attempts to "absolve them of collective European guilt for the genocide of indigenous people". In 2019, it was reported how liberal white Americans were being influenced by white guilt, changing patterns of political and social behaviour to be more racially inclusive since the election of Donald Trump. This included the methods by which Democratic nominees were being considered for the 2020 presidential election.

In October 2019, students at middle school in Massachusetts raised money for the Mashpee Wampanoag Tribe, after learning that the tribe had dealt with the first colonists from The Mayflower. The school director said it had "left all our students with this sense of European guilt", and one student remarked "If we don’t try to repair what our ancestors did, the tribes will die off".

In Australia

Author Sally Morgan 1987's book My Place, which explores Aboriginal identity, has come under critique for providing European Australians with a narrative of colonization in Australia which, critics argue, too generously assuages white settler guilt. Marcia Langton has described the book as a kind of an unearned catharsis for European guilt: "The book is a catharsis. It gives release and relief, not so much to Aboriginal people oppressed by psychotic racism, as to the whites who wittingly and unwittingly participated in it".

In New Zealand

In New Zealand, the legacy of Pākehā settlers has created a localized sense of white guilt in relation to the resulting damage to pre-existing Māori culture and mistreatment of indigenous people. Then opposition leader, Bill English, in 2002, gave a speech rejecting the "cringing guilt" said to be a result of the European colonialism to Aotearoa, and the Pakeha settlers who enacted it. This was in response to the government Race Relations Commissioner, comparing the impact of British settlement in New Zealand to the Taliban's vandalism of the Buddhas of Bamyan.

Academic Elizabeth Rata has proposed that "without the mirror image of unexpiated guilt, a necessary process in the recognition and validation of a shared reality, Pākehā guilt moved, not onto the next stage of externalised shame, but into an internal and enclosed narcissism". In her analysis, she suggests that the Waitangi Tribunal has been a missed opportunity to reconcile white guilt in New Zealand.

Critical opinions

Commentator Sunny Hundal, writing for The Guardian, stated it is "reductionist" to assign political opinions to a collective guilt such as "white guilt" and few people on the left actually hold the views being ascribed to them by the conservative writers who expound on the concept of "white guilt" and its implications. Hundal concludes: "Not much annoys me more than the stereotype that to be liberal is to be full of guilt. To be socially liberal, in my view, is to be more mindful of compassion and empathy for others…to label that simply as guilt is just...insulting."

In 2015, Gary Younge explored white guilt's impotence in society, writing: "It won't close the pay gap, the unemployment gap, the wealth gap or the discrepancy between black and white incarceration. It won't bring back Walter Scott, Trayvon Martin or Brandon Moore." Coleman Hughes has suggested that white guilt causes the misdirection of anti-racist efforts, writing that "where white guilt is endemic, demands to redress racism will be strongest, regardless of how much racism actually exists".

Works about white guilt

• The Tears of the White Man: Compassion as Contempt, a 1983 book by the French philosopher Pascal Bruckner
• The Tyranny of Guilt: An Essay on Western Masochism, a 2006 book by Pascal Bruckner
• White Guilt: How Blacks and Whites Together Destroyed the Promise of the Civil Rights Era, a 2006 book by American author Shelby Steele
• Whites, Jews, and Us: Toward a Politics of Revolutionary Love, a 2016 book by the French-Algerian political activist Houria Bouteldja [fr]

Biological effects of radiation on the epigenome

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Biological_effects_of_radiation_on_the_epigenome 

Ionizing radiation can cause biological effects which are passed on to offspring through the epigenome. The effects of radiation on cells has been found to be dependent on the dosage of the radiation, the location of the cell in regards to tissue, and whether the cell is a somatic or germ line cell. Generally, ionizing radiation appears to reduce methylation of DNA in cells.

Ionizing radiation has been known to cause damage to cellular components such as proteins, lipids, and nucleic acids. It has also been known to cause DNA double-strand breaks. Accumulation of DNA double strand breaks can lead to cell cycle arrest in somatic cells and cause cell death. Due to its ability to induce cell cycle arrest, ionizing radiation is used on abnormal growths in the human body such as cancer cells, in radiation therapy. Most cancer cells are fully treated with some type of radiotherapy, however some cells such as stem cell cancer cells show a reoccurrence when treated by this type of therapy.

Radiation exposure in everyday life

Non-ionising radiations, electromagnetic fields (EMF) such as radiofrequency (RF), or power frequency radiation have become very common in everyday life. All of these exist as low frequency radiation which can come from wireless cellular devices or through electrical appliances which induce extremely low frequency radiation (ELF). Exposure to these radioactive frequencies has shown negative affects on the fertility of men by impacting the DNA of the sperm and deteriorating the testes as well as an increased risk of tumor formation in salivary glands. The International Agency for Research on Cancer considers RF electromagnetic fields to be possibly carcinogenic to humans, however the evidence is limited.

Radiation and medical imaging

See also: Radiation protection

Advances in medical imaging has resulted in increased exposure of humans to low doses of ionizing radiation. Radiation exposure in pediatrics has been shown to have a greater impact as children's cells are still developing. The radiation obtained from medical imaging techniques is only harmful if consistently targeted multiple times in a short space of time. Safety measures have been introduced in order to limit the exposure of harmful ionizing radiation such as the usage of protective material during the use of these imaging tools. A lower dosage is also used in order to fully rid the possibility of a harmful effect from the medical imaging tools. The National Council on Radiation Protection and Measurements along with many other scientific committees have ruled in favor of continued use of medical imaging as the reward far outweighs the minimal risk obtained from these imaging techniques. If the safety protocols are not followed there is a potential increase in the risk of developing cancer. This is primarily due to the decreased methylation of cell cycle genes, such as those relating to apoptosis and DNA repair. The ionizing radiation from these techniques can cause many other detrimental effects in cells including changes in gene expression and halting the cell cycle. However, these results are extremely unlikely if the proper protocols are followed.

Target theory

Target theory concerns the models of how radiation kills biological cells and is based around two main postulates:

1. "Radiation is considered to be a sequence of random projectiles;
2. the components of the cell are considered as the targets bombarded by these projectiles"

Several models have been based around the above two points. From the various proposed models three main conclusions were found:

1. Physical hits obey a Poisson distribution
2. Failure of radioactive particles to attack sensitive areas of cells allow for survival of the cell
3. Cell death is an exponential function of the dose of radiation received as the number of hits received is directly proportional to the radiation dose; all hits are considered lethal

Radiation exposure through ionizing radiation (IR) affects a variety of processes inside of an exposed cell. IR can cause changes in gene expression, disruption of cell cycle arrest, and apoptotic cell death. The extent of how radiation effects cells depends on the type of cell and the dosage of the radiation. Some irradiated cancer cells have been shown to exhibit DNA methylation patterns due to epigenetic mechanisms in the cell. In medicine, medical diagnostic methods such as CT scans and radiation therapy expose the individual to ionizing radiation. Irradiated cells can also induce genomic instability in neighboring un-radiated cells via the bystander effect. Radiation exposure could also occur via many other channels than just ionizing radiation.

The basic ballistic models

The single-target single-hit model

In this model a single hit on a target is sufficient to kill a cell. The equation used for this model is as follows:

${\displaystyle p(k)={\frac {m^{k}}{k!}}e^{-m}}$

Where k represents a hit on the cell and m represents the mass of the cell.

The n-target single-hit model

In this model the cell has a number of targets n. A single hit on one target is not sufficient to kill the cell but does disable the target. An accumulation of successful hits on various targets leads to cell death. The equation used for this model is as follows:

${\displaystyle p(n)=(1-e^{-{\frac {D}{D_{0}}}})^{n}}$

Where n represents number of the targets in the cell.

The linear quadratic model

The equation used for this model is as follows:

${\displaystyle S(D)=e^{-\alpha D-\beta D^{2}}}$

where αD represents a hit made by a one particle track and βD represents a hit made by a two particle track and S(D) represents the probability of survival of the cell.

The three lambda model

This model showed the accuracy of survival description for higher or repeated doses.

The equation used for this model is as follows:

${\displaystyle S(D)=e^{-\lambda _{3}(1-e^{\lambda _{1}D}(1-(1-e^{-(\lambda _{2}-\lambda _{1})D})^{2}))}}$

The linear-quadratic-cubic model

The equation used for this model is as follows:

${\displaystyle S(D)=e^{-\alpha D-\beta D^{2}+\gamma D^{3}}}$

Sublesions hypothesis models

The repair-misrepair model

This model shows the mean number of lesions before any repair activations in a cell.

The equation used for this model is as follows:

${\displaystyle S_{\psi }=e^{-U_{0}}(1+{\frac {U_{0}(1-e^{-\lambda T})}{\epsilon }})^{\psi \epsilon }}$

where Uo represents the yield of initially induced lesions, with λ being the linear self-repair coefficient, and T equaling time

The lethal-potentially lethal model

This equation explores the hypothesis of a lesion becoming fatal within a given of time if it is not repair by repair enzymes.

The equation used for this model is as follows:

${\displaystyle S=e^{-n_{tot}(T+t_{r})}=e^{-N_{tot}}[{\frac {1+N_{PL}}{\epsilon (1-e^{-\epsilon _{PL}t_{r}})}}]^{\epsilon }}$

T is the radiation duration and tr is the available repair time.

The saturable repair model

This model illustrates the efficiency of the repair system decreasing as the dosage of radiation increases. This is due to the repair kinetics becoming increasingly saturated with the increase in radiation dosage.

The equation used for this model is as follows:

${\displaystyle S(D)=e^{-{\frac {n_{0}-c_{0}}{1-{\frac {c_{0}}{n_{0}}}e^{kT(c_{0}-n_{0})}}}}}$

n(t) is the number of unrepaired lesions, c(t) is the number of repair molecules or enzymes, k is the proportionality coefficient, and T is the time available for repair.

Cellular environment and radiation hormesis

Radiation hormesis

Hormesis is the hypothesis that low levels of disrupting stimulus can cause beneficial adaptations in an organism. The ionizing radiation stimulates repair proteins that are usually not active. Cells use this new stimuli to adapt to the stressors they are being exposed to.

Radiation-Induced Bystander Effect (RIBE)

In biology, the bystander effect is described as changes to nearby non-targeted cells in response to changes in an initially targeted cell by some disrupting agent. In the case of Radiation-Induced Bystander Effect, the stress on the cell is caused by ionizing radiation.

The bystander effect can be broken down into two categories, long range bystander effect and short range bystander effect. In long range bystander effect, the effects of stress are seen further away from the initially targeted cell. In short range bystander, the effects of stress are seen in cells adjacent to the target cell.

Both low linear energy transfer and high linear energy transfer photons have been shown to produce RIBE. Low linear energy transfer photons were reported to cause increases in mutagenesis and a reduction in the survival of cells in clonogenic assays. X-rays and gamma rays were reported to cause increases in DNA double strand break, methylation, and apoptosis. Further studies are needed to reach a conclusive explanation of any epigenetic impact of the bystander effect.

Radiation and oxidative stress

Formation of ROS

Ionizing radiation produces fast moving particles which have the ability to damage DNA, and produce highly reactive free radicals known as reactive oxygen species (ROS). The production of ROS in cells radiated by LDIR (Low-Dose Ionizing Radiation) occur in two ways, by the radiolysis of water molecules or the promotion of nitric oxide synthesis (NOS) activity. The resulting nitric oxide formation reacts with superoxide radicals. This generates peroxynitrite which is toxic to biomolecules. Cellular ROS is also produced with the help of a mechanism involving nicotinamide adenosine dinucleotide phosphate (NADPH) oxidase. NADPH oxidase helps with the formation of ROS by generating a superoxide anion by transferring electrons from cytosolic NADPH across the cell membrane to the extracellular molecular oxygen. This process increases the potential for leakage of electrons and free radicals from the mitochondria. The exposure to the LDIR induces electron release from the mitochondria resulting in more electrons contributing to the superoxide formation in the cells.

The production of ROS in high quantity in cells results in the degradation of biomolecules such as proteins, DNA, and RNA. In one such instance the ROS are known to create double stranded and single stranded breaks in the DNA. This causes the DNA repair mechanisms to try to adapt to the increase in DNA strand breaks. Heritable changes to the DNA sequence have been seen although the DNA nucleotide sequence seems the same after the exposure with LDIR.

Activation of NOS

The formation of ROS is coupled with the formation of nitric oxide synthase activity (NOS). NO reacts with O₂⁻ generating peroxynitrite. The increase in the NOS activity causes the production of peroxynitrite (ONOO-). Peroxynitrite is a strong oxidant radical and it reacts with a wide array of biomolecules such as DNA bases, proteins and lipids. Peroxynitrite affects biomolecules function and structure and therefore effectively destabilizes the cell.

Mechanism of oxidative stress and epigenetic gene regulation

Ionizing radiation causes the cell to generate increased ROS and the increase of this species damages biological macromolecules. In order to compensate for this increased radical species, cells adapt to IR induced oxidative effects by modifying the mechanisms of epigenetic gene regulation. There are 4 epigenetic modifications that can take place:

1. formation of protein adducts inhibiting epigenetic regulation
2. alteration of genomic DNA methylation status
3. modification of post translational histone interactions affecting chromatin compaction
4. modulation of signaling pathways that control transcription factor expression

ROS-mediated protein adduct formation

ROS generated by ionizing radiation chemically modify histones which can cause a change in transcription. Oxidation of cellular lipid components result in an electrophilic molecule formation. The electrophilic molecule binds to the lysine residues of histones causing a ketoamide adduct formation. The ketoamide adduct formation blocks the lysine residues of histones from binding to acetylation proteins thus decreasing gene transcription.

ROS-mediated DNA methylation changes

DNA hypermethylation is seen in the genome with DNA breaks at a gene-specific basis, such as promoters of regulatory genes, but the global methylation of the genome shows a hypomethylation pattern during the period of reactive oxygen species stress.

DNA damage induced by reactive oxygen species results in increased gene methylation and ultimately gene silencing. Reactive oxygen species modify the mechanism of epigenetic methylation by inducing DNA breaks which are later repaired and then methylated by DNMTs. DNA damage response genes, such as GADD45A, recruit nuclear proteins Np95 to direct histone methyltransferase's towards the damaged DNA site. The breaks in DNA caused by the ionizing radiation then recruit the DNMTs in order to repair and further methylate the repair site.

Genome wide hypomethylation occurs due to reactive oxygen species hydroxylating methylcytosines to 5-hydroxymethylcytosine (5hmC). The production of 5hmC serves as an epigenetic marker for DNA damage which is recognizable by DNA repair enzymes. The DNA repair enzymes attracted by the marker convert 5hmC to an unmethylated cytosine base resulting in the hypomethylation of the genome.

Another mechanism that induces hypomethylation is the depletion of S-adenosyl methionine synthetase (SAM). The prevalence of super oxide species causes the oxidization of reduced glutathione (GSH) to GSSG. Due to this, synthesis of the cosubstrate SAM is stopped. SAM is an essential cosubtrate for the normal functioning of DNMTs and histone methyltrasnferase proteins.

ROS-mediated post-translation modification

Double stranded DNA breaks caused by exposure to ionizing radiation are known to alter chromatin structure. Double stranded breaks are primarily repaired by poly ADP (PAR) polymerases which accumulate at the site of the break leading to activation of the chromatin remodeling protein ALC1. ALC1 causes the nucleosome to relax resulting in the epigenetic up-regulation of genes. A similar mechanism involves the ataxia telangiectasia mutated (ATM) serine/threonine kinase which is an enzyme involved in the repair of double stranded breaks caused by ionizing radiation. ATM phosphorylates KAP1 which causes the heterochromatin to relax, allowing increased transcription to occur.

The DNA mismatch repair gene (MSH2) promoter has shown a hypermethylation pattern when exposed to ionizing radiation. Reactive oxygen species induce the oxidization of deoxyguanosine into 8-hydroxydeoxyguanosine (8-OHdG) causing a change in chromatin structure. Gene promoters that contain 8-OHdG deactivate the chromatin by inducing trimethyl-H3K27 in the genome. Other enzymes such as transglutaminases (TGs) control chromatin remodeling through proteins such as sirtuin1 (SIRT1). TGs cause transcriptional repression during reactive oxygen species stress by binding to the chromatin and inhibiting the sirtuin 1 histone deacetylase from performing its function.

ROS-mediated loss of epigenetic imprinting

Epigenetic imprinting is lost during reactive oxygen species stress. This type of oxidative stress causes a loss of NF- κB signaling. Enhancer blocking element CCCTC-binding factor (CTCF) binds to the imprint control region of insulin-like growth factor 2 (IGF2) preventing the enhancers from allowing the transcription of the gene. The NF- κB proteins interact with IκB inhibitory proteins, but during oxidative stress IκB proteins are degraded in the cell. The loss of IκB proteins for NF- κB proteins to bind to results in NF- κB proteins entering the nucleus to bind to specific response elements to counter the oxidative stress. The binding of NF- κB and corepressor HDAC1 to response elements such as the CCCTC-binding factor causes a decrease in expression of the enhancer blocking element. This decrease in expression hinders the binding to the IGF2 imprint control region therefore causing the loss of imprinting and biallelic IGF2 expression.

Mechanisms of epigenetic modifications

After the initial exposure to ionizing radiation, cellular changes are prevalent in the unexposed offspring of irradiated cells for many cell divisions. One way this non-Mendelian mode of inheritance can be explained is through epigenetic mechanisms.

Ionizing radiation and DNA methylation

Genomic instability via hypomethylation of LINE1

Ionizing radiation exposure affects patterns of DNA methylation. Breast cancer cells treated with fractionated doses of ionizing radiation showed DNA hypomethylation at the various gene loci; dose fractionation refers to breaking down one dose of radiation into separate, smaller doses. Hypomethylation of these genes correlated with decreased expression of various DNMTs and methyl CpG binding proteins. LINE1 transposable elements have been identified as targets for ionizing radiation. The hypomethylation of LINE1 elements results in activation of the elements and thus an increase in LINE1 protein levels. Increased transcription of LINE1 transposable elements results in greater mobilization of the LINE1 loci and therefore increases genomic instability.

Ionizing radiation and histone modification

Irradiated cells can be linked to a variety of histone modifications. Ionizing radiation in breast cancer cell inhibits H4 lysine tri-methylation. Mouse models exposed to high levels of X-ray irradiation exhibited a decrease in both the tri-methylation of H4-Lys20 and the compaction of the chromatin. With the loss of tri-methylation of H4-Lys20, DNA hypomethylation increased resulting in DNA damage and increased genomic instability.

Loss of methylation via repair mechanisms

Breaks in DNA due to ionizing radiation can be repaired. New DNA synthesis by DNA polymerases is one of the ways radiation induced DNA damage can be repaired. However, DNA polymerases do not insert methylated bases which leads to a decrease in methylation of the newly synthesized strand. Reactive oxygen species also inhibit DNMT activity which would normally add the missing methyl groups. This increases the chance that the demethylated state of DNA will eventually become permanent.

Clinical consequences and applications

Epigenetic affects on a developing brain

Chronic exposure to these types of radiation can have an effect on children from as early as when they are fetuses. There have been multiple cases reported of hindrance in the development of the brain, behavioral changes such as anxiety, and the disruption of proper learning and language processing. An Increase in the cases of ADHD behavior and autism behavior has been shown to be directly correlated with the exposure of EMF waves. The World Health Organization has classified RFR as a possible carcinogen for its epigenetic effects on DNA expression. The exposure to EMF waves on a consistent 24hr basis has shown to lower the activity of miRNA in the brain affecting developmental and neuronal activity. This epigenetic change causes the silencing of necessary genes along with the change in expression of other genes integral for the normal development of the brain.

MGMT- and LINE1- specific DNA methylation

DNA methylation influences tissue responses to ionizing radiation. Modulation of methylation in the gene MGMT or in transposable elements such as LINE1 could be used to alter tissue responses to ionizing radiation and potentially opening new areas for cancer treatment.

MGMT serves as a prognostic marker in glioblastoma. Hypermethylation of MGMT is associated with the regression of tumors. Hypermethylation of MGMT silences its transcription inhibiting alkylating agents in tumor killing cells. Studies have shown patients who received radiotherapy, but no chemotherapy after tumor extraction, had an improved response to radiotherapy due to the methylation of the MGMT promoter.

Almost all human cancers include hypomethylation of LINE1 elements. Various studies depict that the hypomethylation of LINE1 correlates with a decrease in survival after both chemotherapy and radiotheraphy.

Treatment by DNMT inhibitors

DMNT inhibitors are being explored in the treatment of malignant tumors. Recent in-vitro studies show that DNMT inhibitors can increase the effects of other anti-cancer drugs. Knowledge of in-vivo effect of DNMT inhibitors are still being investigated. The long term effects of the use of DNMT inhibitors are still unknown.

Radioactivity in the life sciences

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Radioactivity_in_the_life_sciences 

 

Radioactivity is generally used in life sciences for highly sensitive and direct measurements of biological phenomena, and for visualizing the location of biomolecules radiolabelled with a radioisotope.

All atoms exist as stable or unstable isotopes and the latter decay at a given half-life ranging from attoseconds to billions of years; radioisotopes useful to biological and experimental systems have half-lives ranging from minutes to months. In the case of the hydrogen isotope tritium (half-life = 12.3 years) and carbon-14 (half-life = 5,730 years), these isotopes derive their importance from all organic life containing hydrogen and carbon and therefore can be used to study countless living processes, reactions, and phenomena. Most short lived isotopes are produced in cyclotrons, linear particle accelerators, or nuclear reactors and their relatively short half-lives give them high maximum theoretical specific activities which is useful for detection in biological systems.

DOTA linked to the monoclonal antibody tacatuzumab and chelating yttrium-90

 

Whole-body PET scan using ¹⁸F-FDG showing intestinal tumors and non-specific accumulation in bladder

Radiolabeling is a technique used to track the passage of a molecule that incorporates a radioisotope through a reaction, metabolic pathway, cell, tissue, organism, or biological system. The reactant is 'labeled' by replacing specific atoms by their isotope. Replacing an atom with its own radioisotope is an intrinsic label that does not alter the structure of the molecule. Alternatively, molecules can be radiolabeled by chemical reactions that introduce an atom, moiety, or functional group that contains a radionuclide. For example, radio-iodination of peptides and proteins with biologically useful iodine isotopes is easily done by an oxidation reaction that replaces the hydroxyl group with iodine on tyrosine and histadine residues. Another example is to use chelators such DOTA that can be chemically coupled to a protein; the chelator in turn traps radiometals thus radiolabeling the protein. This has been used for introducing Yttrium-90 onto a monoclonal antibody for therapeutic purposes and for introducing Gallium-68 onto the peptide Octreotide for diagnostic imaging by PET imaging.

Radiolabeling is not necessary for some applications. For some purposes, soluble ionic salts can be used directly without further modification (e.g., gallium-67, gallium-68, and radioiodine isotopes). These uses rely on the chemical and biological properties of the radioisotope itself, to localize it within the organism or biological system.

Molecular imaging is the biomedical field that employs radiotracers to visualize and quantify biological processes using positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging. Again, a key feature of using radioactivity in life science applications is that it is a quantitative technique, so PET/SPECT not only reveals where a radiolabelled molecule is but how much is there.

Radiobiology (also known as radiation biology) is a field of clinical and basic medical sciences that involves the study of the action of radioactivity on biological systems. The controlled action of deleterious radioactivity on living systems is the basis of radiation therapy.

Examples of biologically useful radionuclei

Hydrogen

Tritium (Hydrogen-3) is a very low beta energy emitter that can be used to label proteins, nucleic acids, drugs and almost any organic biomolecule. The maximum theoretical specific activity of tritium is 28.8 Ci/mmol (1.066 PBq/mol). However, there is often more than one tritium atom per molecule: for example, tritiated UTP is sold by most suppliers with carbons 5 and 6 each bonded to a tritium atom.

For tritium detection, liquid scintillation counters have been classically employed, in which the energy of a tritium decay is transferred to a scintillant molecule in solution which in turn gives off photons whose intensity and spectrum can be measured by a photomultiplier array. The efficiency of this process is 4–50%, depending on the scintillation cocktail used. The measurements are typically expressed in counts per minute (CPM) or disintegrations per minute (DPM). Alternatively, a solid-state, tritium-specific phosphor screen can be used together with a phosphorimager to measure and simultaneously image the radiotracer. Measurements/images are digital in nature and can be expressed in intensity or densitometry units within a region of interest (ROI).

Carbon

Carbon-14 has a long half-life of 5,730±40 years. Its maximum specific activity is 0.0624 Ci/mmol (2.31 TBq/mol). It is used in applications such as radiometric dating or drug tests. C-14 labeling is common in drug development to do ADME (absorption, distribution, metabolism and excretion) studies in animal models and in human toxicology and clinical trials. Since tritium exchange may occur in some radiolabeled compounds, this does not happen with C-14 and may thus be preferred.

Sodium

Sodium-22 and chlorine-36 are commonly used to study ion transporters. However, sodium-22 is hard to screen off and chlorine-36, with a half-life of 300,000 years, has low activity.

Sulfur

Sulfur-35 is used to label proteins and nucleic acids. Cysteine is an amino acid containing a thiol group which can be labeled by S-35. For nucleotides that do not contain a sulfur group, the oxygen on one of the phosphate groups can be substituted with a sulfur. This thiophosphate acts the same as a normal phosphate group, although there is a slight bias against it by most polymerases. The maximum theoretical specific activity is 1,494 Ci/mmol (55.28 PBq/mol).

Phosphorus

Phosphorus-33 is used to label nucleotides. It is less energetic than P-32 and does not require protection with plexiglass. A disadvantage is its higher cost compared to P-32, as most of the bombarded P-31 will have acquired only one neutron, while only some will have acquired two or more. Its maximum specific activity is 5,118 Ci/mmol (189.4 PBq/mol).

Phosphorus-32 is widely used for labeling nucleic acids and phosphoproteins. It has the highest emission energy (1.7 MeV) of all common research radioisotopes. This is a major advantage in experiments for which sensitivity is a primary consideration, such as titrations of very strong interactions (i.e., very low dissociation constant), footprinting experiments, and detection of low-abundance phosphorylated species. 32P is also relatively inexpensive. Because of its high energy, however, its safe use requires a number of engineering controls (e.g., acrylic glass) and administrative controls. The half-life of 32P is 14.2 days, and its maximum specific activity is 9131 Ci/mmol.

Iodine

Iodine-125 is commonly used for labeling proteins, usually at tyrosine residues. Unbound iodine is volatile and must be handled in a fume hood. Its maximum specific activity is 2,176 Ci/mmol (80.51 PBq/mol).

A good example of the difference in energy of the various radionuclei is the detection window ranges used to detect them, which are generally proportional to the energy of the emission, but vary from machine to machine: in a Perkin elmer TriLux Beta scintillation counter , the H-3 energy range window is between channel 5–360; C-14, S-35 and P-33 are in the window of 361–660; and P-32 is in the window of 661–1024.

Detection

Autoradiograph of a coronal brain tissue slice, with a radiolabeled GAD67 probe. Most intense signal is seen in subventricular zone.

 

Autoradiograph of Southern blot membrane

Quantitative

In liquid scintillation counting, a small aliquot, filter or swab is added to scintillation fluid and the plate or vial is placed in a scintillation counter to measure the radioactive emissions. Manufacturers have incorporated solid scintillants into multi-well plates to eliminate the need for scintillation fluid and make this into a high-throughput technique.

A gamma counter is similar in format to scintillation counting but it detects gamma emissions directly and does not require a scintillant.

A Geiger counter is a quick and rough approximation of activity. Lower energy emitters such as tritium can not be detected.

Qualitative AND Quantitative

Autoradiography: A tissue section affixed to a microscope slide or a membrane such as a Northern blot or a hybridized slot blot can be placed against x-ray film or phosphor screens to acquire a photographic or digital image. The density of exposure, if calibrated, can supply exacting quantitative information.

Phosphor storage screen: The slide or membrane is placed against a phosphor screen which is then scanned in a phosphorimager. This is many times faster than film/emulsion techniques and outputs data in a digital form, thus it has largely replaced film/emulsion techniques.

Microscopy

Electron microscopy: The sample is not exposed to a beam of electrons but detectors picks up the expelled electrons from the radionuclei.

Micro-autoradiography: A tissue section, typically cryosectioned, is placed against a phosphor screen as above.

Quantitative Whole Body Autoradiography (QWBA): Larger than micro-autoradiography, whole animals, typically rodents, can be analyzed for biodistribution studies.

Scientific methods

Schild regression is a radioligand binding assay. It is used for DNA labelling (5' and 3'), leaving the nucleic acids intact.

Radioactivity concentration

A vial of radiolabel has a "total activity". Taking as an example γ32P ATP, from the catalogues of the two major suppliers, Perkin Elmer NEG502H500UC or GE AA0068-500UCI, in this case, the total activity is 500 μCi (other typical numbers are 250 μCi or 1 mCi). This is contained in a certain volume, depending on the radioactive concentration, such as 5 to 10 mCi/mL (185 to 370 TBq/m³); typical volumes include 50 or 25 μL.

Not all molecules in the solution have a P-32 on the last (i.e., gamma) phosphate: the "specific activity" gives the radioactivity concentration and depends on the radionuclei's half-life. If every molecule were labelled, the maximum theoretical specific activity is obtained that for P-32 is 9131 Ci/mmol. Due to pre-calibration and efficiency issues this number is never seen on a label; the values often found are 800, 3000 and 6000 Ci/mmol. With this number it is possible to calculate the total chemical concentration and the hot-to-cold ratio.

"Calibration date" is the date in which the vial’s activity is the same as on the label. "Pre-calibration" is when the activity is calibrated in a future date to compensate for the decay occurred during shipping.

Comparison with fluorescence

Prior to the widespread use of fluorescence in the past three decades radioactivity was the most common label.

The primary advantage of fluorescence over radiotracers is that it does not require radiological controls and their associated expenses and safety measures. The decay of radioisotopes may limit the shelf life of a reagent, requiring its replacement and thus increasing expenses. Several fluorescent molecules can be used simultaneously (given that they do not overlap, cf. FRET), whereas with radioactivity two isotopes can be used (tritium and a low energy isotope, e.g. ³³P due to different intensities) but require special equipment (a tritium screen and a regular phosphor-imaging screen, a specific dual channel detector, e.g.).

Fluorescence is not necessary easier or more convenient to use because fluorescence requires specialized equipment of its own and because quenching makes absolute and/or reproducible quantification difficult.

The primary disadvantage of fluorescence versus radiotracers is a significant biological problem: chemically tagging a molecule with a fluorescent dye radically changes the structure of the molecule, which in turn can radically change the way that molecule interacts with other molecules. In contrast, intrinsic radiolabeling of a molecule can be done without altering its structure in any way. For example, substituting a H-3 for a hydrogen atom or C-14 for a carbon atom does not change the conformation, structure, or any other property of the molecule, it's just switching forms of the same atom. Thus an intrinsically radiolabeled molecule is identical to its unlabeled counterpart.

Measurement of biological phenomena by radiotracers is always direct. In contrast, many life science fluorescence applications are indirect, consisting of a fluorescent dye increasing, decreasing, or shifting in wavelength emission upon binding to the molecule of interest.

Safety

If good health physics controls are maintained in a laboratory where radionuclides are used, it is unlikely that the overall radiation dose received by workers will be of much significance. Nevertheless, the effects of low doses are mostly unknown so many regulations exist to avoid unnecessary risks, such as skin or internal exposure. Due to the low penetration power and many variables involved it is hard to convert a radioactive concentration to a dose. 1 μCi of P-32 on a square centimetre of skin (through a dead layer of a thickness of 70 μm) gives 7961 rads (79.61 grays) per hour . Similarly a mammogram gives an exposure of 300 mrem (3 mSv) on a larger volume (in the US, the average annual dose is 620 mrem or 6.2 mSv ).