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Saturday, October 21, 2023

Ethylenediaminetetraacetic acid


Ethylenediaminetetraacetic acid
Skeletal formula of ethylenediaminetetraacetic acid
Names
IUPAC name
N,N′-(Ethane-1,2-diyl)bis[N-(carboxymethyl)glycine]
Systematic IUPAC name
2,2′,2′′,2′′′-(Ethane-1,2-diyldinitrilo)tetraacetic acid
Other names
  • EthyleneDiamineTetraAcetic acid
  • Diaminoethane-tetraacetic acid
  • Edetic acid (conjugate base edetate) (INN, USAN)
  • Versene
Identifiers
3D model (JSmol)
Abbreviations EDTA, H4EDTA
1716295
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.409 Edit this at Wikidata
EC Number
  • 200-449-4
144943
KEGG
MeSH Edetic+Acid
RTECS number
  • AH4025000
UNII
UN number 3077
Properties
C10H16N2O8
Molar mass 292.244 g·mol−1
Appearance Colourless crystals
Density 0.860 g cm−3 (at 20 °C)
log P −0.836
Acidity (pKa) 2.0, 2.7, 6.16, 10.26
Thermochemistry
−1765.4 to −1758.0 kJ mol−1
−4461.7 to −4454.5 kJ mol−1
Pharmacology
S01XA05 (WHO) V03AB03 (WHO) (salt)
  • Intramuscular
  • Intravenous
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H319
P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code


Lethal dose or concentration (LD, LC):
1000 mg/kg (oral, rat)
Related compounds
Related alkanoic acids
Related compounds

Ethylenediaminetetraacetic acid (EDTA), also called edetic acid after its own abbreviation, is an aminopolycarboxylic acid with the formula [CH2N(CH2CO2H)2]2. This white, water-soluble solid is widely used to bind to iron (Fe2+/Fe3+) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH. It is thus used to dissolve Fe- and Ca-containing scale as well as to deliver iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably disodium EDTA, sodium calcium edetate, and tetrasodium EDTA, but these all function similarly.

Uses

Textiles and paper

In industry, EDTA is mainly used to sequester (bind or confine) metal ions in aqueous solution. In the textile industry, it prevents metal ion impurities from modifying colours of dyed products. In the pulp and paper industry, EDTA inhibits the ability of metal ions, especially Mn2+, from catalysing the disproportionation of hydrogen peroxide, which is used in chlorine-free bleaching.

Food

In a similar manner, EDTA is added to some food as a preservative or stabiliser to prevent catalytic oxidative decolouration, which is catalysed by metal ions. In soft drinks containing ascorbic acid and sodium benzoate, EDTA mitigates formation of benzene (a carcinogen).

Water softener

The reduction of water hardness in laundry applications and the dissolution of scale in boilers both rely on EDTA and related complexants to bind Ca2+, Mg2+, as well as other metal ions. Once bound to EDTA, these metal complexes are less likely to form precipitates or to interfere with the action of the soaps and detergents. For similar reasons, cleaning solutions often contain EDTA. In a similar manner EDTA is used in the cement industry for the determination of free lime and free magnesia in cement and clinkers.

The solubilisation of Fe3+ ions at or below near neutral pH can be accomplished using EDTA. This property is useful in agriculture including hydroponics. However, given the pH dependence of ligand formation, EDTA is not helpful for improving iron solubility in above neutral soils. Otherwise, at near-neutral pH and above, iron(III) forms insoluble salts, which are less bioavailable to susceptible plant species.

Scrubbing

Aqueous [Fe(EDTA)] is used for removing ("scrubbing") hydrogen sulfide from gas streams. This conversion is achieved by oxidising the hydrogen sulfide to elemental sulfur, which is non-volatile:

2 [Fe(EDTA)] + H2S → 2 [Fe(EDTA)]2− + S + 2 H+

In this application, the iron(III) centre is reduced to its iron(II) derivative, which can then be reoxidised by air. In similar manner, nitrogen oxides are removed from gas streams using [Fe(EDTA)]2−.

The oxidising properties of [Fe(EDTA)] are also exploited in photography, where it is used to solubilise silver particles.

Ion-exchange chromatography

EDTA was used in separation of the lanthanide metals by ion-exchange chromatography. Perfected by F. H. Spedding et al. in 1954, the method relies on the steady increase in stability constant of the lanthanide EDTA complexes with atomic number. Using sulfonated polystyrene beads and Cu2+ as a retaining ion, EDTA causes the lanthanides to migrate down the column of resin while separating into bands of pure lanthanides. The lanthanides elute in order of decreasing atomic number. Due to the expense of this method, relative to countercurrent solvent extraction, ion exchange is now used only to obtain the highest purities of lanthanides (typically greater than 99.99%).

Medicine

Sodium calcium edetate, an EDTA derivative, is used to bind metal ions in the practice of chelation therapy, such as for treating mercury and lead poisoning. It is used in a similar manner to remove excess iron from the body. This therapy is used to treat the complication of repeated blood transfusions, as would be applied to treat thalassaemia.

Dentistry

Dentists and endodontists use EDTA solutions to remove inorganic debris (smear layer) and lubricate the root canals in endodontics. This procedure helps prepare root canals for obturation. Furthermore, EDTA solutions with the addition of a surfactant loosen up calcifications inside a root canal and allow instrumentation (canal shaping) and facilitate apical advancement of a file in a tight or calcified root canal towards the apex.

Eyedrops

It serves as a preservative (usually to enhance the action of another preservative such as benzalkonium chloride or thiomersal) in ocular preparations and eyedrops.

Analysis

In medical diagnosis and organ function tests (here, kidney function test), the chromium(III) complex [Cr(EDTA)] (as radioactive chromium-51 (51Cr)) is administered intravenously and its filtration into the urine is monitored. This method is useful for evaluating glomerular filtration rate (GFR) in nuclear medicine.

EDTA is used extensively in the analysis of blood. It is an anticoagulant for blood samples for CBC/FBCs, where the EDTA chelates the calcium present in the blood specimen, arresting the coagulation process and preserving blood cell morphology. Tubes containing EDTA are marked with lavender (purple) or pink tops. EDTA is also in tan top tubes for lead testing and can be used in royal blue top tubes for trace metal testing.

EDTA is a slime dispersant, and has been found to be highly effective in reducing bacterial growth during implantation of intraocular lenses (IOLs).

Alternative medicine

Some alternative practitioners believe EDTA acts as an antioxidant, preventing free radicals from injuring blood vessel walls, therefore reducing atherosclerosis. These ideas are unsupported by scientific studies, and seem to contradict some currently accepted principles. The U.S. FDA has not approved it for the treatment of atherosclerosis.

Cosmetics

In shampoos, cleaners, and other personal care products, EDTA salts are used as a sequestering agent to improve their stability in air.

Laboratory applications

In the laboratory, EDTA is widely used for scavenging metal ions: In biochemistry and molecular biology, ion depletion is commonly used to deactivate metal-dependent enzymes, either as an assay for their reactivity or to suppress damage to DNA, proteins, and polysaccharides. EDTA also acts as a selective inhibitor against dNTP hydrolyzing enzymes (Taq polymerase, dUTPase, MutT), liver arginase and horseradish peroxidase independently of metal ion chelation. These findings urge the rethinking of the utilisation of EDTA as a biochemically inactive metal ion scavenger in enzymatic experiments. In analytical chemistry, EDTA is used in complexometric titrations and analysis of water hardness or as a masking agent to sequester metal ions that would interfere with the analyses.

EDTA finds many specialised uses in the biomedical labs, such as in veterinary ophthalmology as an anticollagenase to prevent the worsening of corneal ulcers in animals. In tissue culture EDTA is used as a chelating agent that binds to calcium and prevents joining of cadherins between cells, preventing clumping of cells grown in liquid suspension, or detaching adherent cells for passaging. In histopathology, EDTA can be used as a decalcifying agent making it possible to cut sections using a microtome once the tissue sample is demineralised.

EDTA is also known to inhibit a range of metallopeptidases, the method of inhibition occurs via the chelation of the metal ion required for catalytic activity. EDTA can also be used to test for bioavailability of heavy metals in sediments. However, it may influence the bioavailability of metals in solution, which may pose concerns regarding its effects in the environment, especially given its widespread uses and applications.

EDTA is also used to remove crud (corroded metals) from fuel rods in nuclear reactors.

Side effects

EDTA exhibits low acute toxicity with LD50 (rat) of 2.0 g/kg to 2.2 g/kg. It has been found to be both cytotoxic and weakly genotoxic in laboratory animals. Oral exposures have been noted to cause reproductive and developmental effects. The same study also found that both dermal exposure to EDTA in most cosmetic formulations and inhalation exposure to EDTA in aerosolised cosmetic formulations would produce exposure levels below those seen to be toxic in oral dosing studies.

Synthesis

The compound was first described in 1935 by Ferdinand Münz, who prepared the compound from ethylenediamine and chloroacetic acid. Today, EDTA is mainly synthesised from ethylenediamine (1,2-diaminoethane), formaldehyde, and sodium cyanide. This route yields the tetrasodium EDTA, which is converted in a subsequent step into the acid forms:

H2NCH2CH2NH2 + 4 CH2O + 4 NaCN + 4 H2O → (NaO2CCH2)2NCH2CH2N(CH2CO2Na)2 + 4 NH3
(NaO2CCH2)2NCH2CH2N(CH2CO2Na)2 + 4 HCl → (HO2CCH2)2NCH2CH2N(CH2CO2H)2 + 4 NaCl

This process is used to produce about 80,000 tonnes of EDTA each year. Impurities cogenerated by this route include glycine and nitrilotriacetic acid; they arise from reactions of the ammonia coproduct.

Nomenclature

To describe EDTA and its various protonated forms, chemists distinguish between EDTA4−, the conjugate base that is the ligand, and H4EDTA, the precursor to that ligand. At very low pH (very acidic conditions) the fully protonated H6EDTA2+ form predominates, whereas at very high pH or very basic condition, the fully deprotonated EDTA4− form is prevalent. In this article, the term EDTA is used to mean H4−xEDTAx, whereas in its complexes EDTA4− stands for the tetraanion ligand.

Coordination chemistry principles

Metal–EDTA chelate as found in Co(III) complexes
Structure of [Fe(EDTA)(H2O)], showing that the EDTA4− ligand does not fully encapsulate Fe(III), which is seven-coordinate

In coordination chemistry, EDTA4− is a member of the aminopolycarboxylic acid family of ligands. EDTA4− usually binds to a metal cation through its two amines and four carboxylates, i.e., it is It a hexadentate ("six-toothed") chelating agent. Many of the resulting coordination compounds adopt octahedral geometry. Although of little consequence for its applications, these octahedral complexes are chiral. The cobalt(III) anion [Co(EDTA)] has been resolved into enantiomers. Many complexes of EDTA4− adopt more complex structures due to either the formation of an additional bond to water, i.e. seven-coordinate complexes, or the displacement of one carboxylate arm by water. The iron(III) complex of EDTA is seven-coordinate. Early work on the development of EDTA was undertaken by Gerold Schwarzenbach in the 1940s. EDTA forms especially strong complexes with Mn(II), Cu(II), Fe(III), Pb(II) and Co(III).

Several features of EDTA's complexes are relevant to its applications. First, because of its high denticity, this ligand has a high affinity for metal cations:

[Fe(H2O)6]3+ + H4EDTA ⇌ [Fe(EDTA)] + 6 H2O + 4 H+  Keq = 1025.1

Written in this way, the equilibrium quotient shows that metal ions compete with protons for binding to EDTA. Because metal ions are extensively enveloped by EDTA, their catalytic properties are often suppressed. Finally, since complexes of EDTA4− are anionic, they tend to be highly soluble in water. For this reason, EDTA is able to dissolve deposits of metal oxides and carbonates.

The pKa values of free EDTA are 0, 1.5, 2, 2.66 (deprotonation of the four carboxyl groups) and 6.16, 10.24 (deprotonation of the two amino groups).

Environmental concerns

Abiotic degradation

EDTA is in such widespread use that questions have been raised whether it is a persistent organic pollutant. While EDTA serves many positive functions in different industrial, pharmaceutical and other avenues, the longevity of EDTA can pose serious issues in the environment. The degradation of EDTA is slow. It mainly occurs abiotically in the presence of sunlight.

The most important process for the elimination of EDTA from surface waters is direct photolysis at wavelengths below 400 nm. Depending on the light conditions, the photolysis half-lives of iron(III) EDTA in surface waters can range as low as 11.3 minutes up to more than 100 hours. Degradation of FeEDTA, but not EDTA itself, produces iron complexes of the triacetate (ED3A), diacetate (EDDA), and monoacetate (EDMA) – 92% of EDDA and EDMA biodegrades in 20 hours while ED3A displays significantly higher resistance. Many environmentally-abundant EDTA species (such as Mg2+ and Ca2+) are more persistent.

Biodegradation

In many industrial wastewater treatment plants, EDTA elimination can be achieved at about 80% using microorganisms. Resulting byproducts are ED3A and iminodiacetic acid (IDA) – suggesting that both the backbone and acetyl groups were attacked. Some microorganisms have even been discovered to form nitrates out of EDTA, but they function optimally at moderately alkaline conditions of pH 9.0–9.5.

Several bacterial strains isolated from sewage treatment plants efficiently degrade EDTA. Specific strains include Agrobacterium radiobacter ATCC 55002 and the sub-branches of Pseudomonadota like BNC1, BNC2, and strain DSM 9103. The three strains share similar properties of aerobic respiration and are classified as gram-negative bacteria. Unlike photolysis, the chelated species is not exclusive to iron(III) in order to be degraded. Rather, each strain uniquely consumes varying metal–EDTA complexes through several enzymatic pathways. Agrobacterium radiobacter only degrades Fe(III) EDTA while BNC1 and DSM 9103 are not capable of degrading iron(III) EDTA and are more suited for calcium, barium, magnesium and manganese(II) complexes. EDTA complexes require dissociation before degradation.

Alternatives to EDTA

Interest in environmental safety has raised concerns about biodegradability of aminopolycarboxylates such as EDTA. These concerns incentivize the investigation of alternative aminopolycarboxylates. Candidate chelating agents include nitrilotriacetic acid (NTA), iminodisuccinic acid (IDS), polyaspartic acid, S,S-ethylenediamine-N,N′-disuccinic acid (EDDS), methylglycinediacetic acid (MGDA), and L-Glutamic acid N,N-diacetic acid, tetrasodium salt (GLDA).

Iminodisuccinic acid (IDS)

Commercially used since 1998, iminodisuccinic acid (IDS) biodegrades by about 80% after only 7 days. IDS binds to calcium exceptionally well and forms stable compounds with other heavy metal ions. In addition to having a lower toxicity after chelation, IDS is degraded by Agrobacterium tumefaciens (BY6), which can be harvested on a large scale. The enzymes involved, IDS epimerase and C−N lyase, do not require any cofactors.

Polyaspartic acid

Polyaspartic acid, like IDS, binds to calcium and other heavy metal ions. It has many practical applications including corrosion inhibitors, wastewater additives, and agricultural polymers. A Polyaspartic acid-based laundry detergent was the first laundry detergent in the world to receive the EU flower ecolabel. Calcium binding ability of polyaspartic acid has been exploited for targeting of drug-loaded nanocarriers to bone. Preparation of hydrogels based on polyaspartic acid, in a variety of physical forms ranging from fiber to particle, can potentially enable facile separation of the chelated ions from a solution. Therefore, despite being weaker than EDTA, polyaspartic acid can still be regarded as a viable alternative due to these features as well as biocompatibility, and biodegradability.

S,S-Ethylenediamine-N,N′-disuccinic acid (EDDS)

A structural isomer of EDTA, ethylenediamine-N,N′-disuccinic acid (EDDS) is readily biodegradable at high rate in its S,S form.

Methylglycinediacetic acid (MGDA)

Trisodium dicarboxymethyl alaninate, also known as methylglycinediacetic acid (MGDA), has a high rate of biodegradation at over 68%, but unlike many other chelating agents can degrade without the assistance of adapted bacteria. Additionally, unlike EDDS or IDS, MGDA can withstand higher temperatures while maintaining a high stability as well as the entire pH range. MGDA has been shown to be an effective chelating agent, with a capacity for mobilization comparable with that of nitrilotriacetic acid (NTA), with application to water for industrial use and for the removal of calcium oxalate from urine from patients with kidney stones.

Methods of detection and analysis

The most sensitive method of detecting and measuring EDTA in biological samples is selected reaction monitoring capillary electrophoresis mass spectrometry (SRM-CE/MS), which has a detection limit of 7.3 ng/mL in human plasma and a quantitation limit of 15 ng/mL. This method works with sample volumes as small as 7–8 nL.

EDTA has also been measured in non-alcoholic beverages using high performance liquid chromatography (HPLC) at a level of 2.0 μg/mL.

In popular culture

In the movie Blade (1998), EDTA is used as a weapon to kill vampires, exploding when in contact with vampire blood.

Refugee health

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Refugee_health

A hospital in a camp for refugees of the Nigerian-Biagfran Civil War, late 1960s (CDC)

Refugee health is the field of study on the health effects experienced by people who have been displaced into another country or even to another part of the world, as a result of unsafe circumstances such as war or persecution. People who have been displaced can be affected by infectious diseases or some chronic diseases that are uncommon in the country in which they eventually settle. Mental health is an important consideration and can greatly impact people who are displaced. The health status of refugee's can be tied to factors such as the person who migrated's geographic origin, conditions of refugee camps or urban settings where they lived, and personal, physical, and psychological conditions of the person, either pre-existing or acquired while traveling from their homeland to a camp or eventually to their new home.

Major health concerns

In general, people who come from other countries to more wealthier or developed countries are less likely to use general health services but are at greater risk of poor mental health and dying prematurely compared with native populations. People who are refugees are at a higher risk for contracting certain diseases or having other health problems due to factors such as poor nutrition, poor sanitation and lack of adequate medical care.

Non-communicable diseases

A non-communicable disease is a medical condition that is not transmissible and not infectious. It is caused by individual and environmental behaviors. According to the WHO, these diseases lead to an estimated 40 million deaths per year, 70% of deaths worldwide. Development and control of these conditions is directly linked with nutrition and healthy behaviors. Non-communicable diseases have accounted for 19-46% of mortality from the top five refugee-producing countries in 2015. Reports indicate that more than half of Syrian refugee households (resettled in Lebanon) have a member suffering from a non-communicable disease.

Diabetes

Diabetes is a group of chronic metabolic diseases that affect the body's use of blood sugar. There are two main forms of diabetes: type 1 and type 2. Type 1 diabetes is characterized by insulin deficiency and requires daily administered doses of insulin. Causes of Type 1 diabetes are unknown and are currently, not preventable. It is typically onset at an early age. Type 2 diabetes is characterized by the body's inability to properly utilize insulin. Type 2 diabetes is typically onset in adults and is linked with unhealthy behaviors. Another common form of diabetes is gestational diabetes. This occurs in pregnant women and does not necessarily lead to Type 1 or Type 2 diabetes permanently.

Refugees are at an increased risk of developing diabetes because of the tendency towards inadequate nutritional behaviors. According to the CDC, amongst Syrian refugees, there is a 6.1% prevalence of adult-onset diabetes. Iraqi refugees saw a 3% prevalence and Congolese refugees faced less than 1%. A literary analysis on diabetes risk amongst refugee populations suggests that increased diabetes risk among adult refugees may be associated with longer migration histories. The analysis also links increased diabetes prevalence with the transition from traditional, agricultural lifestyles with potentially protective foods, to urbanized, westernized lifestyles that come with migration.

Anemia

Anemia is a condition in which an individual does not have enough healthy red blood cells. This will consequently lead to reduced oxygen flow to the body's organs. Most commonly, this is caused by not consuming enough iron. Anemia is used as a marker for overall micronutrient deficiency. Symptoms usually involve overall fatigue and tiredness, as a result of reduced oxygen flow. There are various treatments for anemia, including iron supplements and vitamin B supplements. Blood transfusions may also be used if blood production is low.

According to the CDC, “an evaluation of anemia prevalence in the Zaatari refugee camp and surrounding areas showed that 48.4% of children younger than 5 years of age, and 44.8% of women 15-49 years of age suffered from anemia”. Amongst Congolese refugees, Sickle Cell Anemia (SCD) is of a much larger concern. In Central America, refugees coming from El Salvador, Guatemala, and Honduras show the highest incidence of anemia cases. The CDC reports that the prevalence for children under 5 years old is 30% in El Salvador, 47% in Guatemala, and 40% in Honduras. In Guatemala, 22% of pregnant women are also anemic. These cases are mostly credited to poor nutrition or a chronic parasitic infection.

Cardiovascular disease and hypertension

Cardiovascular disease is a general term for various heart conditions such as coronary artery disease, cardiac arrest, arrhythmias, and many more. Hypertension is high blood pressure—this is usually defined as blood pressure over 130/80. Cardiovascular disease and hypertension are associated with poor nutrition/diet, sedentary lifestyles, and genetic risk factors.

Amongst Syrian refugees, 4.1% of adults suffered from cardiovascular disease and 10.7% suffered from hypertension. There is also substantial risk amongst Congolese refugees. According to the CDC, amongst Iraqi refugees in Jordan, 33% of those over 15 years of age had hypertension. Another 42% were pre-hypertensive. Bhutanese refugee adults had a 3% prevalence of hypertension, and nearly 1% prevalence of chronic obstructive pulmonary disorder.

Communicable diseases

Tuberculosis

Tuberculosis (TB) is a bacterial infection that mainly affects the lungs. As an airborne disease, TB is spread via inhalation of the bacteria, which subsequently travel to the lungs and other body parts to manifest infection. Once a person is infected, TB can either become latent or active. If latent, the disease is asymptomatic and non-contagious; however, latent TB can become active at any point. Active TB is symptomatic and contagious. Either way, TB should be treated immediately, as untreated infections can be fatal.

An estimated third of the world's population is infected with Mycobacterium tuberculosis. This high incidence necessitates that those conducting the overseas exam (Panel Physicians) screen all refugees for TB and further test anyone suspected of having active TB. Screening for tuberculosis generally involves a tuberculin skin test, followed by a chest X-ray when necessary, and laboratory testing depending on those results. Anyone between the ages of 2 and 14, living in a country with a tuberculosis incidence rate of 20 or more cases per 100,000 people (as identified by the WHO), is required to have a tuberculin skin test. Those aged 15 and older must have a chest x-ray.

In the US, refugee individuals identified as having active tuberculosis must complete treatment before being permitted to enter. Upon arriving in the US, the CDC recommends that all refugees be screened for tuberculosis using a tuberculin skin test. A follow-up chest x-ray is required if the tuberculin skin test is positive, or if the refugee was identified as having TB (either Class A or Class B) in their overseas exam, or if they are infected with HIV.

Over 2 billion people are infected with TB worldwide. Specifically amongst refugee populations, the risk of contracting TB are higher than in the general population, as overcrowding and international travel is higher and more frequent. According to the WHO, as of 2016, the TB incidence rate in Syria is 17 per 100,000 people. Compare this to 3.1 per 100,000 people in the United States.

Infectious hepatitis

There are multiple types of hepatitis, which most broadly can be described as viral infections of the liver. The most common types are viral Hepatitis A, B, and C. Hepatitis B and C can result in chronic infections, while Hepatitis A is solely infectious. As such, Hepatitis A is also referred to as Infectious Hepatitis, and is caused by the Hepatitis A Virus (HAV). HAV can be spread directly or indirectly via fecal contact, causal contact, sexual contact, and foodborne or waterborne pathways. Because of this, refugee populations are more susceptible to this infection. According to a 2016 study conducted in Greece, the rate of Infectious Hepatitis amongst Syrian refugees in certain Greek facilities is 152 per 1,000 people; rates in refugees from Afghanistan and Iraq were much lower, at 8 per 1,000 and 9 per 1,000 people, respectively. The disproportionately higher rate in Syrian refugees can be attributed to the higher proportion of Syrian refugees in the camps, as compared to refugees from other countries of origin. There is no treatment for HAV infections, so hygienic intervention measures and vaccinations are of the highest priority in preventative measures. However, health care is often not prioritized in refugee populations and resources are limited, thus making it difficult to properly control the rate and spread of infection.

Hepatitis B

Hepatitis B infection is endemic in Africa, Southeast Asia, East Asia, Northern Asia, and most of the Pacific Islands. According to the CDC, the rate of chronic infection among persons emigrating to the US from these areas is between 5% and 15%. Many states require or recommend that all refugees be screened for hepatitis B, and proceed with immunizations for all who are susceptible to this infection. In regions where the Hepatitis vaccine is not regulated, new infections occur predominately among infant and young children. As a result, 25% of people who become chronically infected as infants and 15% of people who become chronically infected at an older age die of Hepatitis B related health conditions.

Sexually transmitted infections

Refugees can be at a higher risk for contracting sexually transmitted infections because of a lack of access to protection and/or treatment, as well as the circumstances of war and flight, making them subject to higher incidences of rape and sexual abuse. Refugees are regularly screened for syphilis, gonorrhea, chlamydia, and HIV infection when they relocate.

COVID-19

As the COVID-19 pandemic advances across the world, refugees are among the most vulnerable populations. Coronavirus disease 2019 is a highly-contagious respiratory and vascular disease, caused by Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Due to social and economic conditions, resettled refugees face many of the same challenges that lead to poorer health for some racial and ethnic minority groups in the United States and in other countries. Refugees also face the challenges of a new healthcare system and finding health information they can understand. The density in population of refugee camps, in addition to lack of clean water, social distancing, and sanitation may impact exposure to COVID-19.

Parasitic infections

Intestinal parasites are a major health problem for many groups, including refugees, and the presence of pathogenic parasites requires medical attention. "Over one billion persons worldwide are estimated to be carriers of Ascaris. Approximately 480 million people are infected with Entamoeba histolytica. At least 500 million carry Trichuris. At present, 200 to 300 million people are infected with one or more of the Schistosoma species and it is estimated that more than 20 million persons throughout the world are infected with Hymenolepis nana". Consequences of parasitic infection can include anemia due to blood loss and iron deficiency, malnutrition, growth retardation, invasive disease, and death. Refugees are particularly at risk given the likelihood of poor or contaminated water and poor hygienic conditions in camps. Since 1999, the CDC has recommended that US-bound refugee populations from Africa and Southeast Asia undergo presumptive treatment for parasitic infections prior to departure. The US Protocol includes a single dose of albendazole. In many states, the domestic health screening exam recommends that all refugees be screened for parasitic infections whether or not they appear symptomatic. Screening often includes two stool specimens obtained more than 24 hours apart and/or a CBC with differential for evaluation of eosinophilia.

Malaria

Malaria is considered endemic in the Americas from as far north as Mexico to as far south as Argentina, in Africa from Egypt to South Africa, in Asia from Turkey to Indonesia, and in the islands of Oceania. It is estimated that 300 to 500 million people are infected each year with malaria, and over one million people die every year from the disease, predominantly in sub-Saharan Africa. Based on the high prevalence of asymptomatic malaria in sub-Saharan Africa, the CDC recommends that US-bound refugee populations from this region undergo presumptive treatment prior to departure to the US. For those refugee arrivals from sub-Saharan Africa with no pre-departure treatment documentation, the CDC recommends either they receive presumptive treatment on arrival (preferred) or have laboratory screening to detect Plasmodium infection. For refugees from other areas of the world where asymptomatic malaria is not prevalent, the CDC recommends that any refugee with signs or symptoms of malaria should receive diagnostic testing for Plasmodium, and subsequent treatment for confirmed infections, but not presumptive treatment.

Giardiasis

Giardiasis is an intestinal parasitic infection, where the protozoa is in its flagellate mode of movement. It is most commonly spread through contaminated water and food in developing countries. Symptoms are rather mild, and include abdominal pain, flatulence, and loose stool. Studies have found that Giardiasis is common amongst refugee populations, specifically those coming from Afghanistan. However, the parasite is not particularly adept at sustaining infection within children.

Leishmaniasis

Leishmaniasis is another parasitic infection with a high burden of disease amongst refugee populations. It is a vector-borne parasite, commonly spread by the bite of an infected sand flies. There are two common types of manifestation: cutaneous (skin lesions) and visceral leishmaniasis (infection of internal organs). In 2012, there was an outbreak of Leishmaniasis amongst Syrians. Leishmaniasis is of major concern in the eastern Mediterranean, which is home to the majority of the globe's prevalence (≈57%). Leishmaniasis is most common in this region, as well as in Afghanistan, Iraq, and the Syrian Arab Republic. Thus, refugees coming from these regions, which is the majority of all refugees, are highly susceptible to becoming infected by this parasite. Additionally, refugees from other countries are put at a high risk of contraction, as they often share temporary settlements with refugees from Syria, Afghanistan, and Iraq. As a preventative measure, refugees are administered, when available, albendazole and ivermectin prior to their asylum seeking journey to other countries like the United States. Upon arrival, refugees are typically screened for these infections in order to prevent spread and fatality.

Mental health

As mental illnesses are not necessarily tangible or easily quantifiable, it is easy to disregard the real ramifications that poor mental health can have on a person. These repercussions can materialize in any aspect of a person's life, whether that be physical, social, financial, etc. Further, the manifestations of poor mental health are deeply rooted when trauma is experienced at a young age. Thus, populations vulnerable to traumatic experiences are at a concerningly high risk of mental illnesses and poor mental health.

Prior to World War II, immigrants were mainly driven from their countries by forces such as unemployment, famine and poverty, often combined with various forms of prejudice and oppression whilst war and ethnopolitical conflict were less common causes for emigration. They have known social oppression, including inadequate education, lack of job opportunities, inability to practice their faith or marry whom they wished, and inability to live where they want. Beginning with World War II, however, civilians were increasingly targeted as a strategy of warfare, and since then most newcomers (especially refugees) have been victims of war and/or political repression. Many of them have also experienced or witnessed government-sponsored torture and/or terror. That said, refugees are often survivors who possess amazing resiliency, strength and resourcefulness. An assessment of mental health may be included in a refugee's domestic health screening.

Refugee mental health and integration into a new society are exquisitely interwoven. Traumatic experiences that occurred in the home country or during the resulting flight from that country are common. These experiences, in addition to the stresses of resettling in the host country, increase the chances of a less successful adjustment to the society of the host country. Mental health problems are one of the key barriers to the labor market integration of refugees in host societies. The influence of these traumatic and stressful events may be temporary and manageable with straightforward solutions or may be disabling and enduring.

High rates of mental health concerns have been documented in various refugee populations. Most studies reveal high rates of post-traumatic stress disorder (PTSD), anxiety, depression, and somatization among newly arrived refugees. Variations reported in the prevalence of PTSD and depression may be ascribed to a number of factors, including prior life in their homeland, the experience of flight from that homeland, life in refugee camps, and stressors during and after resettlement in a third country. More specifically, socioeconomic status, educational background, and gender all affect levels of mental illness. A 2005 Lancet review found that 9% (99% CI 8–10%) of refugees in western countries had post-traumatic stress disorder and 5% (4–6%) had major depression  In 2015, a study focused on the impacts of traumatic events on displaced persons from Syria, Lebanon, Turkey, and Jordan. It revealed that 54% of the population studied suffered from a severe emotional disorder. Of the children who participated in the study, 44% revealed depressive symptoms, and 45% showed signs of PTSD. Compared to other children around the globe, these statistics show a 10-fold increase in mental health disorders. Similarly to topics surrounding menstrual health, mental health is considered to be another taboo topic amongst certain cultures. This prevents people from seeking psychiatric help. Currently, there is only one functioning mental health hospital in Syria that tends to psychiatric needs. In 2016, a Syrian-American doctor named M.K. Hamza coined a new term to more accurately describe the effects felt by nearly all refugees affected by the ongoing crisis—human devastation syndrome. There is a severe lack of, and a dire need for, mental health attention and care. These traumatic events typically worsen and amplify progressively in the years following.

Refugees do not access mental health services even when resettled in developed countries, with one study finding that refugees are less likely to utilise mental health services than the national population except for a few specific conditions such as PTSD  Hence, it is critical that mental health issues be addressed in the screening process. Leaving behind all that is familiar and starting a new life in a new country with a different language and culture in addition to previous trauma and dislocation produces an immediate challenge that can have long-term effects. This is true whether an individual is coming from Europe, sub-Saharan Africa, Central America, or elsewhere in the world. Many refugees will not share a Western perspective or vocabulary, so questions will need to be explained through specific examples or re-framed in culturally congruent terms with the assistance of an interpreter or bicultural worker. One option is to administer an efficient and valid screener for emotional distress, such as the Refugee Health Screener - 15, in the context of the overall health screening.

Methods of treatment for refugees with mental health issues must also be culturally congruent. Western psychiatric methods may not applicable to individuals who do not conceive of the body and mind in the same way as people in the United States. For example, studies of Tibetan refugees have shown how important the Tibetan religion of Buddhism is in helping the refugees cope with their situation. The religion provides them with an explanation for their situation and hope for a better future. In some cases, indigenous methods of coping and psychological therapy can be integrated with Western methods of therapy to provide a wide spectrum of mental help to refugees.

The evidence supporting different interventions to try and improve symptoms of post traumatic stress disorder in and other trauma related to their symptoms in refugees, asylum seekers, and people who are dislaced within their own country is weak. It is not clear if interventions that are based in the person's new community that are aimed to help children and adolescents are effective and should be implemented.

Additionally, refugee children face unique barriers to adequate psychological health support due to significant trauma during their vulnerable developmental years.

Women's health

Every woman from every country experiences her own menstrual process. However, some countries are more adept than others at providing proper resources and accessibility for women to easily maintain good hygiene. Menstrual health requires constant and proper upkeep in order to avoid subsequent infections. Menstruation requires attentive care and proper hygienic supplies. Thus, it is no wonder that while in the high income countries, menstrual health is not a major public health concern, but in developing countries or in times of crises, menstruation can pose a distinct problem for women in vulnerable populations.

Proper menstrual care includes washing oneself with soap on a daily basis, and changing menstrual supplies (such as pads or tampons) multiple times per day. Improper care can cause progressive infections, such as bacterial vaginosis (BV) or reproductive tract infection (RTI). With limited access to clean, running water and hygienic supplies (soap, pads, tampons) within refugee camps, monthly periods create health problems for women and girls.

As such, studies have been conducted in various refugee camps to assess the degree of burden that menstruation has on women. Refugees staying in temporary settlements in Myanmar reported poor latrine conditions, describing them as unsafe and dirty, with locks on the doors being a rare occurrence. Additionally, many young girls reported dark, unlit paths at nighttime causing unwarranted assaults by intruders in the camps. Thus, girls reportedly would not use the bathroom once it was dark outside, even if in need of a shower or a fresh pad.

Another obstacle that refugee women face in maintaining their menstrual health is limited to no access to an adequate amount of sanitary supplies. Many refugees do not have the luxury of changing their pads every few hours per day, so a buildup of bacteria is common. Other studies have revealed that when desperate, women will resort to using leaves or old pads to absorb the discharged blood, according to a report by Sommer's team in the journal Conflict and Health.

In addition to limited supplies and sanitary facilities, cultural attitudes towards menstruation create a difficult, taboo environment surrounding the topic. Thus, women and girls may feel too uncomfortable to seek help or advice on tending to their personal needs.

Occupational health

Demand for labor is an important reason for migration. Despite the difficulty in researching immigrant populations, there is evidence that occupational health is an area in which immigrants face disparities. Many migrant or foreign-born workers fill low-wage, temporary or seasonal work in industries and jobs that may pose greater risks for worker health and safety such as agriculture, construction and services. In the United States, agriculture sector occupational risks such as asthma are more likely to affect immigrant workers. For refugee health in the United States, clinic structure and hours often overlap with working hours and require long waiting times that exceed what refugees can set aside, which can serve as a structural barrier to healthcare. Overall, immigrants have higher rates of occupational morbidity and mortality than those who are native born, including higher rates of fatal and non-fatal injury. Evidence from Southern Europe points to higher rates of occupational risks such as working many hours per day and extreme temperatures and greater exposure to poor employment conditions and job precariousness. Health prevention and training programs related to occupational safety and health may not reach immigrants due to language, cultural and/or economic barriers. However, interventions tailored to their needs have been shown to be effective. Developing partnerships with institutions in the immigrant communities is one way of improving access to information and resources to immigrant workers. Improving work conditions can also improve other aspects of immigrant health however the work is often underutilized in efforts to promote migrant health. An emerging occupational health issue for immigrants relates to the health risks faced by people who are trafficked into situations of forced labor and debt bondage.

Interventions

Health Literacy

Health literacy is a crucial component to preventative healthcare and improved public health. A cross-sectional study conducted amongst refugees in Sweden, found that 60% of those assessed had inadequate functioning health literacy and 27% of them had inadequate comprehensive health literacy. The study concluded that health literacy should be taken into consideration when assessing refugee health and that more research is needed to assess the current dynamics and develop strategies to overcome the gaps in health literacy amongst refugees. Through the provision of targeted, adequate health literacy tool kits, populations are more likely to adhere to treatment plans and prevention efforts—particularly in the realm of infectious disease. These health literacy tools must be relevant to the communities, administered in familiar language and vocabulary, and must truly take into account the competencies and limitations of the target audience. Within health literacy initiatives, collaborative learning and social support could contribute to people's understanding and ability to judge, sift and use health information. Consequently, adding these practices to the definition of critical health literacy could prove to be hugely beneficial to patient communities.

Civic orientation

In some countries, e.g. EU and OECD countries, information about the host society is offered to refugee migrants in connection with applying for or obtaining a residence permit. Civic orientation usually include information about the country's history, political system, laws, health, culture and everyday life. Most countries combine the civic orientation with other introduction activities such as language courses. Civics and language courses are commonly test based, meaning that a pass grade is required to obtain a residency or citizenship status.

Non-Communicable Diseases

When addressing the needs of NCD patients within humanitarian crises, there needs to be a more epidemiological approach to assessing prevalence of NCDs to ensure a better understanding of the local needs and risks. After such assessment is made, those new understandings must be targeted to create novel, innovative approaches to mitigate risks and promote healthy behaviors—in an infectious manner. Finally, in order to adequately provide such resources, there must be strong guidance and education continuously available.

Immunizations

Refugees arrive in their new countries with a variety of immunization needs. While refugees may have had vaccinations in their country of origin, often they lack documentation because they were forced to depart their home country in haste. Some may have received immunizations as part of their overseas exam, and some may have received no immunizations. Recommendations by the World Health Organization's (WHO) Expanded Program on Immunizations (EPI) are generally followed by countries worldwide with minor variations in vaccine schedules, spacing of vaccine doses, and documentation. The majority of vaccines used worldwide are from reliable local or international manufacturers, and no potency problems have been detected, with the occasional exception of tetanus toxoid and the oral polio vaccine (OPV).

In the United States, entering refugees are not required to have vaccinations. However, it is mandated that at the time of applying for adjustment of status from legal temporary resident to legal permanent resident, a refugee must be fully vaccinated in accordance with recommendations of the Advisory Committee on Immunization Practices (ACIP). A list of required vaccines in the US can be found on the vaccine schedule page.

Social support

Social support can be very helpful in preventing mental health issues and for coping with living in a new land, so refugees from the same areas should be able to live close to each other. However, even in this case, it may be necessary for social support to be offered by statutory or voluntary agencies from outside the refugees' and asylum seekers' communities in line with local informal and formal structures and networks. One model for such support was proposed by British authors in 2014, the WAMBA process, in which five essential components of support for refugees and asylum seekers were identified:

  • Welcome: a person-centred and benign enquiry as to the asylum seeker's history in a friendly setting and with the use of interpreters if necessary.
  • Accompaniment: the availability of social support in an asylum-seeking client's life (amongst other presences such as an exilic community and intimate attachments) may foster assurance that moments of crisis can be negotiated by asylum seeker and support worker together.
  • Mediation: offering a type of humanitarian solidarity and care which will offset some of the negative consequences of the asylum-seeking process and the hegemonic order which it represents and mediating between the individual asylum seeker and the systemic constraints of the asylum process.
  • Befriending: Befriending is another side to the relationship of accompaniment and which seeks to mitigate the political reality within which asylum seekers find themselves and which is distinctly unfriendly: tightly controlled, suspicious, rebarbative and highly hostile.
  • Advocacy: The professional helping relationship between worker and client can potentially diminish the isolation brought about by the circumstances within which some asylum seekers may live by giving time to hear the voice of the individual and providing support that attends to the individual's needs.

COVID-19 Response

Disease surveillance in refugee camps was already a major part of outbreak response. Contact tracing in refugee camps has become especially important to minimize COVID-19 transmission. In places like Cox's Bazar, the largest refugee settlement in the world, the World Health Organization now tests over 500 samples for COVID-19 a day. Just like any other healthcare facility, infection prevention and control measures are now especially important in refugee health centers. These measures contribute to the prevention of COVID-19 transmission in refugee camps.

But unlike the rest of the world, measures like physical distancing are difficult in refugee camps. Most refugee camps are more densely populated than the Diamond Princess, a cruise ship where an outbreak of COVID-19 led to transmission four times faster than in Wuhan. Additionally, low literacy levels make distribution of health and safety information difficult. In some refugee camps, the UNHCR is addressing these challenges using Community Outreach Members and recorded voice messages sent to mobile phones. Both of these platforms allow the communication of information about mask usage, contact tracing, and quarantine and isolation.

Ultimately, COVID-19 is affecting minorities and low income communities disproportionately. This is especially true for refugees. Evidence shows that an inclusive approach to COVID-19 response is required. Important factors for COVID-19 planning for refugees include creating sanitary and less crowded living conditions, as well as ensuring that refugees are not trapped by states of emergency and lockdowns.

Pluralism (philosophy)

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Pluralism_(philosophy)

Pluralism is a term used in philosophy, referring to a worldview of multiplicity, oft used in opposition to monism (the view that all is one) or dualism (the view that all is two). The term has different meanings in metaphysics, ontology, epistemology and logic. In metaphysics, it is the view that there are in fact many different substances in nature that constitute reality. In ontology, pluralism refers to different ways, kinds, or modes of being. For example, a topic in ontological pluralism is the comparison of the modes of existence of things like 'humans' and 'cars' with things like 'numbers' and some other concepts as they are used in science.

In epistemology, pluralism is the position that there is not one consistent means of approaching truths about the world, but rather many. Often this is associated with pragmatism, or conceptual, contextual, or cultural relativism. In the philosophy of science it may refer to the acceptance of co-existing scientific paradigms which though accurately describing their relevant domains are nonetheless incommensurable. In logic, pluralism is the relatively novel view that there is no one correct logic, or alternatively, that there is more than one correct logic. Such as using classical logic in most cases. but using paraconsistent logic to deal with certain paradoxes.

Metaphysical pluralism

Metaphysical pluralism in philosophy is the multiplicity of metaphysical models of the structure and content of reality, both as it appears and as logic dictates that it might be, as is exhibited by the four related models in Plato's Republic and as developed in the contrast between phenomenalism and physicalism. Pluralism is in contrast to the concept of monism in metaphysics, while dualism is a limited form, a pluralism of exactly two models, structures, elements, or concepts. A distinction is made between the metaphysical identification of realms of reality and the more restricted sub-fields of ontological pluralism (that examines what exists in each of these realms) and epistemological pluralism (that deals with the methodology for establishing knowledge about these realms).

Ancient pluralism

In ancient Greece, Empedocles wrote that they were fire, air, water and earth, although he used the word "root" rather than "element" (στοιχεῖον; stoicheion), which appeared later in Plato. From the association (φιλία; philia) and separation (νεῖκος; neikos) of these indestructible and unchangeable root elements, all things came to be in a fullness (πλήρωμα; pleroma) of ratio (λόγος; logos) and proportion (ἀνάλογος; analogos).

Similar to Empedocles, Anaxagoras was another Classical Greek philosopher with links to pluralism. His metaphysical system is centered around mechanically necessitated nous which governs, combines and diffuses the various "roots" of reality (known as homoioneroi). Unlike Empedocles' four "root elements" and similar to Democritus' multitude of atoms (yet not physical in nature), these homoioneroi are used by Anaxagoras to explain the multiplicity in reality and becoming. This pluralist theory of being influenced later thinkers such as Gottfried Wilhelm Leibniz's theory of monads and Julius Bahnsen's idea of will henades. The notion of a governing nous would also be used by Socrates and Plato, but they will assign it a more active and rational role in their philosophical systems.

Aristotle incorporated these elements, but his substance pluralism was not material in essence. His hylomorphic theory allowed him to maintain a reduced set of basic material elements as per the Milesians, while answering for the ever-changing flux of Heraclitus and the unchanging unity of Parmenides. In his Physics, due to the continuum of Zeno's paradoxes, as well as both logical and empirical considerations for natural science, he presented numerous arguments against the atomism of Leucippus and Democritus, who posited a basic duality of void and atoms. The atoms were an infinite variety of irreducibles, of all shapes and sizes, which randomly collide and mechanically hook together in the void, thus providing a reductive account of changeable figure, order and position as aggregates of the unchangeable atoms.

Ontological pluralism

The topic of ontological pluralism discusses different ways, kinds, or modes of being. Recent attention in ontological pluralism is due to the work of Kris McDaniel, who defends ontological pluralism in a number of papers. The name for the doctrine is due to Jason Turner, who, following McDaniel, suggests that "In contemporary guise, it is the doctrine that a logically perspicuous description of reality will use multiple quantifiers which cannot be thought of as ranging over a single domain." "There are numbers, fictional characters, impossible things, and holes. But, we don't think these things all exist in the same sense as cars and human beings."

It is common to refer to a film, novel or otherwise fictitious or virtual narrative as not being 'real'. Thus, the characters in the film or novel are not real, where the 'real world' is the everyday world in which we live. However, some authors may argue that fiction informs our concept of reality, and so has some kind of reality.

One reading of Ludwig Wittgenstein's notion of language-games argues that there is no overarching, single, fundamental ontology, but only a patchwork of overlapping interconnected ontologies ineluctably leading from one to another. For example, Wittgenstein discusses 'number' as technical vocabulary and in more general usage:

""All right: the concept of 'number' is defined for you as the logical sum of these individual interrelated concepts: cardinal numbers, rational numbers, real numbers etc.;" ... — it need not be so. For I can give the concept 'number' rigid limits in this way, that is, use the word 'number' for a rigidly limited concept, but I can also use it so that the extension of the concept is not closed by a frontier. ...Can you give the boundary? No. You can draw one..."

— Ludwig Wittgenstein, excerpt from §68 in Philosophical Investigations

Wittgenstein suggests that it is not possible to identify a single concept underlying all versions of 'number', but that there are many interconnected meanings that transition one to another; vocabulary need not be restricted to technical meanings to be useful, and indeed technical meanings are 'exact' only within some proscribed context.

Eklund has argued that Wittgenstein's conception includes as a special case the technically constructed, largely autonomous, forms of language or linguistic frameworks of Carnap and Carnapian ontological pluralism. He places Carnap's ontological pluralism in the context of other philosophers, such as Eli Hirsch and Hilary Putnam.

Epistemological pluralism

Epistemological pluralism is a term used in philosophy and in other fields of study to refer to different ways of knowing things, different epistemological methodologies for attaining a full description of a particular field. In the philosophy of science epistemological pluralism arose in opposition to reductionism to express the contrary view that at least some natural phenomena cannot be fully explained by a single theory or fully investigated using a single approach.

Logical pluralism

Logical pluralism can be defined a number of ways: the position that there is more than one correct account of logical consequence (or no single, 'correct' account at all), that there is more than one correct set of logical constants or even that the 'correct' logic depends on the relevant logical questions under consideration (a sort of logical instrumentalism). Pluralism about logical consequence says that because different logical systems have different logical consequence relations, there is therefore more than one correct logic. For example, classical logic holds that the argument from explosion is a valid argument, but in Graham Priest's paraconsistent logic—LP, the 'Logic of Paradox'—it is an invalid argument. However, logical monists may respond that a plurality of logical theories does not mean that no single one of the theories is the correct one. After all, there are and have been a multitude of theories in physics, but that hasn't been taken to mean that all of them are correct.

Pluralists of the instrumentalist sort hold if a logic can be correct at all, it based on its ability to answer the logical questions under consideration. If one wants to understand vague propositions, one may need a many-valued logic. Or if one wants to know what the truth-value of the Liar Paradox is, a dialetheic paraconsistent logic may be required. Rudolf Carnap held to a version of logical pluralism:

In logic there are no morals. Everyone is at liberty to build his own logic, i.e. his own language, as he wishes. All that is required of him is that, if he wishes to discuss it, he must state his methods clearly, and give syntactical rules instead of philosophical arguments.

— Rudolph Carnap, excerpt from §17 in The Logical Syntax of Language

Operator (computer programming)

From Wikipedia, the free encyclopedia https://en.wikipedia.org/wiki/Operator_(computer_programmin...