The lobes of the brain are the major identifiable zones of the human cerebral cortex, and they comprise the surface of each hemisphere of the cerebrum. The two hemispheres are roughly symmetrical in structure, and are connected by the corpus callosum. They traditionally have been divided into four lobes, but are today considered as having six lobes each.
The lobes are large areas that are anatomically distinguishable, and
are also functionally distinct to some degree. Each lobe of the brain
has numerous ridges, or gyri, and furrows, the sulci that constitute further subzones of the cortex. The expression "lobes of the brain" usually refers only to those of the cerebrum, not to the distinct areas of the cerebellum.
The frontal lobe consists of the prefrontal cortex
which is located in the most anterior (farthest away) section of the
frontal lobe. It is critical for one's working memory and executive
control which helps keep goals and complex tasks organized.
The divisions of the prefrontal cortex include orbital, medial, and lateral prefrontal cortex. Within the lateral prefrontal cortex there are two different divisions: the dorsolateral and ventrolateral
prefrontal cortex. The dorsolateral prefrontal cortex is located on top
of the ventrolateral prefrontal cortex and is mainly responsible for
the executive control and manipulation of memories that are retrieved
through episodic memory. The ventrolateral prefrontal cortex is
important for the regulation of meaningful stimuli that a person
experiences throughout their lifetime, such as images, letters, and
names.
Damage to the prefrontal cortex can result in issues with one's
long term and short-term memories, as well as create changes in people's
behaviors and their abilities to plan and organize.
Damage can result from lesions or tumors that have been surgically removed, and traumatic brain injuries (TBI)
experienced from a severe hit to the head causing damage to the brain
from swelling. Most often a TBI is experienced within a person's
childhood from playing competitive sports or an accident from normal
play. Having a traumatic brain injury can increase your chances of
developing neurological psychiatric problems and abusing substances,
such as cannabis, is known to be a risk factor in developing symptoms
associated with schizophrenia. A study found that schizophrenia
symptoms (hearing voices, talking to people who were not there, etc.)
worsened after the usage of cannabis, suggesting that a TBI from
childhood can enhance a development of psychosis due to the changes seen
in the white matter within the frontal-temporal areas.
Several areas of the parietal lobe are important in language processing. The somatosensory cortex can be illustrated as a distorted figure — the homunculus (Latin: "little man"), in which the body parts are rendered according to how much of the somatosensory cortex is devoted to them.
The superior parietal lobule and inferior parietal lobule are the
primary areas of body or spatial awareness. A lesion commonly in the
right superior or inferior parietal lobule leads to hemineglect.
The occipital lobe is the visual processing center of the mammalianbrain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1 (visual one). Human V1 is located on the medial side of the occipital lobe within the calcarine sulcus; the full extent of V1 often continues onto the posterior
pole of the occipital lobe. V1 is often also called striate cortex
because it can be identified by a large stripe of myelin, the Stria of Gennari. Visually driven regions outside V1 are called extrastriate cortex.
There are many extrastriate regions, and these are specialized for
different visual tasks, such as visuospatial processing, color
differentiation, and motion perception.
The temporal lobe is involved in processing sensory input into derived meanings for the appropriate retention of visual memories, language comprehension, and emotion association.
Within the temporal lobe is an area of the brain called the hippocampus
which is associated with forming new memories and learning new things.
The hippocampus has been studied many times in the past for its
correlation with epilepsy showing there to be damage of this area.
Although it has been difficult to determine the exact link between the
temporal lobe and epilepsy, Chauvière (2020) suggests that there is a
positive connection between the circuitry reorganization within the
neurons and temporal lobe structure impacting rhythmic activities that
are important for cognition.
The insular cortex is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal and frontal lobes).
The insular cortex has an important function for sending axons to the
amygdala and responding to tones and somatosensory stimulation.
Berret, et al. (2019) used mice to study the fear response that
is associated with perceived threats from their memory of previously
being shocked on their foot, finding adverse reflex responses in
shocking stimulation whenever the insular cortex was silenced. This
finding supports that the insular cortex takes information to specific amygdala subdivisions creating different components for fear behaviors.
The insular cortex is divided into two parts: the larger anterior
insula and the smaller posterior insula in which more than a dozen
field areas have been identified. The cortical area overlying the insula
toward the lateral surface of the brain is the operculum (meaning lid). The opercula are formed from parts of the enclosing frontal, temporal, and parietal lobes.
The parietal lobe integrates sensory information among various modalities, including spatial sense and navigation (proprioception), the main sensory receptive area for the sense of touch in the somatosensory cortex which is just posterior to the central sulcus in the postcentral gyrus, and the dorsal stream of the visual system. The major sensory inputs from the skin (touch, temperature, and pain receptors), relay through the thalamus to the parietal lobe.
Several areas of the parietal lobe are important in language processing. The somatosensory cortex can be illustrated as a distorted figure – the cortical homunculus
(Latin: "little man") in which the body parts are rendered according to
how much of the somatosensory cortex is devoted to them.
The superior parietal lobule and inferior parietal lobule are the
primary areas of body or spatial awareness. A lesion commonly in the
right superior or inferior parietal lobule leads to hemineglect.
The name comes from the parietal bone, which is named from the Latin paries-, meaning "wall".
Structure
Animation. Parietal lobe (red) of left cerebral hemisphere.
The parietal lobe is defined by three anatomical boundaries: The
central sulcus separates the parietal lobe from the frontal lobe; the parieto-occipital sulcus separates the parietal and occipital lobes; the lateral sulcus (sylvian fissure) is the most lateral boundary, separating it from the temporal lobe; and the longitudinal fissure
divides the two hemispheres. Within each hemisphere, the somatosensory
cortex represents the skin area on the contralateral surface of the
body.
The posterior parietal cortex can be subdivided into the superior parietal lobule (Brodmann areas 5 + 7) and the inferior parietal lobule (39 + 40), separated by the intraparietal sulcus (IPS). The intraparietal sulcus and adjacent gyri are essential in guidance of limb and eye movement,
and—based on cytoarchitectural and functional differences—is further
divided into medial (MIP), lateral (LIP), ventral (VIP), and anterior
(AIP) areas.
The parietal lobe plays important roles in integrating sensory
information from various parts of the body, knowledge of numbers and
their relations, and in the manipulation of objects. Its function also includes processing information relating to the sense of touch. Portions of the parietal lobe are involved with visuospatial processing.
Although multisensory in nature, the posterior parietal cortex is often
referred to by vision scientists as the dorsal stream of vision (as
opposed to the ventral stream in the temporal lobe). This dorsal stream
has been called both the "where" stream (as in spatial vision) and the "how" stream (as in vision for action).
The posterior parietal cortex (PPC) receives somatosensory and visual
input, which then, through motor signals, controls movement of the arm,
hand, and eyes.
Various studies in the 1990s found that different regions of the posterior parietal cortex in macaques represent different parts of space.
The lateral intraparietal (LIP) area contains a map of neurons (retinotopically-coded when the eyes are fixed[11])
representing the saliency of spatial locations, and attention to these
spatial locations. It can be used by the oculomotor system for
targeting eye movements, when appropriate.
The ventral intraparietal (VIP) area receives input from a number of senses (visual, somatosensory, auditory, and vestibular). Neurons with tactile receptive fields represent space in a head-centered reference frame. The cells with visual receptive fields also fire with head-centered reference frames but possibly also with eye-centered coordinates
The medial intraparietal (MIP) area neurons encode the location of a reach target in eye-centered coordinates.
The anterior intraparietal (AIP) area contains neurons responsive to shape, size, and orientation of objects to be grasped as well as for manipulation of the hands themselves, both to viewed and remembered stimuli.
The AIP has neurons that are responsible for grasping and manipulating
objects through motor and visual inputs. The AIP and ventral premotor
together are responsible for visuomotor transformations for actions of
the hand.
More recent fMRI
studies have shown that humans have similar functional regions in and
around the intraparietal sulcus and parietal-occipital junction. The human "parietal eye fields" and "parietal reach region",
equivalent to LIP and MIP in the monkey, also appear to be organized in
gaze-centered coordinates so that their goal-related activity is
"remapped" when the eyes move.
Emerging evidence has linked processing in the inferior parietal
lobe to declarative memory. Bilateral damage to this brain region does
not cause amnesia however the strength of memory is diminished, details
of complex events become harder to retrieve, and subjective confidence
in memory is very low. This has been interpreted as reflecting either deficits in internal attention, deficits in subjective memory states,
or problems with the computation that allows evidence to accumulate,
thus allowing decisions to be made about internal representations.
Clinical significance
Features of parietal lobe lesions are as follows:
Unilateral parietal lobe
Contralateral hemisensory loss
Astereognosis – inability to determine 3-D shape by touch.
Agraphaesthesia – inability to read numbers or letters drawn on hand, with eyes shut.
Damage to this lobe in the right hemisphere results in the loss of
imagery, visualization of spatial relationships and neglect of left-side
space and left side of the body. Even drawings may be neglected on the
left side. Damage to this lobe in the left hemisphere will result in
problems in mathematics, long reading, writing, and understanding
symbols. The parietal association cortex enables individuals to read,
write, and solve mathematical problems. The sensory inputs from the
right side of the body go to the left side of the brain and vice versa.
The syndrome of hemispatial neglect
is usually associated with large deficits of attention of the
non-dominant hemisphere. Optic ataxia is associated with difficulties
reaching toward objects in the visual field opposite to the side of the
parietal damage. Some aspects of optic ataxia have been explained in
terms of the functional organization described above.
Apraxia
is a disorder of motor control which can be referred neither to
"elemental" motor deficits nor to general cognitive impairment. The
concept of apraxia was shaped by Hugo Liepmann about a hundred years ago. Apraxia is predominantly a symptom of left brain damage, but some symptoms of apraxia can also occur after right brain damage.
Amorphosynthesis is a loss of perception on one side of the body caused by a lesion in the parietal lobe. Usually, left-sided lesions cause agnosia,
a full-body loss of perception, while right-sided lesions cause lack of
recognition of the person's left side and extrapersonal space. The term
amorphosynthesis was coined by D. Denny-Brown to describe patients he
studied in the 1950s.
Can also result in sensory impairment where one of the affected
person's senses (sight, hearing, smell, touch, taste and spatial
awareness) is no longer normal.
Toxins are often distinguished from other chemical agents strictly based on their biological origin.
Less strict understandings embrace naturally occurring non-organic toxins, such as arsenic. Other understandings embrace synthetic analogs of naturally occurring organic poisons as toxins, and may or may not embrace naturally occurring non-organic poisons. It is important to confirm usage if a common understanding is critical.
Toxins are a subset of toxicants. The term toxicant is preferred when the poison is man-made and therefore artificial.
The human and scientific genetic assembly of a natural-based toxin
should be considered a toxin as it is identical to its natural
counterpart. The debate is one of linguistic semantics.
The word toxin does not specify method of delivery (as opposed to venom, a toxin delivered via a bite, sting, etc.). Poison
is a related but broader term that encompasses both toxins and
toxicants; poisons may enter the body through any means - typically inhalation, ingestion, or skin absorption. Toxin, toxicant, and poison are often used interchangeably despite these subtle differences in definition. The term toxungen has also been proposed to refer to toxins that are delivered onto the body surface of another organism without an accompanying wound.
A rather informal terminology of individual toxins relates them to the anatomical location where their effects are most notable:
On a broader scale, toxins may be classified as either exotoxins, excreted by an organism, or endotoxins, which are released mainly when bacteria are lysed.
Biological
The term "biotoxin" is sometimes used to explicitly confirm the
biological origin as opposed to environmental or anthropogenic origins. Biotoxins can be classified by their mechanism of delivery as poisons (passively transferred via ingestion, inhalation, or absorption across the skin), toxungens (actively transferred to the target's surface by spitting, spraying, or smearing), or venoms (delivered through a wound generated by a bite, sting, or other such action). They can also be classified by their source, such as fungal biotoxins, microbial toxins, plant biotoxins, or animal biotoxins.
Biotoxins vary greatly in purpose and mechanism, and can be highly complex (the venom of the cone snail can contain over 100 unique peptides, which target specific nerve channels or receptors).
Necrotoxins cause necrosis (i.e., death) in the cells they encounter. Necrotoxins spread through the bloodstream. In humans, skin and muscle tissues are most sensitive to necrotoxins. Organisms that possess necrotoxins include:
Neurotoxins primarily affect the nervous systems of animals. The group neurotoxins generally consists of ion channel toxins that disrupt ion channel conductance. Organisms that possess neurotoxins include:
Myotoxins are small, basic peptides found in snake and lizardvenoms, They cause muscle tissue damage by a non-enzymatic receptor based mechanism. Organisms that possess myotoxins include:
Many
living organisms employ toxins offensively or defensively. A relatively
small number of toxins are known to have the potential to cause
widespread sickness or casualties, but these may be appealing to those
who would use them nefariously for several reasons. They are often
inexpensive and easily available, and in some cases it is possible to
refine them outside the laboratory. As biotoxins act quickly, and are highly toxic even at low doses, they can be more efficient than chemical agents.
Due to these factors, it is vital to raise awareness of the clinical
symptoms of biotoxin poisoning, and to develop effective countermeasures
including rapid investigation, response, and treatment.
The term "environmental toxin" can sometimes explicitly include synthetic contaminants such as industrial pollutants and other artificially made toxic
substances. As this contradicts most formal definitions of the term
"toxin", it is important to confirm what the researcher means when
encountering the term outside of microbiological contexts.
Environmental toxins from food chains that may be dangerous to human health include:
In
general, when scientists determine the amount of a substance that may be
hazardous for humans, animals and/or the environment they determine the
amount of the substance likely to trigger effects and if possible
establish a safe level. In Europe, the European Food Safety Authority
produced risk assessments for more than 4,000 substances in over 1,600
scientific opinions and they provide open access summaries of human
health, animal health and ecological hazard assessments in their
OpenFoodTox database. The OpenFoodTox database can be used to screen potential new foods for toxicity.
The Toxicology and Environmental Health Information Program (TEHIP) at the United States National Library of Medicine
(NLM) maintains a comprehensive toxicology and environmental health web
site that includes access to toxins-related resources produced by TEHIP
and by other government agencies and organizations.
This web site includes links to databases, bibliographies, tutorials,
and other scientific and consumer-oriented resources. TEHIP also is
responsible for the Toxicology Data Network (TOXNET), an integrated system of toxicology and environmental health databases that are available free of charge on the web.
Comprehensive Environmental Response, Compensation, and Liability Act of 1980
Long title
An
act to provide for liability, compensation, cleanup, and emergency
response for hazardous substances released into the environment and the
cleanup of inactive hazardous waste disposal sites.
Superfund is a United States federal environmental remediation program established by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). The program is administered by the Environmental Protection Agency
(EPA). The program is designed to investigate and cleanup sites
contaminated with hazardous substances. Sites managed under this program
are referred to as Superfund sites. There are 40,000 federal Superfund sites across the country, and approximately 1,300 of those sites have been listed on the National Priorities List
(NPL). Sites on the NPL are considered the most highly contaminated and
undergo longer-term remedial investigation and remedial action
(cleanups).
The EPA seeks to identify parties responsible for hazardous
substances released to the environment (polluters) and either compel
them to clean up the sites, or it may undertake the cleanup on its own
using the Superfund (a trust fund) and seek to recover those costs from
the responsible parties through settlements or other legal means.
Approximately 70% of Superfund cleanup activities historically have been paid for by the potentially responsible parties (PRPs), reflecting the polluter pays principle.
However, 30% of the time the responsible party either cannot be found
or is unable to pay for the cleanup. In these circumstances, taxpayers
had been paying for the cleanup operations. Through the 1980s, most of
the funding came from an excise tax
on petroleum and chemical manufacturers. However, in 1995, Congress
chose not to renew this tax and the burden of the cost was shifted to
taxpayers in the general public. Since 2001, most of the cleanup of
hazardous waste sites has been funded through taxpayers generally.
Despite its name, the program suffered from under-funding, and by 2014
Superfund NPL cleanups had decreased to only 8 sites, out of over 1,200.
In November 2021, the Infrastructure Investment and Jobs Act reauthorized an excise tax on chemical manufacturers, for ten years starting in July 2022.
The EPA and state agencies use the Hazard Ranking System
(HRS) to calculate a site score (ranging from 0 to 100) based on the
actual or potential release of hazardous substances from a site. A score
of 28.5 places a site on the National Priorities List, eligible for
long-term, remedial action (i.e., cleanup) under the Superfund program.
As of March 23, 2022, there were 1,333 sites listed; an additional 448 had been delisted, and 43 new sites have been proposed.
The Superfund law also authorizes federal natural resource
agencies, primarily EPA, states and Native American tribes to recover
natural resource damages caused by hazardous substances, though most
states have and most often use their own versions of a state Superfund
law. CERCLA created the Agency for Toxic Substances and Disease Registry (ATSDR).
The primary goal of a Superfund cleanup is to reduce the risks to
human health through a combination of cleanup, engineered controls like
caps and site restrictions such as groundwater use restrictions. A
secondary goal is to return the site to productive use as a business,
recreation or as a natural ecosystem. Identifying the intended reuse
early in the cleanup often results in faster and less expensive
cleanups. EPA's Superfund Redevelopment Program provides tools and
support for site redevelopment.
History
Workers in hazmat suits check the status of a cleanup site
CERCLA was enacted by Congress in 1980 in response to the threat of hazardous waste sites, typified by the Love Canal disaster in New York, and the Valley of the Drums in Kentucky.
It was recognized that funding would be difficult, since the
responsible parties were not easily found, and so the Superfund was
established to provide funding through a taxing mechanism on certain
industries and to create a comprehensive liability framework to be able
to hold a broader range of parties responsible. The initial Superfund trust fund
to clean up sites where a polluter could not be identified, could not
or would not pay (bankruptcy or refusal), consisted of about $1.6
billion and then increased to $8.5 billion. Initially, the framework for implementing the program came from the oil and hazardous substances National Contingency Plan.
The EPA published the first Hazard Ranking System in 1981, and the first National Priorities List in 1983. Implementation of the program in early years, during the Ronald Reagan administration,
was ineffective, with only 16 of the 799 Superfund sites cleaned up and
only $40 million of $700 million in recoverable funds from responsible
parties collected. The mismanagement of the program under Anne Gorsuch Burford,
Reagan's first chosen Administrator of the agency, led to a
congressional investigation and the reauthorization of the program in
1986 through an act amending CERCLA.
1986 amendments
The
Superfund Amendments and Reauthorization Act of 1986 (SARA) added
minimum cleanup requirements in Section 121 and required that most
cleanup agreements with polluters be entered in federal court as a consent decree subject to public comment (section 122). This was to address sweetheart deals between industry and the Reagan-era EPA that Congress had discovered.
Environmental justice initiative
In 1994 President Bill Clinton issued Executive Order 12898, which called for federal agencies to make achieving environmental justice
a requirement by addressing low income populations and minority
populations that have experienced disproportionate adverse health and
environmental effects as a result of their programs, policies, and
activities.
The EPA regional offices had to apply required guidelines for its
Superfund managers to take into consideration data analysis, managed
public participation, and economic opportunity when considering the
geography of toxic waste site remediation.
Some environmentalists and industry lobbyists saw the Clinton
administration's environmental justice policy as an improvement, but the
order did not receive bipartisan support. The newly elected Republican
Congress made numerous unsuccessful efforts to significantly weaken the
program. The Clinton administration then adopted some industry favored
reforms as policy and blocked most major changes.
Decline of excise tax
Until
the mid-1990s, most of the funding came from an excise tax on the
petroleum and chemical industries, reflecting the polluter pays
principle.
Even though by 1995 the Superfund balance had decreased to about $4
billion, Congress chose not to reauthorize collection of the tax, and by
2003 the fund was empty.
Since 2001, most of the funding for cleanups of hazardous waste sites
has come from taxpayers. State governments pay 10 percent of cleanup
costs in general, and at least 50 percent of cleanup costs if the state
operated the facility responsible for contamination. By 2013 federal
funding for the program had decreased from $2 billion in 1999 to less
than $1.1 billion (in constant dollars).
In 2001 EPA used funds from the Superfund program to institute the cleanup of anthrax on Capitol Hill after the 2001 Anthrax Attacks. It was the first time the agency dealt with a biological release rather than a chemical or oil spill.
From 2000 to 2015, Congress allocated about $1.26 billion of
general revenue to the Superfund program each year. Consequently, less
than half the number of sites were cleaned up from 2001 to 2008,
compared to before. The decrease continued during the Obama administration, and since under the direction of EPA Administrator Gina McCarthy Superfund cleanups decreased even more from 20 in 2009 to a mere 8 in 2014.
Reauthorization of excise tax
In November 2021 Congress reauthorized an excise tax on chemical manufacturers, under the Infrastructure Investment and Jobs Act.
The new chemical excise tax is effective July 1, 2022, and is double
the rate of the previous Superfund tax. The 2021 law also authorized
$3.5 billion in emergency appropriations from the U.S. government general fund for hazardous site cleanups in the immediate future.
Removal actions. These are typically short-term response
actions, where actions may be taken to address releases or threatened
releases requiring prompt response. Removal actions are classified as:
(1) emergency; (2) time-critical; and (3) non-time critical. Removal
responses are generally used to address localized risks such as
abandoned drums containing hazardous substances, and contaminated
surface soils posing acute risks to human health or the environment.
Remedial actions. These are usually long-term response
actions. Remedial actions seek to permanently and significantly reduce
the risks associated with releases or threats of releases of hazardous
substances, and are generally larger, more expensive actions. They can
include measures such as using containment to prevent pollutants from
migrating, and combinations of removing, treating, or neutralizing toxic
substances. These actions can be conducted with federal funding only at
sites listed on the EPA National Priorities List
(NPL) in the United States and the territories. Remedial action by
responsible parties under consent decrees or unilateral administrative
orders with EPA oversight may be performed at both NPL and non-NPL
sites, commonly called Superfund Alternative Sites in published EPA
guidance and policy documents.
A potentially responsible party (PRP) is a possible polluter who may eventually be held liable under CERCLA for the contamination or misuse of a particular property or resource. Four classes of PRPs may be liable for contamination at a Superfund site:
the current owner or operator of the site;
the owner or operator of a site at the time that disposal of a hazardous substance, pollutant or contaminant occurred;
a person who arranged for the disposal of a hazardous substance, pollutant or contaminant at a site; and
a person who transported a hazardous substance, pollutant or
contaminant to a site, who also has selected that site for the disposal
of the hazardous substances, pollutants or contaminants.
The liability scheme of CERCLA changed commercial and industrial real
estate, making sellers liable for contamination from past activities,
meaning they can't pass liability onto unknowing buyers without any
responsibility. Buyers also have to be aware of future liabilities.
The CERCLA also required the revision of the National Oil and Hazardous Substances Pollution Contingency Plan 9605(a)(NCP). The NCP guides how to respond to releases and threatened releases of hazardous substances,
pollutants, or contaminants. The NCP established the National
Priorities List, which appears as Appendix B to the NCP, and serves as
EPA's information and management tool. The NPL is updated periodically
by federal rulemaking.
The identification of a site for the NPL is intended primarily to guide the EPA in:
Determining which sites warrant further investigation to assess
the nature and extent of risks to human health and the environment
Identifying what CERCLA-financed remedial actions may be appropriate
Notifying the public of sites, the EPA believes warrant further investigation
Notifying PRPs that the EPA may initiate CERCLA-financed remedial action.
Despite the name, the Superfund trust fund has lacked sufficient
funds to clean up even a small number of the sites on the NPL. As a
result, the EPA typically negotiates consent orders with PRPs to study
sites and develop cleanup alternatives, subject to EPA oversight and
approval of all such activities. The EPA then issues a Proposed Plans
for remedial action for a site on which it takes public comment, after
which it makes a cleanup decision in a Record of Decision (ROD). RODs
are typically implemented under consent decrees by PRPs or under
unilateral orders if consent cannot be reached.
If a party fails to comply with such an order, it may be fined up to
$37,500 for each day that non-compliance continues. A party that spends
money to clean up a site may sue other PRPs in a contribution action
under the CERCLA.
CERCLA liability has generally been judicially established as joint and
several among PRPs to the government for cleanup costs (i.e., each PRP
is hypothetically responsible for all costs subject to contribution),
but CERCLA liability is allocable among PRPs in contribution based on
comparative fault. An "orphan share" is the share of costs at a
Superfund site that is attributable to a PRP that is either
unidentifiable or insolvent.
The EPA tries to treat all PRPs equitably and fairly. Budgetary cuts
and constraints can make more equitable treatment of PRPs more
difficult.
Procedures
A
national map of Superfund sites. Red indicates currently on final
National Priority List, yellow is proposed, green is deleted (usually
meaning having been cleaned up). This map is as of October 2013.Superfund site assessment process
Upon notification of a potentially hazardous waste site, the EPA
conducts a Preliminary Assessment/Site Inspection (PA/SI), which
involves records reviews, interviews, visual inspections, and limited
field sampling.
Information from the PA/SI is used by the EPA to develop a Hazard
Ranking System (HRS) score to determine the CERCLA status of the site.
Sites that score high enough to be listed typically proceed to a
Remedial Investigation/Feasibility Study (RI/FS).
The RI includes an extensive sampling program and risk assessment
that defines the nature and extent of the site contamination and risks.
The FS is used to develop and evaluate various remediation
alternatives. The preferred alternative is presented in a Proposed Plan
for public review and comment, followed by a selected alternative in a
ROD. The site then enters into a Remedial Design phase and then the
Remedial Action phase. Many sites include long-term monitoring. Once the
Remedial Action has been completed, reviews are required every five
years, whenever hazardous substances are left onsite above levels safe
for unrestricted use.
The CERCLA information system (CERCLIS) is a database
maintained by the EPA and the states that lists sites where releases may
have occurred, must be addressed, or have been addressed. CERCLIS
consists of three inventories: the CERCLIS Removal Inventory, the
CERCLIS Remedial Inventory, and the CERCLIS Enforcement Inventory.
The Superfund Innovative Technology Evaluation (SITE) program supports development of technologies for assessing and treating waste
at Superfund sites. The EPA evaluates the technology and provides an
assessment of its potential for future use in Superfund remediation
actions. The SITE program consists of four related components: the
Demonstration Program, the Emerging Technologies Program, the Monitoring
and Measurement Technologies Program, and Technology Transfer
activities.
A reportable quantity (RQ) is the minimum quantity of a hazardous substance which, if released, must be reported.
A source control action represents the construction or
installation and start-up of those actions necessary to prevent the
continued release of hazardous substances (primarily from a source on
top of or within the ground, or in buildings or other structures) into
the environment.
A section 104(e) letter is a request by the government for
information about a site. It may include general notice to a potentially
responsible party that CERCLA-related action may be undertaken at a
site for which the recipient may be responsible.
This section also authorizes the EPA to enter facilities and obtain
information relating to PRPs, hazardous substances releases, and
liability, and to order access for CERCLA activities. The 104(e) letter information-gathering resembles written interrogatories in civil litigation.
A section 106 order is a unilateral administrative order
issued by EPA to PRP(s) to perform remedial actions at a Superfund site
when the EPA determines there may be an imminent and substantial
endangerment to the public health or welfare or the environment because
of an actual or threatened release of a hazardous substance from a
facility, subject to treble damages and daily fines if the order is not obeyed.
A remedial response is a long-term action that stops or
substantially reduces a release of a hazardous substance that could
affect public health or the environment. The term remediation, or
cleanup, is sometimes used interchangeably with the terms remedial
action, removal action, response action, remedy, or corrective action.
A nonbinding allocation of responsibility (NBAR) is a
device, established in the Superfund Amendments and Reauthorization Act,
that allows the EPA to make a nonbinding estimate of the proportional
share that each of the various responsible parties at a Superfund site
should pay toward the costs of cleanup.
Relevant and appropriate requirements are those United States
federal or state cleanup requirements that, while not "applicable,"
address problems sufficiently similar to those encountered at the CERCLA
site that their use is appropriate. Requirements may be relevant and
appropriate if they would be "applicable" except for jurisdictional
restrictions associated with the requirement.
As of December 9, 2021, there were 1,322 sites listed; an additional 447 had been delisted, and 51 new sites have been proposed.
Historically about 70 percent of Superfund cleanup activities
have been paid for by potentially responsible party (PRPs). When the
party either cannot be found or is unable to pay for the cleanup, the
Superfund law originally paid for site cleanups through an excise tax on
petroleum and chemical manufacturers.
The last full fiscal year (FY) in which the Department of the Treasury collected the excise tax was 1995.
At the end of FY 1996, the invested trust fund balance was $6.0
billion. This fund was exhausted by the end of FY 2003. Since that time
Superfund sites for which the PRPs could not pay have been paid for from
the general fund. Under the 2021 authorization by Congress, collection of excise taxes from chemical manufacturers will resume in 2022.
Hazard Ranking System
The Hazard Ranking System is a scoring system used to evaluate potential relative risks to public health and the environment from releases or threatened releases of hazardous wastes
at uncontrolled waste sites. Under the Superfund program, the EPA and
state agencies use the HRS to calculate a site score (ranging from 0 to
100) based on the actual or potential release of hazardous substances
from a site through air, surface water or groundwater.
A score of 28.5 places the site on the National Priorities List, making
the site eligible for long-term remedial action (i.e., cleanup) under
the Superfund program.
Environmental discrimination
Federal actions to address the disproportionate health and
environmental disparities that minority and low-income populations face
through Executive Order 12898 required federal agencies to make
environmental justice central to their programs and policies. Superfund sites have been shown to impact minority communities the most.
Despite legislation specifically designed to ensure equity in Superfund
listing, marginalized populations still experience a lesser chance of
successful listing and cleanup than areas with higher income levels.
After the executive order had been put in place, there persisted a
discrepancy between the demographics of the communities living near
toxic waste sites and their listing as Superfund sites, which would
otherwise grant them federally funded cleanup projects. Communities with
both increased minority and low-income populations were found to have
lowered their chances of site listing after the executive order, while
on the other hand, increases in income led to greater chances of site
listing.
Of the populations living within 1 mile radius of a Superfund site, 44%
of those are minorities despite only being around 37% of the nation's
population.
As of January 2021, more than 9,000 federally subsidized
properties, including ones with hundreds of dwellings, were less than a
mile from a Superfund site.
Case studies in African American communities
In 1978, residents of the rural black community of Triana, Alabama were found to be contaminated with DDT and PCB, some of whom had the highest levels of DDT ever recorded in human history.
The DDT was found in high levels in Indian Creek, which many residents
relied on for sustenance fishing. Although this major health threat to
residents of Triana was discovered in 1978, the federal government did
not act until 5 years later after the mayor of Triana filed a
class-action lawsuit in 1980.
In West Dallas, Texas, a mostly African American and Latino community, a lead smelter
poisoned the surrounding neighborhood, elementary school, and day cares
for more than five decades. Dallas city officials were informed in 1972
that children in the proximity of the smelter were being exposed to
lead contamination. The city sued the lead smelters in 1974, then
reduced its lead regulations in 1976. It wasn't until 1981 that the EPA
commissioned a study on the lead contamination in this neighborhood and
found the same results that had been found a decade earlier. In 1983,
the surrounding day cares had to close due to the lead exposure while
the lead smelter remained operating. It was later revealed that EPA
Deputy Administrator John Hernandez had deliberately stalled the cleanup
of the lead-contaminated hot spots. It wasn't until 1993 that the site
was declared a Superfund site, and at the time it was one of the largest
ones. However, it was not until 2004 when the EPA completed the
clean-up efforts and eliminated the lead pollutant sources from the
site.
The Afton community of Warren County, North Carolina is one of the most prominent environmental injustice cases and is often pointed to as the roots of the environmental justice movement. PCBs were illegally dumped into the community and then it eventually became a PCB landfill. Community leaders pressed the state for the site to be cleaned up for an entire decade until it was finally detoxified.
However, this decontamination did not return the site to its pre-1982
conditions. There has been a call for reparations to the community which
has not yet been met.
Bayview-Hunters Point, San Francisco, a historically African American community, has faced persistent environmental discrimination due to the poor remediation efforts of the San Francisco Naval Shipyard, a federally declared Superfund site.
The negligence of multiple agencies to adequately clean this site has
led Bayview residents to be subject to high rates of pollution and has
been tied to high rates of cancer, asthma, and overall higher health
hazards than other regions of San Francisco.
Case studies in Native American communities
One example is the Church Rock uranium mill spill
on the Navajo Nation. It was the largest radioactive spill in the US
but received a long delay in government response and cleanup after being
placed as a lower priority site. Two sets of five-year cleanup plans
have been put in place by US Congress, but contamination from the Church
Rock incident has still not been completely cleaned up. Today, uranium
contamination from mining during the Cold War era remains throughout the
Navajo Nation, posing health risks to the Navajo community.
Accessing data
The data in the Superfund Program are available to the public.
Superfund Site Search
Superfund Policy, Reports and Other Documents
TOXMAP was a Geographic Information System (GIS) from the Division of Specialized Information Services of the United States National Library of Medicine
(NLM) that was deprecated on December 16, 2019. The application used
maps of the United States to help users visually explore data from the
EPA Toxics Release Inventory
(TRI) and Superfund programs. TOXMAP was a resource funded by the US
Federal Government. TOXMAP's chemical and environmental health
information is taken from NLM's Toxicology Data Network (TOXNET), PubMed, and other authoritative sources.
Future challenges
While
the simple and relatively easy sites have been cleaned up, EPA is now
addressing a residual number of difficult and massive sites such as
large-area mining and sediment sites, which is tying up a significant
amount of funding. Also, while the federal government has reserved
funding for cleanup of federal facility sites, this clean-up is going
much more slowly. The delay is due to a number of reasons, including
EPA's limited ability to require performance, difficulty of dealing with
Department of Energy radioactive wastes, and the sheer number of
federal facility sites.
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