United States
Environmental Protection
Agency
Office of Pesticides and
Toxic Substances TS-793
Washington D C 20460
Arsenic—
what is it?
Toxics Information
Series
Arsenic
Any discussion of arsenic usually prompts visions
of murder and intrigue reminiscent of "Arsenic and Old
Lace". Indeed, the chemical has been extensively
employed as a poison due to its extreme toxic
properties. However, it is also an active ingredient in
an array of commercial products, a by-product of
numerous industrial processes, and occurs naturally in
various chemical forms. As a result, human exposure to
arsenic at various levels is widespread.
This exposure, coupled with recent medical findings
which indicate continued exposure to small amounts of
arsenic may produce adverse health effects, have raised
serious questions about the continued use of the
chemical. This Information Bulletin discusses the risks
of arsenic and what the U.S. Environmental Protection
Agency (EPA) and others are doing to control arsenic in
the environment.
Arsenic is a greyish-white element common in 'the
earth's crust where its compounds occur in association
with many minerals. The commercial use of these min-
erals, especially non-iron metals ores such as copper,
lead and gold necessitates removal of the arsenic. In
the United States arsenic is largely generated as a by-
product of copper smelting. Domestic production of the
compound arsenic trioxide is approximately 12,000 metric
tons every year, and another 9,400 metric tons of
arsenic and arsenic compounds are imported yearly.
Easily combined with other chemicals, arsenic trioxide^
is used as a raw material in the formulation of other
arsenic compounds which are used commercially.
Agricultural products account for about 81 percent
of the U.S. consumption of arsenic. Arsenic-based
insecticides, herbicides, desicants and defoliants are
the major agricultural uses, with cotton production
considered to be the top agricultural consumer. Low
concentrations of arsenic are also found in an-imal feed
additives used to increase the rate of weight gain in
hogs and poultry.
The major nonagricultural use of arsenical
compounds (9.5 percent of the total U.S. consumption) is
for wood perservatives. Other applications for arsenic
include hardeners for metal alloys, semiconductors, and
veterinary drugs. Once widely used as a clarifying
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agent for glass, arsenic has been largely replaced by
other ingredients.
Why is Arsenic has been identified as a public health
arsenic a problem because of its serious toxic effects at low
problem? exposure levels and its pervasiveness in the environ-
ment. Arsenic is an element and therefore cannot be
eliminated from the environment. Like all other
elements, it goes through geological and biological
cycles which redistribute it into different compounds
and to different places. Natural processes such as
oxidation, methylation and demethylation may concentrate
it in hazardous proportions, or may dissipate it,
thereby decreasing its hazardous concentrations.
Because arsenic easily changes forms and readily
combines with other chemicals, the end product of such
processes cannot always be anticipated. Human activi-
ties cause arsenic contamination of the environment
where none previously existed by putting arsenic into
the environment faster than it can be dissipated by
natural processes.
Energy production, pesticide production and use,
and copper smelting are all significant sources of
arsenic discharges to the air. Presently coal-fired
plants are the most significant energy related emissions
source. New technologies of energy production have
important arsenic implications, also. Early data on
coal gasification indicate that two-thirds of the
arsenic present is volatilized (passed off as a vapor in
the gasification process). Oil shale exploitation and
geothermal energy development may also release large
quantities of arsenic gases. Arsenic is emitted to the
air from several other commercial sources: lead and
zinc smelters, iron and steel production, and arsenical
compound production.
Pesticide production and use is probably the
largest single man-made source of arsenic* entry to the
total environment. Although pesticides add to the
atmospheric burden of arsenic, five times that amount is
deposited in the soil through pesticide manufacture and
use. Other releases of arsenic to the soil due to human
activity include fallout of air emissions and solid
waste from smelters and coal-fired plants.
Arsenic discharges to water are much less than air
and soil releases. These releases are the result of
energy production from coal, boron production and use,
zinc and lead production, non-iron metal mining and
milling, phosphorus production and use, pesticide use,
and municipal water and waste water treatment.
Human exposure to arsenic occurs through >11
environmental media—air, water, food. Smelter
emissions result in the most arsenic exposure by air to
the greatest number of people. Pesticide use is also
thought to expose a 'large number of people to atmos-
pheric arsenic during application and through wind
drift. At the present time, there are no^a-creurarte
measures of the number of people exposed to,---arsenic Trf
drinking water nor of the degree of contamination of
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either surface or ground waters in the United States.
Although arsenic concentrations in waters which have
been tested vary widely, the average concentration is
close to natural levels. Plants and animals contain
differing amounts of arsenic depending on the
concentrations in soil and water, thus adding to the
human body burden of arsenic when the plants and animals
are eaten. However, the bioccumulation of arsenic in
the food chain is normally not significant. Although
marint fish and other seafood (especially oysters)
contain larger amounts of arsenic than other foods, the
arsenic is in an organic form which is relatively non-
toxic.
In humans arsenic may be absorbed by the lungs and
the gastro intestinal tract. Chemical species differ
widely in their toxicity with the inorganic forms,
especially trivalent arsenites, being more toxic than
organic arsenic species.
Arsenic causes both acute and chronic health
effects in humans. Acute arsenic poisoning occurs most
commonly from accidental pesticide ingestion.. , The. early
symptoms of acute poisoning include intense -v.omLting,
diarrhea, and cramps, accompanied by burning . .of, the
mouth and throat, inability to swallow and , extreme
abdominal, pain. Victims often have bloody urine and
shock can result from dehydration.
A large body of scientific research exists on the
chronic health effects of arsenic exposure. Chronic
arsenic poisoning, called arsenicism, is most
recognizably characterized by effects to the skin.
Arsenic exposure can also produce neurologic, vascular,
and liver damage. In addition, arsenic is a recognized
human carcinogen. Experiments with laboratory animals
suggest that certain arsenic compounds may also
contribute to the risk of birth defects and genetic
mutations in humans.
Cancer; EJpidemiologic studies have shown that
arseniccauses cancer of the skin. This finding has
been made in studies of people exposed to arsenic in
drinking water, medications, and the workplace
environment. In addition, there are strong suggestions
that occupational exposure to arsenic causes lung
cancer. Hints of association with other tumors have
also been reported.
Neurological effects: Arsenic exposure can produce
peripheral nerve damage and altered electrocardiograms.
Abnormal neurological test findings have resulted from
exposures to arsenic that are too low to produce
symptoms of classical arsenicism. Exposure to amounts
of arsenic in drinking water, much too low to produce
classical arsenicism, has been associated with abnormal
electromyograms, and in one case, children exposed to an
arsenic compound emitted by a coal-burning power plant
have been found to have an increase in the frequency of
a specific hearing loss.
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What is the
government
doing about
this hazard?
Skin effects; Arsenic ism is characterize.: '.:•/ horny
growths on the skin of the hands and feet and c :.rko-nir.g
of the skin of the torso, as well as skin cancer. Skin
symptoms are good indicators of massive arsenic exposure
because they appear in most people with very high
exposure.
Birth defects; Injections of a particular arsenic!
compoundintopregnant animals have caused specific
birth defects in hamsters, rats and mice. However, at
the present time there is no evidence of arsenic-related
birth defects in humans.
Mutations; Animals and humans who have been
exposed to sodium arsenite (a trivalent form of arsenic)
have shown chromosomal defects (as long as 20 years
after exposure in humans). Further research is needed
to determine the exposure levels at which these effects
are produced and the implications for human development.
Other effects; High and prolonged exposure also
cause's cirrosis of the liver and impairment of
peripheral veins.
There are over two hundred individual regulations !
controlling exposure to arsenic and arsenical exposure
of workers, consumers, and the environment through waste
discharges into air, water and land. Major regulations
actually limiting arsenic exposure are administered by
six Federal agencies.
EPA has listed arsenic as a hazardous air pollutant
because of its suspected carcino- genicl'ty. This
listing, under the authority of the Clean Air Act, will
enable the Agency to determine which stationary sources
of arsenic pose signifi- cant risks to the public and to
assign priorities for the development of emission
standards. Using the authority granted by the Clean
Water Act, EPA has set or proposed regulations
controlling the discharge of arsenic and its compounds
into waterways from a^variety of industries.
The Agency has also set a maximum contamination
level for ground water, and has proposed a water quality
criteria based on the latest scientific information.
The criteria can be used for further regulation of
arsenic by EPA or the individual States. Under pro-
visions of the Safe Drinking Water Act, EPA has set
standards from maximum arsenic content in drinking water
and promulgated regulations for the protection of ground
water sources.
In 1978, EPA issued a "rebuttable presumption
against registration" (RPAR) notice on inorganic
arsenical pesticides. Each compound is being considered
in individual risk/benefit analysis. Several, organic
arsenical pesticides are being considered for the RPAR
process, also.
EPA has listed arsenic as a hazardous waste under
the Resource Conservation and Recovery Act regulations
controlling the management of hazardous wastes from
point of manufacture to ultimate disposal.
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The Occupational Safety and Health Administration
(OSHA) promulgated a workplace standard for arsenic
content in the air but the standard has been challenged
in court and the case has not been decided yet.
The Food and Drug Administration (FDA) monitors
food for arsenic content and enforces food tolerance
levels established by EPA.
The Department of Transportation (DOT), the Nuclear
Regulatory Commission (NCR) and the Department of the
Army also regulate arsenic.
In Summary; Arsenic, although naturally present in
all parts of the environment, poses a human health risk
because of increased levels in particular areas caused
by human activity. Government agencies have taken steps
to minimize human exposure to arsenic, and are
considering additional methods to further reduce the
arsenic risk in this country.
ENVIRONMENTAL EFFECTS
In addition to human health effects, increased
arsenic in the environment can have profound effects on
the environment itself. Arsenic compounds are toxic to
all plants and animals. The result of high-level
arsenic contamination is an essentially sterilized
environment. Orchards where inorganic arsenical
pesticides have been heavily used, for instance, must
have the contaminated soil removed before replanting can
take place. Otherwise, the new trees will die because
of the toxic concentrations of arsenic in the treated
soil.
When arsenic compounds enter soil or water they
bind to soil and sediment components. Binding greatly
decreases the amount of arsenic available to cause toxic
effects, but as more arsenic is released it becomes more
readily available because because the bound arsenic is
at equilibrium with available arsenic. Arsenic is
continuously cycling in the environment due to chemical
and biological transformations. Also, man's activities
can significantly alter the cycle by causinu localize^
high concentrations.
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