Arsenic Compounds
(A)
ARSENIC COMPOUN DS
107-02-8
Hazard Summary
Arsenic, a naturally occurring element, is found throughout the environment; for most people, food is the
major source of exposure. Acute (short-term) high-level inhalation exposure to arsenic dust or fumes has
resulted in gastrointestinal effects (nausea, diarrhea, abdominal pain); central and peripheral nervous
system disorders have occurred in workers acutely exposed to inorganic arsenic. Chronic (long-term)
inhalation exposure to inorganic arsenic of humans is associated with irritation of the skin and mucous
membranes and effects in the brain and nervous system. Chronic oral exposure to elevated levels of
inorganic arsenic has resulted in gastrointestinal effects, anemia, peripheral neuropathy, skin lesions,
hyperpigmentation, and liver or kidney damage in humans. Inorganic arsenic exposure of humans, by the
inhalation route, has been shown to be strongly associated with lung cancer, while ingestion of inorganic
arsenic by humans has been linked to a form of skin cancer and also to bladder, liver, and lung cancer.
EPA has classified inorganic arsenic as a human carcinogen.
Arsine is a gas consisting of arsenic and hydrogen. It is extremely toxic to humans, with headaches,
vomiting, and abdominal pains occurring within a few hours of exposure. EPA has not classified arsine for
carcinogenicity.
Please Note: The main sources of information for this fact sheet are EPA's Integrated Risk Information System (IRIS) (7),
which contains information on the carcinogenic effects of inorganic arsenic including the unit cancer risk for
inhalation exposure, and the Agency for Toxic Substances and Disease Registry's (ATSDR's) Toxicological Profile for
Arsenic. (1)
Uses
•	The major use for inorganic arsenic has been in wood preservation, although its use for preservation of
wood used for residential purposes has been phased out. Although reduced from in the past, arsenic,
primarily in organic forms, is also used in a range of agricultural products. Arsine is used in the
microelectronics industry and in semiconductor manufacture. (1)
•	Until the 1 940s, inorganic arsenic was used as therapeutic agents in the treatment of various diseases,
such as leukemia, psoriasis and chronic bronchial asthma. Inorganic arsenic may still be used in
homeopathic or folk remedies in the United States and other countries, and its use has reemerged in an
FDA-approved treatment for a specific type of leukemia. (1)
•	Arsine has much more limited usage, primarily in the semiconductor industry and in the synthesis of
organoarsenic compounds. (2)
Sources and Potential Exposure
• Inorganic arsenic is found throughout the environment; it is released into the air by volcanoes, the
weathering of arsenic-containing minerals and ores, and by commercial or industrial processes. (1)

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•	For most people, diet is the largest source of arsenic exposure, with usually smaller intakes from drinking
water and air. Among foods, some of the highest levels are found in fish and shelfish; however, this arsenic
exists primarily as organic compounds, which are essentially nontoxic. Inorganic arsenic compounds are
the predominant forms in drinking water. (1)
•	Elevated levels of inorganic arsenic may be present in soil, either from natural mineral deposits or
contamination from human activities, which may lead to dermal or ingestion exposure. (1)
¦ Workers in metal smelters and nearby residents may be exposed to above-average inorganic arsenic levels
from arsenic released into the air. (1,2)
•	Other sources of inorganic arsenic exposure include burning plywood treated with an arsenical wood
preservative or dermal contact with wood treated with arsenic. (1)
•	Most arsenic poisoning incidents in industry have involved the production of arsine, a short-lived,
extremely toxic gas. (3)
Assessing Personal Exp osure
•	Measurement of inorganic arsenic in the urine is the best way to determine recent exposure (within the last
1 to 2 days), while measuring inorganic arsenic in hair or fingernails may be used to detect high-level
exposures that occurred over the past 6-1 2 months. (1)
Health Hazard Information
Acute Effects:
Inorganic Arsenic
•	Acute inhalation exposure of workers to high levels of arsenic dusts or fumes has resulted in
gastrointestinal effects (nausea, diarrhea, abdominal pain), while such exposures to inorganic arsenic
have also resulted in central and peripheral nervous system disorders. (1,2)
•	Acute oral exposure to inorganic arsenic, at doses of approximately 600 micrograms per kilogram
body weight per day (|jg/kg/d) or higher in humans, has resulted in death. Oral exposure to lower
levels of inorganic arsenic has resulted in effects on the gastrointestinal tract (nausea, vomiting),
central nervous system (CNS) (headaches, weakness, delirium), cardiovascular system (hypotension,
shock), liver, kidney, and blood (anemia, leukopenia). (1,2)
Arsine
•	Acute inhalation exposure to arsine by humans has resulted in death; it has been reported that a
half-hour exposure to 25 to 50 parts per million (ppm) can be lethal. (3)
•	The major effects from acute arsine exposure in humans include headaches, vomiting, abdominal
pains, hemolytic anemia, hemoglobinuria, and jaundice; these effects can lead to kidney failure. (3)
Chronic Effects (Noncancer):
Inorganic arsenic
• Chronic inhalation exposure to elevated levels of inorganic arsenic in humans is associated with
irritation of the skin and mucous membranes (dermatitis, conjunctivitis, pharyngitis, and rhinitis).
(1,2)

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•	Chronic oral exposure to elevated levels of inorganic arsenic in humans has resulted in
gastrointestinal effects, anemia, peripheral neuropathy, skin lesions, hyperpigmentation, gangrene of
the extremities, vascular lesions, and liver or kidney damage. (1,2) Some recent studies have
reported an association between elevated arsenic levels in drinking water and neurocognitive or
behavioral test results in school age children. (1)
•	No chronic inhalation exposure studies have been performed in animals for any inorganic arsenic
compound. (1)
•	Some animal studies have suggested that inorganic arsenic is an essential dietary nutrient; no
comparable data are available for humans. (4)
•	EPA has not established a Reference Concentration (RfC) for inorganic arsenic. (5)
•	The California Environmental Protection Agency (CalEPA) has established a chronic inhalation
reference level (REL) of 0.00001 5 milligrams per cubic meter (0.00001 5 mg/m3) estimated from a
study indicating decreased intellectual function in 1 0 year old children exposed to elevated arsenic in
drinking water. The CalEPA reference exposure level is a concentration at or below which adverse
health effects are not likely to occur. It is not a direct estimator of risk, but rather a reference point to
gauge the potential effects. At lifetime exposures increasingly greater than the reference exposure
level, the potential for adverse health effects increases. (6)
•	The Reference Dose (RfD) for inorganic arsenic is 0.0003 milligrams per kilogram body weight per
day (mg/kg/d) based on hyperpigmentation, keratosis, and possible vascular complications in
humans. The RfD is an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily
oral exposure to the human population (including sensitive subgroups) that is likely to be without
appreciable risk of deleterious noncancer effects during a lifetime. (5)
•	EPA has medium confidence in the study on which the RfD for inorganic arsenic was based because,
although an extremely large number of people were included in the assessment (>40,000), the doses
were not well characterized and other contaminants were present. The supporting human toxicity
database, while extensive, is somewhat flawed and, consequently, EPA has assigned medium
confidence to the RfD. (5)
Arsine
•	No information is available on the chronic effects of arsine in humans.
3
•	The RfC for arsine is 0.00005 mg/m based on increased hemolysis, abnormal red blood cell
morphology, and increased spleen weight in rats, mice, and hamsters. (3)
•	EPA has medium confidence in the RfC based on: (1) high confidence in the studies on which the RfC
for arsine was based because the sample sizes were adequate, statistical significance was reported,
concentration dose-response relationships were documented, three species were investigated, and
both a no-observed-adverse-effect level (NOAEL) and a lowest-observed-adverse-effect level
(LOAEL) were identified, and (2) medium confidence in the database because while there were three
inhalation animal studies and a developmental/reproductive study, there were no data available on
human exposure. (3)
Reproductive/Develop mental Effects:
Inorganic arsenic
•	Several studies have suggested that women who work in, or live near, metal smelters may have
higher than normal spontaneous abortion rates, and their children may exhibit lower than normal
birthweights. However, these studies are limited because they were designed to evaluate the effects
of smelter pollutants in general, and are not specific for inorganic arsenic. (1)
•	Ingested inorganic arsenic can cross the placenta in humans, exposing the fetus to the chemical. (2)

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•	Oral animal studies have reported inorganic arsenic at very high doses to be fetotoxic and to cause
birth defects. (1)
Arsine
•	Human studies have indicated higher than expected spontaneous abortion rates in women in the
microelectronics industry who were exposed to arsine. However, these studies have several
limitations, including small sample size and exposure to other chemicals in addition to arsine. (3)
Cancer Risk:
Inorganic arsenic
•	Human, inhalation studies have reported inorganic arsenic exposure to be strongly associated with
lung cancer. (1,2)
•	Ingestion of inorganic arsenic in humans has been associated with an increased risk of nonmelanoma
skin cancer and also to an increased risk of bladder, liver, and lung cancer. (1,5)
•	Animal studies have not associated inorganic arsenic exposure via the oral route with cancer, and no
cancer inhalation studies have been performed in animals for inorganic arsenic. (1)
•	The International Agency for Research on Cancer has classified inorganic arsenic in their Group 1 of
substances that are carcinogenic to humans. (7)
•	EPA has classified inorganic arsenic as a Group A, human carcinogen. (5)
•	EPA used a mathematical model, using data from an occupational study of arsenic-exposed copper
smelter workers, to estimate the probability of a person developing cancer from continuously
breathing air containing a specified concentration of inorganic arsenic. EPA calculated an inhalation
unit risk estimate of 4.3 x 1 0 (jjg/m ) . EPA estimates that, if an individual we^re to continuously
breathe air containing inorganic arsenic at an average of 0.0002 |jg/m (2x10 mg/m ) over his or
her entire lifetime, that person would theoretically have no more than a one-in-a-million increased
chance of developing cancer as a direct result of breathing air containing this chemical. Similarly, EPA
3	-6	3
estimates that continuously breathing air containing 0.002 |jg/m (2x10 mg/m ) would result in
not greater than a one-in-a-hundred thousand increased chance of developing cancer, and air
containing 0.02 |jg/m (2x10 mg/m ) would result in not greater than a one-in-ten thousand
increased chance of developing cancer. For a detailed discussion of confidence in the potency
estimates, please see IRIS. (5)
•	EPA has calculated an oral cancer slope factor of 1.5 (mg/kg/d) for inorganic arsenic. (5)
Arsine
•	No cancer inhalation studies in humans or animals are available for arsine. (1)
•	EPA has not classified arsine for carcinogenicity. (3)
Physical Properties
•	Inorganic arsenic is a naturally occurring element in the earth's crust.(1)
•	Pure inorganic arsenic is a gray-colored metal, but inorganic arsenic is usually found combined with other
elements such as oxygen, chlorine, and sulfur. (1)
•	The chemical symbol for inorganic arsenic is As, and it has an atomic weight of 74.92 g/mol. (1)
•	The chemical formula for arsine is AsH^, and it has a molecular weight of 77.95 g/mol. (3)
•	Arsine is a colorless gas with a disagreeable garlic odor. (3)
•	Arsenic combined with elements such as oxygen, chlorine, and sulfur forms inorganic arsenic; inorganic
arsenic compounds include arsenic pentoxide, arsenic trioxide, and arsenic acid. Arsenic combined with

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carbon arid hydrogen forms organic arsenic; organic arsenic compounds include arsanilic acid,
arsenobetaine, and dimethylarsinic acid. (II)
Conversion Factors (only for the gaseous form):	.
To convert concentrations in air (at 2 5°C) from ppm to mg/m : mg/m = (ppm) X (molecular weight of the
compound)/(24.45). For inorgamc arsenic: j ppm = 3.06 mg/m . For arsine: 1 ppm = 3.1 9 mg/m . To convert
concentrations in air from }jg/m to mg/m : mg/m = (fjg/m ) X (1 mg/1,000 pg).
Health Data for Inhalation Exposure (Inorganic Arsenic)
Arsenic, inorganic
10 -
Health numbers*
i
5
J
o
o
c_>
0.1
0.01
0.001
0.0001
0.00001
L0AELc
(nerwDus system)
(0.00046 maAti-n
Ref.
6
Cancer Risk Level
1 in a
Risk
(0.0043 nig An
CalEPA REL
(0.000015 mgrtn5)
|Ref.6 1
Ref
5
Regulatory advisory
numbers15
NIOSH IDLH (5mg/m!)
Ref
8;
ACGIHTLV, OS HA PEL
(0.01 mgrtn8)	
Ref
9
NIOSH ceiling
(0.002 mqfrn8)
Ref.
9
ACGIH TLV—American Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a
time-weighted average: the concentration of a substance to which most workers can be exposed without adverse
effects.
NIOSH IDLH—National Institute of Occupational Safety and Health's immediately dangerous to life or health
concentration; NIOSH recommended exposure limit to ensure that a worker can escape from an exposure condition
that is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from the
environment.
NIOSH REL ceiling value—NIOSH's recommended exposure limit ceiling; the concentration that should not be

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exceeded at any time.
OSHA PEL—Occupational Safety and Health Administration's permissible exposure limit expressed as a time-
weighted average; the concentration of a substance to which most workers can be exposed without adverse effect
averaged over a normal 8-h workday or a 40-h workweek.
The health and regulatory values cited in this factsheet were obtained in August 2012.
a
Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.
b
Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers
are nonregulatory values provided by the Government or other groups as advice. OSHA numbers are regulatory,
whereas NIOSH and ACGIH numbers are advisory.
c
The concentration presented here is the inhalation exposure concentration estimated by California EPA to be
associated with a similar chronic arsenic intake as the drinking water concentration selected to represent a LOAEL
using information from study identified as the basis for the CalEPA chronic reference exposure level.
Summary created in April 1 992, updated in January 2000
References
1.	Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Arsenic (Update). U.S.
Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 2007.
2.	U.S. Environmental Protection Agency. Health Assessment Document for Inorganic Arsenic. EPA/540 /1 -
86/020. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment,
Office of Research and Development, Washington, DC. 1 984.
3.	U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Arsine. National Center
for Environmental Assessment, Office of Research and Development, Washington, DC. 1 994.
4.	Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron,
Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Food and Nutrition Board, Institute of
Medicine. National Academy Press, Washington, D.C. 2001
5.	U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Arsenic. National
Center for Environmental Assessment, Office of Research and Development, Washington, DC. 1 998.
6.	California Environmental Protection Agency (CalEPA). Technical Support Document for the Determination of
Noncancer Chronic Reference Exposure Levels. . Office of Environmental Health Hazard Assessment,
Berkeley, CA. 2008.
7.	IARC. 2012. IARC Monographs on the Evaluation of Carcinogenic Risk to Humans. A Review of Human
Carcinogens: Arsenic, Metals Fibers and Dusts. Volume 1 00C Lyon, France: International Agency for
Research on Cancer, http: monographs.iarc.fr ENC Monographs vollOOC index.php.
8.	American Conference of Governmental Industrial Hygienists (ACGIH). 2009 Guide to Occupational
Exposure Values. ACGIH, Cincinnati, OH. 2009.
9.	National Institute for Occupational Safety and Health (NIOSH). Pocket Guide to Chemical Hazards. U.S.
Department of Health and Human Services, Public Health Service, Centers for Disease Control and
Prevention. Cincinnati, OH. 2007.
A. *This fact sheet addresses the toxicity of the inorganic arsenic compounds as well as the toxicity of the gaseous
arsenic trihydride: arsine.

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