United St*tM OHiet of Ptitiedti and Tome Subttinm
Environmental Protection Office of Pwiade Program (TS-766C)
Agtncy Washington. DC 20460
&EPA Pesticide
Fact Sheet
Name Of Chemical: Arsenic trioxide
Reason for Issuance: special review
Date Issued: Decentoer 1986
Fact"Sheet Number: 110
DESCRIPTION OF CHEMICAL
Common Name: Arsenic Trioxide
Chemical Name: Arsenious oxide -
Trade Names: Refined arsenic trioxide is known as white
arsenic
EPA Shaughnessy Code: 007001
Chemical Abstracts Service (CAS) Number: 1327-53-3
Year of Initial Registration:
f t.
Pesticide Type: Antifoulant agent, Herbicide, Insecticide
and Rodenticide.
Chemical Family: Inorganic Arsenicals
U.S. and Foreign Producers: Grant Laboratories
USE PATTERNS AND FORMULATIONS
Approximately 85% of the pesticidal use of arsenic tri-
oxide is as a liquid rodenticide bait to control rats and
mice. The remaining 15% is used to kill moles and pocket
gophers, as an insecticide bait to control ants and as an
antifoulant agent in boat paints. Arsenic trioxide is
currently registered as a noncrop herbicide; however, there
is no known usage at this time.
0 Methods of Application: Rodenticide baits are applied where
rats, mice, moles and gophers are seen. As an insecticide
it is used in bait stations and as an antifoulant it is
applied by painting.
0 Application Rates: Rodenticide- These baits contain 1.14%
arsenic.
Antifoulant- 2.4% arsenic/gallon batch
Types of Formulations: Pellets, wettable powders, pastes,
ready to use solutions, impregnated material, granular and
as a formulation intermediate.
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3. SCIENCE FINDINGS
Chemical Characteristics
Arsenic trioxide is a form of inorganic arsenic. It
normally exists either as transparent crystals or an amor-
phous white powder with no discernible odor. Arsenic tn—
oxide contains 76% arsenic and is slightly soluble in water
and other solvents which do not promote chemical transform-
ation. However, the compound dissolves in acidic or alkaline
aqueous media to yield either a free acid or salt which are
soluble in a number of solvents. As 2 0 3 sublimes at 193°C,
the density is 3.865 and the molecular weight is 197.84.
The technical chemical contai : s between 90% and 99.5% and
the formulations contain from 0.25% to 25.0% arsenic trioxide.
Arsenic trioxide Is produced as a by—product of copper smelting...
operations. It Is the base compound from which all other
arsenicals are produced.
° Toxicological Characteristics
Inorganic arsenical compounds have been classified as Class
A oncogens, demonstrating positive oncogenic effects based
on sufficient human epidemiological evidence.
Inorganic arsenicals have been assayed for inutagenic activity
in a variety of test systems ranging from bacterial cells
to peripheral lymphocytes from humans exposed to arsenic.
The weight of evidence indicates that inorganic arsenical
compounds are mutagenic.
Evidence exists indicating that there is teratogenic and
fetotoxic potential based on intravenous and intraperitoneal
routes of exposure; however, evidence by the oral route is
insufficient to confirm arsenic trioxide’s teratogenic and
fetotoxic effects.
Inorganic arsenicals are known to be acutely toxic. The
symptoms which follow oral exposure include severe gastro-
intestinal damage resulting in vomiting and diarrhea, and
general vascular collapse leading to shock, coma and death.
Muscular cramps, facial edema, and cardiovascular reactions
are also known to occur following oral exposure to arsenic.
o Environmental Characteristics: The environmental fate of
arsenic trioxide is not well documented. Studies to demon-
strate its fate must take Into account the fact that
inorganic arsenicals are natural constituents of the soil,
and that forms of inorganic arsenic may change depending
on environmental conditions.
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Ecological Characteristics: Arsenic trioxide is moderately
toxic to birds, slightly toxic to fish and moderately toxic
to aquatic invertebrate species.
0 Metabolism: The metabolism of inorganic arsenic compounds
in animals is well known. The pent valent form is metabolized
by reduction into the trivalent form, followed by transform-
ation into organic forms which are excreted within several
days via the urine. All animals exhibit this metabolism
except rats, which retain arsenic in their bodies for up to
90 days.
o Reported Pesticide Incidents: The Agency’s Pesticide
Incident Monitoring System (PIMS) contains many recorded
incidents of accidental poisonings from the use of arsenic
trioxide baits. Between 1966 and 1979, 72 incidents were
reported; ten of these incidents resulted in child fatalitieE.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
The Agency Is proposing to cancel all existing nonwood
registrations of arsenic trioxide. Based upon the risk of acute
toxicity poisonings and the other toxicological characteristics
described above, the Agency has determined that in light of the
limited benefits for nonwood uses of arsenic trioxide the risks
of continued use outweigh the benefits.
° Benefits Analysis: Nationwide, user costs would be expected
to increase by approximately five thousand dollars if arsenic
trioxide were cancelled for moles and pocket gophers, resulting
in no measurable impact. For all other uses negligible impact
is expected.
5. CONTACT PERSON
Douglas McKinney
Special Review Branch, Registration Division
Office of Pesticide Programs (TS—767C)
401 M Street, S.W.
Washington, D.C. 20460
(703) 557—5488
DISCLAIMER: The information presented in this Pesticide Fact
Sheet is for informational purposes only and may not be used
to fulfill data requirements for pesticide registration or
reregistration.
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