Umtrt StttM Offico of PtflieidB ind Toxic Sutatanm
Envuonmtntal Protection Office of Ptstiad* Proflrimj (TS-766C)
Ag«ncy Wutiington, DC 20460
&EPA Pesticide
Fact Sheet
Name Of Chemical: Lead arsenate
Reason for Issuance: special review
Date Issued: December 1386
FacYSheet Number: 112
1. DESCRIPTION OF CHEMICAL
Common Name: Lead Arsenate
Chemical Name: Acid Orthoarsenate - PbHAs04
Basic Orthoarsenate - Pb4(PbOH) (As04)3
Trade Name: Lead Arsenate, Gypsine, Security, Talbot
EPA Shaughnessy Code: Standard (Acid) 013502
Basic 013503
Chemical Abstracts Service (CAS) Number: 7778-40-9
Year of Initial Registration:
Pesticide Type: Growth Regulator, Insecticide, Herbicide, and
Fungicide
Chemical Family: Inorganic Arsenicals
U.S. and Foreign Producers: Mechema Chemicals Ltd.
(Great Britian),
2. USE PATTERNS AND FORMULATIONS
Lead arsenate is currently used as a growth regulator on
17% of the U.S. grapefruit crop. 10,000 pounds of lead
arsenate are also used annually to control cockroaches,
silverfish and crickets. The Agency is unaware of any current
use as a foliar insecticide or as a herbicide.
0 Types and Methods of Application: Airblast sprayer,
foliar aerial dust, bait box.
c Application Rates: Growth Regulator - 1.3 Ibs arsenic/A
Foliar Insecticide - 1.7 Ibs arsenic/A
Types of Formulations: Dust, flowable liquid, wettable powder,
granular, impregnated, wettable powder/dust
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3. SCIENCE FINDINGS
0 Chemical Characteristics
Lead arsenate is a pentavalent form of inorganic arsenic.
It normally exists as white crystals with no discernable
odor. Lead arsenate contains 22% arsenic and is very
slightly soluble in cold water. The melting point of lead
arsenate is 1042°C, the density is 7.80 and the mo1ec 1ar
weight is 347.12. Technical lead arsenate consists of
95—98% lead arsenate. Under most conditions basic lead
arsenate is more stable than acid lead arsenate.
o 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 mutagenic 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 lead arsenate’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
lead arsenate is not well documented. Studies to demonstrate
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 environ-
mental conditjons. Based on very limited data lead arsenate
is not predicted to leach significantly.
o Ecological Characteristics: Lead arsenate is moderately
toxic to birds, slightly toxic to fish and moderately toxic
to aquatic invertebrate species.
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o Metabolism: The metabolism of Inorganic arsenic compounds
in animals is well known. The pentavalent form, such as
lead arsenate, is metabolized by reduction into the tri-
valent form, followed by transformation 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 Tolerance Assessment: Tolerances were established in 40
CFR 180.194 for residues of lead arsenate.
o Reported Pesticide Incidents: The Agency’s Pesticide
Incident Monitoring System (PIMS) has many recorded inci-
dents of accidental poisonings from the use of lead arsenate
baits. Nine of these incidents involved hospitalizations
and 16 involved child poisonings from “roach hive” products.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
The Agency is proposing to cancel all existing nonwood
registrations of lead arsenate, with the exception of the growth
reg ilator use on grapefruit. Measures to mitigate the inhala-
tion risks including dust masks, respirators, which would be
expected to reduce inhalation exposure by 80 and 90 percent,
respectively, and restricting the use to certified applicators
were considered by the Agency during the Special Review. The
Agency has determined that these protective measures would not
reduce risks to an acceptable level in light of the limited
benefits. The Agency has further determined that the toxicolog-
ical risks from all rionwood uses of lead arsenate, except the
grapefruit use, outweigh the limited benefits. The growth regulator
use on grapefruit is being deferred pending further evaluation by
EPA’S Risk Assesment Forum of the carcinogenic potency of inorganic
arsenic from dermal and dietary exposure.
Benefits Analysis: The economic impact from cancellation
of the lead arsenate insecticide baits could range from $.84
to $6.7 million, the actual amount depending on whether the
alternative chemical is applied by homeowners or professionals.
No economic impact is expected as a result of cancellation of
the herbicide and foliar insecticide uses of lead arsenate.
Viable alternatives are available.
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5. CONTACT PERSON
Douglas McKinney
Special Review Br3nch, Registration Division
Office of pesticide Programs (TS—767C)
401 M Street, S.W.
Washington, D.C. 20460
(703) 557—5488
DISCLAIMER The inforrnation presented in this Pesticide Fact
Sheet is for informational purpose only and may not be used
to fulfill data requirements for pesticide registration or
reregistration.
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