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sodium arsenate EPA Pesticide Fact Sheet 12/86

EPA Pesticide Fact Sheet

Name of Chemical: Sodium arsenate
Reason for Issuance: Special review
Date Issued: December 1986
Fact Sheet Number: 114


                    1. DESCRIPTION OF CHEMICAL

- Common Name:  Sodium Arsenate
- Chemical Name:  Sodium Orthoarsenate - Na2HAsO4.7H20
- Trade Names:  None
- EPA Shaughnessy Code:  013505
- Chemical Abstracts Service (CAS) Number:  7778-43-0
- Year of Initial Registration:
- Pesticide Type:  Insecticide
- Chemical Family:  Inorganic Arsenicals
- U.S. and Foreign Producers:  Osmose Wood Preservative Company
  of America, Inc.


                   2. USE PATTERNS AND FORMULATIONS

    Sodium arsenate.is currently registered for use as an ant bait.  
These baits are used in approximately 1% of U.S. homes.

- Methods of Application:  Liquid bait applied where ants are seen.
  Applied as a bait station using cardboard, waxpaper, cotton, or bottle
  caps; or apply directly across ant trails and at entry points as a
  thin line 3 to 4 inches long.
- Application Rates:  Insecticide- The bait used is a 1.3% arsenic
  (metal) solution.
- Types of Formulations:  Ready to use solution, granular.


                        3. SCIENCE FINDINGS

Chemical .Characteristics

- Sodium arsenate is a pentavalent form of inorganic arsenic. It is a
  heptahydrate which normally exists as colorless crystals with no
  discernible odor.  Sodium arsenate contains 24% arsenic and is soluble
  in 5.6 gm at 0 degrees C and 100 gm at 100 degrees C in 100 cc of
  water, soluble in glycerol and slightly soluble in alcohol. The
  melting point of calcium arsenate is 130 degrees C, the density is
  1.88 and the molecular weight is 312.01.  The technical chemical
  contains 98% and the formulations contain from 0.92% to 3.08% sodium
  arsenate.

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 sodium
  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 cardio-
  vascular reactions are also known to occur following oral exposure to
  arsenic.


Environmental Characteristics

- The environmental fate of sodium 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 environmental
  conditions. Based on very limited data sodium arsenate is not
  predicted to leach significantly.


Ecological Characteristics

- Sodium arsenate is moderately toxic to birds, slightly toxic to fish
  and moderately toxic to aquatic invertebrate species.
- Metabolism:  The metabolism of inorganic arsenic compounds in animals
  is well known.  The pentavalent form, such as sodium arsenate, is
  metabolized by reduction into the trivalent 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.
- Tolerance Assessment:  A tolerance for residues of the insecticide
  sodium arsenate on grapes was established at 3.5 ppm in 40 CFR
  180.196.
- Reported Pesticide Incidents:  The Agency's Pesticide Incident
  Monitoring System (PIMS) contains many recorded incidents of
  accidental poisonings from the use of sodium arsenate baits.  190
  children were involved in 186 reported incidents; five of these
  children died and 43 were hospitalized.


           4. SUMMARY OF REGULATORY POSITION AND RATIONALE

    The Agency is proposing to cancel all existing nonwood registrations 
of sodium arsenate.  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 
sodium arsenate the risks of continued use outweigh the benefits.

- Benefits Analysis:  No economic impact is expected as a result of
  cancellation of this use.  Comparatively priced alternatives are
  available.


                      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.