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Aldicarb (Temik) - Chemical Fact Sheet 4/92

DATE ISSUED:             April, 1992
name OF CHEMICAL:        Aldicarb (Temik)
REASON FOR ISSUANCE:     Proposed Tolerance Revocation

                    1. DESCRIPTION OF CHEMICAL

Common Name:  Aldicarb
Chemical Name:  2-methyl-2-(methylthio)propionaldehyde
                O-(methylcarbamoyl)oxime
Class Description:  Member of the carbamate family
Trade Name:  Temik
EPA Shaughnessy Code:  098301
Chemical Abstracts Service (CAS) Number:  116-06-3
Year of Initial Registration:  1970
Pesticide Type:  Insecticide, acaricide, nematicide
U.S. and Foreign Producer:  Rhone-Poulenc (formerly Union Carbide
                            Agricultural Chemical Co.)

                    2. USE PATTERNS AND FORMULATIONS

       Aldicarb is currently registered for use only on cotton, potatoes,
citrus, peanuts, soybeans, sugar beets, pecans, tobacco, sweet potatoes,
ornamentals, seed alfalfa, grain sorghum, dry beans, and sugar cane.

  -- Types and Methods of Application:  Soil incorporated.
  -- Application Rates: 0.3 - 10.0 lbs. active ingredient.
  -- Types of Formulation: Granular formulation (15%, 10%, and 5%).  Also as a
     granular in a mixture with the fungicides pentachloronitrobenzene and 5-
     ethoxy-3-(trichloromethyl)-1 ,2,4-thiadiazole.

                          3. SCIENCE FINDINGS

-- Chemical Characteristics:  Technical aldicarb is a white crystalline solid
with a melting point of 98-100 C (pure material). Under normal conditions,
aldicarb is a heat-sensitive, inherently unstable chemical and must be
stabilized to obtain a practical shelf-life.

-- Toxicological Characteristics:
   Aldicarb is a carbamate pesticide which causes cholinesterase (ChE)
inhibition at very low exposure levels.  It is highly toxic by the oral,
dermal, and inhalation routes of exposure (Toxicity Category 1).  The oral
LD50 value for technical aldicarb is 0.9 mg/kg and 1.0 mg/kg for male and
female rats, respectively.  The acute dermal LD50 for aldicarb in rats is 3.0
mg for males and 2.5 mg for females.  Rats, mice and guinea pigs were exposed
to aldicarb, finely ground, mixed with talc, and dispersed in the air at a
concentration of 200 mg/m3 for five minutes; all animals died.  At a lower
concentration (6.7 mg/M3), a 15 minute exposure was not lethal, however, 5 of
6 animals died during a 30 minute exposure.  Exposure of rats for eight hours
to air that had passed over technical or granular aldicarb produced no
mortality.  Aldicarb applied to the eyes of rabbits at 100 mg of dry powder
caused ChE effects and lethality.

   The toxicity data base for aldicarb is complete.  It includes a 2-year rat
feeding/oncogenicity study which was negative for carcinogenic effects at the
no-observed-effect-level (NOEL) of 0.3 mg/kg bw/day; a 100-day dog feeding
study and a 2-year dog feeding study with NOELs of 0.7 and 0.1 mg/kg bw/day,
respectively, for effects other than cholinesterase inhibition (highest levels
tested (HLT)); an 18-month mouse feeding/carcinogenicity study with a NOEL of
0.7 mg/kg bw/day which was negative for carcinogenic effects at the levels
tested (0.1, 0.3, and 0.7 mg/kg bw/day); a 2-year mouse carcinogenicity study
which was negative for carcinogenic effects; a 6-month rat feeding study using
aldicarb sulfoxide with a NOEL of 0.125 mg/kg bw/day for ChE inhibition; a 3-
generation rat reproduction study with a 0.7 mg/kg bw/day NOEL a rat
developmental toxicity study which was negative for developmental effects at
0.5 mg/kg bw/day (HLT); a hen neurotoxicity study which was negative at up to
4.5 mg/kg bw/day; a mutagenicity study utilizing the rat hepatocyte primary
culture/DNA repair test which was negative for mutagenic effects at 10,00
ug/well; and a mutagenicity test utilizing an in vivo chromosome aberration
analysis in Chinese hamster ovary cells which was negative for mutagenic
effects at 500 ug/ml.

-- Physiological and Biochemical Behavioral Characteristics:

   Aldicarb and its metabolites are absorbed by plants from the soil and
translocated into the roots, stems, leaves, and fruit.  The available data
indicate that the metabolism of aldicarb in plants and small. animals is
similar.

   Aldicarb is metabolized rapidly by oxidation to the sulfoxide metabolite
and followed by a slower oxidation to the sulfone metabolite, which is 5 times
less acutely toxic than aldicarb.  Both metabolites are subsequently
hydrolyzed and degraded further to yield less toxic entities.  Available
studies demonstrate that the administration of aldicarb to a lactating
ruminant results in the rapid metabolism and elimination of the material.  No
residues of the parent compound and little, if any, residues of aldicarb
sulfoxide or aldicarb sulfone are found in the tissues and milk.  The
predominant residue detected in tissues and milk is aldicarb sulfone nitrile .

-- Environmental Characteristics:

   Sufficient data are available to assess the environmental fate of aldicarb.
From the available data, aldicarb has been determined to be mobile in fine to
coarse textured soils, even including those soils with high organic matter
content and has been found to reach ground water.  Aldicarb is not expected to
move horizontally from a bare, sloping field.  Therefore, accumulation of
aldicarb in aquatic nontarget organisms is expected to be minimal.  This is
further supported by an octanol/water partition coefficient of 5 and an
ecological magnification value of 42.

-- Ecological Effects:

   Aldicarb is highly toxic to mammals, birds, estuarine/marine and freshwater
organisms.  LC50 values for the bluegill sunfish and rainbow trout have been
reported as 50 ug/liter and 560 ug/liter, respectively.  A LC50 of 410.7
ug/liter was reported for Daphnia magna.  Studies on the toxicity of aldicarb
to the mallard duck and the bobwhite quail indicate LD50 values of 1.0 and 2.0
mg/kg, respectively.

   Limited exposure to mammals is expected from a dietary standpoint.
However, data from field studies and the use history of aldicarb provide
sufficient information to suggest that application of this pesticide may
result in some mortality, with possible local population reductions of some
avian species.  Whether these effects are excessive, long-lasting, or likely
to diminish wildlife resources cannot be stated with any degree of certainty.
Therefore, additional field studies have been required to further quantify the
impact on avian and small mammal populations.

   Aldicarb has also been found to pose a threat to the endangered Attwaters
Greater Prairie Chicken, living in or near aldicarb-treated fields.
Accordingly, all aldicarb products are required to bear labeling restrictions
prohibiting the use of the product in the Texas counties of Aransas, Austin,
Brazoria, Colorado, Galveston, Goliad, Harris, Refugio, and Victoria if this
species is located in or immediately adjacent to the treatment area.

                         4. CURRENT PROPOSAL

     EPA is proposing to revoke the aldicarb tolerance for use on bananas for
several reasons.  First, it is EPA's general policy to revoke tolerances
associated with pesticide uses which have been canceled [40 CFR 180.32 (b)].
All aldicarb registrations for use on bananas were canceled in 1992. Rhone-
Poulenc, the sole registrant of aldicarb withdrew payment for continued
aldicarb use on bananas in March.  Second, evidence submitted by Rhone-Poulenc
shows that there is a likelihood that residues above the tolerance level would
result following aldicarb applications at the established use rates.  Finally,
EPA is concerned about the potential risk of poisoning to the U.S. population
consuming bananas containing aldicarb residues at levels up to those found in
the market basket survey.  Aldicarb poisoning results in neurotoxicity which
is manifested in humans by a range of symptoms that can include malaise,
muscle weakness, headache, dizziness, sweating, nausea, vomiting and diarrhea.

     Given these circumstances, EPA believes the aldicarb tolerance for
bananas should be revoked immediately. Rhone-Poulenc withdrew world-wide use
of aldicarb on bananas in 1991 and there has been no further use since that
date.  Therefore, EPA does not believe that there are any legally-treated
domestic or international commodities still in the channels of trade.

               5. SUMMARY OF REGULATORY POSITION AND RATIONALE

     This document proposes revocation of the tolerances for residues of the
pesticide aldicarb in or on the raw agricultural commodity bananas.  This
action is being proposed because Rhone-Poulenc, the sole U.S. registrant of
aldicarb, has withdrawn its payments for continued aldicarb use on bananas.
Given these circumstances, EPA believes the aldicarb tolerance for bananas
should be revoked immediately after the final order is promulgated.  Rhone-
Poulenc withdrew all use of aldicarb on bananas in 1991 and there has been no
further use since that time.  Therefore, EPA does not believe that there are
any legally-treated domestic commodities still in the channels of trade.

                           6. CONTACT PERSON

     Karis North
     Special Review Branch
     Special Review and Reregistration Division
     Office of Pesticide Programs (H7508W)
     401 M Street, S.W.
     Washington, D.C. 20460
     (703) 308-8036

Disclaimer:  The information presented in this Pesticide Fact Sheet is for
information purposes only and may not be used to fulfill data requirements for
pesticide registration and reregistration.