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Carbaryl - Chemical Fact Sheet 3/84

                        CHEMICAL FACT SHEET FOR:

                               CARBARYL

FACT SHEET NUMBER:  21

DATE ISSUED:  MARCH 30, 1984

                       1. DESCRIPTION OF CHEMICAL

- Generic Name:  1-napthyl N-methylcarbamate
- Common Name:  carbaryl
- Trade Name:  Sevin
- EPA Shaughnessy Code:  056801
- Chemical Abstracts Service (CAS) Number:  63-25-2
- Year of Initial Registration:  1958
- Pesticide Type:  Insecticide
- Chemical Family:  Carbamates
- U.S. and Foreign Producers:  Union Carbide, Makteshim Chemical Works,
  Inc.

                    2. USE PATTERNS AND FORMULATIONS

- Application sites:  citrus, pome, stone and berry fruits, forage,
  field and vegetable crops, nuts, lawns, forests, ornamental plants,
  rangeland, shade trees, poultry and pets, indoor use
- Types of formulations:  baits, dusts, granules, wettable powders,
  flowables, and aqueous dispersions
- Types and methods of application:  ground and aerial
- Application rates:  range from 0.53 lbs. a.i./A to 6.4 lbs. a.i./A
- Usual carriers: synthetic clays, talc, various solvents

                          3. SCIENCE FINDINGS

Chemical Characteristics

- Physical state:  crystalline solid
- Color:  white
- Odor:  essentially odorless
- Melting point:  142 degrees C

- Vapor pressure:  < 0.005 mm H9 at 26 C
- Flash point:  380 degrees F

Toxicological Characteristics

- Acute Oral LD50:  225 mg/kg, Toxicity Category II
- Acute Dermal LD50:  > 2 g/kg, Toxicity Category III
- Primary Dermal Irritation:  no irritation, Toxicity Category IV
- Primary Eye Irritation:  Conjunctival irritation at 24 hours. Cleared
  at 48 hours. Toxicity Category III
- Acute Inhalation LC50:  data gap

Oncogenicity:

     Ten studies. Each study classified as supplemental. Collectively
these studies provide sufficient evidence that carbaryl is not oncogenic
in experimental animals. Eighteen-month mouse study was negative at 400
ppm. A 2-year rat feeding and oncogenicity study was negative at 200
ppm.

Teratogenicity:

     Twenty-four studies have been evaluated to determine the
teratogenic potential of carbaryl. In evaluating these studies, some
were found to be flawed. Other studies demonstrated no teratogenicity or
maternal toxicity. There are studies which demonstrate teratogenic
effects, although the doses also caused maternal toxicity. Two studies
produced teratogenic effects in the beagle dog. These two studies are
the primary reason carbaryl was made a candidate for RPAR in 1976.

     The Agency has concluded (45 FR 81869) that carbaryl does not
constitute a potential human teratogen or reproductive hazard under
proper environmental usage. However, the Agency is requesting that the
teratology study in the beagle dog be repeated, because the results of
the dog studies continue to be a concern that has never been fully
resolved. A repeat dog study will provide the basis for any appropriate
regulatory action. In the interim, the Agency has determined that a
label precaution stating not to use carbaryl on pregnant dogs is
warranted until a new dog teratology study is submitted and reviewed.

     There have been proposals that there are differences in the
metabolism of carbaryl between the dog and man. These differences,
however, have never been demonstrated. Therefore, a metabolism study in
the beagle dog versus the rat is being required. This metabolism study
should allow us to determine if there are meaningful differences between
the dog and other mammalian species.

Reproduction:  A rat 3-generation study was negative at 200 mg/kg.

Mutagenicity: Carbaryl is characterized as a weak mutagen. The Agency
has determined that carbaryl does not pose a mutagenic risk. No
additional data are being requested.

- 1-year dog feeding study:

- 2-year rat feeding study:  Demonstrated an apparent effect on renal
  function. A kidney effect was also noted in a short-term human study.
  A 1-year dog feeding study using carbaryl is being requested in order
  to determine the effects of carbaryl on kidney dysfunction. The
  results of these may necessitate a re-evaluation of the ADI for
  carbaryl.

Physiological and Biochemical Behavioral Characteristics

- Mechanism of pesticidal action:  A contact insecticide which causes
  reversible carbamylation of the acetylcholinesterase enzyme of
  tissues, allowing accumulation of acetylcholine at cholinergic
  neuroeffector junctions (muscarinic effects), and at skeletal muscle
  myoneural junctions and autonomic ganglia. Poisoning also impairs the
  central nervous system function.
- Metabolism and persistence in plants and animals: Carbaryl is rapidly
  excreted in animals, mainly in the urine. Residues in animals are
  carbaryl, 1-naphthol, and hydroxycarbaryl. The hydroxy metabolites are
  found mainly as glucuronide and sulfate conjugates. Carbaryl is slowly
  taken up into plants, after which it is metabolized. The disappearance
  of carbaryl residue from plant surfaces is attributed to mechanical
  attribution, volatilization and uptake into plant. Photochemical
  degradation does not appear to be a factor. 1-naphthol is the major
  metabolite.

Environmental Characteristics

- Available data are insufficient to fully assess the environmental fate
  of carbaryl.
- Adsorption and leaching in basic soil types:  The Agency is requesting
  data to determine if carbaryl will contaminate groundwater.
- Microbial breakdown:  Carbaryl is degraded by fungi. The soil fungi
  attack carbaryl by hydroxylation of the side chain and ring structure.
- Loss from photodecomposition:  Data gaps. Data are required.
- Bioaccumulation:  Preliminary data indicate that there may be a
  potential for carbaryl and its residue(s) to accumulate in catfish,
  crayfish, snail. duckweed, and algae. Additional data are requested.
- Resultant average persistence:  Carbaryl is metabolized by pure and
  mixed cultures of bacteria, fungi, and to some extent by other soil
  and water organisms. The half-life appears to range from 7 to 28 days
  in aerobic and anaerobic soils, respectively.

Ecological Characteristics

- Avian oral LD50:  Mallard duck, > 2179 mg/kg; Ring-necked pheasant,
  > 2000 mg/kg
- Avian dietary LC50: Mallard duck, > 5000 ppm, Ring-necked pheasant,
  > 5000 ppm, Bobwhite quail, > 5000 ppm
- Freshwater fish LC50:  coldwater fish, rainbow trout, 1.95 ppm;
  warmwater fish, bluegill sunfish, 6.76 ppm
- Acute LC50 freshwater invertebrates - Daphnia pulex - 6.4 ppb
- Acute LC50 estuarine and marine organisms:  Data gap. Data being
  requested.
- Freshwater fish early life-stage:  Fathead minnow, Maximum Acceptable
  Theoretical Concentration (MATC) - >0.21 < 0.68 ppb
- No precautionary language is required for birds or fish. However
  carbaryl is highly toxic to aquatic invertebrates. There is
  insufficient information to characterize the chronic toxicity of
  carbaryl to aquatic invertebrates.

Tolerance Assessments

- The Agency is unable to complete a full tolerance reassessment because
  of certain residue chemistry and toxicology data gaps, namely a 1-year
  dog feeding study and the need for residue data on various processed
  food commodities.

Tolerances:
___________

  Commodity                            Parts Per Million

Alfalfa                                       100
Almonds                                         1
Almonds, hulls                                 40
Apples                                         10
Apricots                                       10
Asparagus                                      10
Bananas                                        10
Barley, grain                                   0
Barley, green fodder                          100
Barley, straw                                 100
Beans                                          10
Beans, forage                                 100
Beans, hay                                    100
Beets, garden (roots)                           5
Beets, garden (tops)                           12
Birdsfoot trefoil, forage                     100
Birdsfoot trefoil, hay                        100
Blackberries                                   12
Blueberries                                    10
Boysenberries                                  12
Broccoli                                       10
Brussels sprouts                               10
Cabbage                                        10
Carrots                                        10
Cauliflower                                    10
Celery                                         10
Cherries                                       10
Chestnuts                                       1
Chinese cabbage                                10
Citrus fruits                                  10
Clover                                        100
Clover, hay                                   100
Collards                                       12
Corn, fresh (including sweet) Kernel (K)        5
  + Corn with husk removed (CWHR)
Corn, fodder                                  100
Corn, forage                                  100
Cotton, forage                                100
Cottonseed                                      0
Cowpeas                                         5
Cowpeas, forage                               100
Cowpeas, hay                                  100
Cranberries                                    10
Cucumbers                                      10
Dandelions                                     12
Dewberries                                     12
Eggplants                                      10
Endive (escarole)                              10
Filberts (hazelnuts)                            1
Flax, seed                                      5
Flax, straw                                   100
Grapes                                         10
Grass                                         100
Grass, hay                                    100
Horseradish                                     5
Kale                                           12
Kohlrabi                                       10
Lentils                                        10

Lettuce                                        10
Loganberries                                   12
Maple sap                                       0.5
Melons                                         10
Millet, proso, grain                            3
Millet, proso, straw                          100
Mustard greens                                 12
Nectarines                                     10
oats, fodder, green                           100
Oats, grain                                     0
Oats, straw                                   100
Okra                                            0
Olives                                         10
Oysters                                         0.25
Parsley                                        12
Parsnips                                        5
Peaches                                        10
Peanuts                                         5
Peanuts, hay                                  100
Pears                                          10
Peas (with pods)                               10
Peavines                                      100
Pecans                                          1
Peppers                                        10
Pistachio nuts                                  1
Plums (fresh prunes)                           10
Poultry, fat                                    5
Poultry, meat                                   5
Potatoes                                        0.2(N)
Prickly pear cactus, fruit                     12 0
Prickly pear cactus, pads                      12.0
Pumpkins                                       10
Radishes                                        5
Raspberries                                    12
Rice                                            5
Rice, straw                                   100
Rutabagas                                       5
Rye, fodder, green                            100
Rye, grain                                      0
Rye, straw                                    100
Salsify (roots)                                 5
Salsify (tops)                                 10
Sorghum, forage                               100
Sorghum, grain                                 10
Soybeans                                        5
Soybeans. forage                              100
Soybeans, hay                                 100
Spinach                                        12
Squash, summer                                 10
Squash, winter                                 10
Strawberries                                   10
Sugar beets, tops                             100
Sunflower seeds                                 1
Sweet potatoes                                  0.2
Swiss chard                                    12
Tomatoes                                       10
Turnips, roots                                  5
Turnips, tops                                  12
Walnuts                                         1
Wheat, fodder, green                          100
Wheat (grain)                                   3
Wheat, straw                                  100
Cattle, fat                                     0.1
Cattle, kidney                                  1
Cattle, liver                                   1
Cattle, meat                                    0.1
Cattle, (mbyp)                                  0.1
Goats, fat                                      0.1
Goats, kidney                                   1
Goats, liver                                    1
Goats, meat                                     0.1
Goats, (mbyp)                                   0.1
Horses, fat                                     0.1
Horses, kidney                                  1
Horses, liver                                   1
Horses, meat                                    0.1
Horses, (mbyp)                                  0.1
Sheep, fat                                      0.1
Sheep, kidney                                   1
Sheep, liver                                    1
Sheep, meat                                     0.1
Sheep (mbyp)                                    0.1
Swine, fat                                      0.1
Swine, kidney                                   1
Swine, liver                                    1
Swine, meat                                     0.1

- Based on established tolerances, the theoretical maximum residue
  contribution (TMRC) for carbaryl residues in the human diet is
  calculated to be 5.48 mg/day. The acceptable daily intake (ADI) of
  carbaryl is 0.1 mg/kg/day. The maximum permissible intake (MPI) is 6
  mg/day. To provide for conformity between U.S. tolerances for carbaryl
  and tolerances established by the Codex Alimentarius, Canada and
  Mexico, the expression of the U.S. tolerances for carbaryl will be
  changed to omit reference to 1-naphthol.
- A 1-year dog feeding study is being requested in order to determine
  the effects of carbaryl on kidney dysfunction. The results of these
  data may require that the ADI for carbaryl be recalculated.
- U.S. tolerances for most raw agricultural commodities are supported by
  current residue chemistry data. In some cases, however, more data are
  required.

Summary Science Statement

     Carbaryl has moderate to low mammalian toxicity. It is not
considered to be an oncogen. It is a weak mutagen. Available data
indicates that carbaryl has only low teratogenic potential. Long-term
dietary studies in rats and dogs and a short-term study in humans
(highest dose only) demonstrate an apparent effect on renal function.

     No reentry interval is necessary for carbaryl. Carbaryl is not
expected to contaminate groundwater. Data are insufficient to assess the
environmental fate of carbaryl.

     Carbaryl is extremely toxic to aquatic invertebrates and certain
estuarine organisms. It is extremely toxic to honeybees. It is
moderately toxic to both warmwater and coldwater fishes and has only low
toxicity to birds.

     A full tolerance reassessment cannot be completed. A 1-year dog
feeding study is required, as well as residue data on numerous processed
commodities.

             4. SUMMARY OF REGULATORY POSITION AND RATIONALE

     The Agency has determined that it should continue to allow the
registration of carbaryl. Adequate studies are available to assess the
acute toxicological effects of carbaryl to humans. None of the criteria
listed in section 162.11(a) of Title 40 of the U.S. Code of Federal
Regulations have been met or exceeded. However, because of gaps in the
data base, a full risk assessment of carbaryl cannot be completed.

     A full tolerance reassessment cannot be completed because of
certain residue chemistry and toxicology data gaps, namely a 1-year dog
feeding study and the need for residue data on various processed
commodities.

     No federal or state reentry intervals have been established for
carbaryl or will be established.

     Available data are insufficient to fully assess the environmental
fate of carbaryl. The Agency is requesting data to determine if carbaryl
will contaminate groundwater.

                       5. SUMMARY OF MAJOR DATA GAPS

- Residue data on various processed commodities
- 1-year dog feeding study
- Teratology study in beagle dog
- Hydrolysis study
- Photodegradation studies
- Soil metabolism studies
- Mobility studies
- Dissipation studies
- Accumulation studies
- Acute LC50 freshwater invertebrates study
- Metabolism study in dog versus rat

                          6. CONTACT PERSON AT EPA

Jay S. Ellenberger
Product Manager (12)
Insecticide-Rodenticide Branch
Registration Division (TS-767C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460

Office location and telephone number:
   Room 202, Crystal Mall #2
   1921 Jefferson Davis Highway
   Arlington, VA 22202
   (703) 557-2386

DISCLAIMER:  THE INFORMATION PRESENTED IN THIS CHEMICAL INFORMATION FACT
SHEET IS FOR INFORMATIONAL PURPOSES ONLY AND NOT TO BE USED TO FULFILL
DATA REQUIREMENTS FOR PESTICIDE REGISTRATION AND REREGISTRATION.