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benomyl (Benlate) Chemical Profile 8/89

                                      benomyl
      CHEMICAL NAME:      Methyl 1-(butylcarbamoyl)-2-benzimidazole carbamate
                          (6)
      TRADE NAME(S):      Benlate, Tersan-1991 (56)
      FORMULATION(S):     Wettable powder 50%; Benlate OD 50% oil
                          dispersible (56).
      TYPE:               Carbamate fungicide
      BASIC PRODUCER(S):  E.I. duPont de Nemours and Co., Inc.
                          Biochemicals Dept.
                          1007 Market St.
                          Wilmington, DE 19898
      STATUS:  General use.  RPAR; criteria possibly met or
      exceeded:  reduction in nontarget species (rebutted), mutagenicity,
      teratogenicity, reproductive effects, hazard to wildlife.  PD 1
      published 12/6/77.  PD 2/3 completed and Notice of Determination
      published 8/30/79; comment period closed 9/28/79.  PD 4 completed and
      Notice of Determination published 10/20/82.  The Notice requires use
      of either cloth or commercially available disposable dust masks by
      mixer/loaders of benomyl intended for aerial application and that
      registrants of benomyl products conduct field monitoring studies to
      identify residues that may enter aquatic sites after use on rice (22).
      PRINCIPAL USES:  Foliar systemic against wide range of diseases on
      fruits, nuts, vegetables, field crops, turf and ornamentals.  Also
      used against Dutch elm disease.  Both a preventative and eradicant
      fungicide (48).
      The DuPont Company has voluntarily withdrawn all postharvest uses of
      benomyl (Benlate) Fungicide in the United States.  Crops affected
      include apples, pears, pineapples, citrus, and all stone fruits.
      The withdrawl from postharvest application is effective as of 8/15/89.
                                   I.  EFFICACY
           Resistance in some fungus strains has been noted (48).
                             II.  PHYSICAL PROPERTIES
      MOLECULAR FORMULA:  C14 H18 N4 O3 (26)
      MOLECULAR WEIGHT:   290.3 (26)
      PHYSICAL STATE:     Colorless crystalline solid (pure compound) (26)
      ODOR:               Faint acrid odor (pure compound) (26)
      MELTING POINT:      Decomposes before melting (pure compound) (26)
      SOLUBILITY:         3.8 mg/l water at pH 7 and 20 C (pure compound)
                          (26)
                          III.  HEALTH HAZARD INFORMATION
      OSHA STANDARD:  NA
      NIOSH RECOMMENDED LIMIT:  NA
      ACGIH RECOMMENDED LIMIT:  TWA (Time Weighted Average) = 0.8 ppm, 10
                                mg/m3; STEL (Short Term Exposure Limit) = 1.3
                                ppm, 15 mg/m3 (15a).
      TOXICOLOGY
           A.  ACUTE TOXICITY
               DERMAL:  It is mildly irritating to the skin but without
                        dermatitis hazard (26).
                        LD50 = >10,000 mg/kg (rabbit) (31d)
               ORAL:    LD50 = >10,000 mg/kg (rat) (6)
               INHALATION:  LC50 = >2 mg/l (dry product, 4-hour exposure,
                            rat) (31d)
               EYES:  10 mg of dry 50% powder or 0.1 ml of 10%
      suspension in mineral oil caused only temporary mild conjunctival
      irritation (rabbit (31d).
           B.  SUB-CHRONIC AND CHRONIC TOXICITY:
           In 90-day feeding trials there was no evidence of toxicity for
      rats receiving 2500 mg/kg diet.  In 2-year feeding trials with rats and
      dogs a low order of toxicity occurred (26).
           In two-year feeding studies (with 2500 ppm the highest dietary
      level), the no-observable effect level was 2500 ppm for rats and 500
      ppm for dogs.  In dogs fed 2500 ppm, there was biochemical evidence of
      impaired liver function and histological evidence of liver cirrhosis.
      No oncogenic effects were observed in either rats or dogs (31d).
      Rat reproduction, 3-generation:  No adverse effect on reproduction
      performance at dietary levels as high as 2500 ppm; no pathological
      changes found in tissues from weanling pups of F3B generation (2500
      ppm) (31d).
      Teratogenicity (rat, rabbit):  Not embryotoxic or teratogenic to rats
      by dietary administration at levels as high as 5000 ppm (equivalent to
      373 mg/kg/day, approx.).  By gavage, statistically significant
      teratogenic response was obtained at dose levels of 62.5 mg/kg/day and
      above, but not at 30 mg/kg/day and below.  No teratogenic effects were
      found in studies with rabbits fed 500 ppm in the diet (equivalent to 20
      mg/kg/day, approx.) (31d).
      Mutagenicity:  Negative results were obtained in the following assays:
      1.   Host mediated assay
      2.   CHO point mutation
      3.   Reverse-mutation tests
      4.   Rat dominant lethal at 2500 ppm in diet
      5.   Drosophila test for measuring recessive lethal damage
      6.   DNA repair (UDS)
      Weak activity has been reported by various investigators in some S.
      typhimurium strains.  However, other Ames tests were negative.  Some
      cytogenetic effects have been reported; such effects may be explained
      by the spindle effects of benomyl (31d).
                        IV.  ENVIRONMENTAL  CONSIDERATIONS
           Hazardous to fish.  Relatively nonhazardous to honey bees.
      Nonphytotoxic when used as directed (48).
           The LC50 for mallard ducks and quail was >5000 mg/kg (26).
      Bluegill sunfish LC50 (96-hour exposure) is 2.6 ppm
      Catfish LC50 (96-hour exposure) is 0.071 ppm
      Goldfish LC50 (96-hour exposure) is 4.2 ppm
      Rainbow trout LC50 (96-hour exposure) is 0.41 ppm (31d).
           Benomyl degrades slowly in the soil.  The half-life of the total
      benzimidazole-containing residues is about 3 to 6 months on turf,
      representing a vegetative situation, and about 6 to 12 months on bare
      soil - J. Ag. Food Chem. 22(3) 413 (1974).  Very little leaching or
      runoff occurs with benomyl even under rigorous exposure conditions
      (31d).
                      V.  EMERGENCY AND FIRST AID PROCEDURES
           The chemical information provided below has been condensed
      from original source documents, primarily from "Recognition and
      Management of Pesticide Poisonings", 3rd ed. by Donald P.  Morgan,
      which have been footnoted.  This information has been provided in
      this form for your convenience and general guidance only.  In
      specific cases, further consultation and reference may be required
      and is recommended.  This information is not intended as a sub-
      stitute for a more exhaustive review of the literature nor for the
      judgement of a physician or other trained professional.
           If poisoning is suspected, do not wait for symptoms to develop.
      Contact a physician, the nearest hospital, or the nearest Poison
      Control Center.
      KNOWN OR SUSPECTED ADVERSE EFFECTS:  Mild irritant.  Does not
      inhibit cholinesterase enzyme (25).
           SKIN CONTACT:  Wash contaminated skin with soap and water (25).
           INGESTION:     Ingestions of small amounts (less than 10 mg/kg
      body weight) occurring less than an hour before treatment, are probably
      best treated by:  Syrup of Ipecac, followed by 1-2 glasses of water.
      Dose for adults and children over 12 years:  30 ml.  Dose for children
      under 12 years:  15 ml (25).
           EYE CONTACT:   Flush contaminated eyes with copious amounts of
      fresh water for 15 minutes (25).
      NOTES TO PHYSICIAN:
      INGESTIONS of LARGE amounts (more than 10 mg/kg) occurring less than an
      hour before treatment, should probably be treated by gastric lavage:
      A.   INTUBATE stomach and ASPIRATE contents.
      B.   LAVAGE stomach with slurry of ACTIVATED CHARCOAL in 0.9% saline.
           Leave 30-50 gm activated charcoal in the stomach before
           withdrawing tube.
      C.   SODIUM SULFATE, 0.25 gm/kg in tap water, as a cathartic.
           CAUTION:  Hydrocarbons (kerosene, petroleum distillates) are
                     included in some formulations of these chemicals.
                     Ingestions of very LARGE AMOUNTS may cause CNS
                     depression.  In this case, IPECAC IS CONTRAINDICATED.
                     Also, gastric intubation incurs a risk of HYDROCARBON
                     PNEUMONITIS.  For this reason observe the following
                     precautions:
                     (1)  If the victim is unconscious or obtunded and
                          facilities are at hand, insert an ENDOTRACHEAL TUBE
                          (cuffed, if available) prior to gastric intubation.
                     (2)  Keep victim's HEAD BELOW LEVEL OF STOMACH during
                          intubation and lavage (Trendelenburg, or left
                          lateral decubitus, with head of table tipped
                          downward).  Keep victim's head turned to the left.
                     (3)  ASPIRATE PHARYNX as regularly as possible to remove
                          gagged or vomited stomach contents.
      INGESTIONS occurring MORE THAN an HOUR before treatment are probably
      best treated only by ACTIVATED CHARCOAL, 30-50 gm, and SODIUM or
      MAGNESIUM SULFATE, 0.25 gm/kg, as described above.
      There are no specific antidotes for these chemicals.  Because
      manifestations of toxicity do occasionally occur in peculiarly
      predisposed individuals, MAINTAIN CONTACT with victim for at least 72
      hours so that unexpected adverse effects can be treated promptly (25).
                        VI.  FIRE AND EXPLOSION INFORMATION
      GENERAL:  Auto ignition temperature:  220 C.  May be ignited by heat or
      open flame.  Fine dust dispersed in air (particularly in confined
      spaces) may ignite if exposed to high temperature ignition source.  Use
      only with adequate ventilation.
      Fire fighting:  If area is heavily exposed to fire and if conditions
      permit, let fire burn itself out since water may increase the area
      contaminated.  Wear self-contained breathing apparatus and appropriate
      protective equipment for fire fighting and cleanup.
      Hazardous decomposition product:  n-butylisocyanate, a strong
      lachrymator (31e).
      EXTINGUISHER TYPE:  Use multi-purpose dry powder or water spray.  Cool
      exposed containers with water (31e).
                                VII.  COMPATIBILITY
           Compatible with other alkaline pesticides (48).
                            VIII.  PROTECTIVE MEASURES
      STORAGE AND HANDLING:  Keep out of reach of children.  Keep away from
      fire and sparks.  Never allow products containing benomyl to become wet
      during storage.  This may lead to certain chemical changes which will
      reduce the effectiveness of these formulations as fungicides.  Keep
      container tightly closed when not in use.  Do not contaminate water,
      food, or feeds by storage.  Do not reuse container (31d).
      PROTECTIVE CLOTHING:  Where dust levels may exceed AEL value, an
      approved pesticide respirator, goggles, and protective clothing should
      be worn (31e).
                       IX.  PROCEDURES FOR SPILLS AND LEAKS
                     IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
                                  (800) 424-9300
                      PESTICIDE TEAM SAFETY NETWORK/CHEMTREC
           Clean up promptly by scoop or vacuum; flush remaining residue with
      water (prevent contamination of sewers or bodies of water).  Where dust
      levels may exceed AEL value, an approved pesticide respirator, goggles,
      and protective clothing should be worn (31e).
                               X.  LITERATURE CITED
       6.  Farm Chemicals Handbook, 66th ed.  1980.  G. L. Berg, C. Sine,
               S. Meister, and H. Shephard, eds.  Meister Publ. Co.,
               Willoughby, OH.
      15a. American Conference of Governmental Industrial Hygienists.  1983.
               TLVs:  threshold limit values for chemical substances and
               physical agents in the work environment with intended changes
               for 1983-84.  Cincinnati, OH.  93 pp.
      22.  U.S. Environmental Protection Agency, Office of Pesticide
               Programs.  1983.  June 1983 status report on rebuttable
               presumption against registration (RPAR) or special review
               process, registration standards and the data call in
               programs.  Washington, DC.  45 pp.
      25.  Morgan, D.P.  1982.  Recognition and management of
               pesticide poisonings, 3rd ed.  U. S. Environmental Protection
               Agency, Washington, DC.  120 pp.
      26.  The Pesticide Manual:  A World Compendium, 6th ed.  1979.  C. R.
               Worthing, ed.  The British Crop Protection Council, Croydon,
               England.  655 pp.
      31d. E. I. du Pont de Nemours and Co., Inc., Biochemicals Department.
               1983.  Technical data sheet:  benomyl.  Wilmington, DE.
      31e. E. I. du Pont de Nemours and Co., Inc., Biochemicals Department.
               1982.  Material safety data sheet for Benlate fungicide.
               Wilmington, DE.
      48.  Harding, W.C.  1979-80.  Pesticide profiles, part two:  fungicides
               and nematicides.  Univ. Maryland, Coop. Ext. Service Bull.
               283, 22 pp.
      56.  Farm Chemicals Handbook, 70th ed.  1984.  R. T. Meister, G. L.
               Berg, C. Sine, S. Meister, and J. Poplyk, eds.  Meister
               Publishing Co., Willoughby, OH.
      8/29/89