WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
VBC/DS/75. 3 (Rev.1)
ORIGINAL : ENGLISH
DATA SHEETS ON PESTICIDES No. 3 Rev.1
CARBARYL
CLASSIFICATION:
Primary use: Insecticide
Secondary use: None
Chemical group: Carbamate
Data sheet No. 3 Rev.1 (8/78)
It must be noted that the issue of a Data Sheet for a
particular pesticide does not imply endorsement of the pesticide by
WHO or FAO for any particular use, or exclude its use for other
purposes not stated. While the information provided is believed to
be accurate according to data available at the time when the sheet
was compiled, neither WHO nor FAO are responsible for any errors or
omissions, or any consequences therefrom.
The issue of this document does Ce document ne constitue pas une
not constitute formal publication. Il ne doit faire
publication. It should not be l'objet d'aucun compte rendu ou
reviewed, abstracted or quoted résumé ni d'aucune citation sans
without the agreement of the l'autorisation de l'Organisation
Food and Agriculture des Nations Unies pour
Organization of the United l'Alimentation et l'Agriculture
Nations or of the World Health ou de l'Organisation Mondiale de
Organization. la Santé.
1. GENERAL INFORMATION
1.1 COMMON NAME: Carbaryl
1.1.1 Identity: 1-naphthalenyl methylcarbamate
1.1.2 Synonyms: Sevin<F;S>³</F>
OMS 29
Local synonyms:
1.2 SYNOPSIS - A moderately toxic carbamate insecticide which is
rapidly metabolized in man and does not accumulate in the
tissues.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics - A white crystalline solid mp 142°C -
the technical product is 99% pure. Non-corrosive.
1.3.2 Solubility - Water 40 mg/l at 30°C; practically insoluble;
soluble in most organic solvents.
It must be noted that the issue of a Data Sheet for a particular
pesticide does not imply endorsement of the pesticide by WHO or FAO for
any particular use, or exclude its use for other purposes not stated.
While the information provided is believed to be accurate according to
data available at the time when the sheet was compiled, neither WHO nor
FAO are responsible for any errors or omissions, or any consequences
therefrom.
The issue of this document does not constitute formal publication.
It should not be reviewed, abstracted or quoted without the
agreement of the Food and Agriculture Organization of the
United Nations or of the World Health Organization.
Ce document ne constitue pas une publication. Il ne dolt faire l'objet
d'aucun compte rendu ou résumé ni d'aucune citation sans l'autorisation
de l'Organisation des Nations Unies pour l'Alimentation et
l'Agriculture ou de l'Organisation Mondiale de la Santé.
R 885 - 1285
1.3.3 Stability - Stable under normal conditions to hydrolysis, light
and heat. Decomposes to 1-naphthol in the presence of alkaline
materials.
1.3.4 Vapour pressure (volatility): Very low: less than 4 x 10-5
torr at 25°C.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations - Water dispersible powders 500, 800 and 850
g/kg; dusts 50100 g/kg; granules 50 and 100 g/kg, oil and water
based liquid suspensions 400-500 g/l. Sprayable powders and
dusts are the most used formulations. There are FAO
specifications for the technical material, dusts and dispersible
powders.
1.4.2 Susceptible pests - A contact insecticide with some systemic
properties, effective against a wide range of insect pests of
field and forage crops, fruit and vegetables; ticks, lice and
fleas.
1.4.3 Use pattern - Pre-harvest treatment of many crops, particularly
cotton, rice, maize, vegetables, potatoes and fruit. Also used
on ornamentals, turf and forest and shade trees. The usual
application rates are 0.25-2 kg/ha, but up to 10 kg/ha may be
used for tree fruits.
Used on cattle, mainly for the control of ticks, lice and fleas,
some of which are disease vectors, and on poultry, cats and dogs.
1.4.4 Unintended effects - No accumulation in the environment. No
evidence of general phytotoxicity when used at recommended rates,
but damage to apples, pears and watermelons has been reported.
Excessive application may retard germination of grasses.
Hazardous to honeybees when applied to corn during pollen shed.
1.5 PUBLIC HEALTH PROGRAMMES - The 50 g/kg formulated powder has been
used for rodent flea control.
1.6 HOUSEHOLD USE - Used in home gardens.
2. TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route - Absorbed by all routes although absorption by
the skin is slow as evidenced by the low dermal toxicity.
2.1.2 Mode of action - Inhibition of cholinesterase which is relatively
rapidly reversible, the half life of the inhibited enzyme being
about 30 minutes.
2.1.3 Excretion products - Vary according to the species. For the rat,
guinea-pig, ewe and man carbaryl is excreted as conjugates of 1-
naphthol. For the monkey and pig there is little hydrolysis of
the ester and the metabolites are conjugates of 4-hydroxycarbaryl
and carbaryl. The major rat metabolites are not found in the
dog. Excretion is largely in the urine.
2.1.4 Toxicity, single dose
Oral: LD50 rat (M): 850 mg/kg
rat (F): 500 mg/kg
Dermal: LD50 rabbit: > 4000 mg/kg
Most susceptible species: possibly guinea-pig LD50 (oral) 280
mg/kg.
2.1.5 Toxicity, repeated doses
Oral: In a dog which received a total of 88.3 mg/kg of carbaryl
intravenously in 11 doses, typical symptoms of-cholinesterase
inhibition occurred after 10 and 15 mg/kg but only a slight
reaction was seen after 5 mg/kg.
Inhalation: Dogs were "acutely poisoned" when exposed in a
chamber at a concentration of 75 mg/m3 for five hours.
Cumulation of compound: Does not accumulate in mammalian tissues.
Cumulation of effect: Dug to its rapid metabolism the repeated
dose necessary to cause cholinesterase depression may only be
slightly less than the single dose.
2.1.6 Dietary studies
Short-term: Survival rate was unaffected by feeding a maximum
of 400 mg/kg diet (60 (mg kg)/day) of carbaryl to mice for 80
weeks.
Increased kidney weights were observed in rats fed 1500 mg/kg (75
(mg/kg)/day) for 96 days.
In dogs given 7.2 mg/kg by capsule on five days a week for one
year there was diffuse cloudy swelling in the kidney tubules. The
no effect level was 1.8 mg/kg (equivalent to a dietary level of
100 mg/kg).
Long-term: Cloudy swelling of the kidney tubules and the central
hepatic cords occurred in rats fed 400 mg/kg (20 (mg/kg)/day)
carbaryl for two years. There was no effect at 200 mg/kg diet
(10 (mg/kg)/day).
2.1.7 Supplementary studies of toxicity
Carcinogenicity
Mouse: No increase in tumour incidence in mice given a maximum
dietary level of 400 mg/kg (20 (mg/kg)/day) for 80 weeks, or in
other studies exposed by dietary, subcutaneous or dermal
applications.
Teratogenicity: Teratogenic effects were observed in the
offspring of dogs given 6.35 mg/kg daily from mating until
weaning but not when given 3.125 mg/kg. in another study terata
were seen from dogs given 5 mg/kg daily but not 2 mg/kg.
Very high doses given to guinea-pigs (300 mg/kg, equivalent to
the LD50) for 10 days during gestation produced abnormal
offspring from the surviving animals.
No terata were observed in offspring from the following pregnant
animals given the maximum dose indicated in parenthesis: mouse
(200 mg/kg diet, equivalent to 10 (mg/kg)/day from day six of
gestation through term), rat (500 (mg/kg)/day throughout
pregnancy), hamster (250 (mg/kg)/day during organogenesis),
rabbit (200 (mg/kg)/day for 10 days) and monkey (0.2, 2.0 and 20
(mg/kg)/day from days 20-38 of gestation).
Mutagenicity: In a dominant lethal study on rats, no evidence of
mutagenic potential was found.
Other effects of reproduction: Changes in the enzymic activity
of the testes and ovaries and reduced female fertility appear in
rats given 5 mg/kg of carbaryl or higher daily for one year.
Neurotoxicity: No delayed neurological lesions in hens
surviving doses up to 2000 mg/kg subcutaneously.
2.1.8 Modifications of toxicity: There was no indication of
potentiation or antagonism when carbaryl was administered
perorally to rats in combination with each of 10 organophosphorus
pesticides.
Association with chlorpromazine produced more than an additive
effect on the suppression by carbaryl of the avoidance response
in rats. The acute toxicity of carbaryl was increased by a
factor of 6.5 when rats were fed a low protein diet.
2.2 TOXICOLOGY - MAN
2.2.1 Absorption - See 2.1.1; ingestion is the main route of
absorption.
2.2.2 Dangerous doses
Single: A man who swallowed 250 mg of carbaryl had violent
epigastric pain 20 minutes after the dose and later profuse
sweating. He developed great lassitude and vomited twice. A
total of 0.3 mg of atropine sulfate was given and recovery was
complete two hours after ingestion.
Repeated: Not known - because of the rapid metabolism it has
been suggested that the dangerous dose may only be slightly
smaller than the dangerous single dose.
2.2.3 Observations of occupationally exposed workers - Workers exposed
to air concentrations of 0.23 to 31 mg/m3 excreted large
amounts of 1-naphthol. Whole blood cell cholinesterase activity
was slightly depressed but there were no clinical signs.
Healthy men with occupational exposure have been found to excrete
conjugated plus free 1-naphthol at the rate of 10 mg/l or higher
in the urine while unexposed men excrete 1.5 to 4.0 mg/l.
2.2.4 Observations on exposure of the general population - Total diet
studies in one country have demonstrated that man ingests 0.15 mg
per day or less of carbaryl in his diet. This is equivalent to
0.002 mg/kg for a 70 kg man.
2.2.5 Observations of volunteers - In men given 0.12 mg/kg of carbaryl
daily for six weeks there was an increase in the ratio of urinary
amino acid nitrogen to that of creatinine (0.18 compared to 0.15
for the control group). It is suggested that carbaryl might
decrease the ability of the proximal convoluted tubules to
reabsorb amino acids. This effect was not observed at a dose
level of 0.06 mg/kg. At neither dose was there any effect on
plasma or erythrocyte cholinesterase.
2.2.6 Reported mishaps - Blurred vision, headache, stomach ache and
vomiting have been reported among workers using carbaryl without
proper precautions. In general recovery was rapid and there were
no deaths.
2.3 TOXICITY TO NON-MAMMALIAN SPECIES
(The entries in these sections are intended to draw attention to
special risks and to give warnings of any needs for special
presentation.)
2.3.1 Fish - Toxic to some fish; 96 hours TLm values usually in the
range of 1-10 mg/l.
2.3.2 Birds - Low toxicity to most birds (usually in the range 800 ->
2000 mg/kg).
2.3.3 Other species - Toxic to bees and crustaceans.
3. FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF
COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY
(For definition of categories, see introduction.)
Liquids 250 g/i or more, category 4.
All other formulations, category 5.
3.2 TRANSPORTATION AND STORAGE
Formulations in category 4 - Should be transported or stored in
clearly labelled rigid and leakproof containers and away from
containers of food and drink. Storage should be under lock and
key and secure from access by unauthorized persons and children.
Formulations in category 5 - Should be transported or stored in
clearly labelled leakproof containers out of reach of children
away from food.
3.3 HANDLING
Formulations in category 4 - Protective clothing (see sheet 4)
should be provided for those handling concentrates. Adequate
washing facilities should be available close at hand. Eating,
drinking and smoking should be prohibited during handling and
before washing after handling.
Formulations in category 5 - No special facilities other than
those needed for handling of any chemical need be required.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINER - If not
decontaminated container must either be burned or crushed and
buried below topsoil. Care must be taken to avoid subsequent
contamination of water sources. Container may be decontaminated
(for method see paragraph 4.3 on sheet 4). Decontaminated
containers should not be used for food and drink.
3.5 SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS
Formulations in category 4 - Pre-employment medical examination
for workers desirable. Workers suffering from active hepatic or
renal disease should be excluded from contact. Pre-employment
and routine cholinesterase tests for workers desirable. If
exposure is considerable, urinary I-naphthol test is advisable.
Training of workers in techniques to avoid contact essential.
Formulations in category 5 - Warning of workers to avoid contact
essential.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
All formulations - Pilot and loaders should have special
training in application methods and early symptoms of poisoning.
Flagmen, if used, should wear overalls and be located well away
from the dropping zone.
3.7 LABELLING
Formulations - Formulations in category 4
Minimum cautionary statement - Carbaryl is a carbamate
insecticide which inhibits cholinesterase. It is poisonous if
swallowed. It may be absorbed through the skin. Avoid skin
contact; wear protective gloves, clean protective clothing and a
respirator when handling the material. Wash thoroughly with soap
and water after using. Keep the material out of reach of
children and well away from foodstuffs, animal feed and their
containers. If poisoning occurs, call a physician. Atropine is
a specific antidote and artificial respiration may be needed.
Pralidoxime and opiates should not be used.
Formulations - Formulations in category 5.
Minimum cautionary statement - This formulation contains
carbaryl, a carbamate insecticide, which inhibits cholinesterase.
It is poisonous if swallowed. Keep the material out of the reach
of children and well away from foodstuffs, animal feed and their
containers.
If poisoning occurs, call a physician. Atropine is a specific
antidote and artificial respiration may be needed.
3.8 RESIDUES IN FOOD
3.8.1 Maximum residue levels - The Joint FAO/WHO Meeting on Pesticide
Residues has recommended maximum residue levels.
4. PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
4.1.1 General - Carbaryl is a moderately toxic carbamate insecticide
which is quickly metabolized and is therefore likely only to be a
hazard as an acute poison. It can be absorbed by mouth, by
inhalation of the dust and also to some extent through the intact
skin. It is important that concentrated formulations be washed
immediately from the skin and eyes.
4.1.2 Manufacture and formulation
T.L.V.: (ACGIH) 5 mg/m3; (USSR) 1 mg/m3.
Although volatility is low, vapour and dusts should be controlled
preferably by mechanical means. Protective equipment for the
skin and respiratory protection should be worn.
4.1.3 Mixers and applicators - When opening the container and when
mixing care should be taken to avoid contact with the mouth and
eyes. If necessary a facial visor and gloves should be worn.
Mixing, if not mechanical, should always be carried out with a
paddle of appropriate length. The applicator should avoid
working in spray mist and avoid contact with the mouth. Splashes
must be washed immediately from the skin or eyes with large
quantities of water. Before eating, drinking or smoking, hands
and other exposed skin should be washed.
4.1.4 Other associated workers (including flagmen in aerial operations)
- Persons exposed to carbaryl and associated with its application
should observe the precautions described above in 4.1.3 under
"mixers and applicators".
4.1.5 Other populations likely to be affected - With good agricultural
practice subject to 4.2 below other populations should not be
exposed to hazardous amounts of carbaryl.
4.2 ENTRY OF PERSON INTO TREATED AREAS - The general population
should be kept out of sprayed areas until the spray has dried.
4.3 DECONTAMINATION OF SPILLAGE AND CONTAINERS - The contents of
containers should be emptied in a diluted form into a deep pit
taking care to avoid ground waters. The empty container may be
decontaminated by rinsing two or three times with water and
scrubbing the sides. An additional rinse should be carried out
with 5% sodium hydroxide solution which should remain in the
container overnight. Impermeable gauntlets should be worn during
this work and a soakage pit should be provided for the rinsings.
Decontaminated containers should not be used for food and drink.
Spillage of carbaryl and its formulations should be removed by
washing with 5% sodium hydroxide solution, if available, and by
rinsing with large quantities of water.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning - Early symptoms may include
excessive sweating, headache, weakness, giddiness, nausea,
vomiting, stomach pains, blurred vision, slurred speech and
muscle twitching.
4.4.2 Treatment before person is seen by a physician, if these symptoms
appear following exposure - The person should stop work
immediately, remove contaminated clothing, wash the affected skin
with soap, if available, and flush the area with large quantities
of water. If swallowed, vomiting should be induced if the person
is conscious.
5. FOR MEDICAL AND LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF POISONING
5.1.1 General information - Carbaryl is a carbamate insecticide of
moderate acute toxicity. It is absorbed via the gastrointestinal
tract and by inhalation. To a lesser extent it is also absorbed
by the intact skin. Its mode of action is by reversibly
inhibiting acetyl cholinesterase. Because of its rapid
metabolism and excretion it does not accumulate in the tissues.
It has been suggested that the dangerous repeated dose may be
only slightly smaller than the dangerous single dose.
5.1.2 Symptoms and signs - Symptoms of poisoning may include excessive
sweating, headache, weakness, giddiness, nausea, vomiting,
stomach pains, blurred vision, slurred speech and muscle
twitching.
5.1.3 Laboratory - Because carbaryl is a reversible inhibitor of
cholinesterase, measurements of blood cholinesterase in cases of
poisoning must be made by a method which minimizes reactivation,
if a depression of cholinesterase is to be demonstrated. The
presence of more than trace amounts of 1-naphthol in the urine is
also indicative of absorption of carbaryl. Men with occupational
exposure to carbaryl have been found to excrete conjugated and
free I-naphthol at the rate of 10 mg/l or slightly higher
compared to levels of 1.5 to 4.0 mg/l in unexposed men. A level
of 31 mg/l in urine in an 18-month-old child 18 hours after
ingestion of an unknown quantity of carbaryl was compatible with
recovery.
5.1.4 Treatment - If the pesticide has been ingested in excess of 1 g
carbaryl equivalent, unless the patient is vomiting, rapid
gastric lavage should be performed using 5% sodium bicarbonate if
available. For skin contact the skin should be washed with soap
water. If the compound has entered the eyes they should be
washed with water or isotonic saline. Since the symptoms of
poisoning with carbaryl disappear comparatively rapidly, atropine
treatment is often not necessary by the time the patient reaches
the place where the antidote is available. In the case of
accidental poisoning or of manifest symptoms 1-2 mg of atropine
sulfate (adult dose) may be given intramuscularly or even
intravenously and repeated as necessary. Care should be taken to
avoid overdosage of atropine in the case of carbaryl poisoning
especially in children. In extreme cases if the patient is
unconscious or in respiratory distress, mechanical respiratory
assistance with oxygen may be required. Contraindications are
oximes such as pralidoxime, barbiturates and central stimulants
of all kinds.
5.1.5 Prognosis - If the acute toxic effect is survived the chances of
complete recovery are very good.
5.1.6 References of previously reported cases - Case histories and
general methods for treatment are given in:
Hayes, W. J., jr (1963) Clinical Handbook on Economic Poisons,
U.S. Publ. Hlth Ser. Publn., No. 476 (revised)
Best, E. M., jr & Murray, B. L. (1962) J. occup. Med.,
4, 507-517
5.2 SURVEILLANCE TESTS - Due to the lability of inhibition,
measurements of the blood cholinesterase level are not suitable
for surveillance. Monitoring of levels of I-naphthol in urine
gives better indication of the degree of absorption.
Test Normal Hazard Symptomatic
level level level
Urinary 1.5-4 mg/l > 10 mg/l > 30 mg/l
1-naphthol and conjugates
5.3 LABORATORY METHODS
5.3.1 Detection and assay of compound - Because of its rapid metabolism
it is unlikely that measurable amounts of carbaryl will be found
in human tissues. Free and conjugated 1-naphthol will, however,
appear in urine after exposure to carbaryl. A method which can
determine carbaryl and I-naphthol separately is described by
Stansbury & Miskus (1964). The official AOAC (1970) method is
suitable for regulatory purposes and this method has recently
been extended by Union Carbide Co. (1973) to include the major
plant metabolites as "total toxic residues". A gas
chromatographic method (Cohen et al., 1970) has also been used
successfully.
5.3.2 Other tests in cases of poisoning - Cholinesterase levels in
blood are unreliable as a routine test to detect poisoning by
carbaryl. However, shortly after absorption, depression of
cholinesterase may be demonstrated by:
Fleisher, J. H. & Pope, E. J. (1954) A.M.A. Arch. Industr.
Hyg, 9, 323
Ellman, G. L., Courtney, K. D., Andres, V., jr & Featherstone, R.
M. (1961) Biochem. Pharmacol., 7, 88-95
Urinary levels of 1-naphthol may also be used to determine the
degree of absorption see:
Carpenter et al. (1961) and Best & Murray (1962)
REFERENCES
Stansbury, N. A., jr & Miskus, R. (1964) In: Zweig, G. (ed.) Analytical
Methods for Pesticides, Plant Growth Regulators and Food
Additives, Vol. II, Academic Press, New York & London, p. 437
AOAC (1970) Official Methods of Analysis of the AOAC, 11th ed., p. 493
Union Carbide Co. (1973) Summary of Carbaryl Residues, Section V
(private communication).
Cohen, I. C., Norcup, J., Ruzicka, J. H. A. & Wheals, B. B. (1970) An
Electron-capture Gas Chromatographic Method for the Determination
of some Carbamate Insecticides as 2,4-Dinitrophenyl Derivatives
of their Phenol Moieties, J. Chromate., 49, 215
Carpenter, C. P., Weill, C. S., Palm, P. E., Woodside, M. W., Nair, J.
H., III & Smythe, H. F., jr (1961) Mammalian Toxicity of 1-
Naphthyl-N-methylcarbamate (Sevin Insecticide), J. Agric. Fd
Chem., 9, 30
Best, E. M., jr & Murray, M. L. (1962) observations on Workers Exposed
to Sevin Insecticide: a preliminary reort, J. occup. Med., 4,
507