WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
VBC/DS/82.55
ORIGINAL: ENGLISH
DATA SHEET ON PESTICIDES No. 55
METHOMYL
CLASSIFICATION:
Primary use: Insecticide
Secondary use : Nematicide
Chemical group: Carbamate
Date issued: January 1983
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: Methomyl (BSI, ISO, ANSI, JMAF)
1.1.1 Identity: IUPAC: S-methyl N-(methylcarbamoyloxy)
thioacetimidate
CAS No. 1: Acetimidic acid, thio-N-
((methylcarbamoyl)oxy)-,methyl ester
CAS Reg. No.: 16752-77-5
Mol. Form.: C5H10N2O2S
Str. Form.:
Mol. Wt.: 162.23
1.1.2 Synonyms: Insecticide 1179; LannateR: Mesomile; NudrinR:
SD 14999; WL 18236
1.2 SYNOPSIS: Methomyl is a broad spectrum carbamate insecticide; a
fast acting anti-cholinesterase agent; and, a direct contact and
stomach action poison. A plant systemic of high acute toxicity to
mammals, it is non-cumulative and rapidly metabolized in both
plants and animals to substances of lower toxicity. Methomyl is
particularly effective against organophosphorus resistant pests.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics - The pure compound is a colourless
crystalline solid with melting point of 78-79°C and a density d24
of 1.2946. Methomyl has a slightly sulfurous odour. 4
The aqueous solution is non-corrosive.
1.3.2 Solubility - (25°C) 58 g/kg water
1000 g/kg methanol
730 g/kg acetone
420 g/kg ethanol
220 g/kg isopropanol
30 g/kg toluene
Completely soluble in most other organic solvents.
1.3.3 Stability - Methomyl is stable in the solid form and in aqueous
solutions at pH 7.0 or less, it rapidly decomposes in alkaline
solutions and in moist soils.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations - Water soluble powders (40 and 900 g
a.i./kg); wettable powder (250 g a.i./kg); water soluble liquid
(200-360 g a.i./kg).
1.4.2 Susceptible pests - Methmyl is effective against a wide range of
plant parasitic insects and stored product pests, especially
those which are resistant to organophosphorus pesticides.
1.4.3 Use pattern - Methomyl is used most effectively as a foliar
treatment of certain vegetable and fruit crops, field crops and
commercial plantings of ornamentals.
1.4.4 Unintended effects - Methomyl is toxic to many beneficial insects
and other arthropods
1.5 PUBLIC HEALTH PROGRAMMES - No recommended usage reported.
1.6 HOUSEHOLD USE - No recommended usage reported.
2. TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption routes - Methomyl may be absorbed from the
gastrointestinal tract; through the intact skin; and through
inhalation of fine spray mist or dust.
2.1.2 Mode of action - Methomyl acts through inhibition of
cholinesterase activity which is rapidly and spontaneously
reversed within minutes.
2.1.3 Excretion products - In animals methomyl is metabolized by
hydrolysis. Metabolism and excretion is very rapid in
rats, the degradation products are carbon dioxide, acetonitrile,
and urinary polar metabolites in a ratio of 1:2:1. Methomyl, its
oxidation products and their glucuronide conjugates have not been
found in rat urine.
2.1.4 Toxicity, single dose
Oral LD50: Rat (M) 14.3-20.2 mg a.i./kg b.w.
Rat (F) 21.8-25.4 mg a.i./kg b.w.
Mouse 10.0 mg a.i./kg b.w
Mule deer 11.0-22.0 mg a.i./kg b.w.
Oral LD50: Beagle 30 mg a.i./kg b.w.
Hamster 30 mg a.i./kg b.w.
Monkey 40 mg a.i./kg b.w.
Guinea-pig 15 mg a.i./kg b.w.
Dermal LD50: Rat (M) 1000 mg a.i./kg b.w.
Rabbit 5880 mg a.i./kg b.w.
Subcutaneous LD50: Rat 9.0 mg a.i./kg b.w.
Inhalation LC50: Rat 77.0 mg a.i./l
During the inhalation test the rats exhibited dose related
clinical signs of toxicity which rapidly disappeared in the
survivors during the post-exposure observation period.
Most susceptible species: Mice appear to be the most susceptible
among the animals tested, fish are the most susceptible among all
animals tested.
2.1.5 Toxicity, repeated doses
Oral: Six male rates given 5.1 (mg/kg b.w.)/day by incubation in
10 doses over two weeks showed only mild signs of toxicity; no
cumulation of effects; and, no depression of cholinesterase
function. There were no mortalities.
Dermal: a 5% aqueous solution of methomyl applied to the intact
skin of male and female rabbits in 15 daily doses at 200 mg/kg
b.w. for six hour intervals produced no cumulative effects; no
mortalities; and, only mild clinical signs of toxicity. In a
similar application to abraided skin the signs were more severe
and only eight of 10 rabbits survived the treatment. No
histopathologic effects were produced in either group.
Dermal irritation and sensitization: Methomyl is a mild,
nonsensitizing skin irritant in guinea-pigs, a mild eye irritant
in guinea-pigs and rabbits.
2.1.6 Dietary studies
Short-term: Rats of both sexes were fed on diets containing
methomyl at 0, 10, 50, 125 and 250 mg/kg of diet for 90 days.
After six weeks the 125 mg diet was raised to 500 mg/kg of diet.
All the test animals survived the treatment. Rats on the two
highest level diets had significantly lower body weight gains
than the control rats. No treatment related clinical,
haematological, biochemical, urinary or histopathologic signs of
toxicity were observed.
One-year-old beagles of both sexes were fed methomyl containing
diets at 0, 50 100, and 400 mg/kg levels for 90 days. No
treatment related adverse effects were observed.
Long-term: Rats of both sexes were placed on diets containing
methomyl at 0, 50, 100, 200 and 400 mg/kg levels for two years.
Males on the 400 mg diet and females on the 200 and 400 mg diet
had significantly reduced body weights. All animals survived the
treatment, histopathologic alterations of kidneys occurred in
males and females at the 400 and 200 mg diet levels respectively,
spleen histopathologic alterations occurred in females at the two
highest treatment levels. There were no treatment related
increases in neoplastic lesions.
In a two-year study, year-old beagles were placed on diets
containing methomyl at 0, 50, 100, 400 and 1000 mg/kg levels. No
treatment related adverse effects were observed in the 50-100 mg
diet groups. Anaemia and histopathologic changes in the kidney
and the spleen were observed in the dogs fed the two highest
level diets. Mild clinical signs of toxicity and histopathologic
changes in the liver and bone marrow were observed only in the
1000 mg diet group. Two mortalities occurred among the females
in the 1000 mg diet group, an original animal and its
replacement. No treatment related increase in neoplastic lesions
was observed. The no-adverse-effect levels for rats and dogs
were calculated from the 100 mg/kg diet to be 5.0 and 2.5 (mg/kg
b.w.)/day respectively.
2.1.7 Supplementary studies of toxicity
Carcinogenicity: No evidence of methomyl-treatment related
carcinogenicity was reported in the dietary and subacute toxicity
studies described in sections 2.1.5 and 2.1.6 above. Methomyl
was found to be carcinogenically inactive in a transplacental,
host-mediated hamster cell culture assay. Nitrosomethomyl was
carcinogenically active in six- to eight-week-old rats given 50
mg/kg b.w. once a week for 10 weeks. There were no survivors by
the 120th week of observation. Fourteen of 16 males and eight of
16 females developed tumours in the nonglandular stomach tissue,
five males and four females had carcinomas.
Nitrosation of ingested methomyl by dietary nitrites in the
acidic gastric environment is unlikely to be carcinogenically
threatening since the reaction yield under the best of conditions
is very low. Under simulated stomach conditions, over a
three-hour period no significant amount of nitrosomethomyl was
produced in an in vitro attempt.
Teratogenicity: No evidence of teratogenetic effects was found in
29-day and full term foetuses of pregnant rabbits fed methomyl at
50 and 100 mg/kg diet levels on days 8-16 of gestation. A study
in rats at levels of 0, 50, 100 and 400 mg/kg of diet showed no
evidence of teratogenic or embryotonic effects.1
1 Information provided by the manufacturer.
Mutagenicity: No evidence of cellular alteration was observed in
circulating erythrocytes in rabbits following a single injection
of a low dose of methomyl. No evidence of mutagenic potential
was found in a number of microbial assay systems; histidine
autotrophs of S. typhimurium, diploid S. cerevisiae, E. coli and
R. subtilis. Liver microsomal enzyme activation of methomyl did
not change its potential but nitrosomethomyl was found to be very
positively mutagenic in the microbial assay systems and in human
skin cell cultures, producing irreversibly DNA alterations in the
latter test.
Reproduction: No adverse effects in reproduction and lactation
performance occurred in a three-generation study of rats fed
methomyl at 50 and 100 mg/kg diet levels. No pathological
changes were observed in the F-3b generation animals.
Neurotoxicity: A 28 mg/kg b.w. dose of 5% methomyl in acetone was
administered orally to one-year-old hens, neither paralysis of
the limbs, nor sciatic nerve degeneration were observed.
2.1.8 Modifications of toxicity - The response in rats, to the combined
administration of methomyl (200 mg/kg diet) and caffeine (30 mg %
aqueous solution) or ethanol (10% aqueous solution) produced
evidence of interaction resulting in decreased growth rates and
elevated relative-weights of adrenals in animals of both sexes.
In males hepatic lipid levels increased, in females the relative-
weights of kidneys and fasting blood glucose levels increased.
2.2 TOXICOLOGY - MAN
2.2.1 Absorption route - Methomyl may be absorbed from the
gastrointestinal tract; through the intact skin; and, by
inhalation of spray mist and dust.
2.2.2 Dangerous doses
Single: The accepted range of the maximum lethal dose is 5-50
mg/kg b.w. In a report of an accidental poisoning, the fatal dose
was found to be 12-15 mg/kg b.w. (see 2.2.6).
Repeated: No information. Because methomyl is rapidly degraded
in organisms and the environment, chronic toxicity is not
expected to be a major problem.
2.2.3 Observations among occupationally exposed workers - There have
been several reports of poisoning among agricultural workers,
pilots, spraymen and pesticide manufacturing workers. Fatalities
are rare and hospitalization is infrequent. Lack of proper
precaution in handling the pesticide is the most frequent cause
of poisoning. Agricultural workers have become ill while using
manual ULV sprayers and during manual dusting of vegetables. The
symptoms are usually mild and often persist for several days. In
one pesticide manufacturing plant, short-term hospitalization of
employees for methomyl related illnesses was a common occurrence
until housekeeping practices and physical conditions were
improved.
2.2.4 Observations on exposure of the general public - No information.
With good agriculture practice the general public should not be
exposed to hazardous amounts of methomyl.
2.2.5 Observations of volunteers - In an allergy screening programme
one out of 29 agricultural workers with a history of exposure to
methomyl showed a positive reaction to a methomyl patch test.
2.2.6 Reported mishaps - There have been many reports of accidental and
suicidal poisonings but few fatalities from ingestion of
methomyl. In one episode in the West Indies, methomyl from an
unlabelled container was used in the preparation of food. Three
fatalities occurred within minutes of eating, death was preceded
by severe clinical signs of toxicity; perfuse sweating,
involuntary defecation, vomiting and convulsions. A dog died
following ingestion of vomitus. Two persons who ate sparingly
(only one showed clinical signs of a mild sort) were treated with
intravenous atropine. The symptomatic patient recovered within
two hours. The lethal doses were estimated to be 12-15 mg/kg
b.w.
2.3 TOXICITY - NON MAMMALIAN SPECIES
2.3.1 Fish
LC50 (96 hr.): Bluegill sunfish 0.87 mg a.i./l
Goldfish 0.1 mg a.i./l
Carp 0.5-10.0 mg a.i./l
Rainbow trout 3.4 mg a.i./l
Channel catfish 0.94 mg a.i./l
Residue studies in fish have shown that methomyl is not
accumulated in body tissues.
2.3.2 Birds
LC50 (8 days): Pekin duck 1890 mg a.i./kg diet
Bobwhite quail 3680 mg a.i./kg diet
LC50 (5 days): Mallard duck 2883 mg a.i./kg diet
Oral LD50 Domestic hens 28 mg a.i./kg b.w.
Mallard duck 15.9 mg a.i./kg b.w
Pekin duck 15.0 mg a.i./kg b.w.
Pheasant 15.4 mg a.i./kg b.w.
Bobwhite quail 15.0 mg a.i./kg b.w.
Japanese quail 34.0 mg a.i./kg b.w.
No compound related adverse effects were observed in field-
caged bobwhite quail subjected to methomyl spray (1 kg a.i. in
280 l of water/ha) six times at five day intervals. There
were no compound related adverse effects observed in Japanese
quail fed diets containing up to 210 mg/kg every third day of
a 30 day feeding study.
2.3.3 Beneficial insects - Freshly applied methomyl is toxic to honey
bees by direct contact and ingestion, it is relatively nontoxic
when dry.
2.3.4 Other species
LC50 (96 hr.): Grass shrimp 0.49 mg a.i./l
Pink shrimp 0.02 mg a.i./l
Mud crab 0.41 mg a.i./l
Fiddler crab 2.38 mg a.i./l
3. FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF
COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY - (For definition of
categories see the Introduction to data sheets)
Liquid formulations of 8.5% and over, Category 2
Other liquid formulations, Category 3
Solid formulations of 35% and over, Category 2
Other solid formulations of 3.5% and over, Category 3
3.2 TRANSPORTATION AND STORAGE
All formulations - Should be transported and stored in clearly
labelled impermeable containers under lock and key, secure from
access by unauthorized persons and children. No food or drink
should be stored in the same compartment.
3.3 HANDLING
All formulations - Full protective clothing (see 4.3 part 4)
should be used by those handling the compound. Adequate washing
facilities should be available at all times during the handling
and should be close to site of handling. Eating, drinking and
smoking should be prohibited during handling and before washing
after handling. A Methomyl respirator should be worn at all
times when spraying. Methomyl formulations should not be
applied by hand-held ULV applicators.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS
All formulations - Container must be either burned or crushed and
buried below topsoil. Care must be taken to avoid subsequent
contamination of water sources. Decontamination of containers in
order to use them for other purposes should not be permitted.
3.5 SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS
All formulations - Pre-employment medical examination of workers
necessary. Workers suffering from active hepatic or renal disease
should be excluded from contact. Pre-employment and periodic
cholinesterase test for workers desirable. Special account should
be taken of the workers' mental ability to comprehend and follow
instructions. Training of workers in techniques to avoid contact
essential.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
All formulations - Pilots and loaders should have special training
in application methods and early symptoms of poisoning, and must
wear a suitable respirator. Use of flagmen not recommended.
Flagmen, if used, should wear protective clothing and be located
well away from the dropping zone.
3.7 LABELLING
All formulations
"DANGER - POISON"
(skull and cross bones insignia)
Methomyl is a carbamate compound which inhibits cholinesterase.
It is of very high toxicity. Contact with the skin, inhalation of
dust or spray, or swallowing may be fatal. Wear protective
gloves, clean protective clothing, and a respirator of the
organic-vapour type when handling this material. Bathe
immediately after work. Ensure that containers are stored under
lock and key. Empty containers must be disposed of in such a way
as to prevent all possibility of accidental contact with them.
Keep the material out of reach of children and well away from
foodstuffs, animal feed and their containers.
In case of contact, immediately remove contaminated clothing
and wash the skin thoroughly with soap and water; for eyes,
flush with water for 15 minutes.
If poisoning occurs, call a physician. Atropine sulfate is a
specific antidote, repeated doses may be necessary.
Artificial respiration also may be needed.
3.8 RESIDUES IN FOOD
Maximum residue levels
Maximum residue levels have been recommended by the Joint
FAO/WHO Meeting on Pesticides Residues.
4. PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
4.1.1 General - Methomyl is a carbamate pesticide of very high
toxicity. It penetrates the intact skin and is also
absorbed by inhalation and from the gastrointestinal tract. Most
formulations should be handled by trained personnel wearing
protective clothing.
4.1.2 Manufacture and formulation - T.L.V. - (A.C.G.I.H.) 2.5 mg/m3.
Formulation should not be attempted without advice from the
manufacturer.
Although volatility is low, vapour and dusts should be controlled
preferably by mechanical means. Protective equipment for the skin
and respiratory protection is usually necessary.
4.1.3 Mixers and applicators - When opening the container and when
mixing, protective impermeable boots, clean overalls, gloves and
respirator should be worn. Mixing, if not mechanical, should
always be carried out with a paddle of appropriate length. When
spraying tall crops or during aerial application a respirator
should be worn as well as an impermeable hood, clothing, boots
and gloves. The applicator should avoid working in spray mist
and avoid contact with the mouth. Particular care is needed when
equipment is being washed after use. All protective clothing
should be washed immediately after use, including the insides of
the gloves. 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 methomyl and associated with its application
should wear protective clothing and 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 methomyl.
4.2 ENTRY OF PERSONS INTO TREATED AREAS - Unprotected persons should
be kept out of treated areas for at least one day.
4.3 SAFE DISPOSAL OF CONTAINERS AND SPILLAGE - Residues in containers
should be emptied in a diluted form into a deep pit taking care to
avoid contamination of 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 a
container overnight. Impermeable gauntlets should be worn
during this work and a soakage pit should be provided for the
rinsings. Decontamination of containers in order to use them for
other purposes should not be pemitted.
Spillage of methomyl and its formulations should be removed by
washing with 5% sodium hydroxide solution and then rinsing with
large quantities of water.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning - Early symptoms of poisoning may
include excessive sweating, headache, weakness, giddiness,
nausea, vomiting, stomach pains, blurred vision, slurred speech,
and muscle twitching. Later there may be convulsions, coma, loss
of reflexes and loss of sphincter control.
4.4.2 Treatment before a person is seen by a physician, if these
symptoms appear following exposure - The person should stop work
immediately, remove contaminated clothing and wash the affected
skin with water and soap, if available, and flush the area with
large quantities of water. If swallowed, vomiting should be
induced if the person is conscious. In the event of collapse,
artificial respiration should be given, bearing in mind that if
mouth-to-mouth respiration is used, vomit may contain toxic
amounts of methomyl.
5. FOR MEDICAL LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF POISONING
5.1.1 General information - Methomyl is a carbamate insecticide of very
high toxicity. It is absorbed from the gastrointestinal tract
and by inhalation, and only to a limited extent through the
intact skin. Its mode of action is by reversibly inhibiting
acetyl cholinesterase. Erythrocyte cholinesterase is more
inhibited than plasma cholinesterase. Symptoms of poisoning are
short lasting and in case of occupational overexposure occur
without delay and at doses well below the fatal dose. Because of
its rapid metabolism and excretion it does not accumulate in the
tissues.
5.1.2 Symptoms and signs - Symptoms of poisoning include excessive
sweating, headache, chest tightness, weakness, giddiness, nausea,
vomiting, stomach pains, salivation, blurred vision, slurred
speech and muscle twitching. Paraesthesia and mild skin reactions
have also been reported.
5.1.3 Laboratory - Because methomyl is a reversible inhibitor of
cholinesterase, measurements of cholinesterase activity should be
made by a method which minimizes the reactivation of inhibted
enzyme. Erythrocyte cholinesterase determination is more
informative than measuring either plasma or whole blood
cholinesterase, but the enzyme will only be inhibited for a short
time (few hours) after exposure. The presence of metabolites of
methomyl in urine is also indicative of exposure.
5.1.4 Treatment - If the pesticide has been ingested, 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 and water. If the compound has
entered the eyes they should be washed with isotonic saline or
water. Since the symptoms of poisoning with methomyl are of
short duration, atropine treatment is usually not necessary by
the time the patient reaches a place where this antidote is
available. Where there are 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, especially when treating children.
In extreme cases, if the patient is unconscious or is in
respiratory distress, oxygen may be required. Provide patient
support as required, including; suction of secretions,
maintenance of airways, i.v. fluids p.r.n. and, bladder
catheterization. Contraindications include barbiturates and
central stimulants of all kinds. The chemical similarities
between methomyl and aldicarb suggest that pralidoxime chloride
(25-50 mg/kg b.w.) may be safely used, in addition to atropine,
to counter nicotinic symptoms of methomyl poisoning when it is
known for certain that contraindicating carbamates are not
involved and, if the severity of the symptoms warrants.
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
Morse, D. L. & Baker, E. L. (1979), Clinical Toxicology, 15 (1),
13; intoxication
Simpson, G. R. & Bermingham, S. (1977) Medical Journal of
Australia, 4, 148, intoxication
Liddle, J. A. et al. (1979) Clinical Toxicology, 15 (2), 159;
fatalities
5.2 SURVEILLANCE TESTS - Due to rapid reactivation of inhibited
enzyme, determination of blood cholinesterase levels is of little,
if any, practical value in determining when workers should be
withdrawn to prevent overexposure. Minor complaints, such as
headache and nausea, cause the worker to stop work and thus
prevent further exposure. The worker quickly recovers,
particularly if appropriate decontamination procedures are
followed.
5.3 LABORATORY METHODS
5.3.1 Detection and assay of compound
Leitch, R. L. & Pease, H. L. (1973) Anal. Methods Pestic. Plant
Growth Regul., 7, 331
Pease, H. C. & Kirkland, J. J. (1968) J. Agric. Food Chem., 16,
554
Rangaswamy, J. R. et al. (1977) J. Assoc. Off. Anal. Chem., 60
(5), 1043
Sundaram, K. M. S. et al. (1979) Jour. Chromatog., 177, 29
Szeto, S. Y. & Sundaram, K. M. S. (1980) Jour. Chromatog., 172,
528
Thean, J. E. et al. (1978) Jour. Assoc. Off. Anal. Chem., 61,
15
Thewari, S. N. & Singh, R. (1979) Jour. Chromatog., 172, 528
Williams, J. H. (1972) Pestic. Sci., 3, 179
5.3.2 Other tests in cases of poisoning - Cholinesterase levels in
blood are unreliable as a routine test to detect poisoning by
methomyl. However, shortly after absorption, inhibition of
erythrocyte cholinesterase may be demonstrated by an appropriate
method.
In plasma; Ellman, G. et al. (1961) Biochem. Pharmacol., 7, 88
In whole blood; Fleischer, J. et al. (1956) Arch. Indust. Hyg.,
14, 510
Wilhelm, K. et al. (1973) Bull. Wld Hlth Org.,
48, 235
Note: This data sheet was drafted in the Bureau of Chemical
Standards, Envirormental Health Directorate, Health and
Welfare, Canada, and subsequently underwent medical,
scientific, and industrial review.