WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
VBC/DS/75.2 (Rev.1)
ORIGINAL : ENGLISH
DATA SHEETS ON PESTICIDES No. 2 (Rev.1)
DICHLORVOS
CLASSIFICATION:
Primary use: Insecticide
Secondary use: Acaricide, nematocide
Chemical group: Organophosphorus
compound
Data sheet No. 2 (Rev.1) August 1978
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: Dichlorvos (ISO) O "
1.1.1 Identity: 2,2-dichloroethenyl dimethyl phosphate
1.1.2 Synonyms: DDVP OMS 14
Local synonyms:
1.2 SYNOPSIS: A volatile organophosphorus insecticide. It is of high
acute toxicity but its rapid metabolism renders it safe under
correct conditions of use. It is directly active without having
to be metabolized first.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics - When pure a colourless liquid, b.p.
35°C at 0.05 Torr, density 1.415 at 25°C. Corrosive to mild
steel and other metals.
1.3.2 Solubility - Water at 20°C, 0.9%, kerosine 2-3%. Miscible with
aromatic hydrocarbon solvents, chlorinated hydrocarbon solvents
and alcohols.
1.3.3 Stability - Stable to heat, hydrolyses in aqueous solutions. The
saturated aqueous solution is decomposed at the rate of 3% per
day (half life 23 days). Decomposition occurs more rapidly in
alkali and in strongly acid solutions. At pH 1 complete
hydrolysis occurs within 50 minutes at room temperature. The
vapour is rapidly hydrolysed in air. Compatible with most
technical pesticides.
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 683
1.3.4 Vapour pressure (volatility) 1.2 x 10-2 Torr at 20°C.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations - Oil-soluble concentrate, 1000 g/l;
emulsifiable concentrates, 14-1000 g/l; aerosols, 4-10 g/l; bait, 1-5
g/l liquid, 5 g/kg dry; impregnated resin strip, giving slow release of
vapour, 200 g/kg.
1.4.2 Pests mainly controlled - Used against a wide range of mite and
insect pests of plants, farm animals and man, and as an anthelmintic.
1.4.3 Use pattern - On plants as a pre-harvest treatment for fruit,
vegetable, rice and field crops. on stored products and in food
processing premises and similar locations in the form of aerosols,
impregnated resin strips and in automatic dispensers. In some
countries it is added to stored grain as a dust, spray or emulsion.
On livestock generally as sprays and aerosols and in pellets for oral
dosing of poultry, pigs and horses as an anthelmintic. In agricultural
premises as a spray or aerosol.
1.4.4 Unintended effects - None under normal conditions of use. Non
persistant. Danger of phytotoxicity to certain sensitive plants such
as ornamentals.
1.5 PUBLIC HEALTH PROGRAMMES - Used extensively in hospitals, food in
store and transport and food processing establishments, and in aircraft
for disinsection during flight.
1.6 HOUSEHOLD USE
1.6.1 Common formulations - Impregnated plastic strips, aerosols and
dilute solutions mixed with other pesticides.
1.6.2 Pests mainly controlled - Flies, mosquitos and crawling insects.
1.6.3 Use pattern - Strips are suspended in air and dichlorvos slowly
released for an effective period of about 3 months, depending on
ventilation.
1.6.4 Unintended effects - None known.
2. TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route - Absorbed by the intact skin as well as by
inhalation and from the gastrointestinal tract.
2.1.2 Mode of action - Cholinesterase inhibition.
2.1.3 Excretion products - Dichlorvos is rapidly metabolized in
mammals; hydrolytic metabolism occurs in all species and leads
presumably to dichloroacetaldehyde which is further metabolized by (i)
reduction to dichloroethanol and excretion in the urine as the
glucuronide and (ii) dechlorination followed by incorporation of the
carbon atoms into endogenous biosyntheses and excretion as carbon
dioxide and hippuric acid in the urine. This may form the basis of a
method of monitoring the exposure of humans to high concentrations of
dichlorvos.
2.1.4 Toxicity, single dose
Oral: LD50 rat (M): 80 mg/kg rat (F): 56 mg/kg
Dermal: LD50 rabbit: 107 mg/kg
Dermal: rat (M): 107 mg/kg rat (F): 75 mg/kg
Most susceptible species: Rat, oral LD50 56-80 mg/kg.
The mouse appears to be more susceptible than the rat to
inhalation.
2.1.5 Toxicity, repeated doses:
Oral: See dietary studies.
Dermal: A dermal dose at 50 mg/kg produced cholinergic signs
in a monkey 20 minutes after administration; after 8 daily doses
at this level, the animal died.
Inhalation: Dogs, cats and rabbits were continuously exposed
for 8 weeks to dichlorvos atmospheres generated from impregnated
polyvinyl chloride strips. Concentrations of dichlorvos in air
were produced in the range of 0.05-0.3 mg/m3. No effects were
found on the general health, behaviour, plasma and erythrocyte
cholinesterase activities and electroencephalographic patterns of
the animals.
Cumulation of compound: Due to its rapid metabolism there is no
accumulation of the compound.
Cumulation of effect: Repeated exposure to sub-lethal amounts
may reduce cholinesterase activity to hazard levels.
2.1.6 Dietary studies
Short-term: A dietary concentration of only 50 mg/kg soon
produced detectable inhibition of plasma and erythrocyte
cholinesterase in rats but a dietary level of 1000 mg/kg (about
50 (mg/kg)/day) was tolerated for 90 days without any diminution
of growth or sign of intoxication.
Long-term: In a 2-year study in rats there was slight plasma and
erythrocyte cholinesterase inhibition at about 50 mg/kg (2.5
(mg)/day) diet but not at about 5 mg/kg (0.25 (mg/kg)/day). No
visible signs of toxicity were evident at the maximum level fed
(about 230 mg/kg on 11.5 (mg/kg)/day). Some hepatocellular
changes were however evident at about 50 mg/kg (2.5 (mg/kg)/day)
and above.
2.1.7 Supplementary studies of toxicity
Carcinogenicity
Rat: There was no increase in tumour incidence from dietary
levels up to 500 mg/kg, an in inhalatory concentrations of up to
5 mg/m3 for up to 2 years.
Teratogenicity
Rat: No terata were observed in a 3-generation reproduction
study with dietary levels up to 500 mg,/kg (25 mg/kg/day).
Rabbit: Daily doses of 31 mg/kg on days 6-11 of gestation did
not produce skeletal malformations in the offspring.
The teratogenic potential of inhaled dichlorvos vapour for
rabbits and rats was investigated. The animals were exposed
throughout pregnancy at concentrations of 0.25 1.25 and 6.25
mg/m3 of dichlorvos. The results gave no indication that
dichlorvos vapour is teratogenic in rabbits or rats even at
exposure concentrations resulting in maternal deaths in rabbits
and causing reduction of plasma, erythrocyte and brain
cholinesterase activities in pregnant animals of both species.
Mutagenicity
Mouse - There was no increase in incidence of aberrations of
bone marrow cells in mice administered a single dose of up to 20
mg/kg of dichlorvos. Mice were exposed to atmospheres containing
vapour concentrations of 64-72 mg/m3 of dichlorvos for 16 hours,
or to 5 mg/m3 for 21 days. Chinese hamsters were exposed by
the inhalation and oral routes to high concentrations of
dichlorvos. In chromosome preparations made from bone marrow and
spermatocytes following exposure, the incidence of chromosome
abnormalities did not differ from the control values.
Male CFI mice were exposed to atmospheres containing dichlorvos
at concentrations of 30 and 55 mg/m3 for 16 hours or to 2.1 and
5.8 mg/m3 for 23 hours daily for 4 weeks. These exposures to
dichlorvos produced no mutagenic effects as expressed by
increased pre-implantation losses or early foetal deaths in
subsequent test mating. No impairment of male fertility was
detected following the exposures to dichlorvos vapour.
Host-mediated assays, using saccharomyces cerevisiae D4 as the
test organism, were carried out on male mice dosed orally with
dichlorvos or exposed to dichlorvos vapour. No enhancement of
mitotic gene conversion was recorded in yeast cells harvested
from mice which had been dosed orally with 50 or 100 mg/kg
dichlorvos or exposed for 5 hours to atmospheres containing 60 or
99 mg/m3 of dichlorvos vapour. In stationary phase cultures of
the yeast treated with dichlorvos, the rate of conversion
increased after 5 hours at a concentration of 4 g/l, but no
effect was evident with 2 g/l dichlorvos.
In vitro - Dichlorvos, when added at specific intervals to
cultures of human lymphocytes at concentrations ranging from 1 to
40 g/l, was cytotoxic to cells at concentrations of 5-40 g/l; the
cytotoxicity was not accompanied by significant cytogenetic
changes.
Man - No increase in chromosome aberrations occurred in a human
subject after exposure to 1 mg/m3 of dichlorvos for 6 hours.
Delayed neurotoxicity
Fowl - There was no histological evidence of demyelination of
the peripheral nerves when atropinized fowls were treated with
sufficient dichlorvos to produce 70% inhibition of
cholinesterase. No paresis or paralysis was observed.
2.1.8 Modifications of toxicity
Potentiation - The acute oral toxicity of rats to dichlorvos
was markedly potentiated by malathion and slightly potentiated by
mevinphos, phosphamidon and trichlorfon. No potentiation was
observed when administered in combination with 23 other
pesticides.
2.2 TOXICOLOGY - MAN
2.2.1 Absorption - See 2.1.1.
2.2.2 Dangerous doses
Single - Serious poisoning occurred in a man who spilled about
120 ml of a 3% oil formulation on his lap (see 2.2.6).
Repeated - See "observations on volunteers".
2.2.3 Observations of occupationally exposed workers - No information
available.
2.2.4 Observations on exposure of the general population - From
observations on hospital patients it is necessary to inhale
dichlorvos at concentrations in the range 0.1-0.2 mg/m3 for 24
hours a day for several days before any plasma cholinesterase
reduction is observed. There were no symptoms at this level.
There have been at least four studies of the value of dichlorvos
for malaria control. In three of them, the concentration of the
insecticide in the air of treated dwellings was measured, ranging
from 0.007 to 0.840 mg/m3, 0.004 to 0.56 mg/m3 and 0.09 to
0.17 mg/m3. People of all ages and conditions were represented
in all the studies. In no instance was there a complaint or
observed illness referable to dichlorvos. In two of the studies,
it was possible to measure cholinesterase activity, but no
abnormality was found, even in the plasma enzyme.
2.2.5 Observations of volunteers
Oral - Dichlorvos given to a group of 5 men in daily doses of
2.5 mg reduced after 20 days feeding plasma cholinesterase
activity to 70% of pre-exposure level.
Symptoms of poisoning became evident when human subjects reached
a dose level of 8 mg/kg after receiving daily doubling doses
starting at 1 mg/kg. At this dosage the erythrocyte
cholinesterase activity was found 20-55% of normal.
In studies designed to test the safety of using dichlorvos for
the disinsection of aircraft, a group of 15 volunteers underwent
intermittent exposure totalling 5 hours per night, 4 nights per
week, for 2 weeks, at a concentration of 0.5 mg/m3 of air; this
produced a gradual, moderate reduction of plasma cholinesterase
activity, but no illness, no impairment of visual performance, no
increase in airway resistance of complex reaction time, and no
change in physical condition or neurological function. There was
no inhibition of erythrocyte cholinesterase activity, and the
lowest single plasma value observed was 34% of normal. Exposure
to half that concentration for 10 half-hour periods each night
for 10 weeks was tolerated without any effect, even on plasma
cholinesterase.
Inhalation - Volunteers were exposed to an average dichlorvos
concentration of 5.8 mg/m3 20 hours a day for up to 20 days.
Plasma cholinesterase activity was reduced to 80%, 70% and 60% of
normal after 12, 24 and 48 hours respectively.
2.2.6 Reported mishaps - After a man spilled about 120 ml of a 3% oil
solution of dichlorvos on his lap, he developed slurred speech,
drowsiness and finally collapsed. Use of oxygen, treatment with
atropine sulfate (mostly intravenously) and supportive treatment
was life-saving. Periodic hallucinations and violent
combativeness occurred during the course of recovery.
An unspecified amount (less than 120 ml) of a 3% oil solution of
dichlorvos was spilled on a man's arm. The man washed with soap
and water 15 minutes later. The only symptoms were dizziness and
nausea.
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 precautions.
2.3.1 Fish - The toxicity to some species of fish is high (LC50
0.5-1 mg/l) but, unless the water is sprayed directly, the hazard
is low in practice owing to relatively rapid hydrolysis.
2.3.2 Birds - No evidence of hazard, but high toxicity to chicks,
starlings, and redwings was found in laboratory studies.
2.3.3 Beneficial insects - Toxic to bees.
3. FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF
COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY - (For definition of
categories see introduction Liquid formulations over 30% Category
3 and over 3% Category 4. Solid formulations over 12% except slow
release strips, Category 4. All other formulations Category 5.
3.2 TRANSPORTATION AND STORAGE
All formulations - Should be transported or stored in clearly
labelled rigid and leakproof containers. No food or drink should
be transported in the same compartment. Storage should be under
lock and key and secure from access by unauthorized persons and
children.
3.3 HANDLING
All formulations in Categories 3 and 4 - Full protective
clothing (see part 4) should be used by all those handling the
compound. Adequate washing facilities should be available at all
times during handling and should be close to the site of
handling. Eating, drinking and smoking should be prohibited
during handling and before washing after handling.
All formulations in Category 5 - No facilities other than those
needed for handling of any chemical need be required.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS
All formulations - Container may be decontaminated (for method
see paragraph 4.3 on part 4).
Decontaminated containers should not be used for food and drink.
Containers that are not decontaminated should be burned or should
be crushed and buried below topsoil. Care must be taken to avoid
subsequent contamination of water sources.
3.5 SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS
All formulations in Categories 3 and 4 - Pre-employment medical
examination including cholinesterase test for workers desirable.
Workers suffering from active hepatic or renal disease should be
excluded from contact. Pre-employment and periodic
cholinesterase tests 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.
Formulations in Category 5 - No special cholinesterase test for
workers necessary. 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 recognition of early
symptoms of poisoning, and must wear a suitable respirator.
Flagmen, if used, should wear overalls and be located well away
from the dropping zone.
3.7 LABELLING
All formulations in Categories 3 and 4 - Minimum cautionary
statement -
"POISON"
(Skull and crossbones insignia)
"Dichlorvos is an organophosphorus compound-which inhibits
cholinesterase. It is poisonous if inhaled, swallowed or
absorbed through the skin. Wear protective gloves, clean
protective clothing, goggles and, when working in enclosed
spaces, a respirator of the organic-vapour type when handling
this material. Avoid prolonged exposure to vapour. Wash hands
and exposed skin after handling and before eating, drinking or
smoking and bathe immediately after work.
Ensure that containers are tightly sealed and stored and disposed
of in such a way as to prevent 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 and pralidoxime
are specific antidotes and artificial respiration may be needed."
Aerosols and strips in Category 5 - Minimum cautionary
statement:
"The vapour from this strip (aerosol) may be toxic if discharged
into unventilated space. Use strictly according to manufacturers
instructions. Keep away from children."
3.8 RESIDUES IN FOOD
3.8.1 Maximum residue limits - Maximum residue limits for dichlorvos
have been recommended by the Joint FAO/WHO Meeting on Pesticide
Residues.
4. PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
4.1.1 General - Dichlorvos is a volatile organophosphorus insecticide
and acaricide of high toxicity which is easily absorbed by
inhalation as well as by the gastrointestinal tract and which
penetrates the intact skin. Formulations of liquid concentrates
should be handled by trained personnel wearing protective
clothing.
4.1.2 Manufacture and formulation
T.L.V.: (ACGIH) 1 mg/m3; (USSR) 0.2 mg/m3. Formulation should
not be attempted without advice from the manufacturer.
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 face mask
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 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 dichlorvos 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 - Due to its rapid
metabolism and breakdown, with correct use in agriculture and
public health, the general population should not be exposed to
hazardous amounts of dichlorvos.
4.2 ENTRY OF PERSON INTO TREATED AREAS - It is advisable that
unprotected persons stay out of areas treated with formulations
in Category 3 for 12 hours.
4.3 DECONTAMINATION OF SPILLAGE AND CONTAINERS - 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 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 dichlorvos and its formulations should be removed by
washing with 5% sodium hydroxide solution and then rinsing with
large quantities of water. Alternatively, sand or sawdust (which
must be burnt in a proper incinerator) may be used to absorb
spillage.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning - As a result of local exposure to
the vapours, the following signs and symptoms may occur: miosis,
frontal headache, rhinorrhea, tightness in chest,
bronchoconstriction or increased secretion, cough. Following
systemic absorption, 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 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 soap and water 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.
5. FOR MEDICAL AND LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT OF CASES OF POISONING
5.1.1 General information - A volatile organophosphorus pesticide of
moderately high acute toxicity which is easily absorbed through
the intact skin as well as by inhalation and via the
gastrointestinal tract. Its mode of action is related to the
inhibition of cholinesterase. It is very rapidly metabolized and
excreted. Sub-toxic doses can be ingested at frequent intervals
without resulting in hazardous build-up.
5.1.2 Symptoms and signs - As a result of local exposure to the
vapours, the following signs and symptoms may occur: miosis,
frontal headache, rhinorrhea, tightness in chest,
bronchoconstriction or increased secretion, cough. Following
systemic absorption, initial symptoms of poisoning may include
excessive sweating, headache, weakness, giddiness, nausea,
vomiting, stomach pains, blurred vision, slurred speech and
muscle twitching. More advanced symptoms of poisoning may be
convulsions, coma, loss of reflexes and loss of sphincter
control.
5.1.3 Laboratory - The most important laboratory finding is reduction
in activity of blood cholinesterase. However, there is some
indication that plasma cholinesterase will recover very quickly
and thus the levels may not give a true indication of the
seriousness of the case of poisoning.
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 large quantities of
water. Local symptoms upon inhalation should be treated with
atropine sulfate. Persons with manifest peripheral symptoms
should be treated with 2 mg of atropine sulfate and 1000-2000 g
of pralidoxime chloride or 250 mg of toxogonin (adult dose) by
slow intravenous injection. More atropine may be given as
needed. Persons with severe intoxication with respiratory
difficulties, convulsions and unconsciousness should immediately
be given atropine and a reactivator. In such severe cases 2 mg
of atropine sulfate should be given initially followed by
repeated doses of 2 mg as required. The patient's condition
including respiration, blood pressure, pulse frequency,
salivation and convulsions should be carefully observed as a
guide to further administration of atropine. If the patient is
cyanotic, artificial respiration should be given at the same time
as atropine sulfate.
The airways should be kept free and artificial respiration should
be applied, if required, preferably by mechanical means. If
necessary intubation should be performed.
Contraindications are morphine, barbiturates, phenothiazine
tranquillizers and central stimulants of all kinds.
5.1.5 Prognosis - Due to the rapid detoxification of dichlorvos, if
the acute toxic effect is survived, the chances of complete
recovery are good. However, in very severe cases prolonged
hypoxia may give rise to permanent brain damage.
5.1.6 References of previously reported cases - Case histories and
general methods for treatment are given in:
Hayes, W. J. jr, Clinical Handbook on Economic Poisons, U.S.
Public Health Ser., No. 476, revised 1963.
See also "Safe use of Pesticides in Public Health" (1967) Wld
Hlth Org. techn. Rep. Ser., No. 356, pp. 58-59.
5.2 SURVEILLANCE TESTS
Test Normal Action Symptomatic
level level level
Plasma cholinesterase 100%* 50% variable
Erythrocyte cholinesterase 100% 70% usually < 40%
5.3 LABORATORY METHODS - References only are given.
5.3.1 Detection and assay of compound - Because of its rapid metabolism
it is unlikely that measurable amounts of dichlorvos will be
found in human tissues. For determination in grain, the
collaboratively tested gas-chromatographic method of the
Committee for Analytical Methods for Residues of Pesticides and
Veterinary Products in Foodstuffs (1973) is recommended. For
other foodstuffs the methods of Elgar et al. (1970) and Abbott et
al. (1970) are suitable. Both are gas-chromatographic. Methods
of residue analysis by cholinesterase inhibition, bioassay and
gas chromatography are also given by Ciba-Geigy Ltd. (1971).
5.3.2 Other tests in cases of poisoning
Levels of cholinesterase in the blood, particularly plasma,
provide the most useful diagnosis of poisoning. See: Michel, N.
0. (1949) J. Lab. Clin. Med., 34, 1564-1568. Ellmen, G. L.,
Courtney, K. D., Andres, V., Jr & Featherstone, R. M. (1961-)
Biochem. Pharmacol., 7, 88-95
------------
* Percentage of pre-exposure activity by any test.
REFERENCES
Committee for Analytical Methods for Residues of Pesticides and
Veterinary Products in Foodstuffs, Panel on Malathion and
Dichlorvos Residues in Grain (1973) The determination of
malathion and dichlorvos residues in grain, Analyst., 98, 19
Elgar, K. E., Marlow, R. G. & Mathews, B. L. (1970) The determination
of residues of dichlorvos in crops and tissues, Analyst., 95,
875
Abbott, D. C., Crisp, S., Tarrant, K. R. & Tatton, J. O'G. (1970)
Pesticide residues in the total diet in England and Wales, 1966-
1967. III. Organophosphorus pesticide residues in the total
diet, Pestic. Sci., 1, 10
Ciba-Geigy Limited (1971) "Nogos Nuvan", Basel, pp. 28-29