IPCS INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
Health and Safety Guide No. 80
MONOCROTOPHOS
HEALTH AND SAFETY GUIDE
UNITED NATIONS ENVIRONMENT PROGRAMME
INTERNATIONAL LABOUR ORGANISATION
WORLD HEALTH ORGANIZATION
WORLD HEALTH ORGANIZATION, GENEVA 1993
Published by the World Health Organization for the International
Programme on Chemical Safety (a collaborative programme of the
United Nations Environment Programme, the International Labour
Organisation, and the World Health Organization)
This report contains the collective views of an international group
of experts and does not necessarily represent the decisions or the
stated policy of the United Nations Environment Programme, the
International Labour Organisation, or the World Health Organization
WHO Library Cataloguing in Publication Data
Monocrotophos : health and safety guide.
(Health and safety guide ; no. 80)
1.Hazardous substances - standards 2.Monocrotophos - standards
3.Monocrotophos - toxicity I.Series
ISBN 92 4 151080 3 (NLM Classification: WA 240)
ISSN 0259-7268
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CONTENTS
INTRODUCTION
1. PRODUCT IDENTITY AND USES
1.1. Identity
1.2. Physical and chemical properties
1.3. Analytical methods
1.4. Uses
2. SUMMARY AND EVALUATION
2.1. Exposure
2.2. Effects on experimental animals and in vitro
test systems
2.3. Effetcs on humans
2.4. Evaluation of the effects on the environment
3. CONCLUSIONS AND RECOMMENDATIONS
3.1. Conclusions
3.2. Recommendations
4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY
ACTION
4.1. Human health hazards, prevention and protection,
first aid
4.1.1. Advice to physicians
4.1.1.1 Symptoms of poisoning
4.1.1.2 Medical treatment
4.1.2. Health surveillance advice
4.2. Explosion and fire hazards
4.3. Storage
4.4. Transport
4.5. Spillage and disposal
4.5.1. Spillage
4.5.2. Disposal
5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION
6. CURRENT REGULATIONS, GUIDELINES, AND STANDARDS
6.1. Previous evaluations by international bodies
6.2. Exposure limit values
6.3. Specific restrictions
6.4. Labelling, packaging, and transport
6.5. Waste disposal
BIBLIOGRAPHY
ANNEX Treatment of organophosphate isecticide poisoning
in man
INTRODUCTION
This Health and Safety Guide is not based on an existing
Environmental Health Criteria monograph, but on evaluations by the
Joint FAO/WHO Meeting on Pesticide Residues and on critical national
reviews.
The first three sections of this Health and Safety Guide present
essential technical information and the hazard evaluation. Section
4 includes advice on preventive and protective measures and
emergency action; health workers should be thoroughly familiar with
the medical information to ensure that they can act efficiently in
an emergency. The section on regulatory information has been
extracted from the legal file of the International Register of
Potentially Toxic Chemicals (IRPTC) and from other United Nations
sources.
The target readership includes occupational health services, those
in ministries, governmental agencies, industry, and trade unions who
are involved in the safe use of chemicals and the avoidance of
environmental health hazards, and those wanting more information on
this topic. An attempt has been made to use only terms that will be
familiar to the intended user. However, sections 1 and 2 inevitably
contain some technical terms.
Revision of the information in this Guide will take place in due
course, and the eventual aim is to use standardized terminology.
Comments on any difficulties encountered in using the Guide would be
very helpful and should be addressed to:
The Director
International Programme on Chemical Safety
World Health Organization
1211 Geneva 27
Switzerland
1. PRODUCT IDENTITY AND USES
1.1 Identity
Chemical structure:
Molecular formula: C7H14NO5P
Common names: Monocrotophos, (Approved by BSI, E-ISO,
F-ISO, JMAF)
IUPAC name: Dimethyl (E)1-methyl-2- (methylcarbamoyl)
vinylphosphate; 3-(dimethoxyphosphinyl-
oxy)- N-methylisocrotonamide
CAS chemical name: (E)-dimethyl-1-methyl-3-(methylamino)-
3-oxo-1-propenyl phosphate (9Cl); dimethyl
phosphate ester with
(E)-3-hydroxy- N-methylcrotonamide
(8 Cl)
Trade names: Nuvacron(R), Azodrin(R)
CAS registry number: 6923-22-4
RTECS registry number: TC4375000
OMS number: 834
Technical monocrotophos is at least 75% pure.
1.2 Physical and chemical properties
Pure monocrotophos is in the form of colourless crystals. It is
soluble in water, acetone, and aliphatic alcohols, but only slightly
soluble in mineral oils. Monocrotophos is fairly resistant to
hydrolysis.
Technical monocrotophos is a reddish brown mixture of solid and
liquid, melting at 25-35 °C. It has a mild ester odour.
Some other relevant physical properties of monocrotophos are given
in Table 1.
Table 1. Physical properties of monocrotophos
Relative molecular mass 223.2
Melting point (°C) 54-55
Boiling point (°C) 125 (at 0.0005 mmHg)
Vapour pressure (20 °C) 0.29 mPa
Solubility in water (20 °C) 1 kg/litre
Half-life in aqueous solution
at pH 5.0 96 days
at pH 7.0 66 days
at pH 9 17 days
Monocrotophos is unstable in short-chain alcohols and glycols.
However, it is stable when stored in glass or polyethylene
containers. In solution at 2 mg/litre (2 ppm), the half-life at
pH 7.0 and 38 °C is 23 days; at pH 4.6 and 100 °C, it is 80 min.
Monocrotophos is corrosive to black iron, drum steel, stainless
steel, and brass.
1.3 Analytical methods
Gas chromatography or HPLC are the analytical methods of choice for
both formulated products and residues. Recommendations for the
methods of analysis of monocrotophos residues have been given by the
Codex Alimentarius Commission (FAO/WHO, 1989).
1.4 Uses
Monocrotophos is a broad-spectrum, fast-acting insecticide with both
systemic and residual contact actions. It is particularly effective
against Lepidoptera, Homoptera, and certain Coleoptera. The main use
of monocrotophos is for foliar application to cotton. To a certain
extent, monocrotophos is also effective against mites.
When applied under cool conditions, monocrotophos has been known to
cause phytotoxic effects in apples, cherries, peaches, and sorghum.
Monocrotophos is available in a variety of formulations. There are
the 200, 400, and 600 g a.i./litre concentrates, the 400, 500, and
600 g a.i./litre water-soluble concentrates, and the 250 g
a.i./litre ULV formulation. Monocrotophos is also available in
mixtures with other pesticides.
2. SUMMARY AND EVALUATION
The information in this section is largely based on evaluations of
the Joint FAO/WHO Meeting on Pesticide Residues.
2.1 Exposure
In the environment, monocrotophos is rapidly degraded (half-life in
soil 1-7 days) but hydrolysis in solutions is rather slow, even at
high pH. Using the recommended pre-harvest intervals (see section
6.3) monocrotophos residues are low.
The general population is not generally exposed to monocrotophos
from the air or water. It is not usually detected as residues in
food in total diet studies.
Occupational exposure to monocrotophos may occur during
manufacturing, formulation, application, and storage. This exposure
is mainly through inhalation and dermal absorption. Higher
occupational exposures may be observed in cases of accident or as a
result of incorrect handling. With correct usage, there should not
be exposure to hazardous amounts.
2.2 Effects on experimental animals and in vitro test systems
Monocrotophos is highly toxic via the oral route. The acute oral
LD50 for rats is 14 mg/kg. The acute dermal LD50 for rats is at
least 135 mg/kg. It is slightly irritating to the skin and mildly
irritating to the eyes.
Monocrotophos can be absorbed following ingestion, inhalation, and
skin contact. In rats, monocrotophos was rapidly eliminated in the
urine. Within 6 h, the excreted materials were primarily hydrolysis
products (70%), unchanged monocrotophos (25%), and traces of the
N-hydroxymethyl and desmethyl metabolites. The elimination rate
then diminished substantially, indicating rapid absorption and
elimination.
In mammals, the primary conversion products of monocrotophos are
dimethyl phosphate, O-desmethyl monocrotophos and N-desmethyl
monocrotophos. N-desmethyl monocrotophos is more toxic than
monocrotophos via the oral and intraperitoneal routes.
Signs of intoxication from exposure to monocrotophos are those
typical of exposure to organophosphorus pesticides. Inhibition of
cholinesterase is the most sensitive indicator of exposure to
monocrotophos and may indicate toxicity. A dietary level of 0.1
mg/kg, equivalent to 0.005 mg/kg body weight per day, is considered
to be the no-adverse-effect level in rats; in dogs, it is 0.5 mg/kg
diet, equivalent to 0.0125 mg/kg per day.
The Joint FAO/WHO Meeting on Pesticide Residues (JMPR) has estimated
the acceptable daily intake in man to be 0-0.00005 mg/kg body
weight.
In a 2-year study on mice at dietary concentrations of 0, 1, 2, 5 or
10 mg/kg, a NOAEL could not be established, because brain
acetylcholinesterase inhibition was detected at the lowest dietary
concentration (approximately 20% inhibition). There was no evidence
of any treatment-related carcinogenic effects.
In a 2-year study on rats at dietary concentrations of 0, 0.01,
0.03, 0.1, 1.0, or 10 mg/kg, the NOAEL was 0.1 mg/kg, equivalent to
0.005 mg/kg body weight per day, based on brain acetylcholinesterase
inhibition at the highest dose. Again, there was no evidence of
carcinogenicity.
Monocrotophos did not cause delayed neuropathy in hens.
In a multigeneration reproduction study on rats at dietary
concentrations of 0, 0.1, 1, 3, or 10 mg/kg, the NOAEL was 1 mg/kg,
equivalent to 0.05 mg/kg body weight per day, based on toxicity in
pups seen in the F2 generation at 3 mg/kg.
In a teratology study on rats at doses of 0, 0.3, 1, or 2 mg/kg body
weight per day, the NOAEL was 0.3 mg/kg body weight per day for both
maternal toxicity and teratogenicity. There was a slightly increased
incidence of malformed and/or misshapen brain at all dose levels,
including the lowest dose level of 0.3 mg/kg body weight per day. A
dose-effect relationship for this uncommon malformation was lacking
and historical control data were not available. It may have been an
artefact. A repeat study is in progress. In a rabbit teratology
study, no teratogenic potential was demonstrated and the maternal
NOEL was 1 mg/kg per day.
An extensive data base showed a weak mutagenic activity in vitro.
In vivo assays gave mostly negative or, rarely, equivocal results.
2.3 Effects on humans
In a 30-day trial with human volunteers, a daily oral dose of 0.006
mg/kg was without effect.
Several cases of monocrotophos poisoning in humans have been
reported.
2.4 Evaluation of the effects on the environment
In the environment, monocrotophos is degraded mainly via hydrolysis
and oxidation. The products of these degradation pathways are
non-cholinesterase inhibiting and of low toxicity. Volatilization
appears to be the major factor in the rapid loss of residues
following application.
Monocrotophos and its metabolites are rapidly degraded in soil,
mainly biologically, to complete mineralization. They will not
accumulate in the environment under normal use conditions.
Monocrotophos is highly toxic for birds, bees, aquatic
invertebrates, and mammals, including wild species. It is moderately
toxic for fish and non-toxic for microorganisms. The acute LD50
for birds is 1.0-6.5 mg/kg, for rainbow trout, 12 mg/litre, and for
honey bees, 33-84 µg/bee.
3. CONCLUSIONS AND RECOMMENDATIONS
3.1 Conclusions
* Under proper conditions of use, exposure of the general
population to monocrotophos is negligible.
* Monocrotophos is highly toxic. Using appropriate safety
precautions, exposure to monocrotophos during manufacture,
formulation, application, and disposal should not pose an
unacceptable human health hazard.
* Monocrotophos is rapidly degraded and is not persistent in the
environment. Care should be taken not to expose aquatic
invertebrates, bees, birds, fish, and mammals to this
insecticide.
3.2 Recommendations
* Cleaning and disposal of contaminated equipment, clothing, and
containers should be in accordance with recommended procedures.
* Pretreatment of effluent waters from formulation plants should
be required.
* Monocrotophos should be used only with proper precautions and
under proper supervision, in order to avoid overexposure.
4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY ACTION
4.1 Human health hazards, prevention and protection, first aid
Monocrotophos has a high acute oral toxicity and a moderate acute
dermal toxicity and can be hazardous for human beings if incorrectly
handled. On overexposure, typical signs and symptoms of
organophosphorus poisoning may occur rapidly. The human health
hazards associated with certain types of exposure to monocrotophos,
together with preventive and protective measures and first aid, are
listed in Table 2.
4.1.1 Advice to physicians
For a more complete treatise on the effects of organophosphorus
insecticides, especially their short- and long-term effects on the
nervous system, please refer to EHC 63: Organophosphorus
insecticides - a general introduction (WHO, 1986). The section on
treatment from the above monograph is reprinted in the Annex to this
publication.
4.1.1.1 Symptoms of poisoning
Signs and symptoms may include a feeling of exhaustion, headache,
blurred vision, weakness, and confusion. Vomiting, abdominal pain,
excessive sweating, and salivating may develop. The pupils are
constricted. Difficulty in breathing may be experienced, due to
congestion of the lungs and weakness of the respiratory muscles.
Arrhythmias and cardiac failure have been reported. On severe
poisoning, there will be muscle spasms, unconsciousness, and
convulsion. Breathing may stop, followed by death.
4.1.1.2 Medical treatment
If ingested and the formulation does not contain petroleum
distillates, induce vomiting, or preferably perform gastric lavage
using 5% sodium bicarbonate. In the case of ingestion of liquid
formulations containing hydrocarbon solvents, vomiting involves a
risk of aspiration pneumonia. Instead, the stomach should be
emptied, as soon as possible, by careful gastric lavage (using a
cuffed endotracheal tube). If possible, identify the solvents
present in the formulation and observe the victim for additional
toxic effects. As early as possible, administer 2 mg of atropine
sulfate iv and 1000-2000 mg of pralidoxime chloride or 250 mg of
obidoxime chloride (adult dose) iv to patients suffering from severe
respiratory difficulties, convulsions, and unconsciousness. Repeated
doses of 2 mg of atropine sulfate should be given, as required,
based on the respiration, blood pressure, pulse frequency,
salivation, and convulsion conditions. Diazepam should be given in
all but the mildest cases in doses of 10 mg, sc or iv, which may be
repeated as required. For children, the doses are 0.04-0.08 mg of
atropine/kg body weight, 250 mg of pralidoxime chloride per child or
4-8 mg of obidoxime chloride per kg body weight.
Artificial respiration should be applied if required.
Morphine, barbiturates, phenothiazine derivatives,
tranquillizers, and all kinds of central stimulants
are contraindicated in the absence of artificial
respiration
The diagnosis of intoxication should be confirmed, as soon as
possible, by determination of the cholinesterase activity in venous
blood.
In all cases of clinical poisoning with monocrotophos and other
organophosphorus insecticides, it is essential to maintain general
surveillance and cholinesterase (ChE) and cardiac monitoring for at
least 14 days, and longer if necessary, and to adopt general
supportive and specific therapy in accordance with the findings.
As stated earlier, more information on the treatment of
organophosphorus insecticide poisoning can be obtained from EHC 63:
Organophosphorus insecticides - a general introduction (WHO, 1986)
and also from the Annex to this Guide.
4.1.2 Health surveillance advice
In human beings exposed to monocrotophos, the cholinesterase
activity of the blood should be monitored regularly. Measurement of
whole blood acetylcholinesterase (AChE) is the most widely adopted
method. Because physiological variations of blood-ChE levels occur
in a healthy person and amongst populations, it is preferable to
compare results with pre-exposure ChE levels.
Table 2. Human health hazards, prevention and protection, first aid
HAZARD/SYMPTOM PREVENTION AND PROTECTION FIRST AID
GENERAL: Cholinesterase Avoid exposure
inhibition
SKIN: Contamination may cause Wear PVC or neoprene gloves and Remove and wash contaminated
poisoning rubber boots clothing; wash contaminated skin
with water and soap
EYES: Redness; irritation Wear safety goggles or face shield Flush eyes with clean water for at
least 15 min; if irritation persists,
obtain medical attention
INHALATION: Excessive Avoid breathing the mist, aerosol, or In case of signs and symptoms of
inhalation may cause poisoning dust; use proper (exhaust) ventilation organophosphorus poisoning, remove
or suitable mask from contaminated area and obtain
medical attention immediately
INGESTION: An unlikely Wash hands before eating, drinking, -
occupational hazard using the toilet, and after work;
do not keep food in areas with
potential exposure
Accidental or intentional swallowing - Obtain medical attention immediately;
may rapidly cause typical signs and induce vomiting if subject is conscious;a
symptoms of organophosphorus if breathing has stopped, apply
poisoning, leading to respiratory artificial respiration
arrest and death
HAZARD/SYMPTOM PREVENTION AND PROTECTION FIRST AID
REPEATED EXPOSURE VIA Wash hands before eating, drinking, Obtain medical attention immediately;
INGESTION, INHALATION, OR using the toilet, and after work induce vomiting if subject is conscious;a
THROUGH THE SKIN if breathing has stopped, apply
may gradually lead to signs, artificial respiration
symptoms, and poisoning;
sensitization may occur
a Caution: if monocrotophos is dissolved in solvents, e.g., petroleum solvents, vomiting may cause pulmonary aspiration.
Depressions of AChE or ChE levels of 20-25% are considered
diagnostic of exposure, but not necessarily indicative of hazard.
Depressions of 30-50% or more are considered indicators for removal
of an exposed individual from further contact with pesticides, until
levels return to normal. Work procedures and hygiene should also be
checked.
4.2 Explosion and fire hazards
Liquid formulations may be flammable. With sufficient burning or
external heat, monocrotophos will decompose, emitting toxic fumes.
Fire-fighters must wear protective clothing and a self-contained
breathing apparatus. Extinguish fires with alcohol-resistant foam or
powder. Confine the use of water spray to the cooling of unaffected
stock, thus avoiding polluted run-off from the site.
4.3 Storage
Technical monocrotophos and its formulations should be stored in the
original labelled containers in locked, well-ventilated storage
areas, preferably dedicated to insecticides. Do not expose to direct
sunlight. Keep products out of reach of children and unauthorized
personnel. Do not store near animal feed or foodstuffs.
4.4 Transport
Comply with any local regulations regarding the movement of
hazardous goods. Do not transport with animal feed or foodstuffs.
Food and animal feed should not be transported in vehicles that have
been used for the transport of pesticides. Before dispatch, make
sure that containers are in good condition and that the labels are
undamaged.
4.5 Spillage and disposal
4.5.1 Spillage
Avoid skin contamination and inhalation of vapour. Cover
contaminated areas and absorb spilled liquid with a 1:3 mixture of
sodium carbonate crystals and damp sawdust, lime, sand, or earth.
Sweep up and place in an impervious container. Ensure that container
is tightly closed and labelled before transfer to a safe place for
disposal.
Spills of powders should be cleaned up using a dustless method
(e.g., by a vacuum cleaner suitable for use with toxic dusts).
Alternatively, mix with damp saw-dust and place in separate
container for subsequent disposal. Dry brushing should not be
carried out, as this creates dust clouds.
Prevent liquid from spreading and contaminating other cargo,
vegetation, or waterways by using a barrier of the most suitable and
readily available material, e.g., earth or sand.
Empty any of the product remaining in the damaged/leaking container
into a clean empty container, which should then be tightly closed
and suitably labelled. Decontaminate emptied leaking containers with
a 10% sodium carbonate (washing soda) solution, added at a rate of
at least 1 litre/20-litre drum. Swirl round to rinse walls, empty,
and add rinsings to sawdust. Do not reuse containers for any other
purpose. Puncture and crush the container to prevent reuse.
4.5.2 Disposal
Large amounts should be incinerated at high temperature in a unit
with effluent gas scrubbing. When no incinerator is available, bury
in an approved dump, or in an area where there is no risk of
contamination of surface or groundwater. Before burying, liberally
mix with sodium carbonate (washing soda) crystals to help neutralize
the product, and with soil rich in organic matter. Comply with any
local legislation.
5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION
Monocrotophos is rather resistant to hydrolysis, but is rapidly
degraded in the soil and in aquatic systems (ponds, rivers), mainly
biologically, to complete mineralization. With normal usage,
monocrotophos will not accumulate.
The insecticide is highly toxic for aquatic invertebrates, birds,
bees, and mammals. It is moderately toxic for fish and earthworms
and non-toxic for microorganisms and algae.
Avoid contamination of the soil, water, and atmosphere by proper
methods of use, storage, transport, handling and waste disposal. In
case of spillage, use the methods advised in section 4.5.1.
6. CURRENT REGULATIONS, GUIDELINES AND STANDARDS
The information given in this section has been extracted from the
International Register of Potentially Toxic Chemicals (IRPTC) legal
file and other United Nations sources. A full reference to the
original national document from which the information was extracted
can be obtained from IRPTC.
The reader should be aware that regulatory decisions about chemicals
taken in a certain country can only be fully understood in the
framework of the legislation of that country. Furthermore, the
regulations and guidelines of all countries are subject to change
and should always be verified with the appropriate regulatory
authorities before application.
6.1 Previous evaluations by international bodies
The Joint FAO/WHO Meeting on Pesticide Residues (JMPR) evaluated
monocrotophos in 1972, 1975, and 1991. The acceptable daily intake
(ADI) was estimated at 0-0.00005 mg/kg body weight in 1991. This was
based on levels causing no toxicological effects of:
- <1 mg/kg diet, equivalent to <0.15 mg/kg body weight per
day in the mouse; and
- 0.1 mg/kg diet, equivalent to 0.005 mg/kg body weight per
day in the rat.
The FAO/WHO Codex Alimentarius Commission (FAO/WHO, 1986)
recommended Maximum Residue Limits (MRLs) in several food
commodities, ranging from 0.002 to 1 mg/kg (see Table 3).
WHO (1992) classified technical monocrotophos as "highly hazardous"
in normal use, based on an oral LD50 in the rat of 14 mg/kg.
6.2 Exposure limit values
Some exposure limit values are given in Table 3.
Table 3. Exposure limit values
Medium Specification Country/ Exposure limit description Value Effective
organization date
AIR Workplace Argentina Maximum permissible concentration
- Time-weighted average (TWA)a 0.25 mg/m3 1979
USA (OSHA) Permissible exposure limit (PEL)
- Time-weighted average (TWA)a 0.25 mg/m3 1989
USA (NIOSH) Recommended exposure limit (REL)
- up to 10-h TWA 0.25 mg/m3 1989
USA (ACGIH) Threshold limit value (TLV)
- Time-weighted average (TWA)a 0.25 mg/m3 1989
- Short-term exposure limit (STEL) deleted
FOOD Uptake from FAO/WHO Acceptable daily intake (ADI) 0-0.00005 mg/kg 1991
body weight
FOOD Residues FAO/WHO Maximum residue limit (MRL)
specified as follows: 0.002-1 mg/kg 1986
- milk 0.002 mg/kg
- cattle, goats, pigs, poultry, sheep (edible
offal and carcass meat in all cases), eggs
(shell-free basis), milk products, poultry 0.02 mg/kg
- carrots, cotton seed oil, maize (grain),
potatoes, soya beans, sugar beets, turnips 0.05 mg/kg
Table 3. (continued)
Medium Specification Country/ Exposure limit description Value Effective
organization date
- coffee (raw beans), cotton seed,
onions, peas 0.1 mg/kg
- beans, brussels sprouts, cabbage,
cauliflower, citrus fruit 0.2 mg/kg
- apples, pears, tomatoes 1 mg/kg
a TWA usually 8 h.
6.3 Specific restrictions
Monocrotophos is approved as a pesticide in many countries. Specific
uses, limitations, and precautions are listed in national regulatory
documents.
In the USA, monocrotophos and its preparations may only be handled
by certified operators. A field sprayed with monocrotophos may not
be entered without protective clothing within 48 h of application.
The registration has, however, been cancelled voluntarily.
In Germany, it may not be handled by adolescents and pregnant and
nursing women.
Preharvest intervals have been set in several countries and are
generally of the order of 7-15 days for vegetables and potatoes, 14
days for cotton, 21 days for tomatoes, maize, and citrus, and 28-30
days for other crops.
6.4 Labelling, packaging, and transport
The United Nations Committee of Experts on the Transportation of
Dangerous Goods classifies monocrotophos in:
- Hazard Class 6.1: poisonous substance;
- Packing Group 2: substances and preparations presenting a
serious risk of poisoning, for formulations
containing 25-100% monocrotophos.
- Packing Group 3: harmful substances and preparations
presenting a relatively low risk of
poisoning, for solid formulations
containing 7-25% active material and liquid
formulations containing 2.5-25% active
material.
The label should appear as follows:
In Packaging Group II
In Packaging Group III
In the International Maritime Dangerous Goods (IMDG) Code,
monocrotophos is classified as a marine pollutant. It should bear
the following mark on the label:
For flammable formulations, the following subsidiary label is
required when the flash-point of the solution is below or equal to
61 °C (closed cup):
There is no WHO specification for monocrotophos, as the material is
not used in public health. However, specifications for technical
material and some formulations (ULV and SLs) have been agreed
between FAO and the manufacturer.
All packages should bear, durably and legibly marked on the
container, the following:
- manufacturer's name;
- technical monocrotophos to specification;
- batch or reference number, and date of test;
- net weight of contents;
- date of manufacture.
and, in the case of the formulated products:
- manufacturer's name;
- monocrotophos to specification;
- monocrotophos ... g/kg;
- batch or reference number, and date of test;
- net weight of contents;
- instructions for dilution;
- date of formulation.
and the following minimum cautionary notice:
Monocrotophos is an organophosphorus compound that inhibits
cholinesterase. It is poisonous if swallowed or inhaled. 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 the reach of children and well away
from foodstuffs and animal feed and their containers.
If poisoning occurs, call a physician. Atropine and
pralidoxime are specific antidotes, and artificial respiration
may be needed.
The monocrotophos content should be declared (minimum 75% for the
technical products) and should not differ from the declared
percentage more than 2% for the technical products and 5-10% for its
formulations.
Containers should be suitable, clean, dry and as specified in the
order and should not adversely affect, or be affected by, the
product, but should adequately protect it from external conditions.
They should comply with pertinent national and international
transport and safety regulations.
Specifications for storage stability are given.
The European Community Legislation requires labelling as dangerous
substance using the symbol:
The label must read:
Very toxic by inhalation, in contact with skin and if
swallowed; keep locked up; keep away from food, drink and
animal feeding stuffs; after contact with skin, wash
immediately with plenty of ...... (to be specified by the
manufacturer); in case of accident or if you feel unwell, seek
medical advice (show the label where possible).
The European Community legislation on the labelling of pesticide
preparations classifies pesticide preparations that contain
monocrotophos into Class 1A as toxic at concentrations >1% and as
harmful at >0.05-1%. Member States should ensure that pesticides
cannot be placed on the market unless their packaging, fastenings,
and labels comply with the requirements laid down.
6.5 Waste disposal
In the USA, any non-domestic waste containing monocrotophos is
considered a hazardous waste and should be notified. Permits are
required for its handling, transport, treatment, storage, or
disposal. Waste incinerators must achieve 99.99% destruction and
removal of this substance.
BIBLIOGRAPHY
CEC (1987) Legislation on dangerous substances - Classification and
labelling in the European Communities. Vol. 1 and 2. Commission of
the European Communities, London, Graham & Trotman, Ltd.
FAO (1985a) Guidelines for the packaging and storage of pesticides.
Rome, Food and Agriculture Organization of the United Nations.
FAO (1985b) Guidelines for the disposal of waste pesticides and
pesticide containers on the farm. Rome, Food and Agriculture
Organization of the United Nations.
FAO (1985c) Guidelines on good labelling practice for pesticides.
Rome, Food and Agriculture Organization of the United Nations.
FAO (1986) International code of conduct on the distribution and
use of pesticides. Rome, Food and Agriculture Organization of the
United Nations.
FAO/WHO (1964-present) Evaluations of pesticide residues in food.
Rome, Food and Agriculture Organization of the United Nations.
FAO/WHO (1986) Codex Maximum Limits for pesticide residues. Codex
Alimentarius Commission, CAC/Vol. XIII., Supplement 1 & 2, 3rd ed.
Rome, Food and Agriculture Organization of the United Nations.
FAO/WHO (1989) Guide to Codex recommendations concerning pesticide
residues. Part 8. Recommendations for methods of analysis of
pesticide residues. 4th ed. Rome, Codex Committee on Pesticide
Residues.
GIFAP (1982) Guidelines for the safe handling of pesticides during
their formulation, packaging, storage and transport. Brussels,
Groupement International des Associations Nationales des Fabricants
de Produits Agrochimiques.
GIFAP (1983) Guidelines for the safe and effective use of
pesticides. Brussels, Groupement International des Associations
Nationales des Fabricants de Produits Agrochimiques.
GIFAP (1984) Guidelines for emergency measures in cases of
pesticides poisoning. Brussels, Groupement International des
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GIFAP (1987) Guidelines for the safe transport of pesticides.
Brussels, Groupement International des Associations Nationales des
Fabricants de Produits Agrochimiques.
HAYES, W.J., Jr & LAWS, E.R., Jr. (1991) Handbook of pesticide
toxicology. 3 vol. New York, Academic Press.
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PLESTINA, R. (1984) Prevention, diagnosis, and treatment of
insecticide poisoning. Geneva, World Health Organization
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restricted or not approved by Governments. 4th ed. New York,
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ANNEX
TREATMENT OF ORGANOPHOSPHATE INSECTICIDE POISONING IN MAN1
All cases of organophosphorus poisoning should be dealt with as an
emergency and the patient sent to hospital as quickly as possible.
Although symptoms may develop rapidly, delay in onset or a steady
increase in severity may be seen up to 48 h after ingestion of some
formulated organophosphorus insecticides.
Extensive descriptions of treatment of poisoning by organophosphorus
insecticides are given in several major references (Kagan, 1977;
Taylor, 1980; UK DHSS, 1983; Plestina, 1984) and will also be
included in the IPCS Health and Safety Guides to be prepared for
selected organophosphorus insecticides.
The treatment is based on:
(a) minimizing the absorption;
(b) general supportive treatment; and
(c) specific pharmacological treatment.
A.1 Minimizing the absorption
When dermal exposure occurs, decontamination procedures include
removal of contaminated clothes and washing of the skin with
alkaline soap or with a sodium bicarbonate solution. Particular care
should be taken in cleaning the skin area where venepuncture is
performed. Blood might be contaminated with direct-acting
organophosphorus esters and, therefore, inaccurate measures of ChE
inhibition might result. Extensive eye irrigation with water or
saline should also be performed. In the case of ingestion, vomiting
might be induced, if the patient is conscious, by the administration
of ipecacuanha syrup (10-30 ml) followed by 200 ml water.
This treatment is, however, contraindicated in the case of
pesticides dissolved in hydrocarbon solvents. Gastric lavage (with
addition of bicarbonate solution or activated charcoal) can also be
performed, particularly in unconscious patients, taking care to
prevent aspiration of fluids into the lungs (i.e., only after a
tracheal tube has been put into place).
The volume of fluid introduced into the stomach should be recorded
and samples of gastric lavage frozen and stored for subsequent
chemical analysis. If the formulation of the pesticide involved is
available, it should also be stored for further analysis (i.e.,
detection of toxicologically relevant impurities). A purgative can
be administered to remove the ingested compound.
1 From EHC 63: Organophosphorus insecticides - a general
introduction. Geneva, World Heralth Organization, 1986.
A.2 General supportive treatment
Artificial respiration (via a tracheal tube) should be started at
the first sign of respiratory failure and maintained for as long as
necessary.
Cautious administration of fluids is advised, as well as general
supportive and symptomatic pharmacological treatment and absolute
rest.
A.3 Specific pharmacological treatment
A.3.1 Atropine
Atropine should be given, beginning with 2 mg iv and given at
15-30-min intervals. The dose and the frequency of atropine
treatment varies from case to case, but should maintain the patient
fully atropinized (dilated pupils, dry mouth, skin flushing, etc.).
Continuous infusion of atropine may be necessary in extreme cases
and total daily doses up to several hundred mg may be necessary
during the first few days of treatment.
A.3.2 Oxime reactivators
Cholinesterase reactivators (e.g., pralidoxime, obidoxime)
specifically restore AChE activity inhibited by organophosphates.
This is not the case with enzymes inhibited by carbamates. The
treatment should begin as soon as possible, because oximes are not
effective on "aged" phosphorylated ChEs. However, if absorption,
distribution, and metabolism are thought to be delayed for any
reasons, oximes can be administered for several days after
intoxication. Effective treatment with oximes reduces the required
dose of atropine. Pralidoxime is the most widely available oxime. A
dose of 1 g pralidoxime can be given either im or iv and repeated
2-3 times per day or, in extreme cases, more often. If possible,
blood samples should be taken for AChE determinations before and
during treatment. Skin should be carefully cleansed before sampling.
Results of the assays should influence the decision whether to
continue oxime therapy after the first 2 days.
There are indications that oxime therapy may possibly have
beneficial effects on CNS-derived symptoms.
A.3.3 Diazepam
Diazepam should be included in the therapy of all but the mildest
cases. Besides relieving anxiety, it appears to counteract some
aspects of CNS-derived symptoms that are not affected by atropine.
Doses of 10 mg sc or iv are appropriate and may be repeated as
required (Vale & Scott, 1974). Other centrally acting drugs and
drugs that may depress respiration are not recommended in the
absence of artificial respiration procedures.
A.3.4 Notes on the recommended treatment
A.3.4.1 Effects of atropine and oxime
The combined effect far exceeds the benefit of either drug singly.
A.3.4.2 Response to atropine
The response of the eye pupil may be unreliable in cases of
organophosphorus poisoning. A flushed skin and drying of secretions
are the best guide to the effectiveness of atropinization. Although
repeated dosing may well be necessary, excessive doses at any one
time may cause toxic side-effects. Pulse-rate should not exceed
120/min.
A.3.4.3 Persistence of treatment
Some organophosphorus pesticides are very lipophilic and may be
taken into, and then released from, fat depots over a period of many
days. It is therefore quite incorrect to abandon oxime treatment
after 1-2 days on the supposition that all inhibited enzyme will be
aged. Ecobichon et al. (1977) noted prompt improvement in both
condition and blood-ChEs in response to pralidoxime given on the
11th-15th days after major symptoms of poisoning appeared due to
extended exposure to fenitrothion (a dimethyl phosphate with a short
half-life for aging of inhibited AChE).
A.3.4.4 Dosage of atropine and oxime
The recommended doses above pertain to exposures, usually for an
occupational setting, but, in the case of very severe exposure or
massive ingestion (accidental or deliberate), the therapeutic doses
may be extended considerably. Warriner et al. (1977) reported the
case of a patient who drank a large quantity of dicrotophos, in
error, while drunk. Therapeutic dosages were progressively increased
up to 6 mg atropine iv every 15 min together with continuous iv
infusion of pralidoxime chloride at 0.5 g/h for 72 h, from days 3 to
6 after intoxication. After considerable improvement, the patient
relapsed and further aggressive therapy was given at a declining
rate from days 10 to 16 (atropine) and to day 23 (oxime),
respectively. In total, 92 g of pralidoxime chloride and 3912 mg of
atropine were given and the patient was discharged on the
thirty-third day with no apparent sequelae.
References to Annex
ECOBICHON, D.J., OZERE, R.L., REID, E., & CROCKER, J.F.S (1977)
Acute fenitrothion poisoning. Can. Med. Assoc. J., 116: 377-379.
KAGAN, JU.S. (1977) [Toxicology of organophosphorus pesticides],
Moscow, Meditsina, pp. 111-121, 219-233, 260-269 (in Russian).
PLESTINA, R. (1984) Prevention, diagnosis, and treatment of
insecticide poisoning. Geneva, World Health Organization
(Unpublished document VBC/84.889).
TAYLOR, P. (1980) Anticholinesterase agents. In: Goodman, L.S. &
Gilman, A., ed. The pharmacological basis of therapeutics. 6th
ed., New York, Macmillan Publishing Company, pp. 100-119.
UK DHSS (1983) Pesticide poisoning: notes for the guidance of
medical practitioners. London, United Kingdom Department of Health
and Social Security, pp. 41-47.
VALE, J.A. & SCOTT, G.W. (1974) Organophosphorus poisoning. Guy's
Hosp. Rep., 123: 13-25.
WARRINER, R.A., III, NIES, A.S., & HAYES, W.J., Jr (1977) Severe
organophosphate poisoning complicated by alcohol and terpentine
ingestion. Arch. environ. Health, 32: 203-205.