IPCS INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
Health and Safety Guide No. 18
DICHLORVOS
HEALTH AND SAFETY GUIDE
UNITED NATIONS ENVIRONMENT PROGRAMME
INTERNATIONAL LABOUR ORGANISATION
WORLD HEALTH ORGANIZATION
WORLD HEALTH ORGANIZATION, GENEVA 1988
This is a companion volume to Environmental Health Criteria 79:
Dichlorvos
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
ISBN 92 4 154337 X
ISSN 0259-7268
The World Health Organization welcomes requests for permission to
reproduce or translate its publications, in part or in full.
Applications and enquiries should be addressed to the Office of
Publications, World Health Organization, Geneva, Switzerland, which
will be glad to provide the latest information on any changes made to
the text, plans for new editions, and reprints and translations
already available.
(c) World Health Organization 1988
Publications of the World Health Organization enjoy copyright
protection in accordance with the provisions of Protocol 2 of the
Universal Copyright Convention. All rights reserved.
The designations employed and the presentation of the material in this
publication do not imply the expression of any opinion whatsoever on
the part of the Secretariat of the World Health Organization
concerning the legal status of any country, territory, city or area or
of its authorities, or concerning the delimitation of its frontiers or
boundaries.
The mention of specific companies or of certain manufacturers'
products does not imply that they are endorsed or recommended by the
World Health Organization in preference to others of a similar nature
that are not mentioned. Errors and omissions excepted, the names of
proprietary products are distinguished by initial capital letters.
CONTENTS
INTRODUCTION
1. PRODUCT IDENTITY AND USES
1.1. Identity
1.2. Physical and chemical properties
1.3. Analytical methods
1.4. Production and uses
2. SUMMARY AND EVALUATION
2.1. Evaluation of effects on animals and human health
2.2. Evaluation of 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. Main 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. INTERNATIONAL CHEMICAL SAFETY CARD
7. CURRENT REGULATIONS, GUIDELINES, AND STANDARDS
7.1. Previous evaluations by international bodies
7.2. Exposure limit values
7.3. Specific restrictions
7.4. Labelling, packaging, and transport
BIBLIOGRAPHY
ANNEX I. Treatment of organophosphate insecticide poisoning in man
INTRODUCTION
The Environmental Health Criteria (EHC) documents produced by the
International Programme on Chemical Safety, include an assessment of
the effects on the environment and on human health of exposure to a
chemical or combination of chemical's, or physical or biological
agents. They also provide guidelines for setting exposure limits.
The purpose of a Health and Safety Guide is to facilitate the
application of these guidelines in national chemical safety
programmes. The first three sections of a Health and Safety Guide
highlight the relevant technical information in the corresponding EHC.
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. Within the Guide is an International Chemical Safety Card
which should be readily available, and should be clearly explained, to
all who could come into contact with the chemical. 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, it is inevitable that sections
1 and 2 contain technical terms. A bibliography has been included for
readers who require further background information.
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 Manager
International Programme on Chemical Safety
Division of Environmental Health
World Health Organization
1211 Geneva 27
Switzerland
THE INFORMATION IN THIS GUIDE SHOULD BE CONSIDERED AS A STARTING POINT
TO A COMPREHENSIVE HEALTH AND SAFETY PROGRAMME
1. PRODUCT IDENTITY AND USES
1.1 Identity
Common name: Dichlorvos
Primary constiment
Chemical structure:
Chemical formula: C4H7Cl2O4P
Relative molecular
mass: 221
Chemical name: 2,2-dichloroethenyl dimethylphosphate
(CAS);
2,2-dichlorovinyl dimethylphosphate
(IUPAC)
Common synonyms: Bayer-19149, DDVF, DDVP,
ENT-20738, OMS-14, SD 1750, C-177
CAS registry 62-73-7
number:
Technical product
Common trade Dedevap, Nogos, Nuvan, Phosvit,
names: Vapona a
Purity: Not less than 97%
Impurities: Depends on the manufacturing process
a The Shell trademark Vapona was formerly used exclusively for
dichlorvos and dichlorvos-containing formulations. Now, this
trademark is used more widely to include formulations containing
other active ingredients.
Additives: On standing, in the presence of traces of
moisture, dichlorvos breaks down with the
formation of acidic products that catalyse
further decomposition of the compound. In the
past, 2-4% epichlorohydrin was added to
stabilize the technical grade product. Other
stabilizers may now be used in some products,
but improved technology and purity has
largely eliminated the need for them.
1.2 Physical and Chemical Properties
Technical dichlorvos is a colourless to amber liquid with a mild
chemical odour. It is hydrolysed by water at a rate of 3% per day at
room temperature. It is corrosive to iron and mild steel.
For some physical properties see the International Chemical Safety
Card.
1.3 Analytical Methods
Dichlorvos residues can be determined by gas liquid chromatography.
The same method can be used for product analysis; alternative methods
include infrared spectrometry, or reaction with an excess of iodine,
which is estimated by titration.
1.4 Production and Uses
Dichlorvos, an organophosphate, is a direct-acting cholinesterase
(ChE) inhibitor. Since 1961, it has been commercially manufactured and
used throughout the world as a contact and stomach insecticide.
At present, the global production of dichlorvos is of the order of
4 million kg per year. It is used to protect stored products, to
protect crops (mainly in greenhouses), to control internal and external
parasites in livestock (granules of impregnated resin), and to control
insects in houses, buildings, and outdoor areas (as aerosols or liquid
sprays or as impregnated cellulose, ceramic, or resin strips).
2. SUMMARY AND EVALUATION
2.1 Evaluation of Effects on Animals and Human Health
Dichlorvos is readily absorbed by the body of mammals via all routes
of exposure, and readily metabolized in the liver. Within 1 h of oral
administration, dichlorvos is found in the liver, kidneys, and other
organs of experimental animals. The substance is rapidly eliminated
via the kidneys, with a half-life of 14 min.
The metabolism of dichlorvos in various species, including man,
follows similar pathways and differences between species relate only
to the rate of metabolism, but this is always rapid.
Dichlorvos is moderately to highly toxic in mammals (oral LD50 for
the rat is 30-110 mg/kg body weight). The classification of dichlorvos
by WHO (1986b) is based on an oral LD50 for the rat of 56 mg/kg body
weight. Signs of intoxication usually occur shortly after exposure and
are typical of an organophosphorus pesticide. A sensitive criterion of
exposure is inhibition of cholinesterase (ChE) activity. In short-term
toxicity studies on mammals, it has been shown that ChE activity is
not decreased at oral doses below about 0.5 mg/kg body weight. In
long-term oral studies on rats at dose levels of 2.5 mg/kg body weight
or more, hepatocellular fatty vacuolization was seen. A dose level of
0.25 mg/kg body weight did not induce ChE inhibition or any other
effects.
The results of reproduction and teratogenicity studies, over a wide
range of dose levels (6.25-500 mg/kg body weight), were negative.
Dichlorvos showed alkylating properties in in vitro studies, but not
in in vivo studies. The results of many in vitro mutagenicity
studies with bacteria and yeast were positive, while those of
in vivo studies were mainly negative.
On the basis of available mutagenicity studies, it is unlikely that
dichlorvos constitutes a mutagenic hazard for man.
Negative results were obtained in carcinogenicity studies on mice and
rats administered dichlorvos via the oral route (dose levels up to
234 mg/kg diet). Two recent carcinogenicity studies were carried out
on mice and rats in which dichlorvos was administered by intubation at
dose levels of between 10 and 40 mg/kg body weight (mice) and 4 and
8 mg/kg body weight (rats) for up to 2 years. Only preliminary
information is available. The evidence for carcinogenicity in these
new studies is difficult to interpret at this time. Only when complete
and final reports become available will it be possible to draw more
definite conclusions.a
The results of studies on hens have neither established nor refuted
the suspicion of delayed neurotoxicity arising from exposure to
dichlorvos. Furthermore, there have been two clinical reports of four
patients suffering from severe poisoning after oral ingestion of
dichlorvos who survived following treatment and who then displayed
neurotoxic effects. Thus, the possibility of delayed neurotoxicity in
man cannot be entirely discounted, but it is likely to occur only
following excessive oral doses.
Human volunteers given single or repeated oral doses of 2 mg
dichlorvos/kg body weight or more showed significant inhibition of
erythrocyte-ChE activity. No inhibition was found at 1 mg/kg body
weight.
Application of dichlorvos to crops and animals results in residues
that rapidly disappear through volatilization and hydrolysis. In
general, residues of dichlorvos and its break-down product,
dichloroacetaldehyde, in food commodities are low and will be further
reduced during processing. The exposure of the general population to
dichlorvos through food and drinking-water is negligible, as has been
confirmed in total diet studies.
In short-term inhalation studies on mammals, 1 or 2 mg dichlorvos/m3
did not inhibit ChE activity.
In a 2-year inhalation study on rats, whole-body exposure to 0.48 mg
dichlorvos/m3 for 23 h/day caused inhibition of plasma- and red
cell-ChE activity, but AchE activity in the brain was not inhibited
and there were no clinical signs. An unquantified, but considerable,
increase in exposure resulting from the grooming of contaminated fur,
a The US National Toxicology Program Peer Review Panel reviewed
these studies and came to the following conclusions:
"Under the conditions of these 2-year gavage studies, there was
some evidence of carcinogenic activity of dichlorvos for male
F344/N rats, as shown by increased incidences of adenomas of the
exocrine pancreas and mononuclear cell leukemia. There was
equivocal evidence of carcinogenic activity of dichlorvos for
female F344/N rats, as shown by increased incidence of adenomas
of the exocrine pancreas and mammary gland fibroadenomas. There
was some evidence of carcinogenic activity of dichlorvos for male
B6C3F1 mice and clear evidence for female B6C3F1 mice, as shown
by increased incidences of forestomach squamous cell papillomas".
and the contamination of food and drinking-water, had contributed to
this effect. The no-observed-adverse-effect level was 0.05 mg/m3.
There was no evidence of carcinogenicity.
After 6-7-h exposure of human volunteers to concentrations of
approximately 1 mg/m3, only inhibition of plasma-ChE activity was
found. This is generally considered as an indication of exposure. The
red cell-AChE activity, taken to be representative of the AChE
activity in the nervous tissue, was not affected.
Residents exposed to an average air concentration of dichlorvos of
0.1 mg/m3, arising from slow-release strips for over one year, did
not show any inhibition of plasma- or erythrocyte-ChE activity, or any
deleterious effects on health.
The main exposure of the general population is through the inhalation
of dichlorvos, when used indoors to control insects. The recommended
use (one slow-release strip/ 30 m3) will give concentrations in the
air of up to 0.1-0.3 mg/m within the first few days, decreasing
thereafter to below 0.1 mg/m3. The air concentration depends on
temperature, humidity, and ventilation.
As long as approved slow-release strips are used according to the
instructions on the label, no health hazard can be expected for man.
However, special care may need to be taken with young children and
sick or elderly people, who are especially vulnerable when
continuously exposed (24 h a day) in poorly ventilated rooms. Other
methods of indoor application should be safe, if the instructions on
the label are followed.
There is some indication that dichlorvos may induce dermatitis and
cross-sensitization in workers also handling other types of
pesticides.
Under occupational conditions, the main route of exposure to
organophosphorus pesticides is, generally, the dermal route. In the
case of dichlorvos, with its high vapour pressure, exposure through
inhalation is also important. In such occupational situations, the
dichlorvos concentrations in air are generally below 1 mg/m3 but,
under certain circumstances, they may rise considerably above this
level. This stresses the need for adequate protection measures to be
taken during occupational exposure and regular monitoring of ChE
activity.
2.2 Evaluation of Effects on the Environment
The presence of dichlorvos as a result of accidental loss or direct
application on soil or in water will not lead to long-term effects,
because of its fast breakdown and evaporation. Furthermore, dichlorvos
will be converted by microorganisms to a number of compounds including
dichloroacetic acid. Certain bacteria can use dichlorvos as a sole
source of carbon. Other strains cannot and are inhibited in their
growth. Thus, the influence of dichlorvos on microorganisms is rather
complex.
Dichlorvos is moderately to highly toxic (range, 0.2-10 mg/litre) for
fresh-water and estuarine species of fish and invertebrates. In
certain fish, concentrations of 0.25-1.25 mg/litre cause inhibition of
brain-and liver-ChE activity. Concentrations of 0.05 mg/litre may
already have deleterious effects, particularly in invertebrates.
Dichlorvos is highly toxic for birds and bees. Caution is advised in
the use and handling of dichlorvos where these species might be
exposed.
No bioaccumulation occurs in the different compartments and organisms.
3. CONCLUSIONS AND RECOMMENDATIONS
3.1 Conclusions
(a) Exposure of the general population to dichlorvos through food and
drinking-water is negligible and does not constitute a health
hazard.
(b) The in-house use of dichlorvos as an insecticide in the form of
sprays or slow-release strips, at recommended levels of use, does
not constitute a short- or a long-term hazard for the general
population. However, continuous (24 h per day) exposure of young
children and sick or elderly people in non- or poorly-ventilated
rooms should be avoided.
(c) Notwithstanding their toxicity, dichlorvos and its formulations
do not present an undue hazard for those occupationally exposed,
when adequate ventilation and skin protection are used.
(d) Except inthe case of gross spillage, the recommended use of
dichlorvos as an insecticide does not pose any acute or long-term
hazards for aquatic and terrestrial organisms, though there may
be an acute hazard for birds and bees.
3.2 Recommendations
(a) Continuous (24 h/day) exposure of young children and sick or
elderly people to dichlorvos in non- or poorly-ventilated rooms
should be avoided.
(b) As dichlorvos from various sources may differ in purity and
impurities, attention should be paid to its composition. This
should conform to FAO and WHO specifications. In the case of
formulations, other components, such as solvents and stabilizers,
should also be considered.
4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY ACTION
4.1 Main Human Health Hazards, Prevention and Protection,
First Aid
Dichlorvos is an organophosphorus insecticide. Technical dichlorvos
and concentrated formulations are moderately to highly toxic and can
be hazardous for human beings, if incorrectly handled. Dichlorvos has
a relatively high vapour pressure and is therefore hazardous through
inhalation; it is also hazardous through ingestion and skin contact,
because of fast absorption. Typical signs and symptoms of
organophosphorus poisoning may occur rapidly with overexposure.
The human health hazards associated with certain types of exposure to
dichlorvos, together with preventive and protective measures and first
aid are listed on the International Chemical Safety Card.
4.1.1 Advice to physicians
4.1.1.1 Symptoms of poisoning
Dichlorvos is a direct inhibitor of cholinesterase. Initially, there
may be feelings of exhaustion, headache, weakness, and confusion.
Then, vomiting, abdominal pain, excessive sweating, and salivation may
develop. The pupils are small. Difficulty in breathing may be
experienced, due to either congestion of the lungs or weakness of the
respiratory muscles. In severe cases of poisoning, muscle spasms,
unconsciousness, and convulsions may develop. Respiration may stop.
For a more complete treatise on the effects of organo-phosphorus
insecticides, especially their short- and long-term effects on the
nervous system, refer to EHC 63: Organophosphorus insecticides - a
general introduction (WHO, 1986a).
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 surfate i.v. and
1000-2000 mg of pralidoxime chloride or 250 mg of obidoxime chloride
(adult dose) intramuscularly or intravenously to patients suffering
from severe respiratory difficulties, convulsions, and unconsciousness.
Repeated doses of 2 mg of attopine surfate should be given, as required,
based on the respiration, blood pressure, pulse frequency, salivation,
and convulsion conditions. 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 kg body weight.
Artificial respiration should be applied if required.
Morphine, barbiturates, phenothiazine derivatives, tranquillizers, and
all killds of central stimulants are contraindicated.
The diagnosis of intoxication should be confirmed as soon as possible
by determination of the cholinesterase activity in venous blood.
For more information on the treatment of organophosphorus insecticides
see EHC No. 63: Organophosphorus insecticides: - a general
introduction (WHO 1986a). The section on therapy from this
publication is attached as Annex 1 of this guide.
4.1.2 Health surveillance advice
Occupational exposure to organophosphorus insecticides can be
monitored by measurement of erythrocyte- and whole blood-ChE activity.
Physiological variations in erythrocyte- and blood-ChE values occur in
healthy persons.
Inhibition of AChE or ChE activity of less than 20-25% is considered
diagnostic of exposure but not necessarily indicative of hazard.
However, work procedures and hygiene should be checked. Inhibition of
30-50% or more is considered an indication that an exposed individual
should be removed from further contact with ChE-inhibiting pesticides,
until values return to normal. Work procedures and hygiene should also
be checked.
4.2 Explosion and fire hazards
Liquid formulations may be flammable. Inform the fire service that
skin contamination and the breathing of fumes must be avoided.
Protective clothing and self-contained breathing apparatus must be
worn.
Extinguish fires with alcohol-resistant foam or powder. The use of
water spray should be confined to the cooling of unaffected stock, to
avoid polluted run-off from the site.
4.3 Storage
Technical dichlorvos and its formulations should be stored in locked,
well ventilated buildings preferably specifically used for insecticide
storage. Do not expose to direct sunlight. Keep products out of reach
of children and unauthorized personnel. Do not store near feed or
foodstuffs.
4.4 Transport
Comply with any local regulations regarding movement of hazardous
goods. Do not load with feed or foodstuffs. Check that containers are
sound and labels undamaged before despatch.
4.5 Spillage and Disposal
4.5.1 Spillage
Stay upwind, avoid skin contamination and inhalation of vapour. Absorb
spilled liquid and cover contaminated areas with 1:3 mixture of sodium
carbonate crystals and damp sawdust, lime, sand, or earth. Sweep up
and place in a closeable impervious container. Ensure that container
is tightly closed and suitably labelled before transfer to a safe
place for disposal.
Prevent liquid from spreading and contaminating other cargo,
vegetation, or waterways with a barrier of the most suitable material
available, e.g., earth or sand. If the spill occurs into a waterway
and the dichlorvos-containing material is immiscible in water and
sinks, dam the waterway to stop flow and to retard dissipation by
water movement. Use a bottom pump, dredging, or underwater vacuum
equipment to remove undissolved material.
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
solution added at the rate of at least 1 litre per 20-litre drum.
Swirl round to rinse walls, empty, and add rinsings to sawdust, etc.
Puncture empty containers to prevent re-use.
4.5.2 Disposal
Contaminated absorbents, containers, surplus product, etc., should be
burnt in a proper incinerator at high temperatures 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 ground water. 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
Dichlorvos is highly toxic for honey bees, birds, and fish. It does
not bioaccumulate and it breaks down rapidly in the environment.
Avoid contamination of soil, water, and the atmosphere by proper
methods of storage, transport, handling, and waste disposal. Caution
is advised in the use and handling of dichlorvos where sensitive non-
target animal species might be exposed.
In case of spillage, use the methods advised in section 4.5.1.
6. INTERNATIONAL CHEMICAL SAFETY CARD
This card should be easily available to all health workers concerned
with, and users of, dichlorvos. It should be displayed at, or near,
entrances to areas where there is potential exposure to dichlorvos,
and on processing equipment and containers. The card should be
translated into the appropriate language(s). All persons potentially
exposed to the chemical should also have the instructions on the
chemical safety card clearly explained.
Space is available on the card for insertion of the National
Occupational Exposure Limit, the address and teleaohone number of the
National Poison Control Centre, and for local trade names.
INTERNATIONAL CHEMICAL SAFETY CARD
DICHLORVOS
Chemical formula: C4H7Cl2O4P
CAS chemical name: (2,2-Dichloroethenyl dimethylphosphate)
CAS: registry number: 62-73-7
PHYSICAL PROPERTIES OTHER CHARACTERISTICS
Boiling point (°C) 35°C (0.05 mmHg) Colourless to amber liquid with a mild chemical
74°C (1 mm Hg) odour; stable to heat, but is hydrolysed by
Vapour pressure 1.6 Pa at 20°C water at a rate of 3% per day at room
Density (25°C) g/ml 1.415 temperature; corrosive to iron and mild steel
Relative molecular mass 221
Solubility:
in water (20°C) 10 g/litre
in kerosine 2-3 g/litre
miscible with most organic solvents
Log n-octanol/water partition
coefficient 1.47
HAZARD/SYMPTOM PREVENTION AND PROTECTION FIRST AID
GENERAL: readily absorbed via skin,
ingestion, and inhalation; may cause
organophosphate poisoning: weakness,
headache, vomiting, excessive sweating
and salivation, pinpoint pupils; in
severe cases: convulsions, unconsciousness,
and death due to respiratory paralysis
PHYSICAL PROPERTIES OTHER CHARACTERISTICS
SKIN: irritation; redness; extensive Wear PVC or neoprene gloves and Remove and wash contaminated
contamination may cause poisoning apron; rubber boots clothing; wash contaminated skin with
water and soap; obtain medical
attention immediately
EYES: irritation; redness Wear safety goggles or face shield Flush eyes with clean water for at
least 15 min; if irritation persists,
obtain medical attention immediately
INHALATION: overexposure may Avoid inhaling the vapour; use In case of signs and symptoms, remove
cause poisoning proper (exhaust) ventilation or from contaminated area and obtain
suitable respiratory protection medical attention immediately
INGESTION: an unlikely Wash hands before eating, drinking,
occupational hazard using the toilet, and after work
Accidental or intentional ingestion Obtain medical attention immediately;
may rapidly lead to severe poisoning if breathing has stopped, apply
artificial respiration.
REPEATED EXPOSURE BY As above As above
INHALATION OR INGESTION,
OR THROUGH SKIN may gradually
lead to signs and symptoms
of inhibition of cholinesterase
activity
SPILLAGE STORAGE FIRE AND EXPLOSION
Absorb spilled liquid and cover Store in locked, well-ventilated Use alcohol-resistant foam or powder;
contaminated area with 1:3 mixture storeroom, away from feed and cool unaffected stock; wear protective
of sodium carbonate crystals and foodstuffs, children, and unauthorized clothing and self-contained
damp sawdust, lime, sand, or earth; personnel breathing apparatus
sweep up and place in closed and
suitably labelled container
(cont'd)
WASTE DISPOSAL
Burn at high temperature in incinerator National Occupational Exposure Limit: UN: 2783, 2784, 3017, 3018
with effluent scrubbing;
comply with local legislation; when National Poison Control Centre:
allowed, treat with washing soda
mixed with soil rich in organic Local trade names:
matter and bury in an approved
dump
7. 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 UN sources. Its intention is to give the reader a
representative but non-exhaustive overview of current regulations,
guidelines, and standards.a
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.
7.1 Previous Evaluations by International Bodies
Dichlorvos was evaluated by the Joint FAO/WHO Expert Committee on
Pesticide Residues (JMPR) in 1965, 1966, 1967, 1969, 1970, 1974, and
1977. In 1966, the JMPR established an Acceptable Daily Intake (ADI)
for man of 0-0.004 mg/kg body weight, a level still maintained as
acceptable.
The Pesticide Development and Safe Use Unit, Division of Vector
Biology and Control, WHO, classified technical dichlorvos as "highly
hazardous" (Class IB) (Plestina, 1984; WHO, 1986a). This division has
also issued a data sheet on dichlorvos (WHO/FAO, 1975).
In 1979, IARC came to the following conclusion in considering the
carcinogenicity of dichlorvos:
- Dichlorvos was tested in different animal species via different
routes; no conclusive evaluation on the basis of these studies
could be made;
- Dichlorvos is an alkylating agent and binds to bacterial and
mammalian nucleic acids;
- It is a mutagen in a number of microbial systems, but there is no
evidence of its mutagenicity in mammals, in which it is rapidly
degraded.
IRPTC has published a volume on Dichlorvos, in its series "Scientific
Reviews of Soviet Literature on Toxicity and Hazards of Chemicals".
a The regulations and guidelines of all countries are subject to
change and should always be verified with the appropriate regulatory
authorities before application.
7.2 Exposure Limit Values
Some exposure limit values are given in the following table.
When no effective date appears in the IRPTC legal file the year of the
reference from which the data are taken is indicated by (r).
7.3 Specific Restrictions
Dichlorvos has been officially approved for use as a pesticide in many
countries, in each of which specific uses are defined as well as
limitations and precautions. Absorption through the skin is indicated
as a potentially hazardous route in the regulatory documents in
Argentina, the countries of the European Community, the USA, and the
USSR.
In Brazil, the maximum concentration of the active substance
authorized for use as an insecticide is 1-5% (weight/weight).
In the USSR, the presence of dichlorvos in fishing waters is not
allowed, but a level of 0.1 mg/litre is allowed in other surface
waters. The preliminary safety limit for soil is 0.1 mg/kg.
7.4 Labelling, Packaging, and Transport
The United Nations Committee of Experts on the Transportation of
Dangerous Goods classifies dichlorvos in:
- Hazard Class 6.1: poisonous substance;
- Packing Group II: a substance presenting a serious risk of
poisoning in transport, for material containing 35-100%
dichlorvos;
- Packing Group III: a substance presenting a relatively low risk
of poisoning in transport, for material containing 7-35%
dichlorvos.
EXPOSURE LIMIT VALUES
Medium Specification Country Exposure limit description Value Effective
organization Date
AIR Work-place Argentina Maximum permissible concentration 1979
- Time-weighted average (TWA) 1 mg/m3
- Short-term exposure limit (STEL) 3 mg/m3
Germany, Maximum work-site concentration (MAK) 1 mg/m3
Federal - Time-weighted average (TWA)
Republic of - 30-min short-term exposure
limit (STEL) 10 mg/m3
United Kingdom Recommended limit (RECL) 1 mg/m3
- Short-term exposure limit (STEL) 3 mg/m3
USA Permissible exposure limit
- Time-weighted average (TWA) 1 mg/m3
USSR Maximum allowable concentration (MAC)
- Ceiling value 0.2 mg/m3 1977
AIR Ambient USSR Maximum allowable concentration (MAC)
(average per day) 0.002 mg/m3
FOOD General FAO/WHO Acceptable daily intake (ADI) 0-0.004 mg/kg 1966
body weight
FOOD Plant Brazil Acceptable limit (AL) 0.1-5 mg/kg 1981
- Safety interval 30 days
Czechoslovakia Maximum residue limit (MRL) 0.02-2 mg/kg 1978
European Community Maximum residue limit (MRL) 0.1 mg/kg 1984
(cont'd)
Medium Specification Country Exposure limit description Value Effective
organization Date
FOOD Plant FAO/WHO Maximum residue limit (MRL) 0.02-5 mg/kg 1978
India Maximum tolerable concentration (MTC) 0.1-1 mg/kg 1976
Japan Acceptable residue limit (ARL) 0.1 mg/kg
Sweden Maximum tolerable concentration (MTC) 0.1-2 mg/kg 1985
USSR Maximum residue limit (MRL) for
specific food items 0-0.3mg/kg 1983
Acceptable daily intake (ADI) 0.04 mg/kg
FOOD Animal Kenya Maximum limit 0.02-5 mg/kg
Sweden Maximum tolerable concentration (MTC) 0.02-0.1 mg/kg 1983
USA Acceptable residue limit (ARL) 0.05-10 mg/kg
The label should be as follows:
In Packing Group II
In Packing Group III
The European Community Legislation requires labelling as dangerous
substance using the symbol:
The label must read:
Toxic by inhalation, in contact with skin and if swallowed; keep
out of reach of children; keep away from food, drink and animal
feeding stuffs - if you feel unwell, seek medical advice (show
the label where possible).
The European Community legislation on labelling of pesticide
preparations classifies dichlorvos in Class lc for the purpose of
determining the label for preparations containing dichlorvos and other
active ingredients.
WHO gives the following product specification for dichlorvos for use
in public health:
Technical dichlorvs: the material shall consist of dichlorvos
togethex with related manufacturing compounds and shall be a pale
amber-coloured liquid free from extraneous impurities or added
modifying agents. It shall contain at least 970 g of dichlorvos
per kg. Acidity and water content are specified and analytical methods
for checking are given.
Technical dichlorvos shall be packed in suitable clean containers,
and all packages shall bear; durably and legibly marked on the
container, the following:
- Manufacturer's name
- Technical dichlorvos to specification WHO/SIT/16.R2
- Batch or reference number, and date of test
- Net weight of contents
- Date of manufacture
and the following minimum cautionary notice:
"POISON (skull-and-crossbones emblem): dichlorvos is an
organophosphorus compound that inhibits cholinesterase. It is
poisonous if swallowed, inhaled, or absorbed through the skin. Wear
protective gloves, clean protective clothing goggles, and a
respirator of the organic-vapour type when handling this material.
Avoid prolonged exposure to fumes. Wash hands and exposed skin after
handling and before eating and bathe immediately after work.
Keep the material out of the reach of children and well away from
foodstuffs, animal feed and theircontainers. Ensure that containers
are tightly sealed, and stored and disposed of in such a way as to
prevent accidental contact.
In case of contact, immediately remove cotstansinated 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."
Similar specifications and instructions are given for dichlorvos
emulsifiable concentrate. FAO gives similar product specifications for
dichlorvos for its use in plant protection. In this case, the
technical material should contain at least 95% active material.
Containers must comply with pertinent national and international
transport and safety regulations.
BIBLIOGRAPHY
FAO (1985a) Guidlines for the packaging and storage of pesticides.
Rome, Food and Agriculture Organization of the United Nations.
FAO (1985b) Guidlines for the disposal of waste pesticides and
pesticide containers on the farm. Rome, Food and Agriculture
Organization of the United Nations.
FAO (1985c) Guidlines on good labelling practice for pesticides.
Rome, Food and Agriculture Organization of the United Nations.
FAO (1986a) International code of conduct on the distribution and use
of pesticides. Rome, Food and Agriculture Organization of the United
Nations.
FAO/WHO (1986b) Guide to Codex recommendations concerning pesticitle
residues. Part 8. Recommendations for methods of analysis of
pesticide residues. 3rd ed. Rome, Codex Committee on Pesticide
Residues.
GIFAP (1982) Guidelines for the safe handling of pesticides during
their formulation, packing, 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 pesticide
poisoning. Brussels, Groupement International des Associations
Nationales des Fabricants de Produits Agrochimiques.
GIFAP (1987) Guidelines for the safe transport of pesticides.
Brussels, Groupement International des Associations Nationales des
Fabricants de Produits Agrochimiques.
IARC (1972-present) LARC Monographs on the Evaluation of Carcinogenic
Risk of Chelnicals to Man. Lyons, International Agency for Research
on Cancer.
IRPTC (1985) IRPTC file on treatment and disposal methods for waste
chemicals. Geneva, International Register of Potentially Toxic
Chemicals, United Nations Environment Programme.
IRPTC (1987) IRPTC legal file 1986. Geneva, International Register
of Potentially Toxic Chemicals, United Nations Environment Programme.
PLESTINA, R. (1984) Prevention, diagnosis, and treatntent of
insecticide poisoning. Geneva, World Health Organization
(Unpublished report No. VBC/84.889).
SAX, N.I. (1984) Dangerous properties of industrial materials. New
York, Van Nostrand Reinhold Company, Inc.
UNITED NATIONS (1986) Recommendations on the transport of dangerous
goods. 4th ed. New York, United Nations.
US NIOSH/OSHA (1981) Occupational health guidelines for chemical
hazards. 3 Vols. Washington DC, US Department of Health and Human
Services, US Department of Labor (Publication No. DHHS(NIOSH) 01-123).
WHO (1986a) EHC No. 63. Organophosphorus Insecticides : a general
introduction. Geneva, World Health Organiyation, 181 pp.
WHO (1986b) The WHO recommended classification of pesticides by
hazard. Guidelines to classification 1986-87. Geneva, World Health
Organization (Unpublished report VBC/86.1).
WHO (1988) EHC No. 79: Dichlorvos. Geneva, World Health
Organization.
WHO/FAO (1975-87) Dichloros. Data sheets on pesticides, Geneva,
World Health Organization (Unpublished documents).
WORTHING, C.R. & WALKER, S.B. (1983) The pesticicle manual. 7th ed.
Lavenham, Lavenham Press Limited, British Crop Protection Council.
ANNEX 1
TREATMENT OF ORGANOPHOSPHATE INSECTICIDE POISONING IN MAN
(From EHC 63: Organophosphorus Insecticides - A General Introduction)
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.
I.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 venupuncture 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 in 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.
I.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.
I.3 Specific Pharmacological Treatment
I.3.1 Atropine
Attopine should be given, beginning with 2 mg i.v. and given at
15-30-min intervals. The dose and the frequency of attopine 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.
I.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 attopine. Pralidoxime is the
most widely available oxime. A dose of 1 g pralidoxime can be given
either i.m. or i.v. 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.
I.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, which are not affected by atropine.
Doses of 10 mg s.c. or i.v. 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.
I.3.4 Notes on the recommended treatment
I.3.4.1 Effects of atropine and oxime
The combined effect far exceeds the benefit of either drug singly.
I.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.
I.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).
I.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 attopine i.v. every 15 min together with continuous i.v. 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 I
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 report No. 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 fof 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.