IPCS INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
Health and Safety Guide No. 24
ALLETHRINS
HEALTH AND SAFETY GUIDE
UNITED NATIONS ENVIRONMENT PROGRAMME
INTERNATIONAL LABOUR ORGANISATION
WORLD HEALTH ORGANIZATION
WORLD HEALTH ORGANIZATION, GENEVA 1989
This is a companion volume to Environmental Health Criteria
87: Allethrins
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 154345 0
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 1989
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. Human exposure to allethrins
2.2. Decomposition and metabolism
2.3. Evaluation of effects on the environment
2.4. Evaluation of human health risks
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
4.1.2. 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
7.5. Waste disposal
BIBLIOGRAPHY
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 chemicals, 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, sections 1 and 2 inevitably
contain some 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
Allethrin is an ester of chrysanthemic acid with allethrolone. It is a
racemic mixture of 8 stereoisomers, which are present in the technical
material roughly in the proportion of 1:1:1:1:1:1:1:1. d-Allethrin,
bioallethrin, esbiothrin, and S-bioallethrin are also available as
selected stereoisomers or in mixtures.
Molecular formula: C19H26O3
Chemical structure: 
1.2 Physical and Chemical Properties
The physical and chemical properties of allethrin and its selected
isomers are given in the International Chemical Safety Card.
1.3 Analytical Methods
Determination of residues and analyses of environmental samples are
carried out using dual-wavelength densitometry (370 or 230 nm), or
derivatization and colorimetric measurement of levels as low as
0.1 mg/kg. Gas chromatography with a flame-ionization detector is used
for the analysis of the technical product.
1.4 Production and Uses
It is estimated that several hundred tonnes of allethrin, d-allethrin,
bioallethrin, esbiothrin, and S-bioallethrin are manufactured and
used each year throughout the world, mainly for the control of
household insects. Formulations include aerosols, sprays, smoke coils,
electric mats, and emulsifiable concentrates, with or without
synergists and other insecticides.
2. SUMMARY AND EVALUATION
2.1 Human Exposure to Allethrins
It is thought that human exposure occurs mainly through the inhalation
of mists from aerosol sprays, and from other household applications,
such as the electric mat and mosquito coil. Air levels arising from
the conventional household application of allethrin in the form of an
aerosol are not expected to exceed 0.5 mg/m3. In the case of
individual isomers, the air levels are probably lower under the same
conditions of use.
Although the levels of allethrins in food have not been determined,
current use patterns indicate that it is unlikely that such dietary
exposure levels would be significant.
No data are available on occupational exposure to the allethrins.
2.2 Decomposition and Metabolism
Allethrin is fairly rapidly decomposed under normal environmental
conditions. Metabolism and excretion from the mammalian body are also
known to take place quite rapidly. There are no indications of
bio-accumulation under normal conditions of use.
2.3 Evaluation of Effects on the Environment
Allethrins are primarily used indoors. No information is available on
levels in the environment. Allethrins are rapidly decomposed when
exposed to sunlight and at temperatures exceeding 400°C, but are
vaporized by slow heating at 150°C.
Allethrins are toxic for fish with LC50 values ranging from 9 to
90 µg/litre. However, they are less toxic for Daphnia and aquatic
insect larvae (150-50 000 µg/litre). The toxicity of allethrin is low
for birds (LD50 2000 mg/kg), but high for honeybees (LD50 3-9 µg/bee).
2.4 Evaluation of Human Health Risks
Although the allethrins have been used for many years, no data have
been reported on their toxicity for human beings. Thus, this has to be
determined by the extrapolation of data from in vitro studies and
studies on experimental animals.
The results of short-term studies on experimental animals suggest that
allethrins are weakly to moderately toxic (oral and dermal LD50 values
ranging from 210 to 4290 mg/kg, inhalation LC50s > 1500 mg/m3).
On the basis of several inhalation studies on mice and rats (using
mosquito coils and mats), at a range of dose levels (10 ×, 20 ×, 25 ×
normal use concentration), the short-term toxicities of S-Bioallethrin
and d-allethrin appear to be low.
Allethrins have shown mild primary eye and skin irritation in rabbits,
but no skin sensitization.
The allethrins were not mutagenic in a variety of test systems
including gene mutations, DNA damage, DNA repair, and chromosomal
effects.
d-Allethrin was not carcinogenic in rats fed diets containing
2000 mg/kg diet over 2 years.
Relatively high doses of allethrin, bioallethrin, or S-Bioallethrin
were not embryotoxic or teratogenic in rabbits, rats, or mice. No
adequate reproduction studies have been reported.
Allethrins at near lethal doses are likely to cause hyperactivity,
tremors, and convulsions and have been classified as Type I
pyrethroids.
No-observed-adverse-effect levels for bioallethrin were established in
a 90-day rat study and a 6-month dog study (1500 mg/kg of diet and
200 mg/kg of diet, respectively, corresponding to 135 mg/kg body
weight per day and 5 mg/kg body weight per day, respectively). In a
2-year dog study, the no-observed-adverse-effect level for allethrin
in the diet was greater than 50 mg/kg body weight (highest dose
tested).
3. CONCLUSIONS AND RECOMMENDATIONS
3.1 Conclusions
General population. Under recommended conditions of use, the
exposure of the general population to allethrins is negligible and is
unlikely to present a hazard.
Occupational exposure. With reasonable work practices, hygiene
measures, and safety precautions, the use of allethrins is unlikely to
present a hazard to those occupationally exposed to it.
Environment: With recommended application rates and conditions of
use, it is unlikely that allethrins or their degradation products will
attain levels of environmental significance. In spite of their
toxicity for fish and honeybees, a problem is only likely to arise in
the case of spillage or misuse.
3.2 Recommendations
Labels for the household use of allethrins should include adequate
instructions for use and storage and, where appropriate, warn of
flammability.
4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY ACTION
4.1 Main Human Health Hazards, Prevention and Protection, First Aid
Allethrins are synthetic pyrethroid insecticides. No cases of
poisoning have been reported either in the general population or
through occupational exposure. The results of experimental animal
studies suggest that, following massive overexposure or accidental
ingestion, neurological symptoms, such as tremors and convulsions,
could occur.
The human health hazards associated with certain types of exposure to
allethrins together with preventive and protective measures and first
aid recommendations are listed on the International Chemical Safety
Card.
4.1.1 Advice to physicians
No specific antidote is known. Treat symptomatically. The main hazard
with liquid formulations is aspiration of the solvent into the lungs,
resulting in chemical pneumonitis.
4.1.2 Health surveillance advice
Pre-exposure and annual general medical examinations should be carried
out on workers regularly exposed to allethrins.
4.2 Explosion and Fire Hazards
Some solvents in pyrethroid formulations are highly flammable. Use dry
powder, carbon dioxide, or alcohol-resistant foam, sand, or earth for
dealing with fires. DO NOT use water. Cool nearby drums with water
spray.
If pyrethroid products are involved in a major fire or in a fire
involving other products, advise the fire service that protective
clothing and breathing apparatus should be worn. Also, warn the
authorities that pyrethroids are highly toxic for fish, and that the
use of water should be confined to the cooling of unaffected stock,
thus avoiding the accumulation of polluted run-off from the site.
4.3 Storage
Store technical material and formulations away from heat, under lock
and key, and out of reach of children, animals, and unauthorized
personnel. Store away from foodstuffs and animal feed in an area
designated for insecticide storage, preferably without drains.
4.4 Transport
Pyrethroids are classified as "harmful" or "low hazard" for transport
purposes. Formulations based on flammable solvents may be subject to
local transport controls. Before dispatch, ensure that containers are
sound and that labels are securely fixed and undamaged. Comply with
local transport regulations.
Accident procedures:
Avoid exposure, if possible by using appropriate protective clothing
and masks. Keep spectators away from the leaking or spilled product
and prevent smoking or the use of naked flames in the immediate
vicinity.
Extinguish fires with dry powder, carbon dioxide, alcohol-resistant
foam, sand, or earth.
Prevent liquid from spreading to other cargo, vegetation, or waterways
by making a barrier with the most readily available material, e.g.,
earth or sand.
Absorb spilled liquid and cover contaminated areas with earth, lime,
sand, or other absorbent material and place in a secure container for
subsequent safe disposal.
4.5 Spillage and Disposal
4.5.1 Spillage
Avoid exposure, if possible by using appropriate protective clothing
and masks.
Empty any product remaining in damaged or leaking containers into a
clean, empty drum and label.
Absorb spillage with lime, damp sawdust, sand, or earth and dispose of
safely (see section 4.5.2). If spillage is large, contain it by
building a barrier using earth or sandbags.
Decontaminate empty, damaged, or leaking containers with a 10% sodium
carbonate solution added at the rate of at least 1 litre per 20-litre
drum. Puncture containers to prevent re-use.
4.5.2 Disposal
Waste containing allethrins should be burnt in a proper high
temperature incinerator with effluent scrubbing. Where no incinerator
is available, contaminated absorbents or surplus products should be
decomposed by hydrolysis at pH 12 or above. Contact with a suitable
hydrolysing agent is required to ensure degradation of the active
ingredient to a safe level.
For emulsifiable material: 5% sodium hydroxide (caustic soda)
solution or saturated (7-10%) sodium carbonate (washing soda) solution
can be used.
For non-emulsifiable material: use a 1:1 mixture (by volume) of
either of the above solutions and a water/oil-soluble solvent, such as
denatured alcohol, monoethylene glycol, hexylene glycol, or isopropyl
alcohol.
Cover the material with the hydrolysing agent and put aside to stand
for 7 days. Before disposal of the resultant waste, the material
should be analysed to ensure that the active ingredient has been
degraded to a safe level.
Never pour untreated waste or surplus products into public sewers or
where there is any danger of run-off or seepage into streams,
watercourses, open waterways, ditches, fields with drainage systems,
or the catchment areas of boreholes, wells, springs, or ponds.
5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION
With recommended techniques and rates of application, it is unlikely
that allethrin and its degradation products will attain levels of
environmental significance. Allethrins are very toxic for fish and
honeybees but, because the exposure levels that normally occur are
very low, this will only cause a problem in the case of spillage.
Avoid spraying over bodies of water. Do not contaminate ponds,
waterways, or ditches with the product or with used containers.
6. INTERNATIONAL CHEMICAL SAFETY CARD
This card should be easily available to all health workers concerned
with, and users of, allethrins. It should be displayed at, or near,
entrances to areas where there is potential exposure to allethrins,
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 telephone number of the
National Poison Control Centre, and for local trade names.
INTERNATIONAL CHEMICAL SAFETY CARD
ALLETHRIN
CAS chemical name: Cyclopropanecarboxylic acid,
2,2-dimethyl-3-(2-methyl-1-propenyl)-,2-methyl-4-oxo-3-(2-propenyl)-2-cyclopentene-1-yl ester
Molecular formula: C19H26O3
CAS registry no. 584-79-2
RTECS registry no. GZ1476000
Physical properties Allethrin d-Allethrin Bioallethrin Esbiothrin S-Bioallethrin Other characteristics
Physical state oil oily viscous viscous liquid Technical allethrin contains 75-95%
liquid liquid liquid allethrin, which is a mixture
of 8 stereoisomers; d-allethrin,
Colour pale -- amber yellow yellow bioallethrin, and S-bioallethrin
yellow differ from allethrin in
stereoisomeric composition; all
four are unstable to light, air,
Odour -- -- aromatic -- -- alkaline conditions, and heat, and
decompose at temperatures above
Relative molecular 302.45 302.45 302.45 302.45 302.45 400°C; at 150°C, they are
mass vaporized without decomposition
Boiling point 140°C 130°C 65.6°C -- -- Allethrin is a synthetic pyrethroid
(0.1 mmHg) (flash) (flash) mainly used for the control of flies
and mosquitos in homes, flying and
Water solubility insoluble insoluble insoluble insoluble insoluble crawling insects in stables and on
livestock, and fleas and ticks on
Solubility in organic solublea soluble solubleb soluble soluble dogs and cats
solvents
INTERNATIONAL CHEMICAL SAFETY CARD (cont'd).
Physical properties Allethrin d-Allethrin Bioallethrin Esbiothrin S-Bioallethrin Other characteristics
25 20 20 20
Density d 4 1.005 d 4 1.005- d 4 0.997 -- d 4 0.980
1.015
Vapour pressure 1.2 × 10-4 -- 3.3 × 10-4 -- --
mmhg mmHg
(30°C) (25°C)
n-Octanol/water -- -- 4.8 × 104 -- --
partition (25°C)
coefficient
a Methanol ( > 1 kg/kg), hexane ( > 1 kg/kg), xylene ( > 1 kg/kg), acetone, carbon tetrachloride, kerosene, petroleum.
b Acetone, ethanol, hexa c, methylene chloride, kerosene.
INTERNATIONAL CHEMICAL SAFETY CARD (cont'd).
Hazards/symptoms Prevention and protection First aid
SKIN: irritating to skin Proper application technique, Remove contaminated clothing, wash skin
proper skin protection with water and soap
EYES: irritating to eyes Face shield; goggles Flush immediately with clean water for at
least 15 minutes
INHALATION: irritant to respiratory Avoid inhalation of fine dust Fresh air
system and mist
INGESTION: unlikely occupational Do not eat, drink or smoke during --
hazard working hours; wash hands before
eating
Accidental or deliberate ingestion Obtain medical attention immediately; if
could lead to neurological symptoms breathing has stopped, apply artificial
such as tremor and convulsions; respiration; do not induce vomiting
main hazard of ingested liquid
formulations is aspiration into lungs
ENVIRONMENT: very toxic for fish Do not contaminate ponds, --
and honeybees waterways, or ditches with
product or used containers
Spillage Storage Fire and Explosion
Absorb spillage with lime, damp Store in locked, well ventilated Some liquid formulations may be highly
sawdust, sand, or earth; sweep up, storeroom, away from feed flammable; DO NOT use water; use dry
place in closed container, and and foodstuffs, children and powder, carbon dioxide, or alcohol-resistant
dispose of safely; avoid contamination unauthorized personnel foam; cool nearby drums with water spray
of personnel, ponds, and waterways
INTERNATIONAL CHEMICAL SAFETY CARD (cont'd).
Waste disposal
Burn in high temperature incinerator National Occupational
with effluent scrubbing; alternatively,
treat with 5% caustic soda as a Exposure Limit:
hydrolysing agent; comply with
local regulations National Poison Control Centre:
Local trade names:
7. CURRENT REGULATIONS, GUIDELINES, AND STANDARDS
The information given in this paragraph has been extracted from the
International Register of Potentially Toxic Chemicals (IRPTC) legal
file and other United Nations sources. The intention is to give the
reader a representative but not exhaustive overview of current
regulations, guidelines, and standards.
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.a
7.1 Previous Evaluations by International Bodies
The FAO/WHO Joint Meeting on Pesticide Residues (JMPR) discussed and
evaluated allethrin at its meeting in 1965, but did not establish an
ADI.
WHO classified the acute hazard for health of technical allethrin and
technical bioallethrin as slight and moderate, respectively (WHO,
1986).
7.2 Exposure Limit Values
In the USA (1983), the maximum residue limit in, or on, specified raw
plant products was 2-4 mg/kg. An exemption from residue tolerance
requirements was made for this insecticide when used before harvest on
certain specified plant products.
In the Federal Republic of Germany, the maximum residue limit on
specified plant products ranges from 0.5 to 3 mg/kg.
7.3 Specific Restrictions
No information available.
7.4 Labelling, Packaging, and Transport
The United Nations Committee of Experts on the Transportation of
Dangerous Goods classifies pyrethroids in:
Hazard Class 6.1: poisonous substance
Packing Group III: a substance presenting a relatively low risk of
poisoning in transport.
a The regulations and guidelines of all countries are subject to
change and should always be verified with the appropriate
regulatory authorities before application.
The label should be as follows:
The bottom half of the label should bear the inscription:
Harmful, stow away from foodstuffs.
The FAO specifications for plant protection products for
d- trans-allethrin (technical product and formulations) advise on
methods for the checking of the composition and purity of the product.
The d- trans-allethrin content shall be declared and may not deviate
more than 2% from this.
Where necessary, containers should be lined with a suitable material
or the interior surfaces treated to prevent corrosion and/or
deterioration of the contents. They should comply with pertinent
national and international transport and safety regulations.
In the countries of the European Community, pyrethroids are classified
as harmful for labelling and packaging purposes. The label must read:
Harmful by inhalation, in contact with skin and if swallowed; keep out
of reach of children; keep away from food, drink; and animal feeding
stuff.
The following symbol should be used:
7.5 Waste Disposal
In the USA, permits are required for the discharge of pyrethroids from
any point source into USA waters; detailed instructions are provided.
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FAO (1985a) Guidelines for the packaging and storage of pesticides.
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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 (1986) Guide to Codex recommendations concerning pesticide
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) IARC monographs on the evaluation of carcinogenic
risk of chemicals to man. Lyons, International Agency for Research on
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chemicals. Geneva, International Register for Potentially Toxic
Chemicals, United Nations Environment Programme.
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insecticide poisoning. Geneva, World Health Organization (unpublished
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UNITED NATIONS (1986) Recommendations on the transport of dangerous
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NIOSH/OSHA (1981) Occupational health guidelines for chemical hazards.
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WHO (in press) Environmental Health Criteria 87: Allethrins --
allethrin, d-allethrin, bioallethrin, S-bioallethrin. Geneva, World
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