IPCS INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
Health and Safety Guide No. 50
CAPTAN
HEALTH AND SAFETY GUIDE
UNITED NATIONS ENVIRONMENT PROGRAMME
INTERNATIONAL LABOUR ORGANISATION
WORLD HEALTH ORGANIZATION
WORLD HEALTH ORGANIZATION, GENEVA 1990
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
Captan : health and safety guide.
(Health and safety guide ; no. 50)
1. Captan - standards I. Series
ISBN 92 4 151050 1 (NLM Classification: WA 240)
ISSN 0259-7268
(c) World Health Organization 1990
Publications of the World Health Organization enjoy copyright
protection in accordance with the provisions of Protocol 2 of the
Universal Copyright Convention. For rights of reproduction or
translation of WHO publications, in part or in toto, application
should be made to the Office of Publications, World Health
Organization, Geneva, Switzerland. The World Health Organization
welcomes such applications.
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 captan
2.2. Uptake, metabolism, and excretion
2.3. Effects on animals
2.4. Effects on human beings
2.5. Effects on the environment
3. CONCLUSIONS AND RECOMMENDATIONS
4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY ACTION
4.1. Main human health hazards, prevention and protection,
first aid
4.1.1. Prevention and protection
4.1.2. First aid
4.2. Advice to physicians
4.3. Explosion and fire hazards
4.4. Storage and transport
4.5. Spillage and disposal
5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION
6. CURRENT REGULATIONS, GUIDELINES, AND STANDARDS
6.1. Exposure limit values
6.2. Specific restrictions
6.3. Transport and labelling
INTRODUCTION
This Health and Safety Guide is not based on an existing Environmental
Health Criteria document, but on critical national reviews. The
hazard evaluation in the Health and Safety Guide was made on the basis
of carefully selected studies, after scrutiny of the original
publications.
In order to assist the peer-review process of the present Health and
Safety Guide, a background companion document was prepared by the IPCS
and can be obtained from the Manager on request; the IPCS does not
intend that the background document should be published.
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 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
Chemical formula: C9H8Cl3NO2S
Chemical structure:
Relative molecular mass: 300.57
Common trade names: Aacaptan; Agrosol S; Agrox 2-WAY and
3-WAY; Amercide; Bangton; Bean Seed
Protectant; Captab; Captaf; Captaf 85W;
Capteneet 26,538; Captane;
Captan-Streptomycin 7.5-0.1 Potato Seed
Piece Protectant; Captan 50W; Captex;
ENT 26,538; Esso Fungicide 406; Flit
406; Fungus Ban Type II; Glyodex 3722;
Granox PFM; Gustafson Captan 30-DD;
Hexacap; Isotox Seed Treater "D" and
"F"; Kaptan; Malipur; Merpan;
Micro-Check 12; Neracid; NA 9099;
NCI-C00077; Orthocide; Orthocide 7.5;
Orthocide 50; Orthocide 406; Osocide;
SR406; Stauffer CAPTAN; Vancide 89;
Vancide 89RE; Vancide P-75; Vangard K;
Vanguard K; Vanicide; Vondcaptan
CAS chemical name: 1H-isoindole-1,3(2H)-dione,3a,4,7,7a-
tetra-hydro-2-[(trichloromethyl)-thio]-
Synonyms: 4-cyclohexene-1,2-dicarboximide,
N-(trichloromethyl) thio-;
1H-isoindole-1,3(2H)-dione, 3a,4,7,7a-
tetrahydro-2-((trichloromethyl)-thio)-;
3a,4,7,7a-tetrahydro- N-(trichloro-
methanesulphenyl)phthalimide;
1,2,3,6-tetrahydro- N-(trichloro-
methylthio)phthalimide;
N-(trichlormethylthio)-phthalimide;
N-trichloromethylmercapto-4-
cyclohexene-1,2-dicarboximide;
N-(trichloromethylmercapto)-delta
(sup4)-tetrahydrophthalimide;
N-trichloromethylthio-cyclohex-4-ene-
1,2-dicarboximide;
N-trichloromethylthio-cis-delta(sup4)-
cyclohexene-1,2-dicarboximide;
N-((trichloromethyl)thio)-4-
cyclohexene-1,2-dicarboximide;
trichloromethyl-thio-1,2,5,6-tetra-
hydrophthalamide;
N-((trichloromethyl)-thio)
tetrahydrophthalimide;
N-trichloromethylthio-3a,4,7,7a-tetra-
hydrophthalimide
CAS registry number: 133-06-2
RTECS registry number: GW5075000
Technical captan is usually 90-95% pure. Tetrahydrophthalimide
(4-cyclohexene-1,2-dicarboximide) and sodium chloride are the main
impurities.
1.2 Physical and Chemical Properties
Pure captan is an odourless white crystalline solid. The technical
product is an amorphous powder that is colourless to beige with a
pungent odour. Since captan decomposes slowly when heated to its
melting point, a melting point range of 158-170 °C has been reported
for the technical product. At 25°C, the vapour pressure of the pure
compound is less than 0.133 mPa. At 25°C, it is practically insoluble
in water (3.3 mg/litre), and soluble in acetone (21 g/litre),
chloroform (70 g/litre), cyclohexanone (23 g/litre), isopropanol
(1.7 g/litre), and xylene (20 g/litre). It is slightly soluble in
petroleum oils.
In the dry state, captan is stable at room temperature. However, in
aqueous solution, it is hydrolysed at a rate that is dependent on the
pH. In alkaline solution, the breakdown is rapid.
1.3 Analytical Methods
Capillary gas-liquid chromatography with electron-capture detection is
a multi-residue method suitable for the routine determination of five
fungicides including captan, folpet, captafol, vinclozolin, and
iprodione.
1.4 Production and Uses
Captan was introduced in 1949 and world production in 1983 was
estimated to be 13 000 tonnes.
It is a broad spectrum fungicide used in the cultivation of both food
and non-food crops, and also as an industrial fungicide. It has no
insecticidal or acaricidal activity. Captan is applied as a
preharvest treatment, particularly to the foliage of fruit and
vegetable crops. It is also used for seed treatment, as a pre-plant
application to the soil, and for post-harvest application. Other uses
include as an agent for cotton-seed treatment and as a therapeutic
agent against fungal infections of the skin.
Captan is also incorporated into plastics, oil-based paints, textiles,
paper, and cosmetics, and is used as a mould- and mildew-proofing
agent in coatings intended for contact with certain types of foods.
2. SUMMARY AND EVALUATION
2.1 Human Exposure to Captan
The highest human exposure to captan is associated with its
manufacture and its occupational use. Because of the widespread use
of captan, exposure of the general population through residues in food
may also be significant. However, the compound is extensively
hydrolysed during thermal and other food processing. Captan residues
in fresh vegetables and fruit can be reduced by such treatments as
washing, blanching, and peeling. Outside the working environment,
exposure through non-agricultural uses is minor.
2.2 Uptake, Metabolism, and Excretion
Captan may be absorbed by ingestion as well as by inhalation, and, to
a very limited extent, by skin exposure. After oral administration,
captan is metabolized to tetrahydrophthalimide (THPI; 4-cyclo-hexene-
1,2-dicarboximide) and the derivatives of the trichloromethylthio
(TMS) side chain. The latter compounds are reactive substances that
are bound to glutathion and further metabolized. Both captan and its
metabolites accumulate in the tissues of animals, and are rapidly
eliminated (> 90% within 24 h). The metabolism of captan differs
between the rat and the mouse in that a greater proportion of a high
dose of captan reaches the small intestine of the mouse compared with
the rat.
2.3 Effects on Animals
The toxicological properties of captan have, in general, been
thoroughly investigated. The acute oral toxicity of the compound is
low. Thus, the acute oral LD50 for the rat has been reported to be
in the range of 9000-12 500 mg/kg body weight. There are indications
that ruminants are more sensitive to captan than some other mammalian
species. Furthermore, experimental animal studies have demonstrated
that protein deprivation may increase oral toxicity. The acute
inhalation toxicity appears to be considerably higher than the oral
toxicity. Captan is irritating to the skin and to the mucous
membranes of the respiratory tract, and also to the eye; it may cause
eye damage.
Long-term administration of high dietary levels of captan to mice
resulted in the induction of benign and malignant tumours of the small
intestine. The situation regarding carcinogenicity in the rat is less
clear; in one study on the rat, a slight increase in the incidence of
kidney tumours was found. However, the carcinogenic potential in
rodents relative to other experimental carcinogens is low. Captan,
which is an alkylating agent, has demonstrated genotoxic properties in
several in vitro systems, but not in vivo. Thus, though captan may
be able to induce genotoxic events in somatic cells, the results
obtained seem to indicate that the potential for causing heritable
effects in mammals is extremely low. There is also no evidence that
captan constitutes a teratogenic hazard, though it may cause fetotoxic
effects at doses toxic for the mother.
2.4 Effects on Human Beings
Captan has caused allergic dermatitis and eye irritation in man. No
other serious adverse health effects have been identified.
2.5 Effects on the Environment
Captan is not acutely toxic for birds but is highly toxic for fish; a
96-h LC50 range of 0.03-0.7 mg/litre has been reported for various
species. Captan is moderately toxic for freshwater invertebrates,
such as Daphnia (48-h LC50 between 1 and 8 mg/litre). Captan is
not persistent, and its use is not considered to be a threat to
terrestrial wildlife. It is not toxic for bees. The environmental
impact of the pesticide is likely to be limited by its high rate of
hydrolysis and the lack of any tendency to bioaccumulate. The
half-life in lake water is 7 h at 12 °C and 1 h at 25 °C. However,
because of its demonstrated high toxicity, exposure of aquatic
organisms to captan through drift and/or run-off is a cause for
concern.
3. CONCLUSIONS AND RECOMMENDATIONS
At high exposure levels, captan has been shown to induce tumours in
mice and it causes mutations in a number of in vitro systems.
Although the carcinogenic potential of captan is considered to be low,
it is, nevertheless, recommended that this pesticide should be applied
with caution, particularly where residues in food can result.
Occupational exposure should be kept to a minimum.
Captan is highly toxic for both freshwater and marine fish and
moderately to highly toxic for freshwater invertebrates. Because of
this high toxicity, it is recommended that adequate precautions should
be taken to prevent contamination of surface and ground water.
4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY ACTION
4.1 Main Human Health Hazards, Prevention and Protection, First Aid
The acute oral toxicity of technical captan for human beings is low,
but the compound may cause dermatitis and eye irritation.
In view of the carcinogenicity induced in experimental animals with
long-term dietary administration of captan, albeit observed only at
high exposure levels, exposure of human beings should be kept at a
minimum.
4.1.1 Prevention and protection
The following precautions should be observed during handling and use,
in order to reduce the risk of accidental contamination:
(a) Avoid contact with skin and eyes.
(b) Do not smoke, drink, or eat in the work-place. Wash hands and
any exposed skin before eating, drinking, and smoking, and after work.
(c) Avoid raising a dust cloud when handling wettable powder
formulations.
(d) Avoid breathing the dust from powder products.
(e) When unloading and handling containers, wear protective PVC or
neoprene gloves.
(f) When handling leaking containers or when dealing with leaks and
spills, wear overalls, PVC or neoprene gloves, boots, and eye/face
protection. If overalls become contaminated, change and wash them
thoroughly before re-use.
(g) Store products in closed original containers, out of reach of
children, and away from food, drink, and animal feed.
4.1.2 First Aid
Acute poisoning by captan is unlikely, unless large amounts are
ingested. In case of over-exposure, apply routine first-aid measures.
If the compound has been spilled on the skin, remove the patient
immediately from the source of contamination, remove all contaminated
clothing, and wash affected areas with soap and running water. If the
material is in the eyes, flush with clean water for at least 15
minutes. In case of ingestion of significant quantities, if the
patient is conscious, give several glasses of water and do not induce
vomiting. In serious cases, medical attention should be sought.
4.2 Advice to Physicians
The acute oral toxicity of captan for human beings is low. There is
no specific antidote. Treat symptomatically when required. In cases
of ingestion of large amounts, gastric lavage may be indicated.
4.3 Explosion and Fire Hazards
Captan is not flammable, but, on heating, may produce toxic fumes,
such as sulfur dioxide, hydrochloric acid, and phosgene.
Extinguish small fires with carbon dioxide, dry powder, or
alcohol-resistant foam. Water spray can be used for larger fires and
for the cooling of unaffected stock, but avoid the accumulation of
polluted run-off from the site.
Beware: Some liquid formulations may be highly flammable and require
alcohol-resistant foam as an extinguishing agent.
4.4 Storage and Transport
All products should be stored in secure buildings, out of reach of
children and animals, and local regulations should be complied with.
Containers should be sound and adequately labelled.
4.5 Spillage and Disposal
Avoid contact with solid or dust. Keep spectators away from any
leakage. This pesticide is highly toxic for fish. Prevent
contamination of other goods or cargo, and nearby vegetation and
waterways.
Absorb spilled liquid products with earth or sand. If available,
sawdust, peat moss, or straw are also suitable absorbents; sweep up
and place in separate container. Empty any product remaining in
damaged or leaking containers into a clean empty container, which
should be suitably labelled. Sweep up any spilled powder with damp
sawdust, taking care not to raise a dust cloud (use vacuum cleaner).
Remove trapped material with suction hoses. Place in separate
container for subsequent disposal. Use mechanical dredges or lifts to
remove immobilized masses of pollutants and precipitates.
Before disposal, captan can be concentrated by gravity separation
followed by dual media filtration and activated carbon adsorption.
Alkaline treatment of captafol leads to the formation of much less
toxic degradation products. For the treatment of large spills, or for
equipment decontamination, the use of an aqueous solution of
commercial low-foaming, hard-water detergent in 5% trisodium
phosphate, or 10-25% sodium hydroxide, is recommended. During
neutralization, hydrogen sulfide may be formed, if insufficient alkali
is used.
Do not deposit captan in a landfill. It is not amenable to biological
treatment at municipal sewage plants.
5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION
Captan is not persistent and small quantities of the compound are
readily hydrolysed in soil and surface waters. However, it is highly
toxic for aquatic organisms. Contamination of ponds, waterways, and
ditches with captan should be avoided. In case of spills, and for
decontamination of equipment and containers, apply methods recommended
in section 4.5.
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. A full reference to the original national document from which
the information was extracted can be obtained from IRPTC. 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).
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 appropriate regulatory authorities
before application.
6.1 Exposure Limit Values
The threshold limit value (TWA) recommended by the US ACGIH for captan
is 5 mg/m3 in air. This value is also enforced in some other
countries, e.g., Argentina, Australia, Canada, the Netherlands, and
the United Kingdom.
On the basis of reproduction studies, a reference dose, RfD (ADI), of
0.013 mg/kg per day for non-neoplastic effects has been established by
the US Environmental Protection Agency. The Joint FAO/WHO Meeting on
Pesticide Residues has established an ADI of 0-0.1 mg/kg body weight.
Using the same data base, the EEC calculated the same ADI value at
0.013 mg/kg per day. Some tolerances for food and animal feed are
given in the table on page 20.
6.2 Specific Restrictions
In the USA, captan constitutes a hazardous chemical under the Clean
Water Act as well as under the Water Pollution Control Act, signifying
that spills must be notified and a permit required for discharge.
As of 1 January 1988, the use of captan as an ingredient in cosmetic
products has been prohibited within the European Economic Community.
In the USSR, the use of captan for the treatment of certain food
commodities is prohibited. Intentions to ban, or severely restrict,
the uses of captan have been announced by control authorities in
Canada, the Federal Republic of Germany, and the USA.
6.3 Transport and Labelling
Conveyance labelling should be as follows:
Supply and use labelling
European Economic Community legislation requires labelling as a
dangerous substance using the symbol:
The label must read:
R20 Harmful by inhalation
R36/37/38 Irritating to eyes, respiratory system and skin
S2 Keep out of reach of children
S13 Keep away from food, drink, and animal feeding stuffs
S21 When using do not smoke
S22 Do not breathe dust
S24/25 Avoid contact with skin and eyes
S36/37/39 Wear suitable protective clothing gloves and eye/face
protection
TOLERANCES AND MAXIMUM RESIDUE LIMITS FOR FOOD PRODUCTS
Country Food product Exposure limit description Value Effective
(mg/kg) date
Brazil Specified plant products Acceptable limit 10-40
Canada Raw agricultural products Acceptable residue limit 5.0 valid 1986
Czechoslovakia Plant products Maximum residue limit 10-20 October 1978
EEC Plant, general products Maximum residue limit 0.1-3.0 1989
Sweden Fruits and vegetables Maximum acceptable 5.0-15.0 June 1985
concentration
USA Raw agricultural products Tolerance 0.05-100 September 1983