WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANIZATION
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
ET L'AGRICULTURE
VBC/DS/75.9 (Rev.1)
ORIGINAL: ENGLISH
DATA SHEETS ON PESTICIDES No. 9 Rev.1
CAPTAN
It must be noted that the issue of a Data Sheet for a
particular pesticide does not imply endorsement of the pesticide by
WHO or FAO for any particular use, or exclude its use for other
purposes not stated. While the information provided is believed to
be accurate according to data available at the time when the sheet
was compiled, neither WHO nor FAO are responsible for any errors or
omissions, or any consequences therefrom.
The issue of this document does Ce document ne constitue pas une
not constitute formal publication. Il ne doit faire
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without the agreement of the l'autorisation de l'Organisation
Food and Agriculture des Nations Unies pour
Organization of the United l'Alimentation et l'Agriculture
Nations or of the World Health ou de l'Organisation Mondiale de
Organization. la Santé.
CLASSIFICATION:
Primary uses: Fungicide
Secondary uses: None
Chemical group: Sulfenimide
Data sheet No. 9, Rev.1 (September 1978)
1. GENERAL INFORMATION
1.1 COMMON NAME: captan (ISO)
1.1.1 Identity: 3a,4,7,7a-tetrahydro-2- (1,1,2,2-tetrachloro-
methyl)thio-1H-isoindole-1,3(2H)-dione.
1.1.2 Synonyms: None
Local synonyms:
1.2 SYNOPSIS - A sulfenimide fungicide of very low mammalian toxicity
which is rapidly hydrolysed in body tissues. It is fairly
persistent on crop surfaces.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics - When pure a white crystalline solid
m.p. 178°C. The technical material is a yellow amorphous powder
of 93-95% purity with a pungent odour and has m.p. 160-170°C.
1.3.2 Solubility - Practically insoluble in water (<O.5 mg/l) and
petroleum oils. Solubility between 10 and 100 mg/i in common
organic solvents.
1.3.3 Stability - Stable at normal temperature except under alkaline
conditions. Decomposes at about 100°C, slowly in dry and rapidly
in moist air. Rapidly decomposed in human blood; the half life
at an initial concentration of 100 µg/ml is 0.9 minutes.
Compatible with most non-alkaline pesticides. Non-corrosive but
forms corrosive decomposition products.
1.3.4 Vapour pressure (volatility) - The pure compound has a vapour
pressure of 1 x 10-5 torr at 25°C but the technical product is
stated to be much higher.
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations - 500 and 830 g/kg wettable powders; 400 g/l
aqueous suspension; 35-100 g/kg dusts for field use; 600-750 g/kg
dust for seed treatment. There are FAO specifications for dusts
and wettable powders.
1.4.2 Susceptible pests - Wide range of fungi, especially scab. rot and
leaf spot of many fruits. Probably recommended for more diseases
on deciduous top fruit than any other fungicide. Gives no
control of powdery mildews and little of rusts. No insecticidal
or acaridal activity. Has been proposed for ringworm control in
animals.
1.4.3 Use pattern - Pre-harvest protective treatment, particularly of
foliage, on many fruits, vegetables and ornamentals, and on turf.
Most important uses include control of apple, pear and peach
scab; apple rot; pear leaf spot and sooty blotch; brown rot of
cherry, peach and plum; leaf spot of sweet cherry. Rates of use
are usually 10 g/l as a high-volume spray or about 3 kg/ha.
Used for rot control in stored potatoes, as post-harvest dip for
fruit and vegetables and as a pre-packing spray for packing
boxes. It is widely used as a seed dressing, particularly on
peas, and as a pre-planting soil fungicide.
Has been used as a growth regulator to increase size of oranges
and tangeloes.
1.4.4 Unintended effects - Generally non-phytotoxic but injury to
D'Anjou and Bosc pears, and to Red Delicious, Winesap and some
other apple varieties has been reported. It is incompatible with
oil and may cause injury if applied after a summer oil
combination. There is a possibility of taint if used on fruit
for processing.
1.5 PUBLIC HEALTH PROGRAMME - None.
1.6 HOUSEHOLD USE - Used in home gardens.
2. TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route - Absorbed by the gastrointestinal tract, no
information on whether the compound can be absorbed by inhalation
or dermally.
2.1.2 Mode of action - Not known.
2.1.3 Excretion products - Captan is rapidly hydrolysed and probably
excreted as tetrahydrophthalimide, tetrahydrophthalamic acid and
tetrahydrophthalic acid. The fate of the trichloromethylthio-
portion of the molecule is uncertain; the chlorine atoms appear
to be liberated as chloride ions.
2.1.4 Toxicity, single dose
Oral: LD50 rat 9000-12 500 mg/kg
Dermal: LD50 not known
Inhalation: No information
Most susceptible species: Not known
2.1.5 Toxicity, repeated doses
Oral: In dogs fed a maxim= of 300 (mg/kg)/day in gradually
increasing doses for 60 weeks, there was no evidence of systemic
toxicity and no gross or histopathological changes in tissues due
to treatment, nor were there any significant changes in
haematological or biochemical findings.
Dermal: No information.
Inhalation: No information.
Cumulation of compound: The compound is rapidly metabolized and
does not accumulate in body tissues.
Cumulation of effect: No information.
2.1.6 Dietary studies
Short-term: Rats were fed increasing doses of captan up to a
maximum level of 10 000 mg/kg diet (500 (mg/kg)/day) for 13
weeks. Levels of 5000 and 10 000 ppm (250 and 500 mg/kg/day)
caused growth retardation.
Long-term: In a two-year feeding study, rats were fed 1000 and
5000 mg/kg of captan (50 and 250 (mg/kg)/day). The only effect
was reduced weight-gain.
2.1.7 Supplementary studies of toxicity
Reproduction: In a three-generation rat reproduction study, the
only effect at 1000 mg/kg diet (50 (mg/kg)/day) was slightly
lowered lactation index in the third generation. There was no
effect at 500 mg/kg (5 (mg/kg)/day).
Teratogenicity:
Rabbit: No malformed foetuses were observed from rabbits given up
to 75 mg/kg of captan orally on days 6-18 of gestation. The same
was true when the metabolite tetrahydrophthalimide given at 75
mg/kg daily on days 6-16 of gestation.
Hamster: No increase in abnormal foetal effects was observed in
pregnant hamsters receiving up to 100 mg/kg of captan daily on
days 1-15 of gestation. There was, however increased foetal
resorption at this level.
Monkey: There were no foetal malformations from monkeys given
up to 75 mg/kg on days 21-34 of gestation. In another study
there was increased foetal mortality at 25 mg/kg on days 22-32 of
gestation but no abnormalities.
Mutagenicity:
Mouse: Dominant lethal mutations were not induced from a
maximum intraperitoneal injection of 7 mg/kg to male mice.
Carcinogenicity:
Mouse: 560 mg/kg diet (84 (mg/kg)/day) of captan for 18 months
did not result in tumour-increase in mice.
Rat: There was no increase in tumour frequency when rats were
fed 5000 mg/kg (250 (mg/kg)/day) of captan for two years or
10 000 mg/kg (500 (mg/kg)/day) for 24 weeks.
2.1.8 Modification of toxicity: The acute toxicity of captan was
increased by a factor of 26 when rats were fed a low protein
diet.
2.2 TOXICOLOGY - MAN
2.2.1 Dangerous doses
Single: Not known.
Repeated: Not known.
2.2.2 Observations of occupationally exposed workers - There is some
evidence that captan can be irritating to the skin, eyes, nose
and mouth.
2.2.3 Observations on exposure of the general population - No
information.
2.2.4 Observations of volunteers - No information
2.2.5 Reported mishaps - No information. No reports of human poisoning
have been located.
2.3 TOXICITY TO NON-MAMMALIAN SPECIES - The entries in these sections
are intended to draw attention to special risks and to give
warnings of any needs for special precautions.
2.3.1 Fish - Toxic to fish.
2.3.2 Birds - Low toxicity.
2.3.3 Other species - Slight toxicity to bees has been reported in
field tests.
3. FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF
COMPOUND
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY
(for definition of categories, see introduction)
All formulations Category 5
3.2 TRANSPORTATION AND STORAGE
All formulation - Should be transported or stored in clearly
labelled leak-proof containers out of reach of children, away
from food and drink.
3.3 HANDLING
All formulations - Captan may be irritating to the skin, eyes,
nose and mouth. Avoid inhaling dust.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS
All formulations - Containers may be decontaminated (for method
see para. 4.3 in part 4). Decontaminated containers should not
be used for food and drink. Containers that are not
decontaminated should be burned or should be crushed and buried
below topsoil. Care must be taken to avoid subsequent
contamination of water sources.
3.5 SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS
All formulations - Pre-employment or periodic medical
examinations not necessary. Warning of workers to minimize
contact essential.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT -
No special regulations recommended.
3.7 LABELLING - Minimum cautionary statement: "Captan is a fungicide
of very low toxicity; however the dust may be irritating to the
eyes, nose or mouth".
3.8 RESIDUES IN FOOD
3.8.1 Maximum residue levels - The Joint FAO/WHO Meeting on Pesticide
Residues has recommended maximum residue levels.
4. PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
4.1.1 General - Captan is a sulfenimide fungicide of very low toxicity
which is absorbed from the gastrointestinal tract and rapidly
metabolized. It does not accumulate in tissues.
4.1.2 Manufacture and formulation - T.L.V. 5 mg/m3 (ACGIH). Vapour
and dust should be controlled by mechanical means. Protective
equipment for skin and respiratory protection is desirable.
4.1.3 Mixers and applicators - When opening the container and when
mixing care should be taken to avoid contact with the mouth and
eyes. If necessary a facial visor and gloves should be worn.
Mixing, if not mechanical, should always be carried out with a
paddle of appropriate length.
Splashes should be washed immediately from the skin or eyes with
large quantities of water. Before eating, drinking or smoking,
hands and other exposed skin should be washed.
4.1.4 Other associated workers (including flagmen in aerial operations)
- Persons exposed to captan and associated with its application
should observe the precautions described above in 4.1.3 tinder
"mixers and applicators".
4.1.5 Other populations likely to be affected - None.
4.2 ENTRY OF PERSON INTO TREATED AREAS - Persons may enter treated
areas immediately.
4.3 DECONTAMINATION OF SPILLAGE AND CONTAINERS - Residues in
containers should be emptied in a diluted form into a deep pit
taking care to avoid ground waters. The empty container may be
decontaminated by rinsing two or three times with water and
scrubbing the sides. Hands should be protected during this work.
An additional rinse should be carried out with 5% sodium
hydroxide solution which should remain in the container
overnight. Decontaminated containers should not be used for food
and drink. Spillage should be removed as much as possible
followed by washing the area with 5% sodium hydroxide solution
and then rinsing with large quantities of water.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning - As there are no reports of
poisoning with captan, the early symptoms are not known. There
may be some irritation to the skin, eyes, nose and mouth.
4.4.2 Treatment before person is seen by a physician, if these symptoms
appear following exposure - If excessive irritation occurs or if
abnormal symptoms appear following exposure to captan the person
should stop work, remove contaminated clothing and wash the
affected skin with soap and water, if available, and flush the
area with large quantities of water. If swallowed, vomiting
should be induced.
5. FOR MEDICAL AND LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT IN CASES OF POISONING
5.1.1 General information - Captan is a sulfenimide fungicide of very
low toxicity which is absorbed from the gastrointestinal tract.
It is rapidly metabolized and probably excreted as
tetrahydrophthalimide, tetrahydrophthalamic acid and
tetrahydrophthalic acid. It does not accumulate in the body
tissues.
5.1.2 Symptoms and signs - There may be some irritation to the skin,
eyes, nose and mouth. As there are no reports of poisoning with
captan the symptoms are not known, but gastrointestinal
irritation and possible renal damage might be expected from
animal experiments.
5.1.3 Laboratory - There are no practical laboratory methods; levels of
the metabolites tetrahydrophthalimide, tetrahydrophthalimic acid
and tetrahydrophthalic acid in blood and urine may give an
indication of the degree of absorption of captan.
5.1.4 Treatment - If a large quantity of captan has been ingested,
vomiting should be induced, or if the induction fails, gastric
lavage should be performed using 5% sodium bicarbonate solution,
if available. If there is skin irritation, the skin should be
washed with soap and water. If the compound has entered the
eyes, they should be washed with isotonic saline. Further
treatment should be symptomatic.
5.1.5 Prognosis - Not known.
5.1.6 References of previously reported cases - No information;
poisoning by captan has not been reported.
5.2 SURVEILLANCE TESTS - There are no practical surveillance tests.
5.3 LABORATORY METHODS - References are given only.
5.3.1 Detection and assay of compound - The colorimetric determination
of residues of captan in fruit and vegetables is described by the
AOAC (1965), and the application of the method to other crops,
meat, milk and blood is reviewed by Ospenson et al. (1964).
Captan can be determined in fruits by the gas-chromatographic
method of Baker & Flaherty (1972). This distinguishes between
captan, folpet, and captafol, and should be suitable for
regulatory purposes.
Zweig & Sherma (1972) give references to GC methods for captan
and recommend the procedure of Pack (1967) (originally applied to
difolatan) for crops.
5.3.2 Other tests in cases of poisoning - None.
REFERENCES
AOAC (1965) Official methods of analysis of the AOAC, 10th ed.,
p. 390
Baker, P. B. & Flaherty, B. (1972) Fungicide residues. Part II. The
simultaneous determination of residues of folpet, captan, and
captafol in selected fruits by the gas chromatography, Analyst,
97, 713
Ospenson, J. N. et al. (1964) In: Zweig, G., ed., Analytical methods
for pesticides, plant growth regulators and food additives,
Vol. III, New York and London, Academic Press, p. 11
Pack, D. E. (1967) ibid., Vol. V, p. 299
Zweig, G. & Sherma, J. (1972) ibid., Vol. VI, p. 548