E X T O X N E T
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Pesticide
Information
Profile
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Chlorothalonil
Publication Date: 5/94
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TRADE OR OTHER NAMES
Trade names include Bravo, Chloro-thalonil, Daconil 2787, Exotherm
Termil, Forturf, Mold-Ex, Nopcocide N-96, Ole, Pillarich, Repulse, and
Tuffcide. The compound can be found in formulations with many other
pesticide compounds.
REGULATORY STATUS
Chlorothalonil is classified as a General Use Pesticide (GUP) by the
U.S. Environmental Protection Agency.
INTRODUCTION
Chlorothalonil is a broad-spectrum organochlorine pesticide
(fungicide) used to control fungi that threaten vegetables, trees, small
fruits, turf, ornamentals, and other agricultural crops. It also controls
fruit rots in cranberry bogs, and is used in paints.
TOXICOLOGICAL EFFECTS
ACUTE TOXICITY
Chlorothalonil is slightly toxic to mammals, but it can cause severe
eye and skin irritation in certain formulations (13). Chlorothalonil
containing products have a range of signal words, including: WARNING
(Bravo 720, 500), CAUTION (Exotherm Termil), and DANGER (Bravo W-75,
Daconil W-75). Each of these products has a different formulation and
product concentration and thus requires a different signal word. Very high
doses may cause a loss of muscle coordination, rapid breathing, nose
bleeding, vomiting, and hyperactivity. Dermatitis, vaginal bleeding,
bright yellow and/or bloody urine, and kidney tumors may also occur,
followed by death (4).
The oral LD50 is > 10,000 mg/kg for rats (13), and 6,000 mg/kg for
mice (7). The acute dermal LD50 for both albino rabbits and albino rats is
10,000 mg/kg (6). In albino rabbits, 3 mg of chlorothalonil applied to the
eyes caused mild irritation that subsided within seven days of exposure
(8).
CHRONIC TOXICITY
In a number of tests of varying lengths of time, rats which were fed
a range of doses of chlorothalonil generally showed no effects on physical
appearance, behavior, or survival. Kidney changes such as kidney
enlargement were common (8). In a two-year dietary rat study, the lowest
dose of chlorothalonil that produced no adverse effects in the animals was
60 ppm (3 mg/kg) (15).
Human eye and skin irritation is linked to chlorothalonil exposure.
Fourteen out of 20 workers exposed to 0.5% chlorothalonil in a wood
preservative developed dermatitis. All workers showed swelling and
inflammation of the upper eyelids (8). Allergic skin responses have also
been noted in vegetable and in horticultural workers (12).
Reproductive Effects
In a long-term rat study, high doses fed to both males and females did
not affect reproduction or the litters that were produced. However, body
weight gains for males and females of each generation were decreased (8).
Administration of high doses of chlorothalonil to pregnant rabbits
through the stomach during the sensitive period of gestation resulted in
four of the nine mothers aborting (8). These studies suggest that
chlorothalonil will not affect human reproduction except at very high
doses.
Teratogenic Effects
Female rats given high doses of chlorothalonil through the stomach
during the sensitive period of gestation had normal fetuses, even though
that dose was toxic to the mothers (8). One study of birth defects in
rabbits showed no effects (5). Thus, chlorothalonil is expected to produce
no birth defects in humans.
Mutagenic Effects
Mutagenicity studies on various animals, bacteria, and plants indicate
that chlorothalonil does not cause any chromosomal changes (3, 5, 8). The
compound is therefore not expected to pose mutagenic risks to humans.
Carcinogenic Effects
Chlorothalonil is a potential human carcinogen, known to affect the
kidney, ureter, and bladder in experimental animals (7). Male and female
rats fed chlorothalonil daily over a lifetime developed carcinogenic and
benign kidney tumors at the higher doses (8). In another study, where mice
were fed high daily doses of chlorothalonil for two years, females
developed tumors in the fore-stomach area (attributed to irritation by the
compound) and males developed carcinogenic and benign kidney tumors (8).
However, this latter study was inconclusive as to the relationship between
dose of chlorothalonil and the presence of cancer in the test animals.
Organ Toxicity
Chronic studies of rats and dogs fed high dietary levels show that
chlorothalonil is toxic to the kidney. In addition to less urine output,
changes in the kidney included enlargement, greenish-brown color, and
development of small grains (9).
Skin contact with chlorothalonil may result in dermatitis or light
sensitivity (12).
Fate in Humans and Animals
Chlorothalonil is rapidly excreted, primarily unchanged, from the
body. It is not thought to be stored in animal tissues. Rats and dogs fed
very high doses for two years eliminated almost all of the chemical in
urine, feces, and expired air. After two years, the amount of the
breakdown product found in the liver tissues was considered insignificant
in both dogs and rats (8). At lower concentrations, chlorothalonil leaves
the body within 24 hours. Residues have not been found in the tissues or
milk of dairy cows (9).
ECOLOGICAL EFFECTS
Effects on Birds
Chlorothalonil is practically non-toxic to birds. The LD50 in mallard
ducks is nearly 5000 mg/kg (6). Most avian wildlife are not significantly
affected by this compound (13).
Effects on Aquatic Organisms
Chlorothalonil and its metabolites are highly toxic to fish, aquatic
invertebrates, and marine organisms. Fish, such as rainbow trout (LC50 of
0.25 mg/l), bluegills (LC50 of 0.3 mg/l) and channel catfish (LC50 of
0.43 mg/l) are noticeably affected even when chlorothalonil levels are low
(less than 1 ppm).
Chlorothalonil is not very water soluble, does not store in fatty
tissues and is rapidly excreted from the body. Its bioaccumulation factor
is quite low, about 425 times the background water concentration.
Effects on Other Organisms (Nontarget species)
The compound is non-toxic to bees (14).
ENVIRONMENTAL FATE
Breakdown of Chemical in Soil and Groundwater
In aerobic soils, the half-life for chlorothalonil is from one to
three months. Increased soil moisture or temperature increases
chlorothalonil degradation. It is not degraded by sunlight on the soil
surface (6).
Chlorothalonil has high binding and low mobility in silty loam and
silty clay loam soils, and has low binding and moderate mobility in sand.
In studies conducted in water over ten weeks time, chlorothalonil, at low
levels, was generally stable (8).
Chlorothalonil was not found in any of 560 groundwater samples
collected from 556 sites (8).
Breakdown of Chemical in SurfaceWater
In very basic water (pH 9.0), about 65% of the chlorothalonil was
degraded into two major metabolites after ten weeks (8). Chlorothalonil
was reported to be found in one surface water location in Michigan at 6.5
mg/L (8).
Breakdown of Chemical in Vegetation
Chlorothalonil's residues may remain on above-ground crops at harvest,
but will dissipate over time. Chlorothalonil is a fairly persistent
fungicide on plants, depending on the rate of application. Small amounts
of one metabolite are found in harvested crops (9).
PHYSICAL PROPERTIES AND GUIDELINES
Chlorothalonil is an aromatic halogen compound, a member of the
chloronitrile chemical family. It is a grayish to colorless crystalline
solid which is odorless to slightly pungent. It is non-corrosive and
stable in moderately alkaline or acidic aqueous solutions.
Chlorothalonil's molecular weight is 265.89 g/mol. At high temperatures,
this pesticide may decompose to emit hydrochloric acid.
Exposure Guidelines:
| RfD: | 0.015 mg/kg |
| HA: | 0.5 mg/l |
| ADI: | 0.015 mg/kg (8) |
| PEL: | N/A |
Physical Properties:
| CAS #: | 1897-45-6 |
| Chemical name: | tetrachloroisophthalonitrile |
| Solubility in water: | 0.6 mg/l @ 25 degrees C (5) (Considered insoluble). |
| Solubility in solvents: | Soluble in acetone, butanone, dimethyl formamide, and dimethyl sulfoxide (20 g/kg); cyclohexanone (30 g/kg); kerosene (< 10g/kg); xylene (80 g/kg); methyl ethyl ketone; mineral seal oil (ALL @ 25 degrees C) (6). |
| Melting point: | 250-251 degrees C (10) |
| Boiling point: | 350 degrees C (4) |
| Vapor pressure: | 1.3 Pa @ 40 degrees C (10) |
| Partition Coefficient (octanol/water) (log): | 1.32 (calculated (2, 8, 11)) |
| Adsorption Coefficient: | 1,300 - 14,000 (calculated (1, 2)) |
| Chemical Class/use: | organochlorine/fungicide |
BASIC MANUFACTURER
ISK Biotech Corporation
5966 Heisley Road
P.O. Box 8000
Mentor, OH 44061-8000
Telephone: (216) 357-4100
Review by Basic Manufacturer:
Comments solicited: October, 1992
Comments received: December, 1993
REFERENCES
Hunter, R., et al. 1984. User Manual for the QSAR system. Center
for Data Systems and Analysis. Montana State University.
Leo, A. 1978. Report on the calculation of octanol/water log P
values for structures in the EPA files. Claremont, CA.
National Library of Medicine. 1992. Hazardous Substances Databank.
Chlorothalonil. 13 February 1992.
Occupational Health Services Inc. 1987. Material Safety Data Sheet:
Chlorothalonil. 2/25/87. NY.
"Pesticide Tolerance for Chlorothalonil." Federal Register, 27 June
1985, 40 CFR Part 180.
Worthing, C.R., ed. 1983. The Pesticide Manual: Seventh Edition.
The British Crop Protection Council, Croydon, England.
Sweet, D.V., ed. 1987. Registry of Toxic Effects of Chemical
Substances Microfiche January 1987. NIOSH, Washington, DC.
U.S. Environmental Protection Agency. 1987. Office of Drinking
Water. "Chlorothalonil Health Advisory." Draft Report. August 1987.
Vettorazzi, G. 1979. International Regulatory Aspects for Pesticide
Chemicals. CRC Press. Boca Raton, FL.
Windholz, M., et al., eds. 1983. Chlorothalonil. The Merck Index:
An Encyclopedia of Chemicals, Drugs, and Biologicals. 10th Edition. Merck
& Co., Inc., Rahway, NJ.
Woodard, R. 1985. Interagency Delta Health Aspects Monitoring
Program, Project Report. California Department of Water Resources.
Edwards, I. R., D. G. Ferry, and W. A. Temple. 1991. Fungicides and
Related Compounds. in Handbook of Pesticide Toxicology, Volume 3: Classes
of Pesticides. Wayland J. Hayes, Jr. and Edward R. Laws, Jr., eds.
Academic Press, Inc., New York, NY.
Walker, M. M. and L. H. Keith. 1992. U.S. Environmental Protection
Agency's Pesticide Fact Sheet Database. Lewis Publishers, Chelsea, MI.
The Agrochemicals Handbook: Third Edition. 1991. The Royal Society
of Chemistry, Unwin Brothers Ltd., Surrey, England.
U.S. Environmental Protection Agency. 1984. Chlorothalonil: Fact
Sheet Number 36. September 30, 1984. Washington, DC.
Disclaimer: Please read
the pesticide label prior to use. The information contained at this web
site is not a substitute for a pesticide label. Trade names used herein
are for convenience only; no endorsement of products is intended, nor is
criticism of unnamed products implied. Most of this information is historical
in nature and may no longer be applicable.
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