---

The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

---

E X T O X N E T

Extension Toxicology Network

Pesticide Information Profiles

A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

EXTOXNET primary files maintained and archived at Oregon State University

Revised June 1996

Chlorothalonil

Trade and Other Names: Trade names for chlorothalonil include Bravo, Chlorothalonil, Daconil 2787, Echo, 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. It is classified as toxicity class II - moderately toxic, due to its potential for eye irritation. 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.

Chemical Class: chloronitrile

Introduction: Chlorothalonil is a broad-spectrum organochlorine 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.

Formulation: The compound can be found in formulations with many other pesticide compounds.

Toxicological Effects:

• Acute toxicity: Chlorothalonil is slightly toxic to mammals, but it can cause severe eye and skin irritation in certain formulations [2]. Very high doses may cause a loss of muscle coordination, rapid breathing, nose bleeding, vomiting, hyperactivity, and death. Dermatitis, vaginal bleeding, bright yellow and/or bloody urine, and kidney tumors may also occur [17]. The oral LD50 is greater than 10,000 mg/kg in rats and 6000 mg/kg in mice [9,17]. The acute dermal LD50 in both albino rabbits and albino rats is 10,000 mg/kg (9,17). In albino rabbits, 3 mg of chlorothalonil applied to the eyes caused mild irritation that subsided within 7 days of exposure [35].
• Chronic toxicity: In a number of tests of varying lengths of time, rats fed a range of doses of chlorothalonil generally showed no effects on physical appearance, behavior, or survival [35]. Skin contact with chlorothalonil may result in dermatitis or light sensitivity [35]. Human eye and skin irritation is linked to chlorothalonil exposure; 14 of 20 workers exposed to 0.5% chlorothalonil in a wood preservative developed dermatitis. All workers showed swelling and inflammation of the upper eyelids [35]. Allergic skin responses have also been noted in farm workers [7].
• Reproductive effects: Administration of high doses of chlorothalonil to pregnant rabbits through the stomach during the sensitive period of gestation was required to induce abortion in 4 of the 9 mothers. This and other studies suggest that chlorothalonil will not affect human reproduction at expected exposure levels [35].
• Teratogenic effects: Long-term studies indicate that high doses fed to rats caused reduced weight gains for males and females in each generation studied [35]. 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 [35]. A study of birth defects in rabbits showed no effects [36]. Chlorothalonil is not expected to produce birth defects in humans.
• Mutagenic effects: Mutagenicity studies on various animals, bacteria, and plants indicate that chlorothalonil does not cause any genetic changes [17,35,36]. The compound is not expected to pose mutagenic risks to humans.
• Carcinogenic effects: Based on evidence from animal studies, chlorothalonil's carcinogenic potential is unclear. Male and female rats fed chlorothalonil daily over a lifetime developed carcinogenic and benign kidney tumors at the higher doses [35]. In another study, where mice were fed high daily doses of chlorothalonil for 2 years, females developed tumors in the fore-stomach area (attributed to irritation by the compound) and males developed carcinogenic and benign kidney tumors [35].
• 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 [37].

• Fate in humans and animals: Chlorothalonil is rapidly excreted, primarily unchanged, from the body. It is not stored in animal tissues. Rats and dogs fed very high doses for 2 years eliminated almost all of the chemical in urine, feces, and expired air [17,38]. At lower concentrations, chlorothalonil leaves the body within 24 hours. Residues have not been found in the tissues or milk of dairy cows fed chlorothalonil [17].

Ecological Effects:

• Effects on birds: Chlorothalonil is practically nontoxic to birds. The LD50 in mallard ducks is 5000 mg/kg [9]. Most avian wildlife are not significantly affected by this compound [17].
• Effects on aquatic organisms: Chlorothalonil and its metabolites are highly toxic to fish, aquatic invertebrates, and marine organisms. Fish, such as rainbow trout, bluegill, and channel catfish are noticeably affected even when chlorothalonil levels are low (less than 1 mg/L). The LC50 is 0.25 mg/L in rainbow trout, 0.3 mg/L in bluegills, and 0.43 mg/L in channel catfish [9]. Chlorothalonil does not store in fatty tissues and is rapidly excreted from the body. Its bioaccumulation factor is quite low [17].
• Effects on other organisms: The compound is nontoxic to bees [9].

Environmental Fate:

• Breakdown in soil and groundwater: Chlorothalonil is moderately persistent. In aerobic soils, the half-life is from 1 to 3 months. Increased soil moisture or temperature increases chlorothalonil degradation. It is not degraded by sunlight on the soil surface [17]. Chlorothalonil has high binding and low mobility in silty loam and silty clay loam soils, and has low binding and moderate mobility in sand [35]. Chlorothalonil was not found in any of 560 groundwater samples collected from 556 U.S. sites [35].
• Breakdown in water: In very basic water (pH 9.0), about 65% of the chlorothalonil was degraded into two major metabolites after 10 weeks. Chlorothalonil was found in one surface water location in Michigan at 6.5 mg/L [35].
• Breakdown 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 may be found in harvested crops [37].

Physical Properties:

• Appearance: Chlorothalonil is an aromatic halogen compound, a member of the chloronitrile chemical family. It is a grayish to colorless crystalline solid that is odorless to slightly pungent [9].
• Chemical Name: tetrachloroisophthalonitrile [9]
• CAS Number: 1897-45-6
• Molecular Weight: 265.92
• Water Solubility: 0.6 mg/L @ 25 C [9]
• Solubility in Other Solvents: acetone s.s.; dimethyl sulfoxide s.s.; cyclohexanone s.s.; kerosene i.s.; xylene s.s. [9]
• Melting Point: 250-251 C [9]
• Vapor Pressure: 1.3 mPa @ 40 C [9]
• Partition Coefficient: 437 (calc.): 20.9 [17]
• Adsorption Coefficient: 1380 [14]

Exposure Guidelines:

• ADI: 0.03 mg/kg/day [27]
• MCL: Not Available
• RfD: 0.015 mg/kg/day [8]
• PEL: Not Available
• HA: 0.5 mg/L (longer-term) [35]
• TLV: Not Available

Basic Manufacturer:

Crystal Chemical Inter-America
10303 N.W. Freeway, Suite 512
Houston TX 77083

• Phone: 713-956-6196
• Emergency: Not Available
  

References:

References for the information in this PIP can be found in Reference List Number 6

DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide product labeling or other regulatory requirements. Please refer to the pesticide product labeling.