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The information in this profile may be out-of-date.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.

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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

Thiram

Trade and Other Names: Common names include thiram (U.S.), thiuram (Japan), and TMTD (former U.S.S.R.), TMT, and TMTDS. Trade names include AAtack, Arasan, Aules, Fermide 850, Fernasan, FMC 2070, Hexathir, Mercuram, Micropearls, Nomersan, Pomarsol, Puralin, Rezifilm, Rhodiasan Express, Spotrete, Tersan, Thiosan, Thiotex, Thiramad, Thirame, Thiuramin, Thirasan, Tirampa, Tiuramyl, TMTC, TMTD 50 Borches, Trametan, Tuads, and Tulisan.

Regulatory Status: Thiram is registered as a General Use Pesticide (GUP) by the U.S. Environmental Protection Agency (EPA). It is classified as toxicity class III - slightly toxic. Pesticide products containing thiram bear the Signal Word CAUTION on the product label.

Chemical Class: dimethyl dithiocarbamate

Introduction: Thiram is a dimethyl dithiocarbamate compound used as a fungicide to prevent crop damage in the field and to protect harvested crops from deterioration in storage or transport. Thiram is also used as a seed protectant and to protect fruit, vegetable, ornamental, and turf crops from a variety of fungal diseases. In addition, it is used as an animal repellent to protect fruit trees and ornamentals from damage by rabbits, rodents, and deer. Thiram is available as dust, flowable, wettable powder, water dispersible granules, and water suspension formulations, and in mixtures with other fungicides. Thiram has been used in the treatment of human scabies, as a sunscreen, and as a bactericide applied directly to the skin or incorporated into soap.

Formulation: Thiram is available as dust, flowable, wettable powder, water dispersible granules, and water suspension formulations, and in mixtures with other fungicides.

Toxicological Effects:

• Acute toxicity: Thiram is slightly toxic by ingestion and inhalation, but it is moderately toxic by dermal absorption. Acute exposure in humans may cause headaches, dizziness, fatigue, nausea, diarrhea, and other gastrointestinal complaints. In rats and mice, large doses of thiram produced muscle incoordination, hyperactivity followed by inactivity, loss of muscular tone, labored breathing, and convulsions. Most animals died within 2 to 7 days [4]. Thiram is irritating to the eyes, skin, and respiratory tract. It is a skin sensitizer. Symptoms of acute inhalation exposure to thiram include itching, scratchy throat, hoarseness, sneezing, coughing, inflammation of the nose or throat, bronchitis, dizzines, headache, fatigue, nausea, diarrhea, and other gastrointestinal complaints. Persons with chronic respiratory or skin disease are at increased risk from exposure to thiram [4]. Ingestion of thiram and alcohol together may cause stomach pains, nausea, vomiting, headache, slight fever, and possible dermatitis. Workers exposed to thiram during application or mixing operations within 24 hours of moderate alcohol consumption have been hospitalized with symptoms. The 4-hour inhalation LC50 for thiram is greater than 500 mg/L in rats. Reported oral LD50 values for thiram are 620 to over 1900 mg/kg in rats; 1500 to 2000 mg/kg in mice; and 210 mg/kg in rabbits [1,3]. The dermal LD50 is greater than 1000 mg/kg in rabbits [4] and in rats [1,3].
• Chronic toxicity: Symptoms of chronic exposure to thiram in humans include drowsiness, confusion, loss of sex drive, incoordination, slurred speech, and weakness, in addition to those due to acute exposure. Repeated or prolonged exposure to thiram can also cause allergic reactions such as dermatitis, watery eyes, sensitivity to light, and conjuntivitis [1]. Except for the occurrence of allergic reactions, harmful chronic effects from thiram have been observed in test animals only at very high doses. In one study, a dietary dose of 125 mg/kg/day thiram was fatal to all rats within 17 weeks. Oral doses of about 49 mg/kg/day to rats for 2 years produced weakness, muscle incoordination, and paralysis of the hind legs. Rats fed 52 to 67 mg/kg/day for 80 weeks exhibited hair loss, and paralysis and atrophy of the hind legs. Symptoms of muscle incoordination and paralysis from thiram poisoning have been shown to be associated with degeneration of nerves in the lower lumbar and pelvic regions. Day-old white leghorn chicks fed 30 and 60 ppm for 6 weeks exhibited bone malformations [1]. At doses of about 10% of the LD50 for 15 days, thiram reduced blood platelet and white blood cell counts, suppressed blood formation, and slowed blood coagulation in rabbits [1].
• Reproductive effects: Very high oral doses of approximately 1200 mg/kg/day thiram to mice on days 6 to 17 of pregnancy caused resorption of embryos and retarded fetal development. In another study, doses of 132 mg/kg/day for 13 weeks produced infertility in male mice, while doses of 96 mg/kg/day for 14 days delayed the estrous cycle in females [1]. The feeding of 50 mg/kg/day thiram from day 16 of pregnancy to 21 days after birth caused reduced growth and survival of the pups. Pups that were transferred to untreated dams at birth remained healthy, while pups transferred from untreated to treated dams showed toxic effects [1]. These data suggest that reproductive effects occur at high doses not likely to be experienced by humans.
• Teratogenic effects: Cleft palate, wavy ribs, and curved long leg bones were observed in the offspring of mice that ingested very high thiram doses of 1200 mg/kg/day on days 6 to 17 of pregnancy. Maternal doses of 125 mg/kg/day thiram were teratogenic in hamsters, causing incomplete formation of the skull and spine, fused ribs, abnormalities of the legs, heart, great vessels, and kidneys [1]. Developmental toxicity was observed in a three-generation study of rats fed 5.0 mg/kg/day [1,4]. These data suggest that high doses are required to cause teratatogenic effects.
• Mutagenic effects: Thiram has been found to be mutagenic in some test organisms but not in others [1]. Thus, the evidence is inconclusive.
• Carcinogenic effects: When administered to mice at the highest dose possible, thiram was not carcinogenic. Dietary levels as high as 125 mg/kg/day for 2 years did not cause tumors in rats [1]. These data indicate that thiram is not carcinogenic.
• Organ toxicity: Studies have shown evidence of damage to the liver by thiram in the form of decreased liver enzyme activity and increased liver weight [1]. Thiram may also cause damage to the nervous system, blood, and kidneys [4].

• Fate in humans and animals: In the body, carbon disulfide is formed from the breakdown of thiram and does contribute to the toxicity of thiram to the liver [1,3]. Thiram is not a member of the ethylene(bis)dithiocarbamate (EBDC) chemical family, and thus it should not generate ethylene thiourea (ETU) [1].

Ecological Effects:

• Effects on birds: Thiram is practically nontoxic to birds. The reported dietary LC50 of thiram in Japanese quail is greater that 5000 ppm [36]. Reported dietary LC50 values in pheasants and mallard ducks are 2800 ppm and 673 ppm, respectively [14]. The LD50 for the compound in red-winged blackbirds is greater than 100 mg/kg [3].
• Effects on aquatic organisms: Thiram is highly toxic to fish [4]. The LC50 for the compound is 0.23 mg/L in bluegill sunfish, 0.13 mg/L in trout, and 4 mg/L in carp [17]. Thiram is not expected to bioconcentrate in aquatic organisms [19].
• Effects on other organisms: Thiram is nontoxic to bees [3].

Environmental Fate:

• Breakdown in soil and groundwater: Thiram is of low to moderate persistence. It is nearly immobile in clay soils or in soils high in organic matter. Because it is only slightly soluble in water (30 mg/L) and has a strong tendency to adsorb to soil particles, thiram is not expected to contaminate groundwater. The soil half-life for thiram is reported as 15 days [20]. Thiram degrades more rapidly in acidic soils and in soils high in organic matter. In a humus sandy soil, at pH 3.5, thiram decomposed after 4 to 5 weeks, while at pH 7.0, thiram decomposed after 14 to 15 weeks. Thiram persisted for over 2 months in sandy soils, but disappeared within 1 week from a compost soil. The major metabolites of thiram in the soil are copper dimethyldithiocarbamate, dithiocarbamate, dimethylamine, and carbon disulfide [19]. In soil, thiram will be degraded by microbial action or by hydrolysis under acidic conditions. Thiram will not volatilize from wet or dry soil surfaces [19].
• Breakdown in water: In water, thiram is rapidly broken down by hydrolysis and photodegradation, especially under acidic conditions. Thiram may adsorb to suspended particles or to sediment [19].
• Breakdown in vegetation: No data are currently available.

Physical Properties:

• Appearance: Thiram is a white to yellow crystalline powder with a characterisitc odor [3].
• Chemical Name: tetramethylthiuram disulfide [3]
• CAS Number: 137-26-8
• Molecular Weight: 240.44
• Water Solubility: 30 mg/L at 25 C [3]
• Solubility in Other Solvents: s.s in ethanol; s. in acetone and chloroform [3]
• Melting Point: 146 C [3]
• Vapor Pressure: Negligible at room temperature [3]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 670 [11]

Exposure Guidelines:

• ADI: 0.01 mg/kg/day [33]
• MCL: Not Available
• RfD: 0.005 mg/kg/day [27]
• PEL: 5 mg/m3 (8-hour) [28]
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

ELF Atochem North America, Inc.
2000 Market Street
Philadelphia, PA 19103-3222

• Phone: 215-419-7219
• Emergency: 800-523-0900
  

References:

References for the information in this PIP can be found in Reference List Number 4

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.