Definition
ChEBI: An organic disulfide that results from the formal oxidative dimerisation of N,N-dimethyldithiocarbamic acid. It is widely used as a fungicidal seed treatment.
General Description
A liquid solution of a white crystalline solid. Primary hazard is to the environment. Immediate steps should be taken to limit spread to the environment. Easily penetrates the soil to contaminates groundwater and waterways.
Reactivity Profile
THIRAM(137-26-8) is incompatible with oxidizing materials and strong acids. Also incompatible with strong alkalis and nitrating agents .
Air & Water Reactions
Insoluble in water. Decomposes in acidic media to give toxic products. Decomposes to an extent on prolonged exposure to heat, air or moisture.
Health Hazard
Inhalation of dust may cause respiratory irritation. Liquid irritates eyes and skin and may cause allergic eczema in sensitive individuals. Ingestion causes nausea, vomiting, and diarrhea, all of which may be persistent; paralysis may develop.
Potential Exposure
Thiram is a dithiocarbamate. Some thiurams have been used as rubber components: thiram is used as a rubber accelerator and vulcanizer; a seed, nut, fruit, and mushroom disinfectant; a bacteriostat for edible oils and fats; and as an ingredient in suntan and antiseptic sprays and soaps. It is also used as a fungicide, rodent repellent; wood preservative; and may be used in the blending of lubricant oils.
Fire Hazard
Special Hazards of Combustion Products: Toxic and irritating oxides of sulfur are formed. Carbon disulfide may be formed from unburned material.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.
Shipping
UN2771 Thiocarbamate pesticides, solid, toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.
Incompatibilities
Dust may form explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine,fluorine, etc.); contact may cause fires or explosions. Keep away from strong alkaline materials, strong acids, strong bases and nitrating agents.
Description
Tetramethylthiuram disulfide is a rubber chemieal, an
accelerator of vulcanization. It represents the most
commonly positive allergen contained in the "thiuram
mix". The most frequent occupational categories are
the metal industry, homemakers, health services and
laboratories, building industries, and shoemakers.
Waste Disposal
Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Thiram can be dissolved in alcohol or other flammable solvent and burned in an incinerator with an afterburner and scrubber.
Physical properties
Colorless to white to cream-colored crystals. May darken on exposure to air or light.
Hazard
Toxic by ingestion and inhalation, irritant
to skin and eyes. Body weight and hematologic
effects. Questionable carcinogen.
Agricultural Uses
Fungicide, Rodenticide: Thiram is used as a fungicide to prevent crop damage
in the field and to prevent crops from deterioration
in storage or transport. Thiram is also used as a seed, nut,
fruit, and mushroom disinfectant 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 has been used in the
treatment of human scabies, as a sun screen, and as a bactericide
applied directly to the skin or incorporated into soap. Thiram is used as a rubber accelerator and vulcanizer
and as a bacteriostat for edible oils and fats. It is also used
as a rodent repellent, wood preservative, and may be used
in the blending of lubricant oils. Registered for use in EU
countries. Registered for use in the U.S.
Trade name
AAPIROL®; AATACK®; AATIRAM®;
ACCELERATOR T®; ACCELERATOR THIURAM®;
ACCEL TMT®; AGROSOL POUR-ON®; ANLES®;
ARASAN®[C]; ATIRAM®; ATTACK®; AULES®;
CHIPCO THIRAM 75®; CRYLCOAT®; CUNITEX®;
CYURAM DS®; DELSAN®; EBECRYL®; EKAGOM
TB®; EVERSHIELD T SEED PROTECTORANT®;
FALITIRAM®; FERMIDE®; FERNACOL®;
FERNASAN®; FERNIDE®; FLO PRO T SEED
PROTECTANT®; FMC 2070®[C]; FORMALSOL®;
HERMAL®; HERYL®; HEXATHIR®; HY-VIC®;
KODIAK T®; KREGASAN®; LIQUID MOLY-CO-THI®;
MERCURAM®; METIURAC®; MOLY-T®; NA2771®;
NOBECUTAN®; NOMERSAN®; NORMERSAN®;
OPTIMA®; PANORAM 75®; POLYRAM
ULTRA®; POMARSOL®; POMARSOL FORTE®;
POMASOL®; PRO-GRO®; PURALIN®; RAXIL®;
REZIFILM®; ROOTONE®; ROYAL TMTD®; RTUBAYTAN-
THIRAM®; RTU FLOWABLE SOYBEAN
FUNGICIDE®; SADOPLON®; SOLUCRYL®;
SPOTRETE®; SPOTRETE-F®; SQ 1489®; SRANANSF-
X®; TERSAN 75®[C]; TERSANTETRAMETHYL
DIURANE SULFIDE®; TETRAPOM®;
TETRASIPTON®; THIANOSAN®; THILLATE®;
THIMAR®; THIMER®; THIOKNOCK®; THIOSAN®;
THIOSCABIN®; THIOTEX®; THIOTOX®; THIRAM
75®; THIRAM 80®; THIRAMAD®; THIRAM B®;
THIRAMPA®; THIRASAN®; THIULIN®; THIULIX®;
THIURAD®; THIURAMIN®; THIURAMYL®;
THYLATE®; TIRAMPA®; TITAN FL®; TRAMETAN®;
TRIDIPAM®; TRIPOMOL®; TUADS®; TUEX®;
TULISAN®; UCECOAT®; UCECRYL®; UVECRYL®;
VANCIDA TM-95®; VANCIDE TM®; VITAFLO 280®;
VITAVAX® Thiram; VITAVAX-T®; VUAGT-1-4®;
VULCAFOR TMTD®; VULKACIT MTIC®;
VULKACIT THIURAM®; VULKACIT THIURAM/C®
Carcinogenicity
Thiram also was not carcinogenic in rats
by gavage or in mice by single subcutaneous
injection. In skin painting studies in mice
thiram had tumor-initiating and -promoting
activity but was not a complete carcinogen.
Thiram was genotoxic to insects, plants,
fungi, and bacteria: it induced sister chromatid
exchange and unscheduled DNA synthesis in
cultured human cells. Despite established
genotoxicity in vitro, it showed no clastogenic
and/or aneugenic activity in vivo after oral
administration to mice at the maximum tolerated
dose.
Environmental Fate
Biological. In both soils and water, chemical and biological mediated reactions can
transform thiram to compounds containing the mercaptan group (Alexander, 1981).
Odeyemi and Alexander (1977) isolated three strains of Rhizobium sp. that degraded
thiram. One of these strains, Rhizobium meliloti, metabolized thiram to yield dimethy-
lamine (DMA) and carbon disul?de which formed spontaneously from dimethyldithiocar-
bamate (DMDT). The conversion of DMDT to DMA and carbon disul?de occurred via
enzymatic and nonenzymatic mechanisms (Odeyemi and Alexander, 1977).
When thiram (100 ppm) was inoculated with activated sludge (30 ppm) at 25°C and
pH 7.0 for two weeks, 30% degraded. Metabolites included methionine, elemental sulfur,
formaldehyde, dimethyldithiocarbamate-α-aminobutyric acid and the corresponding keto
aci
To a non-autoclaved alluvial sandy loam (pH 7.3) fortified and inoculated with the
bacterium Pseudomonas aeruginosa, 40 and 86% degradation were observed after 4 and
24 days, respectively. In autoclaved soil, thiram degradation was not affected. Degradat
Soil. Decomposes in soils to carbon disul?de and dimethylamine (Sisler and Cox,
1954; Kaars Sijpesteijn et al., 1977). When a spodosol (pH 3.8) pretreated with thiram
was incubated for 24 days at 30°C and relative humidity of 60–90%, dimethylamine formed
as the major product. Minor degradative products included nitrite ions (nitration reduction)
and dimethylnitrosamine (Ayanaba et al., 1973).
Plant. Major plant metabolites are ethylene thiourea, thiram monosul?de, ethylene
thiram disul?de and sulfur (Hartley and Kidd, 1987).
Metabolic pathway
Dialkyldithiocarbamates chelate copper and inhibit pyruvate dehydrogenase.
It is likely that the mode of action of chelators is principally through
their effect on lipoamide containing dehydrogenases (Corbett et al., 1984).
Thiram generates dimethyldithiocarbamic acid by being cleaved in acidic
conditions and in biological media. The acid is conjugated with glucose
and alanine in plants and with glucuronic acid in mammals. Dimethyldithiocarbamic
acid is further degraded to dimethylamine and CS2. An
extensive review of the properties of dithiocarbamate pesticides was published
by the World Health Organisation (WHO, 1988) from which much
of the following information is taken.
Purification Methods
Crystallise thiram (three times) from boiling CHCl3, then recrystallise it from boiling CHCl3 by adding EtOH dropwise to initiate crystallisation, and allow it to cool. Finally it is precipitated from cold CHCl3 by adding EtOH (which retains the monosulfide in solution). [Ferington & Tobolsky J Am Chem Soc 77 4510 1955, Beilstein 4 IV 242.]
Degradation
Thiram is decomposed in acidic media. It deteriorates on prolonged
exposure to heat, air or moisture. DT50 values are estimated as 128 days,
18 days and 9 hours at pH 4, 7 and 9, respectively (PM). The dimethyldithiocarbamate
(2) is stable in alkaline media but unstable in acidic
conditions, decomposing to dimethylamine and carbon disulfide. In
water, the dimethyldithiocarbamate can be oxidatively degraded to a
number of products. The rate of degradation depends on pH and the
type of any cations that might be present. The rate of decomposition and
production of CS2 is decreased by cations in the following order Na+ >
Zn2+> Fe3+> Cu2+. Thiram was completely degraded in sewage water in
12 days.
An ethanolic solution of unlabelled thiram (4 g l-1) was exposed to UV
light for 48 hours. The reaction tube was encircled by low pressure Hg
lamps that gave more than 85% of their total radiation at 253.7 nm. Pure
nitrogen was bubbled through the solutions. Photo-oxidation studies were
done similarly except that oxygen was bubbled through the solution.
In further experiments, irradiation was by visible light from a tungsten
lamp and again oxygen was bubbled through the solution. The outlet
gases from the UV study were condensed in a cold trap and analysed
by GC-MS. Traces of carbon disulfide and dimethylamine were
identified. The reaction mixture was also analysed by GC-MS and
three products were identified as tetramethyl hydrazine (3), N,N-dimethylthioformamide
(4) and tetramethylthiourea (5). The identity of
the latter was confirmed by IR and NMR. The reaction mixture was concentrated
and applied to TLC plates and sulfur and tetramethylthiourea
(5) were identified as the main products of photolysis. The same
products with the addition of sulfur dioxide and carbon dioxide were
produced by UV light and oxygen. Oxidation of thiram in the presence
of visible light together with Rose Bengal as a photosensitiser also gave the same products in almost identical yields. The results confirm that
C-S and S-S bond fissions are primary photochemical steps with
dithiocarbamates.
Toxicity evaluation
Thiram cytotoxicity appears to result from its potential to
disrupt cellular defense mechanisms against oxidative stress. In
cultured human skin fibroblast, thiram results in an increase in
oxidative markers such as lipid peroxidation and oxidation of
reduced glutathione and decrease in other endogenous antioxidant.
Toxic effects of thiram have been described in humans
and animal model systems ranging from liver injury, testicular
toxicity, ophthalmological changes, and development of
micronuclei in bone marrow. However, the mechanisms of
these effects are not characterized and inconsistent across
various studies.
