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THIOACETAMIDE
CAS No: 62-55-5
I. PHYSICAL AND CHEMICAL PROPERTIES (From HSDB, 1994)
Molecular weight 75.14
Boiling point
not available
Melting point 113-114 °C
Vapor pressure
not available
Air concentration conversion 1 ppm = 3.1 mg/m 3
II.
HEALTH ASSESSMENT VALUES
Unit Risk Factor: 1.7 E-3 (µg/m 3 ) -1
Slope Factor: 6.1 E+0 (mg/kg-day) -1
[Female mouse liver tumor data (Gothoskar et al., 1970), contained in Gold et al. (1984)
database, expedited Proposition 65 methodology (Cal/EPA, 1992), with cross-route
extrapolation.]
III.
CARCINOGENIC EFFECTS
Human Studies
No studies on the potential carcinogenic effects of thioacetamide in humans are known to exist.
Animal Studies
Male albino rats (10/group) were exposed to thioacetamide in the diet for 18 months (Fitzhugh and
Nelson, 1948). Dietary thioacetamide levels were 0, 50, 100, 250, 500 or 1000 mg/kg diet. Animals
exposed to 1000 mg/kg diet thioacetamide survived for less than one month; animals exposed to 250 or
500 mg/kg diet thioacetamide also had increased mortality. One animal in the 500 mg/kg diet exposure
group developed a hepatocellular carcinoma (the number of surviving animals in this group was
unspecified). One animal of the 6 survivors in the 50 and 100 mg/kg diet exposure groups developed a
hepatocellular adenoma. No liver tumors were observed in the control animals.
Gupta (1955, 1956) exposed 150 male and female Wistar rats to 32 mg/kg diet thioacetamide in the
diet for more than 23 weeks; an untreated control group of 50 animals was included in the study. Bile
duct tumors (unspecified type) were observed in 18/36 animals killed between 9 and 23 weeks; no liver
tumors were noted in the control animals. Liver tumor metastases to the ovaries were noted in 4/5
animals treated for 47 weeks or longer.
Male and female Swiss mice were fed diet containing 0.03% thioacetamide for 65 weeks (89 mice
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