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BENZIDINE
CAS No: 92-87-5
I. PHYSICAL AND CHEMICAL PROPERTIES (From HSDB, 1994)
Molecular weight 184.2
Boiling point 402°C
Melting point
115-120°C
Vapor pressure
0.0005 mm Hg
Air concentration conversion 1 ppm = 7.53 mg/m 3 @ 25°C
II.
HEALTH ASSESSMENT VALUES
Unit Risk Factor: 1.4 E-1 (µg/m 3 ) -1
Slope Factor: 5.0 E+2 (mg/kg-day) -1
[Calculated from a cancer potency factor derived by RCHAS/OEHHA (CDHS, 1988)]
III.
CARCINOGENIC EFFECTS
Human Studies
Case et al. (1954) examined mortality among British chemical workers exposed to benzidine. Among
the population examined (total number not specified), ten deaths were certified as due to bladder
cancer. The death rate from bladder cancer in the male Welsh and English population predicts 0.72
deaths from this cause, giving a standard mortality ratio of 13.9 (10/0.72, p < 0.001). Non-fatal
bladder cancers were also noted among the exposed population.
Mancuso and El-Atar (1967) examined the incidence of urinary tract cancer among 639 male
employees of an Ohio plant where benzidine and β-naphthylamine were made, with potential exposure
occurring between 1938 and 1939. Six cases of bladder cancer occurred among white workers, giving
a population incidence of 204 per 10 5 . The expected incidence of bladder cancer among Ohio white
males is 4.4 per 10 5 . The authors do not present the significance of the change in incidence because of
exposure of workers to other compounds.
Zavon et al. (1973) conducted a prospective study of workers exposed to benzidine during its
manufacture. The authors report on the health surveillance of all 25 employees of a chemical plant who
were exposed to benzidine from 3 to 28 years (1930-1958). During the 13 year follow-up period
(1957-1970), 11 cases of transitional cell bladder cancer and 2 cases of benign bladder tumors
developed. Among the workers with bladder cancers, two also developed kidney carcinomas and one
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