home edit2 whole TSD November 2002 PDF format - OEHHA

URETHANE
CAS No: 51-79-6
I. PHYSICAL AND CHEMICAL PROPERTIES (From HSDB, 1994)
Molecular weight 89.09
Boiling point
182-184°C
Melting point
48-50°C
Vapor pressure 0.36 mm Hg @ 25°C
Air concentration conversion 1 ppm = 3.64 mg/m 3
II.
HEALTH ASSESSMENT VALUES
Unit Risk Factor: 2.9 E-4 (µg/m 3 ) -1
Slope Factor: 1.0 E+0 (mg/kg-day) -1
[Calculated from a potency factor derived by RCHAS/OEHHA (CDHS, 1989)]
III.
CARCINOGENIC EFFECTS
Human Studies
There are no studies available directly linking urethane exposure to induction of cancer in humans.
Urethane is, however, frequently present in alcoholic beverages, particularly brandy, whisky and wine,
and IARC has recognized alcoholic beverages as carcinogenic to humans (IARC, 1988). Although
other compounds present in alcoholic beverages may account for this effect, urethane may be a
contributor to alcohol-related increases in cancer incidence.
Animal Studies
CDHS (1989) has identified nearly 200 studies which demonstrate the carcinogenicity of urethane in
animals. Below are summaries of those determined to be most relevant in the establishment of the
reference cancer potency value, with emphasis on studies performed by realistic routes of exposure and
in multiple doses.
Pietra and Shubik (1960) exposed male and female Syrian golden hamsters (10/sex) to drinking water
containing 0.2% urethane for life. Control animals (49 male and 14 female) received plain drinking
water. Animals were autopsied at death. Among exposed animals, males showed increased incidence
of dermal melanotic tumors (7/10 exposed, 1/49 control; p < 0.01, Fisher’s exact test). Male and
female animals showed an increased incidence of forestomach papillomas (males: 4/10 exposed, 0/49
537