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N-NITROSODI-N-BUTYLAMINE
CAS No: 424-16-3
I. PHYSICAL AND CHEMICAL PROPERTIES (From HSDB, 1995)
Molecular weight 158.2
Boiling point
116° C @ 14 mm Hg
Melting point
0.5° C
Vapor pressure
Not found
Air concentration conversion 1 ppm = 6.46 mg/m 3 @ 25° C
II.
HEALTH ASSESSMENT VALUES
Unit Risk Factor: 3.1 E-3 (µg/m 3 ) -1
Slope Factor: 1.1 E+1 (mg/kg-day) -1
[Calculated from a cancer potency factor derived by CDHS (1988)]
III.
CARCINOGENIC EFFECTS
Human Studies
There is no direct evidence that links nitrosamines, including N-Nitrosodi-n-butylamine (NDBA), to
human cancer. The US EPA (1980) and IARC (1978) concluded that the epidemiological studies to
date were inadequate to establish a valid causal relationship between nitrosamine exposure and human
cancer. The US EPA (1980) also concluded that it was highly improbable that humans are refractory to
the carcinogenic effects of nitrosamines considering the number of animal species that show increased
tumor incidence following nitrosamine exposure. IARC (1978) concluded: “Although no
epidemiological data were available, N-nitrosodi-n-butyl amine should be regarded, for practical
purposes, as if it were carcinogenic to humans.”
Animal Studies
Groups of DB rats were exposed to NDBA in the drinking water for an unspecified duration (Druckrey
et al., 1967). The rats were exposed to 10, 20, 37, and 75 mg/kg-day NDBA. The incidence of liver
carcinomas and adenomas was 2/10, 4/10, 13/16, and 4/4, respectively. No data on control rats were
reported. Median time-to-tumor decreased from 540 days at 10 mg/kg-day, to 150 days at 75 mg/kgday.
Male Wistar rats (15 total) were exposed for 24 weeks to 0.05% NDBA in drinking water (Okajima et
al., 1971). Nine animals served as controls. At the end of this period, the 12 remaining animals were
necropsied and found to have papillomas of the bladder. Eleven of the 12 animals had bladder
carcinomas, 4 had hepatocellular carcinomas, and all had papillomas or carcinomas of the esophagus.
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