Carcinogenicity of inhaled benzene in CBA mice.
This study investigated benzene-induced neoplasia in CBA/Ca mice, with special emphasis on hematopoietic tissues. Ten-week-old male CBA/Ca mice were exposed to 300 ppm benzene via inhalation for 6 hr/day, 5 days/week, for 16 weeks and held 18 months after the last exposure. There were 125 benzene-exposed and 125 sham-exposed mice. Malignant lymphoma was a statistically significant cause of early mortality in the benzene-exposed mice. Fourteen benzene-exposed mice developed lymphoma (lymphoblastic, lymphocytic, or mixed) as compared to only 2 sham-exposed mice. Benzene-exposed mice also developed preputial gland squamous cell carcinomas (60% in benzene-exposed vs 0% in sham-exposed) and had an increased incidence of lung adenomas (36% vs 14%). Moderate to marked granulocytic hyperplasia was present in benzene-exposed animals, with a 36% incidence in the bone marrow and 6% in the spleen, as compared to the sham-exposed with 8 and 0%, respectively. Interpretation of the granulocytic response as a direct effect of benzene was complicated by the presence of inflammation in the mice. Although inhaled benzene was clearly carcinogenic in CBA mice, it did not induce granulocytic leukemia.
Farris
G M
GM
Chemical Industry Institute of Toxicology, Research Triangle Park, North Carolina 27709.
Everitt
J I
JI
Irons
R D
RD
Popp
J A
JA
D000280:Administration, Inhalation; D000818:Animals; D001554:Benzene / Q000633:toxicity*; D001772:Blood Cell Count / Q000187:drug effects; D001853:Bone Marrow / Q000473:pathology; D015197:Carcinogenicity Tests; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000473:pathology; D006098:Granulocytes / Q000187:drug effects; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000139:chemically induced / Q000473:pathology; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D009369:Neoplasms / Q000139:chemically induced* / Q000473:pathology; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000139:chemically induced / Q000473:pathology
D001554:Benzene