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Myelogenous leukemia in rodents inhaling benzene
Abstract:
Studies during the past five decades have failed to demonstrate myelogenous leukemia in laboratory animals exposed to benzene despite epidemiologic evidence linking such exposure to myelogenous leukemia in man. We report four cases of myeloproliferative disease among rodents exposed to benzene, 6 h a day, 5 days weekly, for life. There was one case of chronic myelogenous leukemia, one of acute myeloblastic leukemia, and one of granulocytic hyperplasia among 40 CD-1 mice exposed to 300 ppm benzene; and one case of chronic myelogenous leukemia among 40 rats exposed to 100 ppm benzene. Although not statistically significant as compared to the respective control groups, the fact that myelogenous leukemia has not been reported in control animals of these two strains is suggestive of a causative role for benzene.
Insights
Benzene exposure caused myeloproliferative diseases, including leukemia, in rodents. This study suggests a potential link between benzene and human myelogenous leukemia, despite previous failed animal studies.
Area of Science:
- Toxicology
- Hematology
- Carcinogenesis
Background:
- Epidemiologic studies link human benzene exposure to myelogenous leukemia.
- Previous animal studies have failed to replicate this link.
- Benzene is a known human carcinogen.
Purpose of the Study:
- To investigate the potential of benzene exposure to induce myelogenous leukemia in laboratory rodents.
- To explore benzene's role in myeloproliferative diseases.
Main Methods:
- Rodents (mice and rats) were exposed to benzene (300 ppm for mice, 100 ppm for rats) for life, 6 hours/day, 5 days/week.
- Hematopoietic tissues were examined for signs of myeloproliferative disease.
- Results were compared to control groups.
Main Results:
- Four cases of myeloproliferative disease were observed in benzene-exposed rodents.
- These included chronic myelogenous leukemia, acute myeloblastic leukemia, and granulocytic hyperplasia in mice, and chronic myelogenous leukemia in rats.
- While not statistically significant, these findings are notable as myelogenous leukemia is rare in control animals of these strains.
Conclusions:
- Benzene exposure in rodents resulted in myeloproliferative diseases, including leukemia.
- The occurrence of these diseases in exposed animals, though not statistically significant, suggests a potential causative role for benzene.
- Further research is warranted to elucidate the mechanisms and confirm the link between benzene and myelogenous leukemia.
