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Effects of inhaled ammonium sulfate on benzo[a]pyrene carcinogenesis
Abstract:
The effect of inhaled ammonium sulfate on benzo[a]pyrene carcinogenesis in the lungs of Syrian golden hamsters was studied. Exposure to ammonium sulfate at an airborne concentration 20 times average United States ambient levels resulted in a significant depression (p less than 0.05) of benzo[a]pyrene carcinogenesis in the first 6 mo of the study. However, at 2 yr, the termination of the study, there were no differences in cancer incidence between groups receiving benzo[a]pyrene and benzo[a]pyrene plus ammonium sulfate. In addition, at the concentration studied, inhaled ammonium sulfate did not significantly increase the incidence or severity of pneumonitis or pulmonary fibrosis in the hamster. However, this inhalation did increase the incidence of emphysema but not the severity. The decreased incidence of cancer during the first 6 mo of this study in animals receiving both benzo[a]pyrene and ammonium sulfate suggests that interaction between sulfate and benzo[a]pyrene does occur, but is insufficient to afford long-term protection against the development of cancer. No enhancement of carcinogenesis by benzo[a]pyrene occurs in the presence of inhaled sulfate.
Insights
Inhaled ammonium sulfate initially reduced lung cancer from benzo[a]pyrene in hamsters. However, this protective effect disappeared by the study
Area of Science:
- Environmental toxicology
- Chemical carcinogenesis
- Pulmonary pathology
Background:
- Benzo[a]pyrene is a known lung carcinogen.
- Ammonium sulfate is an ambient air pollutant.
- Interactions between pollutants and carcinogens are complex.
Purpose of the Study:
- To investigate the effect of inhaled ammonium sulfate on benzo[a]pyrene-induced lung cancer in Syrian golden hamsters.
- To assess the impact of ammonium sulfate on non-cancerous lung pathologies.
Main Methods:
- Syrian golden hamsters were exposed to benzo[a]pyrene alone or with ammonium sulfate.
- Airborne concentrations of ammonium sulfate were 20 times average U.S. ambient levels.
- Cancer incidence and pulmonary pathologies were evaluated over 2 years.
Main Results:
- A significant depression in benzo[a]pyrene carcinogenesis was observed in the first 6 months.
- No difference in cancer incidence was found at the 2-year study termination.
- Inhaled ammonium sulfate increased emphysema incidence but not severity, and did not worsen pneumonitis or fibrosis.
Conclusions:
- Ammonium sulfate interacts with benzo[a]pyrene, but this interaction is insufficient for long-term cancer protection.
- Inhaled ammonium sulfate does not enhance benzo[a]pyrene-induced lung carcinogenesis.
- Ammonium sulfate exposure at high concentrations may contribute to emphysema development.