© 1986 Oxford University Press
research-article |
Influence of Housing Conditions for Mice on the Results of a Dermal Oncogenicity Bioassay
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*Bushy Run Research Center, Mellon Institute-Union Carbide Corporation Export, Pennsylvania 15632
Applied Toxicology Department, Union Carbide Corporation Danbury, Connecticut 06817
Exxon Corporation Research and Environmental Health Division East Millstone, New Jersey 088 73
Influence of Housing Conditions for Mice on the Results of a Dermal Oncogenicity Bioassay. DEPASS, L.R., WEIL, C.S., BALLANTYNE, B., LEWIS, S.C, LOSCO, P.E., REID, J.B., AND SIMON, G.S. (1986). Fundam. Appl. Toxicol. 7, 601-608. Male C3H/HeJ mice were thrice weekly given 25 µl applications of 0.25, 0.05, or 0.01% (w/w) benzo(a)pyrene (BaP) in acetone, or acetone alone, to clipped dorsal skin from 12 to 14 weeks of age for the remainder of their life spans. There were two groups of 40 mice for each treatment regimen, one group being housed in conventional stainless-steel wire mesh cages and the other in polycarbonate cages with wood shavings held in an enclosed ventilated cabinet. Under both housing conditions, tumor incidence was directly related and latency inversely related to BaP concentration. The time-adjusted incidence of epidermal neoplasms was significantly greater for the groups housed in polycarbonate cages. Mortality rates were directly related to BaP concentration and were significantly enhanced by the polycarbonate-cage housing conditions for the high and intermediate concentrations. Survival patterns for the two acetone control groups were similar. These findings indicate that differences in housing conditions can influence both the incidence and the latency of local neoplasms produced in response to the chronic application of a carcinogen in dermal oncogenesis bioassays.