Sensitivity of Mice to Benzo(a)pyrene Skin Cancer following Acclimation to Cool and Warm Temperature

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Abstract
Skin tumorigenesis induced by benzo(a)pyrene (BaP) in male C3H/HeJ mice was accelerated in a cool (Ta = 16.degree. C) and inhibited in a warm (Ta = 32.degree. C) environment, compared to the normal Ta = 23.degree. C. For example, repetitive, topical application of 0.2 mg BaP/wk in 0.08 toluene resulted in the mean tumor appearance time occurring 4-5 wk earlier in cool and 2-3 wk later in warm compared with the 21-22 wk average in normal Ta; the average number of tumors per mouse increasing twice as fast in cool as in warm Ta; and shortened survival in cool, lengthened in warm. There were few metastases to internal organs at any temperature. Once initiated, tumors progressed similarly in all Ta''s to squamous cell carcinomas. Cool and warm Ta per se had little effect on spontaneous tumors, survival, body weight, rectal temperature or hair growth. Skin temperature was 1-2.degree. C lower in cool and 1-2.degree. C higher in warm Ta than the normal 32-33.degree. C. Physiological adaptation was particularly evident in the 66% average higher food intake in cool and 63% lower in warm Ta. These results may help in defining environmental risks in cancer, in increasing the efficiency of cancer screening trials and in exploring physiological modifiers of carcinogenesis.