A study of environmental influence upon salivary gland neoplasia in rats

Abstract

An animal model system was used in an attempt to explore suspect relationships between 3 groups of possible carcinogenic co-factors (nutritional, endocrine, and thermal) and the seemingly high salivary gland cancer experience of Arcticdwelling Eskimos. Two hundred and thirty weanling Sprague-Dawley rats were randomized into 7 groups to study effects of vitamin A deficiency, hypercortisonism, hyperthyroidism, hypercortisonism plus hyperthyroidism combined, and a windy, cold, humid environment upon submaxillary salivary glands challenged with implanted 20 percent 7,12-dimethylbenzanthracene pellets. Animals were sacrificed at 14 weeks. Of the 7 regimens, only vitamin A deficiency increased malignant epithelial neoplasm yield. Increased yield in vitamin A deficient group (I) compared to the sum of nutritionally adequate control groups (II and III) was significant at the 0.001 level, and with all groups II-VII individually (p = 0.0001) or combined (p = 0.00004). No significant yield difference was found among the other 6 groups (II-VII).