Annual Report of Program Activities, National Institute of Environmental Health Sciences

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Excerpt from Annual Report of Program Activities, National Institute of Environmental Health Sciences: Fiscal Year 1981At the much lower concentration of exposure, additional factors come into play if cancer is still to occur which may arise from eating, drinking, and smoking habits as well as from vocational preferences. They may present a different kind of exposure less readily quantitated and much less easily controlled.The reason for the difference is shown in animal experiments where at high exposure over a long period of time a large percentage of the animals will get tumors, while at lower levels the susceptible group gets smaller and a level of exposure will be reached that shows no adverse effect a level erroneously considered a no-effect level. At that level introduction of prolonged treat ment with a promoter will still produce tumors. The contributions of initiator and promoter towards carcinogenesis depend on temporal relationships as well as target organ specificities.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.