depends upon: (a) concentration of caffeine; (fc) time of addition of caffeine; (c) length of exposure; and (d) carcinogen used. The addition of caffeine to cells treated 1 hr previously with carcinogen resulted in the potentiation of toxicity. Toxicity increased with caffeine concentration and length of exposure to carcinogen-containing medium. With 50 ¿ig caffeine per ml medium for 2 days cl...

An approach is presented to the assessment of carcinogen risks in which the dominant effect of carcinogen exposure is life shortening and the impact falls both on those individuals who would have gotten cancer without the carcinogen exposure as well as the new cancer cases. This analysis is based on the interaction of age-specific tumor incidence rates and population survival in terms of age-sp...

background: welding can produce dangerous fumes containing various metals especially carcinogenic ones. occupational exposure to welding fumes is associated with lung cancer. therefore, welders in gas transmission pipelines are known as a high-risk group. this study was designed to determinate the amounts of metals cr, ni, and cd in breathing zone and urine of welders and to assess the possibil...

We described previously a simple test on petri plates for detecting chemical carcinogens as mutagens, using an especially sensitive set of bacterial strains to detect mutagenic acitivty and a mammalian liver extract for carcinogen activity. We now extend the utility of the method by introducing two new bacterial strains which can detect with great sensitivity many carcinogens which we did not d...

A complex network of interactions between the stroma, the extracellular matrix and the epithelium drives mammary gland development and function. Two main assumptions in chemical carcinogenesis of the mammary gland have been that carcinogens induce neoplasia by causing mutations in the DNA of the epithelial cells and that the alterations of tissue architecture observed in neoplasms are a consequ...

The carcinogen 4,4'-diaminobiphenyl (benzidine) has been compared in vitro with its terphenyl analogue 4,4''-diaminoterphenyl using the Salmonella reverse mutation assay and the BHK cell-transformation assay. The responses observed, taken together with a consideration of chemical structures, indicate that the terphenyl compound is a potential carcinogen. These findings may contribute to an unde...