Abstract
Our environment is a sea of chemicals composed of hundreds and thousands of chemicals with great diversity of pharmacological function and structure. Human populations are therefore generally exposed simultaneously to numbers of toxicants, including complex mixtures of chemicals of unknown and variable origin at low doses, some of which are carcinogens and some of which are non-carcinogens. Exposure may occur in different ways and interactions between multiple chemicals acting simultaneously or sequentially in humans are a very important issue for carcinogenic risk assessment and management. Experimental data demonstrate that at very low doses, summation or synergistic enhancement of carcinogenesis is unlikely, particularly in cases of non-genotoxic carcinogens. In this review, we would like to present published data on summation and/or synergistic effects of carcinogens, dependent on the dose applied.
