Many carcinogens have been detected in our environment, and chemicals which have shown to induce cancers in experimental animals have been large eliminated. However, there are still many chemicals which have not been studied in rodent carcinogenicity tests. We review the evaluation of carcinogenic risks of environmental chemicals to humans.
Carcinogenic risk to human is evaluated primarily in three different phases: 1)carcinogenity studies in animal experiments, 2) in vitro short-term screening studies arid finally, 3)human epidemiological studies. There are 30 chemicals, processes or industries which have been subject to these three phases and determined to be carcinoganic to human by the International Agency for Research on Cancer(IARC). Carcinogenic risk of chemicals should be evaluates quantatively by their threshold doses, TD_(50) and virtually safe dose(VSD). Furthermore, the target organ of the carcinogen should also be taken into account, which has been emphasized by the demonstration of carcinogenicity of BHA in the fortestomach of rats. Summational, synergistic, antagonistic and ihibitory effects of chemicals should also be discussed. It is important to estabilish a guideline for detecting and eliminating environment carcinogens in order to prevent cancer in human.
|