人类癌肿的80—90%是与环境因素有关.环境因素包括空气、水、食物中的污染物以及放射线、工作环境接触的有害物质和个人习惯等.由此认为大多数瘤肿是可以预防的.由于很少的癌肿由单一因素引起,多数癌肿可能是环境和宿主间的多种因素相互作用产生,因此确定特异性致癌因子和评价它们的致癌作用是一项相当艰巨的工作. 80-90% of human cancers are related to environmental factors. Environmental factors include air, water, contaminants in food, radiation, harmful substances in the work environment, and personal habits. It is believed that most tumors can be prevented. Due to the fact that very few cancers are caused by a single factor, most cancers may be generated by interactions between various factors of the environment and the host. Therefore, the identification of specific carcinogenic factors and evaluation of their carcinogenic effects is a very arduous task.