大多数鉴别为致癌物的分子本身并不具有毒害作用，通常需要在体内代谢成具有亲电作用的形式，然后与ＤＮＡ上的亲核部位发生不可逆反应，从而改变基因的表达。在致癌物代谢转化过程中，细胞色素Ｐ４５０家族及谷胱甘肽Ｓ－转移酶起主要作用，细胞色素Ｐ４５０大多位于肝内，其 Most of the molecules identified as carcinogens are not toxic by themselves and usually need to be metabolized into electrophilic forms in the body, and then react irreversibly with nucleophilic sites on DNA, thereby altering gene expression. In the process of metabolism and conversion of carcinogens, the cytochrome P450 family and glutathione S-transferase play a major role, and cytochrome P450 is mostly located in the liver.