近年来普遍认为,人类在环境中广泛接触各种化学、放射和其他物理因子,其中某些已知是致变异和致癌的因素。曾提出假说,各种尚未查明的物质进入生物圈,可导致变异率相应增加。所谓变异是指遗传物质DNA组成和排列发生突然的并可遗传的改变。 In recent years it has generally been assumed that humans have extensive exposure to various chemical, radiological and other physical factors in the environment, some of which are known to be mutagenic and carcinogenic. Hypothesis was made that all kinds of unidentified substances entering the biosphere could lead to a corresponding increase in mutation rate. The so-called mutation refers to genetic material DNA composition and arrangement of sudden and genetic changes.