Although the basic cause of cancer has still not been discovered, it was pointed out in the US after large scale research was undertaken in the 1980's into the reasons behind cancer deaths that there is an 80 % correlation between the occurrence of cancer and the environment. Besides smoking, the environment includes food additives, chemical fertilizers, industrial raw materials, chemical products, and environmental pollution.
雖然今天癌症的基本病因尚未被發現，但美國在一九七○年代大規模對癌症死亡原因進行研究後指出，癌症的發生和環境有百分之八十的關係；所謂環境，除了抽煙，包括食物添加劑、農藥、工業原料、化學物質、環境污染等。