Recently, the Occupational Safety and Health Administration (OSHA) proposed regulations regarding lists of environmental substances that allegedly pose potential occupational carcinogenic risk. Known carcinogens such as bis(chloromethyl) ether, along with natural substances such as estradiol, estriol, estrone, progesterone, tannic acid, maltose, and lactose, were included in the general OSHA list. Clear distinction between true hazards and essential endogenously formed biochemicals was not made. A major reappraisal of the OSHA list is essential. The revised document should indicate the conditions under which various classes of substances constitute human health hazards — including dosage levels and routes of entry.