The quantitative risk estimates are presented in three ways. Users are referred to Section I of this IRIS file for information on long-term toxic effects other than carcinogenicity. Ten rat bioassays and one mouse assay have shown statistically significant increases in renal tumors with dietary and subcutaneous exposure to several soluble lead salts. Animal assays provide reproducible results in several laboratories, in multiple rat strains with some evidence of multiple tumor sites. Short term studies show that lead affects gene expression.
Human evidence is inadequate.
There are four epidemiologic studies of occupational cohorts exposed to lead and lead compounds. Selevan et al. Although similar excesses were observed in the smelter workers, they were not statistically significant. All of the available studies lacked quantitative exposure information, as well as information on the possible contribution from smoking. All studies also included exposures to other metals such as arsenic, cadmium, and zinc for which no adjustment was done.