The reproductive toxicity and carcinogenicity of lead: A critical review

Lead is a known reproductive toxin. In males, it causes reduction in sperm count and reductions in fertility. In females, it increases risk of miscarriage. Recent research has shown that these reproductive effects occur at relatively low levels of exposure that previously were considered safe. Research to assess these effects at ever lower levels of exposure is ongoing and much needed. Lead is a potent neurodevelopmental toxin. Prospective longitudinal studies of outstanding quality demonstrate that prenatal and early postnatal exposure to lead at levels as low as 10-20 μg/dl results in damage to the central nervous system [Bellinger et al., 1987; Wasserman et al, 1997]. This damage results in diminished intelligence and altered behavior [CDC, 1991; NAS, 1993]. These effects appear to be irreversible, untreatable, and lifelong [Needleman et al., 1990]. The only rational approach to their control is to reduce prenatal and early life exposure to lead. Lead is a proven, 'sufficient' animal carcinogen. It can cause renal cancer and possibly brain tumors in rats and mice. In humans, IARC had previously considered the evidence 'inadequate' to assess the carcinogenicity of lead. However, new data have accumulated on the cancer risk of workers exposed to lead, including results presented at the 1999 Conference in Gargano. Such new data would justify a re-evaluation of the available evidence in the near future.