LEAD TOXICITY - CURRENT CONCERNS

Over the 20-year period since the first issue of Environmental Health Perspectives was published, there has been considerable progress in th e understanding of the potential toxicity of exposure to lead. Many of these advances have been reviewed in published symposia, conferences, and review papers in EHP. This brief review identifies major advances as well as a number of current concerns that present opportunities fo r prevention and intervention strategies. The major scientific advance has been the demonstration that blood lead (PbB) levels of 10-15 mug/ dL in newborn and very young infants result in cognitive and behaviora l deficits. Further support for this observation is being obtained by prospective or longitudinal studies presently in progress. The mechani sm(s) for the central nervous system effects of lead is unclear but in volve lead interactions within calcium-mediated intracellular messenge r systems and neurotransmission. Effects of low-level lead exposure on blood pressure, particularly in adult men, may be related to the effe ct of lead on calcium-mediated control of vascular smooth muscle contr action and on the renin-angiotensin system. Reproductive effects of le ad have long been suspected, but low-level effects have not been well studied. Whether lead is a carcinogen or its association with renal ad enocarcinoma is a consequence of cystic nephropathy is uncertain. Majo r risk factors for lead toxicity in children in the United States incl ude nutrition, particularly deficiencies of essential metals, calcium, iron, and zinc, and housing and socioeconomic status. A goal for the year 2000 is to reduce prevalence of blood lead levels exceeding 15 mu g/dL.