[Lead in the 90's: "new" rules for the "oldest" of environmental toxins?].

Present lead (Pb) exposures in working and general environments are undoubtedly lower than several decades ago so that mean blood lead levels (PbB) in the main industrial sectors using lead, such as ceramics and accumulator manufacturing, are now about 30 micrograms/100 ml and in the general population between 10 and 15 micrograms/100 ml and in some situations decidedly below 10 micrograms/100 ml. At the same time increasingly more accurate and sometimes original knowledge has been acquired on the effects of low-level Pb exposure, especially the effects on the nervous system, the cardiovascular system, the endocrine and immune systems, on heme-containing enzymes, and on the reproductive system. The question of a possible mutagenic and carcinogenic action of Pb is, however, still open. It is also clear that many of the above effects were observed for PbB levels considerably below the current limit levels. For certain effects, like those on heme, the central nervous system, and blood pressure, it has not been possible to establish a threshold below which they will not occur. With effects that are so different in nature and degree and with changed exposure conditions, a critical re-examination of the assumptions on which current knowledge and prevention models are based appeared appropriate. In particular, action models are proposed for discussion which, besides the priority aim of restricting use of Pb to those situations where there is no alternative and to those working environments which guarantee compliance with modern regulations and prevention procedures, have two differentiated objectives: the first is to eliminate the dose-dependent effects occurring at exposures higher than those in the general population; the second is to reduce to the lowest possible level the effects with no threshold or with as yet unestablished threshold, by means of actions in favour not only of occupationally exposed groups but also the general population.