Exposure Assessment: Lead Neurotoxicity Is the Center for Disease Control's goal to reduce lead below 10 µg/dl blood in all children younger than 72 months by 2010, good enough?

Blood lead threshold levels have been decidedly downward over the past forty years. While it may be possible that the bottom has been reached or that new research might at some point reverse the trend--something that does happen with other chemicals, although rarely--recent evidence suggests that the direction of the trend for lead will continue. In part this is due to better data at lower concentrations of lead, simply showing or confirming what has been suggested for a long time by insufficient data. And in part this is due to an appreciation and ability to test much more subtle effects of lead toxicity. The results of the jury verdict in Rhode Island that held paint manufacturers responsible for lead paint that remains in homes and the toxic consequences of this situation, come at a time of growing understanding of the more subtle toxic effects of lead in the neurological development of children; that is, that (much) lower blood lead (BPb) than previously shown or considered, can be toxic and over a wider range of adverse affects. The rapid change in which significantly lower lead toxicity and the stakes involved has been recognized is reflected in the speed of change in acceptable threshold levels. The 1990 decision by the U.S. Department of Health and Human Services to eliminate all BPb> 25 µg/dl in children 6 months through 5 years of age by 2000 (Healthy People 2000) was followed in 1991 by a reduction in that 25 µg/dl threshold of concern to 10 µg/dl by the Centers for Disease Control (CDC 1991). By the late 1990’s a new, Healthy People 2010 goal was set to eliminate all BPb> 10 µg/dl (Myer et al 2003; US Dept HHS 2000)