Very low lead exposures and children's neurodevelopment.
OBJECTIVE
We remain far from achieving the goal of eliminating lead-associated neurodevelopmental morbidities in children. New evidence regarding the blood lead levels at which morbidities occur have led to calls for the Centers for Disease Control and Prevention to reduce the current screening guideline of 10 microg/dl. The review evaluates the basis for these calls.


RESULTS
Adverse outcomes, such as reduced intelligence quotient and academic deficits, occur at levels below 10 microg/dl. Some studies suggest that the rate of decline in performance is greater at levels below 10 microg/dl than above 10 microg/dl, although a plausible mechanism has not been identified. Increased exposure is also associated with neuropsychiatric disorders such as attention deficit hyperactivity disorder and antisocial behavior. Functional imaging studies are beginning to provide insight into the neural substrate of lead's neurodevelopmental effects. Current protocols for chelation therapy appear ineffective in preventing such effects, although environmental enrichment might do so.


CONCLUSIONS
No level of lead exposure appears to be 'safe' and even the current 'low' levels of exposure in children are associated with neurodevelopmental deficits. Primary prevention of exposure provides the best hope of mitigating the impact of this preventable disease.
Bellinger
David C
DC
Children's Hospital Boston, Harvard Medical School, Harvard School of Public Health, Boston, Massachusetts 02115, USA. david.bellinger@childrens.harvard.edu
D015913:Chelation Therapy; D002648:Child; D002657:Child Development / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D062665:Epidemiological Monitoring; D006801:Humans; D007360:Intelligence / Q000187:drug effects; D007854:Lead / Q000097:blood* / Q000633:toxicity; D020264:Lead Poisoning, Nervous System, Childhood / Q000097:blood* / Q000188:drug therapy / Q000453:epidemiology*; D008297:Male; D008606:Mental Processes / Q000187:drug effects; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000187:drug effects; D013647:Task Performance and Analysis
D007854:Lead