Intellectual Impairment in
Children with Blood Lead Concentrations below 10 µg per Deciliter
Richard L.
Canfield, Ph.D., Charles R. Henderson, Jr., M.A., Deborah A. Cory-Slechta,
Ph.D., Christopher Cox, Ph.D., Todd A. Jusko, B.S., and Bruce P. Lanphear, M.D.,
M.P.H.
Background Despite dramatic declines in children's blood lead
concentrations and a lowering of the Centers for Disease Controland
Prevention's level of concern to 10 µg per deciliter(0.483 µmol per
liter), little is known about children'sneurobehavioral functioning
at lead concentrations below thislevel.
Methods We measured blood lead
concentrations in 172 childrenat 6, 12, 18, 24, 36, 48, and 60
months of age and administeredthe StanfordBinet Intelligence Scale
at the ages of 3and 5 years. The relation between IQ and blood lead
concentrationwas estimated with the use of linear and nonlinear
mixed models,with adjustment for maternal IQ, quality of the home
environment,and other potential confounders.
Conclusions Blood lead
concentrations, even those below 10 µgper deciliter, are inversely
associated with children's IQ scoresat three and five years of age,
and associated declines in IQare greater at these concentrations
than at higher concentrations.These findings suggest that more U.S.
children may be adverselyaffected by environmental lead than
previously estimated.
Source Information
From the Division of
Nutritional Sciences (R.L.C.) and the Department of Human Development (C.R.H.),
College of Human Ecology, Cornell University, Ithaca, N.Y.; the Departments of
Environmental Medicine (D.A.C.-S.) and Biostatistics and Computational Biology
(C.C.), University of Rochester School of Medicine, Rochester, N.Y.; the
Division of Epidemiology, Statistics, and Prevention, National Institute of
Child Health and Human Development, National Institutes of Health, Department of
Health and Human Services, Bethesda, Md. (C.C.); the Department of Epidemiology,
School of Public Health and Community Medicine, University of Washington,
Seattle (T.A.J.); and Cincinnati Children's Environmental Health Center,
Children's Hospital Medical Center, Cincinnati (B.P.L.).
Address reprint
requests to Dr. Canfield at the Division of Nutritional Sciences, College of
Human Ecology, Cornell University, Ithaca, NY 14853, or at
rlc5@cornell.edu.
ALL INFORMATION, DATA, AND
MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION
PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS
OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR
LEGAL ADVICE. THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND
COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH
YOUR HEALTH CARE PROVIDER.
"A foolish faith in authority is the worst enemy of truth."
-- Albert Einstein, letter to a friend, 1901
"I know of no safe depository of the ultimate powers of the society but the people themselves, and if we think them not enlightened enough to exercise control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion by education."
-- Thomas Jefferson, letter to William C. Jarvis, September 28, 1820
"What's the point of vaccination if it doesn't protect you from the unvaccinated?"
-- Sandy Gottstein
"Who gets to decide what the greater good is and how many will be sacrificed to it?"