| Recent Developments in Low-Level Lead Exposure and Intellectual Impairment in Children Karin Koller,1 Terry Brown,1 Anne Spurgeon,2 and Len Levy1 1Medical Research Council Institute for Environment and Health, University of Leicester, Leicester, United Kingdom; 2Institute of Occupational Health, University of Birmingham, Birmingham, United Kingdom Abstract
>In the last decade children's blood lead levels have fallen significantly in a number of countries, and current mean levels in developed countries are in the region of 3 µg/dL. Despite this reduction, childhood lead poisoning continues to be a major public health problem for certain at-risk groups of children, and concerns remain over the effects of lead on intellectual development in infants and children. The evidence for lowered cognitive ability in children exposed to lead has come largely from prospective epidemiologic studies. The current World Health Organization/Centers for Disease Control and Prevention blood level of concern reflects this and stands at 10 µg/dL. However, a recent study on a cohort of children whose lifetime peak blood levels were consistently < 10 µg/dL has extended the association of blood lead and intellectual impairment to lower levels of lead exposure and suggests there is no safety margin at existing exposures. Because of the importance of this finding, we reviewed this study in detail along with other recent developments in the field of low-level lead exposure and children's cognitive development. We conclude that these findings are important scientifically, and efforts should continue to reduce childhood exposure. However, from a public health perspective, exposure to lead should be seen within the many other risk factors impacting on normal childhood development, in particular the influence of the learning environment itself. Current lead exposure accounts for a very small amount of variance in cognitive ability (1-4%) , whereas social and parenting factors account for 40% or more. Key words: children, cognitive function, intellectual impairment, IQ, lead exposure. Environ Health Perspect 112:987-994 (2004) . doi:10.1289/ehp.6941 available via http://dx.doi.org/ [Online 28 April 2004]
Address correspondence to K. Koller, MRC Institute for Environment and Health, University of Leicester, 94 Regent Rd., Leicester LE1 7DD, UK. Telephone: 44 0 116 223 1629. Fax: 44 0 116 223 1601. E-mail: kew13@le.ac.uk The authors are indebted to R. Canfield, Cornell University, Ithaca, New York, USA, for providing further details of his study. We gratefully acknowledge the support of the U.K. Department for Environment, Food and Rural Affairs. The authors declare they have no competing financial interests. Received 18 December 2003 ; accepted 28 April 2004.
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