Bp. Lanphear et al., Cognitive deficits associated with blood lead concentrations < 10 mu g/dL in US children and adolescents, PUBL HEA RE, 115(6), 2000, pp. 521-529
Citations number
33
Categorie Soggetti
Public Health & Health Care Science","Envirnomentale Medicine & Public Health
Objective. Lead is a confirmed neurotoxicant, but the lowest blood lead con
centration associated with deficits in cognitive functioning and academic a
chievement is poorly defined. The purpose of the present study was to exami
ne the relationship or relatively low blood lead concentrations-especially
concentrations < 10 micrograms per deciliter (mug/dL)-with performance on t
ests of cognitive functioning in a representative sample of US children and
adolescents.
Methods. The authors used data from the Third National Health and Nutrition
Examination Survey (NHANES III), conducted from 1988 to 1994, to assess th
e relationship between blood lead concentration and performance on tests of
arithmetic skills, reading skills, nonverbal reasoning, and shortterm memo
ry among 4.853 children ages 6-16 years.
Results. The geometric mean blood lead concentration for children in the st
udy sample was 1.9 mug/dL: 172 (2.1%) had blood lead concentrations greater
than or equal to 10 mug/dL. After adjustment for gender, race/ethnicity, p
overty, region of the country, parent or caregiver's educational level, par
ent or caregiver's marital status parent, serum ferritin level, and serum c
otinine level, the data showed an inverse relationship between blood lead c
oncentration and scores on four measures of cognitive functioning. For ever
y I mug/dL increase in blood lead concentration, there was a 0.7-point decr
ement in mean arithmetic scores, an approximately 1-point decrement in mean
reading scores, a 0.1-point decrement in mean scores on a measure of nonve
rbal reasoning, and a 0.5-point decrement in mean scores on a measure of sh
ort-term memory. An inverse relationship between blood lead concentration a
nd arithmetic and reading scores was observed Tor children with blood lead
concentrations lower than 5.0 mug/dL.
Conclusion. Deficits in cognitive and academic skills associated vvith lead
exposure occur at blood lead concentrations lower than 5 mug/dL.