Lead Exposure and Intelligence in 7-Year-Old Children: The Yugoslavia Prospective Study

Abstract

For a prospecdive study of lead exposure and early development, we recruited pregnant women from a lead smelter town and from an un town in Yugoslavia and followed their children through 7 years ofage. In this paper we consider associations between lifetime lead exosure, estimated by the area under the blood lead (BPb) versus time curve (AUC7), and intelligence, with particular concern for identiying lead's behavioral signature. The Wechsler Intelligence Scales for Children-Version III (WISC-III) was administered to 309 7-year-old children, 261 of whom had complete data on intllince, blood lead, and relevant sociodemographic covariates [i.e., Home Observation for the Measurement of the Environment (HOME), birth weight, gender, sibship size, and maternal age, ethnicity, intelligence, and education]. These showed anticipated associations with 7-year intelligence, eplaning 4147% of the variance in Full Scale, Performance, and Verbal IQ. Before covarate adjustment, AUC7 was unrelated to intelligece; after adjustment, AUC7 explained a s4iflcant 2.8%-4.2% of the variace in IQ. After adjustment, a change in lifitime BPb from 10 to 30 pg/dl related to an estimated decrease of 4.3 Full Scale IQpoints; estimated decreases for Verbal and Performance IQ were 3.4 and 4.5 points, respeely. AUC7 was significantly and negtily related to three WISC-III factor scores: -Freedom from Distactibility, Perceptual Organization, and Verbal Comprehension; the association with Perceptual Organization was the strongest. Consistent with previous studies, the IQ/lead association is small relative to more powerful social factors. Findings offer suppor for lead's behavioral siture: perceptual-motor skils are significantly more sensitive to leud exposure than are the language-related aspects of intelligence. Key swrd:. child development, intelligence, lead, perceptual motor functioning, WISC-IlI. Environ Heakh Perspect 105:956-962 (1997). hp//ehis.nie/inih.gov

Lead Toxicity: Does the Critical Level of Lead Resulting in Adverse Effects Differ between Adults and Children?

“…By the end of 2002, the majority of human data indicated that there were persistent and deleterious effects of BPb levels above 10 µg/dl on children's brain function, including lowered intelligence, behavioral problems and diminished school performance [76][77][78][79][80][81][82][83] ; whereas, German researchers, who evaluated 24 selected publications in a meta-analysis 84,85) , concluded that neurobehavioral deficits due to lead exposure in adults were associated with average BPb levels between 37 and 52 µg/dl. Thereafter, Canfield et al reported that BPb levels, even those below 10 µg/dl, were inversely associated with children's intelligence quotient (IQ) scores at 3 and 5 yr of age, and that associated declines in IQ were greater at these levels than at higher levels 4) .…”

Lead sources, behaviors, and socioeconomic factors in relation to blood lead of native american and white children: a community-based assessment of a former mining area.

“…Numerous studies have shown that children with only moderately increased BPbs (10-15 µg/dL) suffer disproportionately from cognitive and neurobehavioral deficits, including lower intelligence quotient scores and diminished attention span, bilateral coordination, visual-motor control, upper-limb speed, dexterity, and fine motor skills (8)(9)(10)(11)(12)(13)(14)(15). In addition, there is mounting evidence of deleterious effects associated with BPbs even below 5 µg/dL; these include hearing loss, adverse hematologic effects, dental carries, and diminished cognitive and academic skills (16)(17)(18)(19)(20)(21).…”

Caracterização das alterações de linguagem em crianças com histórico de intoxicação por chumbo

“…This data, in association with the others presented, doesn't permit to attribute the language disorder found only to the neurotoxic effects of lead. As mentioned previously, despite the lead has a significant influence in children's development, the existente of other environmental factors -such as the environment where children live, the cultural and schooling level of parents and the quality of schools -may be even stronger (10,12).…”

“…Some authors suggest that even lower lead levels than the accepted by the World Health Organization present risk for disorders in the skills mentioned above, indicating that a security margin does not exist for lead exposure (3,(7)(8)(9). On the other hand, certain studies do not find correlation between the blood lead level and the neuropsychological dysfunctions presented by contaminated children, evidencing that genetic and environmental factors may aggravate the hindering effects of the lead in the neural development, making some children more vulnerable to the neurotoxic effects of the metal, or yet, despite having a significant influence in children's development, other environmental factors may be even stronger (10)(11)(12).…”