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Environmental exposure to lead and children's intelligence at the age of seven years. The Port Pirie Cohort Study.
N Engl J Med. 1992 Oct 29; 327(18):1279-84.NEJM

Abstract

BACKGROUND

Exposure to lead in early childhood is thought to result in delayed neuropsychological development. As yet there is little longitudinal evidence to establish whether these effects persist into later childhood.

METHODS

We measured IQ scores in 494 seven-year-old children from the lead-smelting community of Port Pirie, Australia, in whom developmental deficits associated with elevated blood lead concentrations had already been reported at the ages of two and four years. Exposure to lead was estimated from the lead concentrations in maternal blood samples drawn antenatally and at delivery and from blood samples drawn from the children at birth (umbilical-cord blood), at the ages of 6 and 15 months and 2 years, and annually thereafter. Data relating to known covariates of child development were collected systematically for each child throughout the first seven years of life.

RESULTS

We found inverse relations between IQ at the age of seven years and both antenatal and postnatal blood lead concentrations. After adjustment by multiple regression for sex, parents' level of education, maternal age at delivery, parents' smoking status, socioeconomic status, quality of the home environment, maternal IQ, birth weight, birth order, feeding method (breast, bottle, or both), duration of breast-feeding, and whether the child's natural parents were living together, the relation with lead exposure was still evident for postnatal blood samples, particularly within the age range of 15 months to 4 years. For an increase in blood lead concentration from 10 micrograms per deciliter (0.48 mumol per liter) to 30 micrograms per deciliter (1.45 mumol per liter), expressed as the average of the concentrations at 15 months and 2, 3, and 4 years, the estimated reduction in the IQ of the children was in the range of 4.4 points (95 percent confidence interval, 2.2 to 6.6) to 5.3 points (95 percent confidence interval, 2.8 to 7.8). This reduction represents an approximate deficit in IQ of 4 to 5 percent.

CONCLUSIONS

Low-level exposure to lead during early childhood is inversely associated with neuropsychological development through the first seven years of life.

Authors+Show Affiliations

CSIRO Division of Human Nutrition, Adelaide, Australia.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

1383818

Citation

Baghurst, P A., et al. "Environmental Exposure to Lead and Children's Intelligence at the Age of Seven Years. the Port Pirie Cohort Study." The New England Journal of Medicine, vol. 327, no. 18, 1992, pp. 1279-84.
Baghurst PA, McMichael AJ, Wigg NR, et al. Environmental exposure to lead and children's intelligence at the age of seven years. The Port Pirie Cohort Study. N Engl J Med. 1992;327(18):1279-84.
Baghurst, P. A., McMichael, A. J., Wigg, N. R., Vimpani, G. V., Robertson, E. F., Roberts, R. J., & Tong, S. L. (1992). Environmental exposure to lead and children's intelligence at the age of seven years. The Port Pirie Cohort Study. The New England Journal of Medicine, 327(18), 1279-84.
Baghurst PA, et al. Environmental Exposure to Lead and Children's Intelligence at the Age of Seven Years. the Port Pirie Cohort Study. N Engl J Med. 1992 Oct 29;327(18):1279-84. PubMed PMID: 1383818.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Environmental exposure to lead and children's intelligence at the age of seven years. The Port Pirie Cohort Study. AU - Baghurst,P A, AU - McMichael,A J, AU - Wigg,N R, AU - Vimpani,G V, AU - Robertson,E F, AU - Roberts,R J, AU - Tong,S L, PY - 1992/10/29/pubmed PY - 1992/10/29/medline PY - 1992/10/29/entrez SP - 1279 EP - 84 JF - The New England journal of medicine JO - N Engl J Med VL - 327 IS - 18 N2 - BACKGROUND: Exposure to lead in early childhood is thought to result in delayed neuropsychological development. As yet there is little longitudinal evidence to establish whether these effects persist into later childhood. METHODS: We measured IQ scores in 494 seven-year-old children from the lead-smelting community of Port Pirie, Australia, in whom developmental deficits associated with elevated blood lead concentrations had already been reported at the ages of two and four years. Exposure to lead was estimated from the lead concentrations in maternal blood samples drawn antenatally and at delivery and from blood samples drawn from the children at birth (umbilical-cord blood), at the ages of 6 and 15 months and 2 years, and annually thereafter. Data relating to known covariates of child development were collected systematically for each child throughout the first seven years of life. RESULTS: We found inverse relations between IQ at the age of seven years and both antenatal and postnatal blood lead concentrations. After adjustment by multiple regression for sex, parents' level of education, maternal age at delivery, parents' smoking status, socioeconomic status, quality of the home environment, maternal IQ, birth weight, birth order, feeding method (breast, bottle, or both), duration of breast-feeding, and whether the child's natural parents were living together, the relation with lead exposure was still evident for postnatal blood samples, particularly within the age range of 15 months to 4 years. For an increase in blood lead concentration from 10 micrograms per deciliter (0.48 mumol per liter) to 30 micrograms per deciliter (1.45 mumol per liter), expressed as the average of the concentrations at 15 months and 2, 3, and 4 years, the estimated reduction in the IQ of the children was in the range of 4.4 points (95 percent confidence interval, 2.2 to 6.6) to 5.3 points (95 percent confidence interval, 2.8 to 7.8). This reduction represents an approximate deficit in IQ of 4 to 5 percent. CONCLUSIONS: Low-level exposure to lead during early childhood is inversely associated with neuropsychological development through the first seven years of life. SN - 0028-4793 UR - https://www.unboundmedicine.com/medline/citation/1383818/Environmental_exposure_to_lead_and_children's_intelligence_at_the_age_of_seven_years__The_Port_Pirie_Cohort_Study_ DB - PRIME DP - Unbound Medicine ER -