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Pre- and postnatal lead exposure and behavior problems in school-aged children
D Bellinger1, A Leviton, E Allred
1Neuroepidemiology Unit, Children's Hospital, Boston, Massachusetts 02115.
Insights
Early childhood lead exposure, measured by tooth lead levels, is linked to increased problem behaviors in children. Prenatal lead exposure, however, showed no significant association with behavioral issues.
Area of Science:
- Environmental Health
- Developmental Psychology
- Pediatrics
Background:
- Early lead exposure is a known neurotoxin.
- The relationship between lead exposure timing and behavioral outcomes requires further investigation.
Purpose of the Study:
- To prospectively evaluate the association between early lead exposure and later problem behaviors in children.
- To differentiate the impact of prenatal versus postnatal lead exposure on behavior.
Main Methods:
- A prospective cohort study of 8-year-old children.
- Lead levels measured in umbilical cord blood (prenatal) and shed deciduous teeth (postnatal).
- Child behavior assessed using the Teacher Report Form of the Child Behavior Profile.
Main Results:
- Prenatal lead exposure (cord blood lead) was not associated with problem behaviors.
- Postnatal lead exposure (tooth lead) was significantly associated with higher total problem behavior scores.
- Increased internalizing and externalizing behavior scores were observed with higher tooth lead levels.
Conclusions:
- Postnatal lead exposure is a significant correlate of social and emotional dysfunctions in children.
- These findings suggest lead exposure may contribute to behavioral problems, though residual confounding is possible.
Abstract:
The association between early lead exposure and later problem behaviors was evaluated prospectively in a cohort of 8-year-old children born during a 12-month period at one hospital. Lead levels in umbilical cord blood (means = 6.8 micrograms/dl, SD = 3.1) and the dentin of a shed deciduous tooth (means = 3.4 micrograms/g, SD = 2.4) provided measures of prenatal and postnatal exposure, respectively. Ratings on the Teacher Report Form of the Child Behavior Profile provided information about children's problem behaviors. Cord blood lead level was not associated with the overall prevalence or nature of problem behaviors. In both crude and adjusted analyses, tooth lead level was significantly associated with total problem behavior scores (approximately 2 points in T score per log unit increase in tooth lead). Significant tooth lead-associated increases in both internalizing and externalizing scores were also observed (approximately 1.5 points in T score per log unit increase). Weaker associations were noted between tooth lead level and the prevalence of "extreme" problem behavior scores. The extent to which these associations reflect residual confounding is uncertain. These data suggest, however, that social and emotional dysfunctions are correlates and may be expressions of increased lead exposure.