The goal of the proposed research is to determine whether low-level lead exposure is a risk factor for social and emotional problems in a community- based cohort of approximately 1,800 8 year old children. The role of timing of exposure will be evaluated using two indices of lead exposure for each child: umbilical cord blood lead level, a measure of prenatal exposure, and dentine lead level, widely considered to be a cumulative measure of postnatal exposure. The measure of children's behavior problems will be teachers' ratings on the Teacher Report Form of the Child Behavior Profile (TRF-CBP). This instrument provides scores on several """"""""narrow- band"""""""" scales: anxious, social withdrawal, unpopular, self-destructive, aggressive, nervous-overactive, inattentive, obsessive-compulsive (boys only), and depressed (girls only). In addition, a total """"""""Behavior Problem"""""""" score and two """"""""broad-band"""""""" scores, """"""""Externalizing"""""""" and """"""""Internalizing"""""""", are derived for both sexes. Multiple linear and logistic regression analysis will be used to assess the associations between the measures of children's lead exposure and their scores on the TRF-CBP. These scores will treated as continuous measures (i.e., the measured values), or classified as """"""""normal/abnormal"""""""" based on cut-off values defined in the TRF-CBP standardization sample (i.e., normalized T score >98th percentile on narrow-band scores, >89th percentile on the total and broad-band scales) or on sample-based cut-offs if the numbers of children with extreme scores are insufficient to ensure adequate power. A large number of potential confounding variables will be considered in the analyses. In a maternal interview and an obstetric/pediatric record review conducted shortly after a child's birth, information was collected on sociodemographic characteristics, maternal reproductive and medical history, the course of the index pregnancy, labor, and delivery, and neonatal status. A parent questionnaire completed when a child was 7 years old provides information about postnatal medical history, early behavior problems, rearing environment, and social status.
