The sample included 110 Nunavik Inuit children tested at preschool age. Children were tested first and then children's mothers were interviewed. Maternal and child health was obtained from medical records and maternal interviews. Child's blood and hair samples were taken in order to test for contemporaneous PCBS and Hg exposure. Concentrations of PCB congeners IUPAC as well as chlorinated pesticides and mercury were obtained through cord serum analyses. A neurological exam was performed, gross motor and fine neuromotor functions were assessed, as well as visual evoked and cognitive evoked potentials through electrophysiological testing. An evaluation of the child behavioural and emotional status during testing was also obtained. Demographic, socio-familial and biological potential confounds were documented via maternal interviews. These variables include socio-economic status, highest grade attained by the primary caregiver, number of children and adults at home, qualitu of intellectual stimulation provided by the family (HOME interview), maternal mental well-being (IDESQ), maternal cogntivie abilities (Raven's progressive Matrices), and family violence (Conflict Tactic Scales). Detailed procedures for insuring the integrity of the data have been developed in our laboratory based on recommendations of the U.S. Environmental Protection Agency's Expert Committee on Pediatric Neurobehavioral Evaluations (Jones et al., 1983). Data have been published. This project is completed.