This 5-year study involves about 300 school age children from the 14 Nunavik communities. Our study consists of a follow-up of our three cohorts of Nunavik children at 10 years of age. Blood and hair samples were obtained from each child. The most prevalent PCB congeners and organochlorine pesticides were analyzed from plasma. Mercury was measured from blood and hair samples. Each mother and child was evaluated in two assessments. The child's intellectual and neuromotor functions, attention, working memory, executive functions, neuromotor and visual-spatial functions, event-related potential (ERP) assessments, affective and behavioral functions and physical growth were assessed during the testing session. Seven sets of control variables have been assessed during the maternal interview: demographic background, situational variables, PCBs and methylmercury concentrations, prenatal exposure to other toxic, iron deficiency anemia, perinatal risk, and quality of the social environment. A detailed procedure 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 now completed.