The purpose of this research is to examine the long term consequences of prenatal exposure to PCBs and MeHg. This project is designed to study domains of effects overlooked in most of the previous studies. Of particular interest is the impact of exposure on neurophysiological and neurological endpoints that could be related to learning difficulties and disabilities. This study will support the health risk assessment process by providing dose-effect analysis for the neurophysiological and neurological domains of effects of preschool age children from Nunavik (Canada). The total sample will comprise 100 Nunavik Inuit children aged 5-6years. The following exclusion criteria will be applied: Apgar below 5 at 5 minutes of life, evidence of birth trauma, less than 37 weeks of gestation and less than 2500 grams at birth, congenital or chromosomal anomalies, epilepsy, significant disease history, major neurological impairment, fetal alcohol syndrome, presence of facial dysmorphologies associated with fetal alcohol effects.