Identification of functional domains affected by developmental exposure to methylmercury: Faroe islands and related studies.

The Faroe Islands study is a prospective study designed to assess the neurological and behavioral consequences of in utero exposure to methylmercury (meHg). Maternal exposure to meHg was through consumption of fish and intermittent higher-level exposure through pilot whale meat, while consumption of pilot whale blubber resulted in maternal exposure to PCBs. Analysis of the neurobehavioral domains affected revealed impairment in attention, memory, and auditory processing, impairment in primary auditory function, and to a lesser extent motor impairment. For four of the eight endpoints affected by meHg exposure atp < .10, impairment was also correlated (p < .10) with in utero PCB exposure as measured by cord tissue PCB levels. Further analyses provide evidence for an independent effect of PCBs and meHg on these endpoints. Cross-sectional studies in a smaller number of children in the Amazon and Madeira by the same group of investigators, in which average meHg maternal hair levels were about twice as high those in the Faroe Islands, identified auditory, visual, and/or motor deficits, with little or no evidence of deficits in attention or memory. However, the results of the cross-sectional studies must be interpreted with caution, due to limited statistical power as well as a lack of opportunity to correlate effects to in utero exposure.