Fetal methylmercury study in a Peruvian fish-eating population.

Maternal consumption during pregnancy of methylmercury (MeHg)-contaminated fish in Japan and of MeHg-contaminated bread in Iraq caused psychomotor retardation in the offspring. Studies in Iraq suggested adverse fetal effects when maternal hair mercury concentrations were as low as 20 ppm. This prospective study involved 131 infant-mother pairs in Mancora, Peru with peak maternal hair MeHg levels during pregnancy from 1.2 ppm to 30.0 ppm, geometric mean 8.3. The MeHg was believed to be derived from marine fish in the diet. There was no increase in the frequency of neurodevelopmental abnormalities in early childhood. The possible role of selenium or other protective mechanisms in marine fish is discussed. This previously unpublished study was conducted between 1981 and 1984. Our report of August 1985 to the funding agencies has been circulated, and the data were presented at the Twelfth International Neurotoxicology Conference in Hot Spring, Arkansas, October 30 to November 2, 1994. The current account has not been modified or updated since 1985. For reference to interim publications on fetal MeHg studies in Iraq and New Zealand see Marsh et al., 1995.