Hair Mercury Levels of Women of Reproductive Age in Ontario, Canada: Implications to Fetal Safety and Fish Consumption

roductive age in relation to fish intake in e Motherisk Program for information onICP-MS Inductively coupled plasma mass spectrometryC ompared with other types of meat, fish are a source of high-quality lean protein and n-3 polyunsaturated fatty acids, which are essential for growth of the developing fetal brain.1 The predominant drawback of fish consumption for ex-pectant mothers is that all fish contain traces of methyl mercury, a known developmental neurotoxin. Methyl mercury concentration varies widely among fish species. Top predatory fresh-water fish frommercury-contaminated lakes typically con-tain the highest levels.2 Although epidemics in which large numbers of people were affected by high doses of methyl mercury in Japan3 and Iraq4 affirmed the fact that consumption of high concentrations of methyl mercury in foodstuffs by pregnant women can cause severe neurodevelopment problems in offspring,5 the implications of much lower level exposures, such as those occurring in fish-eating populations today, are largely unknown. The threshold that will adversely affect the developing fetus is debated. In January 2001, the US Food and Drug Administration (FDA) and the US Environmental Protection Agency (EPA) issued advisories counselling pregnant women to avoid consuming specified long-lived predatory fish, which may contain high levels of organic mercury, and to limit ingestion of all other fish.6,7 After this advisory was issued, it has been found that many Amer