Regional and temporal trends in blood mercury concentrations and fish consumption in women of child bearing Age in the united states using NHANES data from 1999-2010.

BACKGROUND: The primary route of exposure to methylmercury (MeHg), a known developmental neurotoxicant, is from ingestion of seafood. Since 2004, women of reproductive age in the U.S. have been urged to eat fish and shellfish as part of a healthy diet while selecting species that contain lower levels MeHg. Yet few studies have examined trends in MeHg exposure and fish consumption over time in this group of women with respect to their geographical location in the U.S. METHODS: Data from six consecutive cycles of the National Health and Nutrition Examination Survey (NHANES), 1999-2010 (n = 9597) were used to determine trends in blood mercury for women aged 16-49 residing in different regions in the US, and according to age, race/ethnicity, income level, and fish consumption using geographic variables. RESULTS: Overall, mean blood mercury concentrations differed across survey cycles and mercury concentrations were lower in 2009-2010 compared to 1999-2000. There were regional patterns in fish consumption and blood Hg concentrations with women living in coastal regions having the highest fish consumption in the past 30 days and the highest blood Hg levels compared to women residing inland. CONCLUSIONS: On average, U.S. women of reproductive age were consuming more fish and blood mercury levels were lower in 2009-2010 compared to 1999-2000. However, efforts to encourage healthy fish consumption may need to be tailored to different regions in the U.S. given the observed spatial variability in blood mercury levels.

Selenium: Mercury Molar Ratios in Freshwater Fish in the Columbia River Basin: Potential Applications for Specific Fish Consumption Advisories.

Fish provide a valuable source of beneficial nutrients and are an excellent source of low fat protein. However, fish are also the primary source of methylmercury exposure in humans. Selenium often co-occurs with mercury and there is some evidence that selenium can protect against mercury toxicity yet States issue fish consumption advisories based solely on the risks that methylmercury pose to human health. Recently, it has been suggested the selenium: mercury molar ratio be considered in risk management. In order for agencies to utilize the ratio to set consumption guidelines, it is important to evaluate the variability in selenium and mercury in different fish species. We examined 10 different freshwater fish species found within the Columbia River Basin in order to determine the inter- and intra-specific variability in the selenium: mercury molar ratios and the selenium health benefit values. We found significant variation in selenium: mercury molar ratios. The mean molar ratios for each species were all above 1:1, ranging from 3.42:1 in Walleye to 27.2:1 in Chinook salmon. There was a positive correlation between both mercury and selenium with length for each fish species apart from yellow perch and rainbow trout. All species had health benefit values greater than 2. We observed considerable variability in selenium: mercury molar ratios within fish species collected in the Columbia River Basin. Although incorporating selenium: mercury molar ratios into fish consumption holds the potential for refining advisories and assessing the risk of methylmercury exposure, the current understanding of how these ratios apply is insufficient, and further understanding of drivers of variability in the ratios is needed.