The paper builds on existing literature, highlighting current understanding and identifying unresolved issues about MeHg exposure, health effects, and risk assessment, and concludes with a consensus statement. Methylmercury is a potent toxin, bioaccumulated and concentrated through the aquatic food chain, placing at risk people, throughout the globe and across the socioeconomic spectrum, who consume predatory fish or for whom fish is a dietary mainstay. Methylmercury developmental neurotoxicity has constituted the basis for risk assessments and public health policies. Despite gaps in our knowledge on new bioindicators of exposure, factors that influence MeHg uptake and toxicity, toxicokinetics, neurologic and cardiovascular effects in adult populations, and the nutritional benefits and risks from the large number of marine and freshwater fish and fish-eating species, the panel concluded that to preserve human health, all efforts need to be made to reduce and eliminate sources of exposure.
Associations with known factors such as age, race, and sex were confirmed using this data set. Understanding the prevalence of abnormal thyroid tests among reproductive-aged women informs decisions about screening in this population. The finding that individuals on thyroid hormone replacement medication often remain hypothyroid or become hyperthyroid underscores the importance of monitoring.
BackgroundThe current, continuous National Health and Nutrition Examination Survey (NHANES) has included blood mercury (BHg) and fish/shellfish consumption since it began in 1999. NHANES 1999–2004 data form the basis for these analyses.ObjectivesThis study was designed to determine BHg distributions within U.S. Census regions and within coastal and noncoastal areas among women of childbearing age, their association with patterns of fish consumption, and changes from 1999 through 2004.MethodsWe performed univariate and bivariate analyses to determine the distribution of BHg and fish consumption in the population and to investigate differences by geography, race/ethnicity, and income. We used multivariate analysis (regression) to determine the strongest predictors of BHg among geography, demographic factors, and fish consumption.ResultsElevated BHg occurred more commonly among women of childbearing age living in coastal areas of the United States (approximately one in six women). Regionally, exposures differ across the United States: Northeast > South and West > Midwest. Asian women and women with higher income ate more fish and had higher BHg. Time-trend analyses identified reduced BHg and reduced intake of Hg in the upper percentiles without an overall reduction of fish consumption.ConclusionsBHg is associated with income, ethnicity, residence (census region and coastal proximity). From 1999 through 2004, BHg decreased without a concomitant decrease in fish consumption. Data are consistent with a shift over this time period in fish species in women’s diets.
Mercury (Hg) is well studied and research continues as our knowledge of its health risks increases. One expanding area of research not well emphasized to date is the endocrine effects of Hg. This review summarizes the existing literature on the effects of Hg on the endocrine system and identifies gaps in the knowledge. It focuses on the thyroid, adrenal, and reproductive systems, including the accumulation of Hg in the endocrine system, sex differences that are manifested with Hg exposure, reproductive effects in male and female animals including humans, and Hg effects on the thyroid and adrenal systems. We concluded that there are five main endocrine-related mechanisms of Hg across these systems: (a) accumulation in the endocrine system; (b) specific cytotoxicity in endocrine tissues; (c) changes in hormone concentrations; (d) interactions with sex hormones; and (e) up-regulation or down-regulation of enzymes within the steroidogenesis pathway. Recommendations for key areas of research to better understand how the endocrine effects of Hg affect human and wildlife health were developed, and include increasing the amount of basic biological information available about Hg and wildlife species, exploring the role of Hg in the presence of other stressors and chemicals, understanding sublethal and indirect effects of Hg on adverse outcomes, developing better methods to extrapolate effects across species, and understanding the effects of Hg on multiple organ systems following exposure of an animal. Greater inclusion of endocrine endpoints in epidemiological and field studies on humans and wildlife will also advance the research in this area.
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