Methylmercury Exposure and Health Effects in Humans: A Worldwide Concern

Department of Biological Sciences, Institute for Environmental Sciences, University of Québec, Montreal, Canada.
AMBIO A Journal of the Human Environment (Impact Factor: 2.29). 03/2007; 36(1):3-11. DOI: 10.1579/0044-7447(2007)36[3:MEAHEI]2.0.CO;2
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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.

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    • "Although organic matter and mercury (Hg) exist naturally in water, both constituents have become identified as human health concerns. Mercury, particularly methylmercury (MeHg), in aquatic systems can bioaccumulate to lethal levels in upper trophic level organisms (Mergler et al. 2007; Crump and Trudeau 2009). Organic material—particularly dissolved organic matter (DOM)—is also a concern in potable water supplies, as a fraction reacts during the disinfection process to form halogenated, carcinogenic by-products, such as trihalomethanes and haloacetic acids (Richardson et al. 2007). "
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    ABSTRACT: The presence of mercury (Hg), particularly methylmercury (MeHg), is a concern for both human and ecological health as MeHg is a neurotoxin and can bioaccumulate to lethal levels in upper trophic level organisms. Recent research has demonstrated that coagulation with metal-based salts can effectively remove both inorganic mercury (IHg) and MeHg from solution through association with dissolved organic matter (DOM) and subsequent flocculation and precipitation. In this study, we sought to further examine interactions between Hg and DOM and the resulting organo-metallic precipitate (floc) to assess if (1) newly added IHg could be removed to the same extent as ambient IHg or whether the association between IHg and DOM requires time, and (2) once formed, if the floc has the capacity to remove additional Hg from solution. Agricultural drainage water samples containing ambient concentrations of both DOM and IHg were spiked with a traceable amount of isotopically enriched IHg and dosed with ferric sulfate after 0, 1, 5, and 30 days. Both ambient and newly added IHg were removed within hours, with 69-79 % removed. To a separate sample set, isotopically enriched IHg was added to solution after floc had formed. Under those conditions, 81-95 % of newly added Hg was removed even at Hg concentrations 1000-fold higher than ambient levels. Results of this study indicate coagulation with ferric sulfate effectively removes both ambient and newly added IHg entering a system and suggests rapid association between IHg and DOM. This work also provides new information regarding the ability of floc to remove additional Hg from solution even after it has formed.
    Environmental Management 09/2015; DOI:10.1007/s00267-015-0601-2 · 1.72 Impact Factor
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    • "In the mid–Tapajós River basin, mercury is present in the aquatic ecosystems as a consequence of deforestation and " slash-andburn " agricultural practices that cause intensive erosion of soils rich in naturally occurring mercury (Roulet et al. 2000). As a result of the bioaccumulation and concentration of the contaminant in the aquatic food web, higher trophic-level fish from the Tapajós waters frequently have elevated levels of methyl mercury, a potent neurotoxin (Sampaio da Silva et al. 2005, Mergler et al. 2007). For the fish-eating communities living along the Tapajós River, bioindicators of mercury exposure, i.e., mercury in blood and hair, increase with increased fish consumption (Lebel et al. 1998, Passos and Mergler 2008), and villagers are at risk of a variety of adverse health effects associated with their exposure (Passos and Mergler 2008, Fillion et al. 2011). "
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    ABSTRACT: Social networks are a significant way through which rural communities that manage resources under common property regimes obtain food resources. Previous research on food security and social network analysis has mostly focused on egocentric network data or proxy variables for social networks to explain how social relations contribute to the different dimensions of food security. Whole-network approaches have the potential to contribute to former studies by revealing how individual social ties aggregate into complex structures that create opportunities or constraints to the sharing and distribution of food resources. We used a whole-network approach to investigate the role of network structure in contributing to the four dimensions of food security: food availability, access, utilization, and stability. For a case study of a riparian community from the Brazilian Amazon that is dependent on fish as a key element of food security, we mapped the community strong-tie network among 97% of the village population over 14 years old (n = 336) by integrating reciprocated friendship and occupational ties, as well as close kinship relationships. We explored how different structural properties of the community network contribute to the understanding of (1) the availability of fish as a community resource, (2) community access to fish as a dietary resource, (3) the utilization of fish for consumption in a way that allows the villagers to maximize nutrition while at the same time minimizing toxic risks associated with mercury exposure, and (4) the stability of the fish resources in local ecosystems as a result of cooperative behaviors and community-based management. The contribution of whole-network approaches to the study of the links between community-based natural resource management and food security were discussed in the context of recent social-ecological changes in the Amazonian region.
    ECOLOGY AND SOCIETY 09/2015; 20(3):18. DOI:10.5751/ES-07483-200318 · 2.77 Impact Factor
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    • "One such ecosystem in which this is the case is the South River (Waynesboro, VA, USA). Mercury contamination from industrial activities occurred in the South River during the first half of the twentieth century (Carter 1977), and the potential for impacts on wildlife and recreational river use remains (Mergler et al. 2007). For instance, Hg biomagnification in the river food web results in high Responsible editor: Sabine Elisabeth Apitz Electronic supplementary material The online version of this article (doi:10.1007/s11368-015-1100-z) contains supplementary material, which is available to authorized users. "
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    ABSTRACT: Purpose Mercury (Hg) released into the environment often accumulates to high concentrations in sediments, creating a potential risk to aquatic wildlife. The in situ application of sorbents such as activated carbon is one promising option for reducing the bioavailability of sediment-bound Hg. Materials and methods The present study evaluates the influence of contact time of two sorbents (Sedimite® and Cowboy® biochar) applied to sediment taken downstream and upstream of a historic Hg discharge into the South River (Virginia, USA) on bioaccumulation in and detrital processing by Hyalella azteca. Results and discussion Hg bioaccumulation decreased when sediments were mixed with both sorbents, but their respective efficiency depended on their initial particle size and contact time. Hyalella showed a slight increase in detrital processing and substantial increase in Hg bioaccumulation when exposed to contaminated relative to uncontaminated sediment. Sedimite® adversely affected detrital processing but reduced Hg bioaccumulation. In contrast, Cowboy® biochar did not impact detrital processing but appeared to decrease bioaccumulation less effectively than Sedimite®. This difference in sorbent efficacy lessened with duration. It remains unclear whether the Sedimite®-induced reduction in detrital processing is substantially worse than that associated with natural fines settling on detritus in depositional reaches of rivers. Conclusions The differences in efficacy of the two materials in reducing bioavailability suggest the need for further studies addressing both the mechanisms causing the reduction in Hg bioavailability as well as associated ecological risks prior to field application of these materials at the larger scale.
    Journal of Soils and Sediments 05/2015; 15(5). DOI:10.1007/s11368-015-1100-z · 2.14 Impact Factor
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