Methylmercury exposure in a subsistence fishing community in Lake Chapala, Mexico: an ecological approach

Abstract

BackgroundElevated concentrations of mercury have been documented in fish in Lake Chapala in central Mexico, an area that is home to a large subsistence fishing community. However, neither the extent of human mercury exposure nor its sources and routes have been elucidated.MethodsTotal mercury concentrations were measured in samples of fish from Lake Chapala; in sections of sediment cores from the delta of Rio Lerma, the major tributary to the lake; and in a series of suspended-particle samples collected at sites from the mouth of the Lerma to mid-Lake. A cross-sectional survey of 92 women ranging in age from 18-45 years was conducted in three communities along the Lake to investigate the relationship between fish consumption and hair mercury concentrations among women of child-bearing age.ResultsHighest concentrations of mercury in fish samples were found in carp (mean 0.87 ppm). Sediment data suggest a pattern of moderate ongoing contamination. Analyses of particles filtered from the water column showed highest concentrations of mercury near the mouth of the Lerma. In the human study, 27.2% of women had >1 ppm hair mercury. On multivariable analysis, carp consumption and consumption of fish purchased or captured from Lake Chapala were both associated with significantly higher mean hair mercury concentrations.ConclusionsOur preliminary data indicate that, despite a moderate level of contamination in recent sediments and suspended particulate matter, carp in Lake Chapala contain mercury concentrations of concern for local fish consumers. Consumption of carp appears to contribute significantly to body burden in this population. Further studies of the consequences of prenatal exposure for child neurodevelopment are being initiated.

Lead, Arsenic, and Manganese Metal Mixture Exposures: Focus on Biomarkers of Effect

“…Several chemicals inhibit acetylcholine esterase (AChE), causing neurotoxicity [71] via ACh accumulation in the synaptic cleft with an ensuing overstimulation of muscarinic and nicotinic ACh receptors. AChE is anchored to the plasma membrane and there is evidence that lipid peroxidation arising from oxidative stress may alter its activity [72–74].…”

Global methylmercury exposure from seafood consumption and risk of developmental neurotoxicity: a systematic review

“…The characteristics of the selected studies are provided in Table 3 and Table 4 (both available at: http://www.who.int/ bulletin/volumes/92/04/13-116152). 74,75 Chile, 76 China, [77][78][79][80][81] Colombia, 82 Italy, 83,84 Kazakhstan, 85 Mexico, 87 Morocco, 88 Nicaragua, 89 Norway, 115 the Republic of Korea, 86 Romania, 90 Slovakia, 81,91 Sweden, 92 Taiwan, China, 93 the United States 94 and Venezuela (Bolivarian Republic of), 95 the pooled central THHg median biomarker was 0.8 µg/g (upper bound: 4.6). In 14 subpopulations consuming fish periodically from non-industry-contaminated waters in Botswana, 96 Canada, [97][98][99][100][101][102] Norway, 115 Portugal, 117 Spain, 118 Sweden, 81,92,[112][113][114]119 the United Kingdom of Great Britain and Northern Ireland 120,121 and the United States 122-131 was 0.4 µg/g (upper bound: 2.9).…”

Stable isotope evidence for trophic overlap of sympatric Mexican Lake Chapala silversides (Teleostei: Atherinopsidae: Chirostoma spp.)

“…Mexican lakes have been subject to numerous anthropogenic effects (e.g., pollution, habitat modifications, species introductions, overexploitation, among others) (Lyons et al, 2000;Hansen et al, 2006;López-Hernández et al, 2007;Trasande et al, 2010). Their fish fauna contains a relatively high number of imperiled species, and species that are of significant commercial and cultural importance (Lyons et al, 1998;MoncayoEstrada et al, 2012).…”