Research

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

Leonardo Trasande^1,2 , Juanita E Cortes³ , Philip J Landrigan^1,2 , Mary I Abercrombie⁵ , Richard F Bopp⁵ and Enrique Cifuentes^1,4

¹  Department of Community and Preventive Medicine, Mount Sinai School of Medicine, 1 Gustave L Levy Place, Box 1057, New York, NY 10029, USA

²  Department of Pediatrics, Mount Sinai School of Medicine, 1 Gustave L Levy Place, Box 1057, New York, NY 10029, USA

³  Instituto Mexicano de Tecnologia de Agua (Mexican Institute of Water Technology, IMTA), Paseo Cuauhnáhuac 8532, Colonia Progreso, CP 62550, Jiutepec, Morelos, México

⁴  Environmental Health Unit, Instituto Nacional de Salud Publica (National Institute of Public Health, INSP), Universidad No 655, Col Santa María Ahuacatitlán, Cerrada Los Pinos y Caminera, Cuernavaca, Morelos CP 62100, México

⁵  Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Jonsson-Rowland Science Center, 1W19, 110 8th Street, Troy, NY 12180, USA

author email corresponding author email

Environmental Health 2010, 9:1doi:10.1186/1476-069X-9-1

Published:	11 January 2010

Abstract

Background

Elevated 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.

Methods

Total 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.

Results

Highest 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.

Conclusions

Our 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.