Methylmercury exposure in a subsistence fishing community in Lake Chapala, Mexico: an ecological approach.
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.
Trasande
Leonardo
L
Department of Community and Preventive Medicine, Mount Sinai School of Medicine, 1 Gustave L Levy Place, Box 1057, New York, NY 10029, USA.
Cortes
Juanita E
JE
Landrigan
Philip J
PJ
Abercrombie
Mary I
MI
Bopp
Richard F
RF
Cifuentes
Enrique
E
D000328:Adult; D000818:Animals; D002347:Carps / Q000378:metabolism; D004781:Environmental Exposure / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D005260:Female; D005398:Fisheries / Q000706:statistics & numerical data; D005506:Food Contamination / Q000032:analysis / Q000706:statistics & numerical data; D005618:Fresh Water / Q000737:chemistry*; D006197:Hair / Q000378:metabolism; D006801:Humans; D008767:Methylmercury Compounds / Q000032:analysis* / Q000378:metabolism; D008800:Mexico; D008875:Middle Aged; D017747:Seafood / Q000706:statistics & numerical data; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism; D055815:Young Adult
D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical