Prenatal mercury exposure in a multicenter cohort study in Spain.

BACKGROUND: Mercury is a ubiquitous heavy metal that may negatively affect human health. It is desirable to investigate mercury exposure in vulnerable populations. OBJECTIVE: To determine the concentrations of total mercury (T-Hg) in cord blood and to evaluate the role of maternal fish consumption in a Spanish mother and child cohort. METHODS: A total of 1883 mother and child pairs from a population-based cohort were included between 2004 and 2008. T-Hg concentrations were measured in whole cord blood and maternal seafood consumption was ascertained by means of a food-frequency questionnaire. Linear regression was used in stratified analyses, while a joint model was adjusted using a mixed-effects linear model. RESULTS: Maternal daily seafood consumption was 78g/d and the geometric mean for T-Hg was 8.2µg/L. Maternal fish intake during pregnancy, mother's age, country of origin, educational level, employment status and parity, as well as area of study and season of delivery, were associated with cord blood T-Hg levels. A doubling in consumption of large oily fish was associated with an increase of 11.4% (95%CI: 3.8 to 19.6%) in cord blood T-Hg levels, followed by an increase of 8.4% (95%CI: 5.7 to 11.2%) in the case of canned tuna and 8.3% (95%CI: 5.5 to 11.1%) in that of lean fish. CONCLUSION: A high proportion of newborns had elevated concentrations of cord blood T-Hg according to the current US-EPA reference dose (5.8µg/L for methylmercury). Mercury concentrations were related to maternal fish consumption, with large oily fish being the main contributor.

Estimation and validation of mercury intake associated with fish consumption in an EPIC cohort of Spain.

OBJECTIVE: To estimate mercury intake due to fish consumption among the individuals from Gipuzkoa participating in the European Prospective Investigation into Cancer (EPIC), and to validate the estimation of mercury exposure through diet, by measuring blood mercury level. DESIGN AND SETTING: The population for the EPIC Gipuzkoa cohort was recruited from 1992 to 1995. Each individual's diet was assessed regarding habitual intake over the previous year, using the diet history method. Blood samples were taken at the time of the interview. The mercury content of the fish species consumed was supplied by the Food Chemical Surveillance Programme in the Basque Country. SUBJECTS: For the estimation, 8417 volunteers, men and women, aged 35-65 years, of the EPIC cohort; for the validation, a random sample of 120 individuals stratified by fish intake was taken. RESULTS: The validation study confirmed the relationship between fish consumption and mercury intake, as well as between fish consumption and mercury in erythrocytes. 99.9% of individuals have intakes below 75% of the Provisional Tolerable Weekly Intake (PTWI) of mercury established by the World Health Organization. But the limit dosage recommended by the United States Environmental Protection Agency, measured by the average risk index, would be exceeded often. CONCLUSIONS: No individual from the cohort would exceed the PTWI of mercury. Nevertheless, owing to the amount of fish consumed, certain individuals would have mercury intakes approaching the recommended limits. With a view to the future, we believe mercury in fish must continue to be monitored closely in order to assess the risks for the population.