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 78 g/d and the geometric mean for T-Hg was 8.2 mu g/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 (5.8 mu g/L for methylmercury). Mercury concentrations were related to maternal fish consumption, with large oily fish being the main contributor. (C) 2010 Elsevier Ltd. All rights reserved.