Seafood consumption and blood mercury concentrations in adults aged ≥20 y, 2007-2010

Seafood is part of a healthy diet, but seafood can also contain methyl mercury-a neurotoxin. The objective was to describe seafood consumption in US adults and to explore the relation between seafood consumption and blood mercury. Seafood consumption, obtained from a food-frequency questionnaire, and blood mercury data were available for 10,673 adults who participated in the 2007-2010 NHANES-a cross-sectional nationally representative sample of the US population. Seafood consumption was categorized by type (fish or shellfish) and by frequency of consumption (0, 1-2, 3-4, or ≥5 times/mo). Linear trends in geometric mean blood mercury concentrations by frequency of seafood consumption were tested. Logistic regression analyses examined the odds of blood mercury concentrations ≥5.8 μg/L (as identified by the National Research Council) based on frequency of the specific type of seafood consumed (included in the model as continuous variables) adjusted for sex, age, and race/Hispanic origin. In 2007-2010, 83.0% ± 0.7% (±SE) of adults consumed seafood in the preceding month. In adults consuming seafood, the blood mercury concentration increased as the frequency of seafood consumption increased (P < 0.001). In 2007-2010, 4.6% ± 0.39% of adults had blood mercury concentrations ≥5.8 μg/L. Results of the logistic regression on blood mercury concentrations ≥5.8 μg/L showed no association with shrimp (P = 0.21) or crab (P = 0.48) consumption and a highly significant positive association with consumption of high-mercury fish (adjusted OR per unit monthly consumption: 4.58; 95% CI: 2.44, 8.62; P < 0.001), tuna (adjusted OR: 1.14; 95% CI: 1.10, 1.17; P < 0.001), salmon (adjusted OR: 1.14; 95% CI: 1.09, 1.20; P < 0.001), and other seafood (adjusted OR: 1.12; 95% CI: 1.08, 1.15; P < 0.001). Most US adults consume seafood, and the blood mercury concentration is associated with the consumption of tuna, salmon, high-mercury fish, and other seafood.