Seafood consumption and blood mercury concentrations in adults aged ≥20 y, 2007-2010.
Level 3 - non-randomized controlled study
Nationally representative cross-sectional survey (NHANES 2007–2010)
PubMed 24522443 · doi:10.3945/ajcn.113.077081
What was done
Researchers analyzed data from 10,673 adults aged ≥20 years who participated in the 2007–2010 National Health and Nutrition Examination Survey (NHANES). Seafood intake was assessed via a food-frequency questionnaire and categorized by type (fish or shellfish) and monthly frequency (0, 1–2, 3–4, or ≥5 times/month). Blood mercury concentrations were measured, linear trends were assessed across intake categories, and multivariable logistic regression evaluated the odds of having blood mercury ≥5.8 µg/L (the National Research Council reference cutoff) adjusted for sex, age, and race/Hispanic origin.
What was found
Overall, 83.0% ± 0.7% of adults reported eating seafood in the prior month, and 4.6% ± 0.39% had blood mercury ≥5.8 µg/L. Blood mercury concentrations increased linearly with increasing frequency of seafood intake (P < 0.001). In adjusted models, the odds of blood mercury ≥5.8 µg/L were strongly associated with monthly consumption of high-mercury fish (adjusted OR: 4.58; 95% CI: 2.44, 8.62; P < 0.001), tuna (aOR: 1.14; 95% CI: 1.10, 1.17; P < 0.001), salmon (aOR: 1.14; 95% CI: 1.09, 1.20; P < 0.001), and other seafood (aOR: 1.12; 95% CI: 1.08, 1.15; P < 0.001). No significant association was found for shrimp (P = 0.21) or crab (P = 0.48).
Why it matters
This study provides population-level quantification of how specific seafood choices influence blood mercury thresholds, showing that while general seafood consumption is prevalent, risk for elevated blood mercury is primarily tied to specific finfish types rather than common shellfish like shrimp and crab.
Limits
The study is cross-sectional, precluding causal determination. Dietary intake was self-reported via a food-frequency questionnaire, which is susceptible to recall bias. Specific preparation methods, portion sizes, and sources of seafood were not detailed in the abstract, and residual confounding cannot be ruled out.
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