More than half of US youth consume seafood and most have blood mercury concentrations below the EPA reference level, 2009-2012.
Level 4 - case-series / case-control
Cross-sectional observational study of survey data (NHANES)
PubMed 25644354 · doi:10.3945/jn.114.203786
What was done
Data were analyzed from 5,656 US youth aged 1–19 years participating in the 2009–2012 National Health and Nutrition Examination Survey (NHANES), a nationally representative cross-sectional survey. Seafood consumption in the previous 30 days was assessed alongside blood mercury concentrations measured on the examination day. Log-linear regression was used to evaluate the association between the consumption frequency of specific seafood types and blood mercury concentrations, controlling for age, sex, and race/Hispanic origin.
What was found
Overall, 62.4% ± 1.4% of youth reported consuming seafood in the past 30 days (48.5% ± 1.5% fish; 38.4% ± 1.4% shellfish). The geometric mean blood mercury concentration was 0.50 ± 0.02 µg/L in seafood consumers compared to 0.27 ± 0.01 µg/L in non-consumers. Less than 0.5% of youth had blood mercury levels ≥5.8 µg/L. In adjusted models, blood mercury was positively associated with the frequency of consuming high-mercury fish (swordfish and shark; expβ: 2.40, 95% CI: 1.23, 4.68), salmon (expβ: 1.41, 95% CI: 1.26, 1.55), tuna (expβ: 1.38, 95% CI: 1.29, 1.45), crabs (expβ: 1.35, 95% CI: 1.17, 1.55), shrimp (expβ: 1.12, 95% CI: 1.05, 1.20), and other seafood (expβ: 1.23, 95% CI: 1.17, 1.32). No significant associations were observed for breaded fish or catfish consumption.
Why it matters
These findings indicate that despite widespread seafood consumption among US youth, blood mercury concentrations rarely exceed the EPA reference safety threshold of 5.8 µg/L.
Limits
The study is cross-sectional, precluding longitudinal exposure assessment. Seafood consumption relied on 30-day self-reported recall, which is subject to recall error and misclassification. Blood mercury was measured at a single time point, and the study did not measure clinical, cognitive, or neurodevelopmental outcomes.
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