Vejrup et al. 2022 — Prenatal MeHg from fish and child behavior in Norwegian MoBa cohort
Vejrup et al. examined whether prenatal methylmercury (MeHg) exposure from fish intake was associated with emotional and behavioural problems in children at age 3 using data from 51,238 mother-child pairs in the Norwegian MoBa cohort. Maternal blood Hg was measured as a biomarker; dietary MeHg intake was estimated from a food frequency questionnaire. The median blood Hg in the cohort was 1.02 µg/L (90th percentile 2.22 µg/L), and the median dietary MeHg intake was 0.15 µg/kg body weight per week (well below EFSA’s tolerable weekly intake of 1.3 µg/kg bw/week). The study found no adverse association between prenatal MeHg exposure at these levels and child emotional or behavioural problems, supporting the conclusion that typical Norwegian fish consumption during pregnancy does not produce MeHg exposure sufficient to impair childhood behavioural development.
Key numbers
- Cohort: Norwegian MoBa; n = 51,238 mother-child pairs
- Maternal blood Hg: median 1.02 µg/L; 90th percentile 2.22 µg/L (total Hg, reflecting predominantly MeHg in fish consumers)
- Dietary MeHg intake: median 0.15 µg/kg bw/week; estimated from FFQ
- EFSA tolerable weekly intake (TWI) for MeHg: 1.3 µg/kg bw/week
- Outcome: child emotional and behavioural problems at age 3 years (Strengths and Difficulties Questionnaire)
- No statistically significant adverse association found at observed exposure levels
- Principal fish species contributing to MeHg exposure in the Norwegian diet: fatty fish and lean fish as assessed by FFQ
Methods (brief)
Prospective cohort study within the Norwegian Mother, Father and Child Cohort Study (MoBa). Dietary assessment via validated FFQ at gestational week 22. Blood Hg measured at recruitment (first trimester). MeHg dietary intake estimated from Norwegian food composition tables and seafood consumption data. Child outcome assessed at age 3 via Strengths and Difficulties Questionnaire (SDQ) subscales. Covariates included maternal education, fish consumption patterns, and other dietary factors. License: CC BY-NC.
Implications
Certification: Provides blood Hg biomarker data from a large Nordic population with high fish consumption. Median blood Hg of 1.02 µg/L is well below clinical concern levels; no adverse behavioral effects at typical dietary MeHg exposure. Relevant context for seafood-adjacent product categories and for HMT&C standards that address tHg and MeHg in products containing fish oil, marine collagen, or other marine-derived ingredients.
Courses: Large-cohort design with both biomarker and dietary assessment makes this an excellent teaching case for the relationship between fish consumption, MeHg exposure, and developmental outcomes at typical population exposure levels.
App: Dietary MeHg estimate (median 0.15 µg/kg bw/week from Norwegian fish consumption pattern) provides a reference point for intake modelling; should not be applied without adjustment to populations with higher fatty-fish consumption.