Chang et al. 2015 — Mercury in Korean Weaning-Age Infants
This 2015 Korean cohort study measured total mercury in hair and blood of 252 healthy weaning-age infants (6–22 months) in Seoul, finding geometric mean hair Hg of 0.22 µg/g and blood Hg of 0.94 µg/L. Fish intake was a key predictor of mercury levels.
Key numbers
Hair mercury (n=252, µg/g): Geometric mean 0.22 (95% CI 0.20–0.24); median 0.20; range 0.1–1.3; IQR 0.10–0.30. Five infants had hair Hg >1.0 µg/g. Hair-to-blood ratio: median 202.7, IQR 135.1–326.1.
Blood mercury (n=109, µg/L): Geometric mean 0.94 (95% CI 0.89–0.99); median 0.82; range 0.37–4.15; IQR 0.63–1.28.
Methods
Hair Hg: AAS or CVAAS (not specified in excerpt). Blood Hg: CVAAS or ICP-MS. 2 cohorts (2009/2010, 2013/2014). Seoul urban infants. Fish intake associated with higher Hg biomarkers.
Implications
Health: Korean infants in this age range have blood Hg median 0.82 µg/L; this is below the US EPA reference level for methylmercury (5.8 µg/L blood, or 1 ppm in hair), but 5 infants had hair Hg >1.0 µg/g (approaching the 1 ppm hair reference). Fish introduction during weaning drives the upper tail.
App: Fish-containing weaning foods are the primary driver of MeHg/tHg exposure in infants; flag fish-containing baby foods for Hg.