Rothenberg et al. 2021 — Maternal methylmercury exposure through rice ingestion and child neurodevelopment, rural China
This Environmental Health prospective cohort study by a U.S.-China collaboration (Rothenberg lead, Harvard, USC, U South Carolina, Guangxi University of Chinese Medicine, Duke, Emory) is the first U.S.-quality cohort study quantifying maternal methylmercury exposure from rice ingestion paired with child neurodevelopmental outcomes through 36 months. The study enrolls 391 peripartum women in rural China where rice is the dominant dietary MeHg source (in contrast to the fish-based MeHg pathway documented in U.S. and European populations), measures peripartum hair MeHg as the exposure biomarker, and assesses child neurodevelopment using the Bayley Scales of Infant Development 2nd Edition (Mental Developmental Index and Psychomotor Developmental Index) at 12 and 36 months in 264 and 190 children respectively. The paper is the canonical reference for the rice-as-MeHg-pathway dietary route and is directly relevant to the HMTc rice-based subcategory rows where MeHg has historically been a documented data gap because most MeHg surveillance focuses on fish.
Key conclusions
Rothenberg and colleagues document that rice ingestion is a meaningful MeHg exposure pathway in populations with high rice consumption and that prenatal rice-derived MeHg exposure is associated with measurable child neurodevelopmental outcomes through 36 months in the Bayley framework. The paper supports treating rice as a MeHg-relevant matrix in addition to the better-characterized fish-MeHg pathway, particularly in populations with rice-dominant diets and in regions with elevated environmental Hg loading (the Wanshan / Guizhou mercury-mining context of which the rural-China cohort is representative).
Methods (brief)
Eligible peripartum women in rural China were enrolled (n=391) and provided peripartum hair samples for MeHg quantification. Children’s neurodevelopment was assessed at 12 months (n=264, 68 percent retention) and 36 months (n=190, 48 percent retention) using the Bayley Scales of Infant Development 2nd Edition. Statistical analysis used cohort-comparison methods to associate prenatal MeHg exposure with MDI and PDI outcomes.
Implications
- Certification: First U.S.-quality cohort evidence that rice is a MeHg exposure matrix relevant to HMTc rice-based subcategory rows. Supports closing the MeHg-in-rice-cereal data gap that has been outstanding through the IandC Phase 6 readiness assessment. The study does not directly report rice MeHg concentrations (it reports hair MeHg as exposure biomarker), so it is not a primary occurrence source for the rice-cereal MeHg cell, but it establishes the rice-MeHg exposure pathway and the neurodevelopmental endpoint that motivates the HMTc concern.
- Courses: Standard recent reference for the rice-MeHg pathway in rice-dominant populations and the Wanshan mercury-mining regional context.
- App: Supports vulnerable-population flagging for prenatal MeHg exposure via rice in high-rice-consumption populations.