Tatsuta 2024 — Dietary Intake Of Methylmercury By 0-5 Years Children
Summary
This duplicate-diet study measured total mercury and methylmercury in diets consumed by Japanese children aged 0-5 years. It is the strongest newly ingested Category 1 source for methylmercury because it measures MeHg directly and connects higher intake during later baby-food stages with fish-consumption patterns.
Key numbers
- The study collected 3-day duplicate diet samples from 276 diet-stage observations across formula milk, baby food stages, and toddler meal stages.
- Total mercury was measured by cold vapor atomic absorption spectrometry and methylmercury was measured by gas chromatography-electron capture detection.
- Formula milk had median total mercury of 0.020 ng/g wet weight and median estimated methylmercury intake of 2.2 ng/kg body weight per day.
- Baby food stage 3 had median total mercury of 0.445 ng/g wet weight and median estimated methylmercury intake of 22.5 ng/kg body weight per day.
- Baby food stage 4 had median total mercury of 0.500 ng/g wet weight and median estimated methylmercury intake of 36.9 ng/kg body weight per day.
- Among diet samples with total mercury at or above 1 ng/g, the median methylmercury concentration was 1.70 ng/g and methylmercury accounted for 90.0% of total mercury.
- The authors reported that 38 infants or children, 13.8% of the study population, had estimated methylmercury intake above the U.S. EPA reference dose.
- The authors linked the increase during baby-food stages three and four to Japanese guidance and consumption patterns involving red-meat fish beginning around 9 months.
Methods (brief)
Duplicate portions of all consumed foods and beverages were collected for 3 days, homogenized, lyophilized, and analyzed for total mercury and methylmercury. Hair samples were also collected and analyzed for total mercury. THg and MeHg values below detection limits were handled using the study’s substitution rules.
Limitations
The study is diet-stage-based rather than HMTc finished-product-row-based. It does not isolate commercial fish-containing baby foods from all foods consumed during a diet stage, and it reflects Japanese dietary guidance and fish-consumption patterns. It is nevertheless directly relevant to the fish-containing baby-food row because it measures MeHg and discusses fish as a driver of exposure.
Implications
- Certification: Strong evidence that total mercury and methylmercury need separate handling and that fish-containing infant foods require special review.
- Courses: Good teaching source for total mercury versus methylmercury and duplicate-diet exposure methods.
- App: Supports ingredient-list caution for fish-containing baby foods, while preserving the difference between finished product categories and total diet exposure.
- Microbiome: No direct microbiome endpoint.