Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was studied?
This mercury exposure assessment, the Portugal total diet study, quantified baseline dietary exposure of Portuguese adults to methylmercury and inorganic mercury using a harmonized Total Diet Study (TDS) design. Investigators prepared 227 pooled, “as-consumed” samples representing 95% of the adult diet and analyzed total mercury by accredited DMA-80 methods, then apportioned methylmercury and inorganic mercury using EFSA’s conservative speciation assumptions. Exposure was modeled with Monte Carlo Risk Assessment software (Observed Individual Mean) and compared with EFSA tolerable weekly intakes (TWIs). Key outputs included mean, median, and 95th percentile intakes across sex and age strata, the percentage exceeding TWIs, and food-item contributions. Cod and hake emerged as dominant sources; exceedance risks were most pronounced for high consumers and for women of childbearing age, directly informing HTMC risk-based certification and consumer guidance.
Most important findings
| Critical point | Details |
|---|---|
| Overall methylmercury exposure approaches TWI | Mean 1.25 µg/kg bw/week (≈96% of the 1.3 µg/kg bw/week TWI); P95 5.45 µg/kg bw/week; 27.6% exceeded TWI. Distribution is right-skewed; half the individuals had near-zero exposure days. |
| Consumers’ only risk is high | Among fish/seafood consumers, mean methylmercury rose to 2.46 µg/kg bw/week and median to 1.57 µg/kg bw/week—189% and 121% of TWI, respectively. |
| Childbearing-age women show elevated high-end exposure | Mean 1.13 µg/kg bw/week; P95 5.56 µg/kg bw/week; 25% exceeded TWI. For consumers-only in this subgroup, the mean reached 2.50 µg/kg bw/week (192% of TWI). |
| Key contributors (as eaten) | Dried cod contributed 16.5–26.0% and hake 8.7–18.1% of methylmercury exposure across strata; mixed fish stew, scabbardfish, and canned tuna were secondary contributors. |
| Inorganic mercury generally below concern | Mean 0.37 µg/kg bw/week (UB) with P95 1.27; 3.5% exceeded the 4 µg/kg bw/week TWI. Fish/seafood and composite dishes contributed 78–88% of inorganic exposure; tap water added ~0.006 µg/kg bw/week (~1.6% of total). |
| Analytical and modeling framework | ISO/IEC 17025 DMA-80 method; left-censor handling via UB/LB; EFSA speciation defaults (100% MeHg in fish; 80% MeHg in non-fish seafood). Exposure modeled with MCRA OIM linking FoodEx2 consumption and occurrence. |
Who was studied?
The overall population comprised 3,272 Portuguese adults aged 18–74 years (both sexes), with subgroups for adults (18–64), elderly (65–74), males, females, and 905 women of childbearing age (18–45). Consumption was mapped via FoodEx2; foods were bought in Greater Lisbon (2014–2016) and prepared per typical habits (washing, trimming, cooking). This population context among the world’s highest seafood consumers made the mercury exposure assessment of the Portuguese total diet study sensitive to fish-driven risk, particularly for vulnerable subgroups.
Key implications
For HTMC, the primary regulatory impacts include justifying species-specific guidance aligned to EFSA TWIs, prioritizing high-MeHg taxa. Certification requirements should emphasize sampling of dried cod and hake supply chains and transparent consumer advisories for childbearing women. Industry applications include product labeling tiers and sourcing shifts toward low-MeHg species without eroding omega-3 benefits. Research gaps involve contemporary consumption data, speciation analytics below current LODs, and longitudinal biomonitoring. Practical recommendations are to validate buyers’ lists against risk tables, tighten HACCP verification for high-risk species, and align retailer messaging with national advice.
Citation
Vasco E, Dias MG, Oliveira L. Mercury Exposure Assessment from the First Harmonised Total Diet Study in Portugal. Exposure and Health. 2025;17:119-152. doi:10.1007/s12403-024-00649-1
Mercury (Hg) is a neurotoxic heavy metal found in various consumer products and environmental sources, making it a major public health concern. Its regulation is critical to protect vulnerable populations from long-term health effects, such as neurological impairment and cardiovascular disease. The HMTC program ensures that products meet the highest standards for mercury safety.
