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 reviewed?
This EFSA CONTAM Panel scientific opinion systematically reviewed toxicology, exposure, analytical methods, legislation, and risk characterisation for mercury species in food, with emphasis on methylmercury in fish and inorganic mercury in other foods. It reassessed health-based guidance values, notably deriving a tolerable weekly intake (TWI) of 1.3 µg/kg body weight for methylmercury and confirming 4 µg/kg for inorganic mercury, and quantified European dietary exposures by age group. For fish, species-level occurrence data and conversion assumptions for total mercury to methylmercury were applied; for other foods, inorganic mercury predominated. The review evaluated biomarkers (hair and blood), toxicokinetics, developmental neurotoxicity evidence, and considered countervailing nutrients (n-3 LCPUFAs) when interpreting cohort findings. The phrase mercury-and-methylmercury-in-food is central here because the opinion anchors certification-relevant limits, enforcement targets, and consumer risk thresholds across the EU.
Who was reviewed?
The evaluation encompassed European food monitoring data from 20 countries (≈59,650 results, 2002–2011) covering 20 FoodEx groups, with dense sampling of “Fish and other seafood.” Population exposure modelling used EFSA’s Comprehensive European Food Consumption Database across infants, toddlers, children, adolescents, adults, the elderly, and the very elderly, and highlighted women of childbearing age and high fish consumers as key subgroups. Cohorts from the Faroe Islands and Seychelles informed dose–response for neurodevelopment; toxicokinetics and biomonitoring data underpinned conversions from maternal hair to blood to intake. Because mercury-and methylmercury-in-food risks differ by species and intake, results are parsed by consumer percentile and fish type (e.g., tuna, swordfish, pike, halibut).
Most important findings
| Critical point | Details |
|---|---|
| Health-based guidance values | TWI established at 1.3 µg/kg bw/week for methylmercury (expressed as Hg) based on maternal hair 11.5 mg/kg no-effect basis and toxicokinetic modelling; inorganic mercury TWI confirmed at 4 µg/kg bw/week using kidney endpoints and BMDL10 0.06 mg/kg bw/day with UF = 100. These TWIs are pivotal for HTMC limit-setting. |
| Exposure—methylmercury | Mean exposure generally below TWI, but toddlers/children in some surveys and 95th percentiles across age groups near or above TWI; high fish consumers may exceed TWI by ~6×. Unborn children are the most vulnerable group. |
| Exposure—inorganic mercury | Mean dietary exposure below TWI, but inhalation of elemental Hg from dental amalgam adds to internal inorganic Hg and may push total above TWI in some individuals. |
| Key contributors | “Fish meat” dominates methylmercury exposure; predatory species such as tuna, swordfish, cod/whiting, pike, and hake are highest contributors in adults and children. |
| Biomarkers & TK | “Fish meat” dominates methylmercury exposure; predatory species such as tuna, swordfish, cod/whiting, pike, and hake are the highest contributors in adults and children. |
| Analytical methods | For foods, total Hg commonly by CV-AAS/CV-AFS/ICP-MS; speciation via GC-MS/GC-ICP-MS or HPLC-ICP-MS; isotope-dilution improves trueness; need for CRMs for inorganic Hg beyond fish/seafood. |
| Regulatory maxima | EU maximum levels: 0.5 mg/kg w.w. for most fishery products; 1.0 mg/kg w.w. for certain predatory species; 1 µg/L for drinking water; Codex guidance 0.5 mg/kg MeHg for non-predatory fish and 1 mg/kg for predatory fish. |
| Risk characterization | For methylmercury, exceedance risk concentrates in high consumers and specific species; for inorganic Hg, diet alone seldom exceeds TWI; combined with amalgam inhalation, exceedance becomes plausible. Risk management should balance fish’s nutritional benefits. |
| Conversion assumptions | In exposure modelling, total Hg was conservatively converted: fish/fish products CF = 1.0 to methylmercury and 0.2 to inorganic Hg; crustaceans/molluscs 0.8 to methylmercury and 0.5 to inorganic Hg; other foods assumed inorganic Hg. |
Key implications
For regulators, mercury-and methylmercury-in-food TWIs compel species-specific risk management and consumer guidance while preserving fish’s benefits. Certification requirements for HTMC should enforce validated speciation methods, species-level ML verification, biomarker-linked intake checks, and clear flags for high-Hg predators. Industry applications include sourcing policies, lot-level testing, and labelling advisories. Research gaps involve better inorganic Hg CRMs and refined blood: hair ratios. Practical recommendations include prioritising low-Hg species, monitoring high-percentile consumers, and contextualising results with n-3 LCPUFA benefits.
Citation
EFSA Panel on Contaminants in the Food Chain (CONTAM). Scientific Opinion on the risk for public health related to the presence of mercury and methylmercury in food. EFSA Journal. 2012;10(12):2985. doi:10.2903/j.efsa.2012.2985
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.
