BfR 2024 — Methylmercury in fish and seafood: health risk assessment from the BfR MEAL study
The German Federal Institute for Risk Assessment (BfR) issued this opinion in May 2024 to assess health risks from methylmercury (MeHg) in fish and seafood, using concentration data from the first German Total Diet Study (BfR MEAL study) that directly measured MeHg by ICP-MS — rather than converting from total Hg using a conversion factor. The highest MeHg concentrations were found in tuna (fillet: 0.38 mg/kg), smoked dogfish and ocean perch (0.12 mg/kg), consistent with their position as large or predatory species; species with low MeHg such as pollack, herring, carp, and trout were all below 0.10 mg/kg. At mean consumption levels, MeHg exposure remains below the EFSA TWI of 1.3 µg/kg body weight per week across all age groups; however, at the 95th percentile, adolescents aged 14–<18 years (2.18 µg/kg bw per week, UB) and tuna consumers in particular exceed the TWI.
Key numbers
BfR MEAL study: MeHg and total Hg in pool samples of ready-to-eat fish (mg/kg), national pools unless noted
| Species | Total Hg (mg/kg) | MeHg (mg/kg) | MeHg/tHg (%) |
|---|---|---|---|
| Cod | 0.09 | 0.08 | 86 |
| Codfish liver | 0.02 | 0.01 | 68 |
| Spiny dogfish, smoked (“Schillerlocke”) | 0.52 | 0.58 | 111* |
| Eel | 0.10 | 0.10 | 94–96 |
| Eel, smoked | 0.08 | 0.08 | 97 |
| Fish fillet, baked | 0.02 | 0.02 | 95–96 |
| Fish fingers | 0.01 | <0.01 | 76 (below LOQ) |
| Halibut | 0.08 | 0.08 | 103* |
| Halibut, smoked | 0.11 | 0.09 | 108* |
| Herring in sauce | 0.04 | 0.03 | 77 |
| Herring, smoked | 0.08 | 0.07 | 91 |
| Herring, fried/pickled | 0.05 | 0.05 | 95 |
| Herring, pickled (Matjes/Bismarck) | 0.03 | 0.03 | 113* |
| Herring, Rollmops | 0.04 | 0.04 | 95 |
| Ocean perch | 0.12 | 0.12 | 96 |
| Plaice/sole | 0.06 | 0.06 | 103* |
| Coalfish/Alaska pollack | 0.06 | 0.07 | 108* |
| Salmon | 0.02 | 0.02 | 91 |
| Salmon, smoked | 0.03 | 0.02 | 76 |
| Striped catfish/pangasius | <0.001 | <0.010 | below LOQ |
| Tuna (fillet) | 0.37 | 0.38 | 105* |
| Tuna in own juice/sauce (canned) | 0.13 | 0.12 | 94 |
| Tuna in oil (canned) | 0.18 | 0.15 | 87 |
| Tuna, smoked | 0.67 | 0.70 | 95 |
| Mussels | 0.02 | 0.01 | 65 |
| Shrimps | 0.02 | 0.02 | 82 |
| Squid/cuttlefish | 0.02 | 0.02 | 118* |
*Values >100% due to measurement uncertainties (30% for total Hg, 12% for MeHg) and use of two different methods in separate laboratories.
LOQ for total Hg: 0.001 mg/kg. LOQ for MeHg: 0.01 mg/kg. Only pangasius (total Hg), fish fingers (MeHg), and carp (Western region, MeHg) were below their respective LOQs.
Regional pool samples: Carp and Trout (four regional pools, DE)
- MeHg range: 0.01–0.03 mg/kg; total Hg range: 0.01–0.03 mg/kg; no systematic regional differences detected.
MeHg exposure assessment for German population (fish and seafood consumers only, UB scenario)
| Age group | N consumers (N total) | Mean MeHg (µg/kg bw/wk) | P95 MeHg (µg/kg bw/wk) |
|---|---|---|---|
| Children 0.5–<6 yr (KiESEL) | 279 (952) | 0.21 | 0.76 |
| Children 6–<12 yr (EsKiMo II) | 341 (1,190) | 0.24 | 0.93 |
| Adolescents 14–<18 yr (NVS II) | 68 (744) | 0.47 | 2.18 |
| Adults 18–<25 yr | 184 (1,393) | 0.40 | 1.53 |
| Adults 25–<35 yr | 363 (1,961) | 0.33 | 1.04 |
| Adults 35–<45 yr | 561 (2,788) | 0.31 | 1.00 |
| Adults 45–<55 yr | 527 (2,443) | 0.32 | 0.94 |
| Adults 55–<65 yr | 508 (1,939) | 0.35 | 1.11 |
| Elderly 65–<80 yr | 705 (2,657) | 0.35 | 1.03 |
| All adolescents/adults ≥14 yr | 2,916 (13,926) | 0.34 | 1.06 |
| Women of childbearing age 18–<45 yr | 521 (3,018) | 0.33 | 1.02 |
EFSA TWI for MeHg: 1.3 µg/kg bw per week (expressed as Hg). At P95, adolescents aged 14–<18 yr reach 2.18 µg/kg bw/wk (UB) — 1.7× the TWI. High-consumption tuna consumers aged 14–<18 yr reach 4.64 µg/kg bw/wk.
Contribution to MeHg exposure by species (all ages): Pollack is the dominant contributor (KiESEL: 63%; EsKiMo II: 54%; NVS II: 34%) because of high consumption frequency despite low MeHg; tuna contributes 19% in adults (NVS II) due to high concentration despite lower consumption frequency.
MeHg/total Hg conversion factors: BfR MEAL data confirm the EFSA (2012) conversion factors of 1.0 (fish) and 0.8 (molluscs/crustaceans) are broadly valid. Cod liver (68%) and smoked salmon (76%) showed lower ratios; the seafood values ranged 65% (mussels) to 82% (shrimps).
Monitoring comparison (2012–2021, total Hg, raw/unprocessed fish):
- Eel (n=79): mean 0.11, P95 0.25, max 0.90 mg/kg
- Herring (n=82): mean 0.05, P95 0.08, max 0.12 mg/kg
- Ocean perch (n=102): mean 0.10, P95 0.19, max 0.55 mg/kg
- Tuna (n=111): mean 0.20, P95 0.54, max 0.69 mg/kg
- Canned tuna in own juice (n=74): mean 0.14, P95 0.39, max 0.48 mg/kg
- Carp (n=61): mean 0.02, P95 0.05, max 0.13 mg/kg
Methods (brief)
The BfR MEAL study (Germany’s first Total Diet Study) purchased ready-to-eat fish and seafood from four geographic regions of Germany (North, South, East, West). National pool samples comprised 15–20 individual samples each; regional pool samples comprised 15 individual samples from the respective region. Both total Hg and MeHg were determined independently: total Hg by one laboratory and MeHg by ICP-MS in a second laboratory, enabling direct comparison rather than use of conversion factors. LOQ for total Hg: 0.001 mg/kg; LOQ for MeHg: 0.01 mg/kg. Exposure assessment used individual consumption data from KiESEL (0.5–5 yr), EsKiMo II (6–12 yr), and NVS II (≥14 yr) and applied both lower bound (LB, values <LOQ set to 0) and upper bound (UB, values <LOQ set to LOQ) scenarios. Health-based guidance value: EFSA (2012) TWI of 1.3 µg MeHg/kg bw per week.
Implications
Certification: This government-tier document directly measures MeHg (not inferred from total Hg) across a wide range of ready-to-eat fish species in Germany, providing species-level MeHg data relevant to HMT&C product certification for seafood and canned fish categories. The tuna data (fillet: 0.38 mg/kg MeHg; canned in juice: 0.12 mg/kg MeHg) anchors any canned tuna certification discussion. The BfR’s explicit finding that preparation/processing does not substantially alter the MeHg/total Hg ratio is relevant to equivalence arguments between raw and processed product standards.
Courses: The adolescent P95 exceedance of the TWI (2.18 µg/kg bw/wk vs 1.3 µg/kg bw/wk TWI) driven by tuna consumption illustrates the species-selection message that HMT&C and course curricula should emphasize — the overall fish-consumption mean is below the TWI, but species choice matters acutely for high-consuming adolescents.
App: Species-level MeHg values (tuna fillet 0.38, canned tuna in juice 0.12, salmon 0.02, pollack 0.06–0.07 mg/kg) provide the basis for contamination-profile MeHg entries in fish ingredient pages.