Heavy metals in food databaseFishChecked 2026.10.03
Salmon: mercury
Salmon is a fish with low mercury: in the national compilation, average total mercury was 0.034 ppm (85 samples). It is not in the MHLW’s table of guidance amounts for pregnant women, and the government explains that its mercury concentration is low and there is no need to give special warnings. It is also the fish that the most people answered they eat “often” in a questionnaire across 14 regions of Japan (62.0%).
Levels measured in Japanese government surveys and studies
| Metal | Form / state | Mean | Range / max | Samples | Survey |
|---|---|---|---|---|---|
| Mercury | Salmon, total mercury | 0.034 | max 0.160 | 85 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Coho salmon (gin-zake), total mercury | 0.129 | max 2.000 | 22 samples | MHLW, compiled through fiscal 2008 |
Units are mg/kg (= ppm). Values are for the edible portion of fish on the market and appear to be wet weight (the sources do not say). Total mercury and methylmercury were not necessarily measured in the same samples. Methylmercury in salmon is from 2 samples, so there is no average value.
Limits (Japan, international, EU)
| Set by | Limit | Note |
|---|---|---|
| Japan (mercury) | Total mercury 0.4 ppm, methylmercury 0.3 ppm (provisional regulatory limit for fish and shellfish) | A value notified by the Ministry of Health and Welfare in 1973 (Showa 48). Tuna-type fish, fish and shellfish from rivers (excluding lakes and marshes), deep-sea fish and shellfish, and others are exempt; other fish and shellfish are covered. |
| Codex (mercury) | Methylmercury 0.5 mg/kg (guideline level for fish). For predatory fish such as shark, swordfish, and tuna, 1 mg/kg | A 1991 guideline of the Codex Alimentarius Commission. |
| EU (mercury) | 0.30 mg/kg (muscle of salmon and trout) | The value from Regulation 2022/617, carried over into Regulation (EU) 2023/915. Wet weight. |
| US FDA/EPA advice (2021) | Best Choices (2–3 times a week) | Advice for people who are pregnant or breastfeeding and for children aged 1 to 11. One serving is about 113 g (4 ounces). |
Good to know
- The MHLW Q&A explains why shrimp, salmon, and cod, for which US advice gives amounts to eat, are not in Japan’s precautions: in a survey of fish and shellfish distributed in Japan (about 450 species, about 16,400 samples), their mercury concentrations were low and there is no need to give special warnings.
- The mercury in one serving (about 80 g) of salmon (substituting the average total mercury of 0.034 ppm) is about 2.7 μg. That is about 2% of the FSCJ’s tolerable weekly intake (2.0 μg/kg body weight per week; 111 μg per week for a 55.5 kg person) (Urayomi’s calculation). Methylmercury in salmon is from only 2 samples, so there is no average value.
- Coho salmon has an average total mercury of 0.129 ppm and a maximum of 2.000 ppm (22 samples), a higher average than salmon, with individual variation. Methylmercury is from only 1 sample (0.220 ppm), so no trend can be stated.
- The FAO/WHO joint expert consultation (2010) is reported to say that fish (especially fatty fish) lower the risk of death from coronary heart disease. Japan’s MHLW also explains that fish and shellfish are generally rich in highly unsaturated fatty acids such as EPA and DHA. In a systematic review (Mozaffarian and Rimm, 2006), eating fish 1–2 times a week was associated with 36% lower coronary death and 17% lower total mortality.
- In a UK observational study (ALSPAC, 11,875 pregnant women), children of mothers who ate less than 340 g of seafood a week tended to be more likely to be in the lowest quarter for verbal IQ. This is an association based on dietary questionnaires, and cause is not known. Mercury itself was not measured.
- Cadmium is low in muscle: chum salmon (shiro-zake) was <0.01 (18 samples) in the MAFF survey. The fish survey values are from a compilation through fiscal 2008 and may differ from fish on the market today.
Related explainers
Pages for each metal
Sources
- MHLW, “Notes on Eating Fish and Shellfish and Mercury for Pregnant Women,” Q&A
- MHLW, Document 2-4, “Survey Results on Mercury in Fish and Shellfish (Summary)” (May 2010)
- MAFF, “Survey Data on Cadmium in Domestic Agricultural, Livestock, and Fishery Products: Fish and Shellfish” (fiscal 1997–2002)
- FAO/WHO joint expert consultation, report on the risks and benefits of fish consumption (2010)
- Mozaffarian D, Rimm EB. JAMA 2006;296:1885-1899 (systematic review of the benefits and risks of fish)（PMID 17047219）
- Hibbeln JR et al. Lancet 2007;369:578-585 (ALSPAC, UK)（PMID 17307104）
- European Commission, Regulation (EU) 2022/617 (maximum levels for mercury in food)
- US FDA/EPA, “Advice about Eating Fish” (October 2021)
Last checked 2026.10.03 (against the original government documents and papers, collected and cross-checked in Gemini Notebook).
Heavy metals occur naturally in soil and the sea, and every food contains small amounts. This page lists facts from government surveys, limits and assessments and from published papers; it does not judge any food as good or bad. Where there is official advice — such as on eating fish during pregnancy — follow it.