Heavy metals in food databaseFishChecked 2026.10.03
Yellowfin tuna, albacore, and young Pacific bluefin: mercury
Yellowfin tuna (kihada), albacore (bincho), and meji-maguro (young Pacific bluefin) are tunas that the MHLW says pregnant women can eat “as usual,” even though they are all “tuna.” In national compilations, the average total mercury was 0.270 ppm in yellowfin, 0.229 in albacore, and 0.165 in young Pacific bluefin, lower than in Pacific bluefin. However, another survey found higher values for albacore.
Levels measured in Japanese government surveys and studies
| Metal | Form / state | Mean | Range / max | Samples | Survey |
|---|---|---|---|---|---|
| Mercury | Yellowfin, total mercury | 0.270 | 0.030–2.400 | 209 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Yellowfin, methylmercury | 0.194 | 0.010–1.236 | 52 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Albacore, total mercury | 0.229 | 0.020–0.350 | 21 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Albacore, methylmercury | 0.164 | 0.120–0.250 | 15 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Young Pacific bluefin (meji), total mercury | 0.165 | 0.020–0.430 | 36 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Young Pacific bluefin (meji), methylmercury | 0.206 | 0.160–0.240 | 7 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Yellowfin, total mercury | 0.26 (median 0.17) | 0.05–1.4 | 120 samples | MAFF, fiscal 2007–2010 |
| Mercury | Yellowfin, methylmercury | 0.23 (median 0.13) | 0.04–1.2 | 120 samples | MAFF, fiscal 2007–2010 |
| Mercury | Albacore, total mercury | 0.52 (median 0.48) | 0.17–1.4 | 120 samples | MAFF, fiscal 2007–2010 |
| Mercury | Albacore, methylmercury | 0.44 (median 0.40) | 0.15–1.1 | 120 samples | MAFF, fiscal 2007–2010 |
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. The MAFF rows (fiscal 2007–2010) give the median next to the mean.
How much to eat (official advice)
- Yellowfin tuna, albacore, young Pacific bluefin (meji-maguro), and canned tuna are said to be fine for pregnant women to eat as usual (MHLW, revised June 2010).
- Even among fish called “tuna,” the ones covered by the guidance amounts are Pacific bluefin, southern bluefin, and bigeye.
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). It does not apply to tuna-type fish (tuna, billfish (kajiki), and skipjack (katsuo)), fish and shellfish from rivers (excluding lakes and marshes), deep-sea fish and shellfish, and others. We found no official document explaining the reason for these exemptions. |
| 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) | 1.0 mg/kg (muscle of tuna, skipjack, shark, swordfish, and others) | The value from Regulation 2022/617, carried over into Regulation (EU) 2023/915. Wet weight. |
| US FDA/EPA advice (2021) | Good Choices (once a week): yellowfin, albacore | 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
- These are fish with confusing names. Meji-maguro is young Pacific bluefin, and albacore is also called bincho-maguro, so market names get mixed up. Adult Pacific bluefin is covered by the guidance amounts but young meji-maguro is not, so the same species is treated differently. → Pacific bluefin and southern bluefin tuna
- The methylmercury in one serving (about 80 g) is about 15.5 μg for yellowfin (average 0.194 ppm), about 13 μg for albacore (0.164 ppm), and about 16.5 μg for young Pacific bluefin (0.206 ppm). That is about 14%, 12%, and 15% 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).
- Albacore figures differ by survey. In the MHLW compilation (May 2010), average total mercury was 0.229 ppm (21 samples) and methylmercury was 0.164 ppm (15 samples). In the MAFF survey (fiscal 2007–2010, 120 samples), total mercury was 0.52 ppm and methylmercury was 0.44 ppm. The national guidance has not been revised since June 2010.
- In the US, yellowfin and albacore are “once a week” Good Choices, so the line is drawn differently from Japan’s “no limit.” In US measurements, average total mercury was 0.354 ppm in yellowfin (231 samples) and 0.358 ppm in albacore (43 samples), not greatly different from the Japanese compilation. → How Japan’s standards differ from other countries’
- There is individual variation. The maximum total mercury in yellowfin was 2.4 ppm and the maximum methylmercury was 1.236 ppm. For fish with few methylmercury samples, such as young Pacific bluefin (7 samples) and albacore (15 samples), the averages are not stable.
- Cadmium is low in muscle: in the MAFF survey, yellowfin was <0.01 (maximum 0.01) and albacore 0.01 (maximum 0.02), 5 samples each.
Related explainers
Pages for each metal
Sources
- MHLW, “Notes on Eating Fish and Shellfish and Mercury for Pregnant Women” (revised June 2010)
- 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, “Data Collection of Survey Results on Hazardous Chemicals in Food (Fiscal 2003–2010)”
- US FDA/EPA, “Advice about Eating Fish” (October 2021)
- US FDA, “Mercury Levels in Commercial Fish and Shellfish (1990-2012)”
- MAFF, “Survey Data on Cadmium in Domestic Agricultural, Livestock, and Fishery Products: Fish and Shellfish” (fiscal 1997–2002)
- European Commission, Regulation (EU) 2022/617 (maximum levels for mercury in food)
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.