Heavy metals in food databaseShellfish, squid and crabChecked 2026.10.03
Squid and shiokara: cadmium, mercury
In Japanese flying squid (surumeika), cadmium in the flesh (muscle) is low, averaging 0.25 ppm (MAFF, 300 samples), while the innards average 15 ppm (maximum 48), about 60 times higher. Ika no shiokara (salted, fermented squid), a processed product that uses the innards, averages 2.63 ppm (maximum 9.9) in commercial products. The Consumer Affairs Agency says that the possibility of harm in an ordinary diet is low, but to watch out for a lopsided diet of eating large amounts of the same food every day.
Levels measured in Japanese government surveys and studies
| Metal | Form / state | Mean | Range / max | Samples | Survey |
|---|---|---|---|---|---|
| Cadmium | Japanese flying squid, muscle | 0.25 (median 0.22) | 0.03–1.0 | 300 samples | MAFF, fiscal 2010 |
| Cadmium | Japanese flying squid, innards | 15 (median 14) | 1.7–48 | 300 samples | MAFF, fiscal 2010 |
| Cadmium | Japanese flying squid, edible portion (innards excluded) | 0.29 | 0.03–1.30 | 56 samples | MAFF, fiscal 1997–2002 |
| Cadmium | Japanese flying squid, liver (digestive gland) | 33.90 | 6.60–96.00 | 41 samples | MAFF, fiscal 1997–2002 |
| Cadmium | Cuttlefish (kouika), edible portion (innards excluded) | <0.01 | max 0.01 | 15 samples | MAFF, fiscal 1997–2002 |
| Cadmium | Squid shiokara | 2.63 | 0.09–9.9 | 30 samples | MAFF, fiscal 2002 (shiokara) |
| Cadmium | Squid shiokara (kuro-zukuri, with ink) | 3.26 | 1.40–6.5 | 5 samples | MAFF, fiscal 2002 (shiokara) |
| Mercury | Japanese flying squid, total mercury | 0.054 | max 0.170 | 141 samples | MHLW, compiled through fiscal 2008 |
Units are mg/kg (= ppm). Cadmium is total cadmium and appears to be wet weight of the seafood (the sources do not say). Shiokara values were measured on commercial products made into a paste. Mercury is total mercury.
Limits (Japan, international, EU)
| Set by | Limit | Note |
|---|---|---|
| Japan (cadmium) | No cadmium limit for fish and shellfish | The cadmium standards under the Food Sanitation Act cover only rice (0.4 mg/kg or less in brown rice and polished rice) and mineral waters (0.003 mg/L). For foods other than rice, no standard is set because creating one would do little to reduce intake; the policy is to respond with measures at the production stage and surveys of actual levels (Consumer Affairs Agency). |
| Codex (cadmium) | Cephalopods 2 mg/kg (innards excluded) | It does not apply to innards or shiokara. |
| EU (cadmium) | Cephalopods 1.0 mg/kg (innards excluded) | The value from Regulation (EU) 2023/915. It does not apply to innards or shiokara. |
| 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. |
| EU (mercury) | Cephalopods 0.30 mg/kg | The value from Regulation 2022/617, carried over into Regulation (EU) 2023/915. Wet weight. |
Good to know
- The cadmium concentration is completely different in the flesh and the innards. In the MAFF fiscal 2010 survey (300 samples each), Japanese flying squid muscle averaged 0.25 ppm (maximum 1.0) and the innards averaged 15 ppm (maximum 48). In the fiscal 1997–2002 survey, too, the edible portion averaged 0.29 and the liver averaged 33.9 (maximum 96). The methods differ, so the innard values of the two surveys cannot be set side by side.
- The Consumer Affairs Agency explains that some innards of mollusks such as shellfish, squid, and octopus, and of crustaceans such as shrimp and crab, are high in cadmium, and that some shiokara-type products made from them are also relatively high. It says these are foods eaten since long ago, that the possibility of harm in an ordinary diet is low, and to watch out for a lopsided diet of eating large amounts of the same food every day.
- Compared with the Codex limit for cephalopods of 2 and the EU limit of 1.0 (both with innards excluded), the Japanese flying squid muscle average of 0.25 is low, and the maximum of 1.0 equals the EU limit. However, these limits cover the flesh with innards removed, and do not apply to innards or shiokara. Japan has no limit, and the domestic surveys were not judged against any limit.
- Japanese cadmium intake (2022) is 2.03 μg/kg body weight per week, about 29% of the FSCJ’s tolerable intake (7 per week) and about 81% of EFSA’s (2.5 per week). The difference is because the basis of the yardsticks differs. The flesh of cuttlefish is <0.01 (15 samples), so there is also a difference by kind of squid. → Cadmium page
- Mercury is low: the average total mercury of Japanese flying squid is 0.054 ppm (141 samples). In the MHLW’s sample menus, squid is also among the foods that need no caution. In a questionnaire across 14 regions of Japan, 47.0% of people said they eat squid “often.”
- In an old one-off report (1983, dry weight), the muscle of Japanese flying squid had total arsenic of 17.2 and inorganic arsenic of 0.00. The number of samples is unknown, and it may differ from products on the market now.
- The cadmium surveys of fish and shellfish are from fiscal 1997–2002 and fiscal 2010, and may differ from products on the market today. The sources do not give the collection years of individual items.
Reducing it at home (shown in tests)
- Muscle and innards of Japanese flying squid differ by about 60 times on average (0.25 and 15 ppm, MAFF fiscal 2010). In terms of concentration, not eating the innards, or eating less of them, is what helps most. However, no public agency is saying “do not eat them”; the Consumer Affairs Agency asks for a “well-balanced diet.”
- We found no official test showing how much cooking (such as soaking then boiling in fresh water, yudekoboshi) reduces cadmium.
Related explainers
Pages for each metal
Sources
- MAFF, “Data Collection of Survey Results on Hazardous Chemicals in Food (Fiscal 2003–2010)”
- MAFF, “Survey Data on Cadmium in Domestic Agricultural, Livestock, and Fishery Products: Fish and Shellfish” (fiscal 1997–2002)
- Consumer Affairs Agency, Q&A on “Cadmium in Rice”
- FSCJ, Cadmium: Summary of the Food Health Impact Assessment
- MAFF, “International Standards for Cadmium in Food” (Codex)
- European Commission, Regulation (EU) 2023/915 (maximum levels for contaminants in food)
- MHLW, Document 2-4, “Survey Results on Mercury in Fish and Shellfish (Summary)” (May 2010)
- MHLW, “Notes on Eating Fish and Shellfish and Mercury for Pregnant Women,” Q&A
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.