Heavy metals in food databaseShellfish, squid and crabChecked 2026.10.03
Crab and crab innards: cadmium, mercury
Cadmium in crab flesh (muscle) is on the low side, averaging 0.08 ppm in horsehair crab (kegani) and 0.16 ppm in red snow crab (benizuwaigani). The crab innards (kani miso), on the other hand, averaged 1.99 ppm in horsehair crab and 11.74 ppm in the innards of red snow crab, higher than the flesh. We found no survey values for cadmium in snow crab (zuwaigani) or king crab (tarabagani).
Levels measured in Japanese government surveys and studies
| Metal | Form / state | Mean | Range / max | Samples | Survey |
|---|---|---|---|---|---|
| Cadmium | Horsehair crab (kegani), muscle | 0.08 | 0.02–0.17 | 30 samples | MAFF, fiscal 1997–2002 |
| Cadmium | Horsehair crab (kegani), innards (miso) | 1.99 | 0.79–3.50 | 15 samples | MAFF, fiscal 1997–2002 |
| Cadmium | Red snow crab (benizuwaigani), muscle | 0.16 | 0.04–0.48 | 30 samples | MAFF, fiscal 1997–2002 |
| Cadmium | Red snow crab (benizuwaigani), innards | 11.74 | 2.30–23.0 | 15 samples | MAFF, fiscal 1997–2002 |
| Cadmium | Japanese blue crab (gazami, watarigani), muscle | 0.07 | <0.01–0.29 | 30 samples | MAFF, fiscal 1997–2002 |
| Cadmium | Japanese blue crab (gazami, watarigani), innards (miso) | 0.69 | 0.09–1.90 | 30 samples | MAFF, fiscal 1997–2002 |
| Mercury | Snow crab (zuwaigani), total mercury | 0.070 | 0.010–0.180 | 15 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Red snow crab (benizuwaigani), total mercury | 0.302 | 0.130–0.500 | 10 samples | MHLW, compiled through fiscal 2008 |
| Mercury | Red snow crab (benizuwaigani), methylmercury | 0.194 | 0.080–0.300 | 10 samples | MHLW, compiled through fiscal 2008 |
Units are mg/kg (= ppm). Cadmium is total cadmium and appears to be wet weight (the sources do not say). Mercury is total mercury and methylmercury, from small surveys of 10 to 15 samples.
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) | We could not confirm a value for crustaceans | — |
| EU (cadmium) | Crustaceans 0.50 mg/kg (muscle of the legs and abdomen; for crab, muscle of the legs) | The value from Regulation (EU) 2023/915. The cephalothorax (crab innards, kani miso) is not among the covered parts. |
| 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). Red snow crab is exempt as a deep-sea shellfish. |
| EU (mercury) | Crustaceans 0.50 mg/kg (muscle of the legs and abdomen; for crab, muscle of the legs) | The value from Regulation 2022/617, carried over into Regulation (EU) 2023/915. Wet weight. |
Good to know
- The cadmium concentration differs between the flesh and the innards. Horsehair crab miso is about 25 times its muscle (1.99 and 0.08), red snow crab innards are about 70 times its muscle (11.74 and 0.16), and Japanese blue crab (watarigani) miso is about 10 times its muscle (0.69 and 0.07) (averages, MAFF fiscal 1997–2002).
- The Consumer Affairs Agency says that some innards of mollusks such as shellfish, squid, and octopus, and of crustaceans such as shrimp and crab, are high in cadmium, while explaining that 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.
- The EU limit for crustaceans (0.50) covers the muscle of the legs and abdomen, and for crab it is the leg muscle. Crab innards (kani miso) are not a covered part. Red snow crab innards reach a maximum of 23 ppm and Japanese blue crab miso a maximum of 1.90 ppm, so there is a range by kind. → How Japan’s standards differ from other countries’
- For mercury, the average total mercury of snow crab is 0.070 ppm (15 samples), and that of red snow crab is 0.302 ppm (10 samples; methylmercury 0.194). Red snow crab is a deep-sea shellfish, which is exempt from the provisional regulatory limit (total mercury 0.4), and with few samples, the trend cannot be stated with confidence.
- 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). In a questionnaire across 14 regions of Japan, 15.4% of people said they eat crab “often.” → Cadmium page
- We found no Japanese official survey values for processed products other than crab miso. The fish and shellfish surveys are from fiscal 1997–2002 and may differ from products on the market today.
Reducing it at home (shown in tests)
- Muscle and miso of horsehair crab differ by about 25 times on average (0.08 and 1.99 ppm). In terms of concentration, not eating the innards such as miso, or eating less of them, is what helps most. However, no public agency is saying “do not eat them.”
- We found no official test showing how much cooking reduces cadmium.
Related explainers
Pages for each metal
Sources
- 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
- 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)
- European Commission, Regulation (EU) 2022/617 (maximum levels for mercury in food)
- MAFF, “Provisional Regulatory Limits for Mercury in Fish and Shellfish”
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.