Heavy metals in food databaseExplainerChecked 2026.10.03
Arsenic and Cadmium in Brown and White Rice: Is Eating It Every Day OK? Measurements of Japanese Rice and How to Reduce Them
Arsenic and cadmium in Japanese rice as measured by MAFF, the difference between brown and white rice, how much rinsing and cooking methods reduce them, and how Japan’s standards differ from those abroad, organized with figures from public sources and research.
Short answer
In Japanese rice (2022–24 crops, 899 samples), inorganic arsenic averaged 0.13 mg/kg in brown rice (median 0.12, maximum 0.37) and 0.09 in polished rice (maximum 0.23). Cadmium averaged 0.04 in brown rice (maximum 0.24) and 0.03 in polished rice (maximum 0.23); no sample exceeded the standard of 0.4.
For arsenic and cadmium, the difference between brown and white rice is not the same. Polishing brings inorganic arsenic to about 60–70% of the brown rice level (because it is concentrated in the bran layer). Polishing reduces cadmium by only 2–5%. Rinsing cuts inorganic arsenic in white rice by about 20% but barely reduces it in brown rice, and cadmium barely changes with rinsing or cooking.
Japan’s Food Sanitation Act standard covers cadmium only (0.4 mg/kg for brown and polished rice); we found no standard for inorganic arsenic in rice. Codex is 0.2 for polished rice and 0.35 for brown rice, and the EU is 0.15 for polished and 0.25 for brown. MAFF says that within a balanced diet, eating brown rice or nuka-zuke (rice-bran pickles) poses no health problem.
Measurements of Japanese rice: falling over the years
This is MAFF’s nationwide survey. The mean for inorganic arsenic in brown rice fell from 0.21 in the 2012 crop to 0.12–0.13 in the 2022–24 crops. The share of brown rice above 0.2 fell from 19.7% in the previous survey (2017–19 crops) to 7.4% in the latest (2022–24 crops). MAFF says the reduction measures appear to be working.
| Crop year | Inorganic arsenic in brown rice, mean (max) | Inorganic arsenic in polished rice, mean (max) | Samples (each) |
|---|---|---|---|
| 2003–05 | 0.15 (0.37) | — | 600 |
| 2012 | 0.21 (0.59) | 0.12 (0.26) | 600 |
| 2017 | 0.15 (0.38) | 0.092 (0.26) | 500 |
| 2018 | 0.15 (0.37) | 0.098 (0.25) | 500 |
| 2019 | 0.17 (0.60) | — | 500 |
| 2022 | 0.13 (0.37) | 0.09 (0.23) | 300 |
| 2023 | 0.12 (0.35) | 0.09 (0.20) | 300 |
| 2024 | 0.13 (0.34) | 0.09 (0.21) | 299 |
For cadmium in Japanese rice: in the 1997–98 crop survey (37,250 samples), the mean was 0.06 and the maximum 1.2, and 96 samples (0.3%) exceeded the standard of 0.4.
| Survey | Samples | Cadmium mean mg/kg | Max | Above 0.4 |
|---|---|---|---|---|
| 1997–98 crops, brown rice | 37,250 | 0.06 | 1.2 | 96 samples (0.3%) |
| 2009–10 crops, brown rice | 2,000 | 0.05 | 0.40 | 0 |
| 2022–24 crops, brown rice | 899 | 0.04 | 0.24 | 0 |
| 2022–24 crops, polished rice | 899 | 0.03 | 0.23 | 0 |
- The 2022–24 and 2009–10 surveys have different limits of quantification (0.01 and 0.04). “Mean 0.05 → 0.04” compares surveys with different detection power, so the trend is better read from the distribution (the share at or below 0.1 went from 91.0% to 96.0%).
- In a survey of paddy soils and other samples (2013–16, 3,007 samples nationwide), inorganic arsenic in brown rice averaged 0.15 with a maximum of 0.64. One analysis found that each 1°C higher mean daily temperature after heading was associated with about 9.9% higher inorganic arsenic in brown rice.
Brown versus white rice: arsenic falls in white rice, cadmium barely changes
- Inorganic arsenic: concentrated in the bran layer (about 9% of the outer part of brown rice). Polished rice is about 60–70% of brown rice. The polished-to-brown ratio is an average of 63% (min 38, max 86) for the 2017–18 crops (1,000 samples) and a median of 75% (mean 73%) for the 2022–24 crops (893 samples), so the figure differs between surveys. MAFF’s materials do not explain why.
- Degree of polishing: in MAFF’s test (10 samples), a milling yield of 91% gave a 51% reduction (range 38–61%), 89% gave 53%, and 80% gave 60%. Light polishing (gobu-zuki, milling yield 95%) gives about half the reduction of normal polishing (12–25%).
- Cadmium: with brown rice as 100, polished rice is an average of 95% (2022–24 crops, 755 samples) and an average of 96.8% in a 2001 test. Polishing removes only 2–5%, and MAFF summarizes that rinsing and cooking also change it very little. Rice bran is higher than brown rice.
- Nutrition: MAFF says brown rice is richer than white rice in vitamins B1 and E, iron, and dietary fiber, and that within a balanced diet, eating brown rice or nuka-zuke (rice-bran pickles) poses no health problem.
- One analysis found that inorganic arsenic in rice bran is about 1 mg/kg, 10–20 times that of ordinary grain (Sun 2008). We found no public survey of Japanese rice bran or nuka-zuke.
Standards differ by country
| Food and substance | Japan | Codex | EU (Regulation 2023/915) |
|---|---|---|---|
| Polished rice, inorganic arsenic | No standard | 0.2 (adopted 2014) | 0.15 (excluding parboiled rice) |
| Brown rice, inorganic arsenic | No standard | 0.35 (adopted 2016) | 0.25 (including parboiled rice) |
| Rice crackers, inorganic arsenic | No standard | — | 0.30 |
| Brown and polished rice, cadmium | 0.4 (brown and polished rice; in force from the end of February 2011) | 0.4 (polished rice) | 0.15 |
- Japan’s cadmium standard was changed by an April 2010 revision from less than 1.0 ppm in brown rice to 0.4 ppm or less in brown and polished rice.
- Japan has no standard for inorganic arsenic in rice, so it cannot be said that anything “exceeded the standard.” Against other countries’ yardsticks, the mean of 0.09 for Japanese polished rice is 60% of the EU limit for polished rice (0.15), and the maximum of 0.23 exceeds it. The brown rice maximum of 0.37 is slightly above Codex’s brown rice limit of 0.35. The number of samples above 0.35 has not been published (5 samples, 0.6%, were above 0.3 and up to 0.4).
- The share exceeding the EU’s brown rice limit of 0.25 falls within the 0.2-to-0.3 band (6.8%), and the exact share has not been published. Likewise for cadmium, the share above the EU’s 0.15 has not been published (the band above 0.1 and up to 0.2 is 3.9%).
Washing and cooking: methods that reduce it and methods that do not
| Study or source | Method | Change in inorganic arsenic |
|---|---|---|
| MAFF guide | Rinse white rice 3 times (ion-exchanged water) | About 20% less (barely reduced in brown rice) |
| Same | Wash-free rice processing (bran-rubbing method) | About 10% less |
| Naito 2015 (NARO and others; 3 Japanese white rice samples plus brown rice) | Rinsing 3 times / cooking in a small amount of water (water:rice 1.4–2.0:1, until the water is gone) | Rinsing left 71–83% (17–29% less). Not removed by cooking in a small amount of water |
| Raab 2009 (UK) | Water:rice 2.5:1 / 6:1 | No removal at 2.5:1. 45% less at 6:1 (35% less total arsenic) |
| Carey 2015 (UK) | Water:rice 12:1, coffee percolator | 57±5% at 12:1, 49±7% with the percolator |
| Menon 2021 (UK) | Parboil, then let the rice absorb water | 54% less in brown rice, 73% less in white rice |
| Menon 2024 (UK) | Cooking with water containing arsenic (10 and 50 μg/L) | Arsenic in the rice increases |
- With the usual Japanese way of cooking (in a rice cooker, with no water left over), arsenic is not reduced. What reduces it is cooking in extra water and discarding the water, and nutrients such as water-soluble minerals and vitamins escape along with it (Menon 2021 reported that nutrient losses were smaller for brown rice).
- We found no study that tested this under Japanese water conditions (water low in arsenic), nor any treatment of how this method fits Japanese eating habits.
- Cadmium barely changes with rinsing or cooking (studies cited in MAFF’s risk profile).
Reducing it in paddy fields: the arsenic–cadmium trade-off
- Water management moves arsenic and cadmium in opposite directions. Flooding around heading makes the soil reducing, so cadmium is taken up less, but arsenic rises. Draining after heading lowers arsenic, but cadmium increases. In June 2024, MAFF drew up guidelines for reducing both.
- Low-uptake varieties: “Koshihikari Kan-1” (NARO, variety registered in 2015) lost the function of the manganese transporter OsNramp5 and takes up little manganese or cadmium, so cadmium in its brown rice is extremely low. NARO says that even with draining, cadmium stays extremely low while arsenic can also be reduced.
- Soil dressing (kyakudo): a measure that brings in clean soil to cover contaminated fields. Under the Act on Prevention of Soil Contamination of Agricultural Land, 6,428 ha were designated as countermeasure areas by the end of fiscal 2013, and countermeasure projects and the like were completed on 6,103 ha.
Where it sits in the whole diet
- Inorganic arsenic: about 70% of Japanese intake comes from rice (66.7% on average for fiscal 2014–17). For total arsenic, rice is 6.1% and seafood accounts for 59.0%. The 2024 hazard quotient for inorganic arsenic was 1.28–1.80 (using the yardstick the report chose), and of the four metals only inorganic arsenic exceeded 1. The Food Safety Commission of Japan has not set a tolerable intake.
- Cadmium: in 2022, rice and rice products accounted for 34.1%. The 2022 intake of 2.03 μg/kg/week is 29% of the Food Safety Commission’s 7, 35% of JECFA’s (about 5.8 converted to weekly), and 81% of EFSA’s 2.5 (Urayomi’s calculation).
- Japanese research: in the JPHC cohort, dietary arsenic was not associated with cancer overall (there was a tendency toward an association with lung cancer in men, stronger in men who currently smoke; because the effect of smoking is mixed in, this result alone cannot show that arsenic is the cause).
- It cannot be said flatly either that “brown rice is dangerous” or that “arsenic is not a problem.” MAFF and the Food Safety Commission advise not relying on particular foods, while EFSA 2024 and JECFA 2025 say there may be a concern even at average intake. We lay out the numbers and leave the judgment to the reader.
Sources
- MAFF, survey of cadmium and arsenic in 2022–24 crop rice (December 19, 2025)
- MAFF, “Survey on Arsenic in Foods”
- MAFF, “Guide to Reducing Arsenic in Rice” (revised February 2022)
- MAFF, “Q&A on Arsenic”
- MAFF, actual cadmium concentrations in domestic agricultural products
- MAFF, cadmium standards (Japan and international)
- NARO, “Reducing Arsenic and Cadmium in Rice”
- EU Regulation 2023/915
- Naito S et al. Food Chem 2015 (polishing, rinsing, and cooking of Japanese rice)（PMID 25172713）
- Raab A et al. J Environ Monit 2009（PMID 19137137）
- Carey M et al. PLoS One 2015（PMID 26200355）
- Menon M et al. Sci Total Environ 2021（PMID 33153748）
- Menon M et al. Sci Total Environ 2024（PMID 38176556）
- Sawada N et al. Cancer Causes Control 2013 (JPHC)（PMID 23666560）
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.