What is the best way to cook rice to remove arsenic?

Arsenic is naturally present in most soils worldwide and enters rice through a pathway that other grains largely avoid. Rice is cultivated in flooded paddy fields. When soil is submerged and oxygen-depleted, soil microbes reduce arsenate (the oxidized, less mobile form) into arsenite (the reduced, more mobile form that moves freely through water and into plant roots). Rice plants have specialized transporters — originally evolved to absorb silica — that also efficiently take up arsenite, drawing it into the grain as the plant matures.

The arsenic comes mainly from the environment rather than from food processing: levels are higher in certain soils and rocks and where arsenic-containing pesticides were once used on food crops, and mining and coal-fired power plants add pollution⁵.

Inorganic vs. Organic Arsenic

Not all arsenic in rice is equally harmful. Rice contains two kinds:

• Inorganic arsenic (arsenite and arsenate): the form associated with cancer and cardiovascular harm. This is the form regulators and toxicologists use in risk assessments.
• Organic arsenic (mainly dimethylarsinic acid, DMA): generally considered less toxic, though its toxicity is not fully understood.

The balance depends on where the rice was grown. In one analysis, rice from the United States was mostly the DMA type, whereas rice from Asia and Europe was mostly the inorganic type, and its authors noted that the health risk of DMA is not well enough understood to be sure how much safer the DMA type is¹⁰.

Which Types of Rice Have the Most

Brown rice consistently has more arsenic than white rice, because arsenic concentrates in the outer bran layer that is milled away to make white rice. In a Spanish survey, brown varieties averaged 189 µg/kg of total arsenic versus 132 µg/kg for white rice⁶.

Origin matters too. In a data set of 901 polished (white) rice samples from 10 countries, median total arsenic varied about 7-fold: Egypt (0.04 mg/kg) and India (0.07 mg/kg) had the lowest, and the United States (0.25 mg/kg) and France (0.28 mg/kg) the highest⁹. Because the share that is inorganic differs by origin, total arsenic alone does not rank the risk¹⁰.

Rice products are a particular concern for infants: in the Spanish survey, baby cereals and breakfast cereals were the most important contributors to infants' inorganic arsenic exposure, and rice was the major contributor for adults⁶. In 2020 the FDA finalized an action level of 100 µg/kg (100 ppb) for inorganic arsenic in infant rice cereal. In its 2018 sampling, 76% of infant rice cereal samples were at or below that level, compared with 36% in 2011–2013¹¹.

How Cooking Reduces Arsenic

Arsenic in rice is largely water-soluble, so cooking methods that use more water and discard it reduce the inorganic arsenic that ends up in the final grain. A 2019 review found that polishing the grain, washing it repeatedly, and using an excess volume of water all reduce the arsenic in cooked rice, but at the cost of nutrients, and that cooking in continuously percolating water has recently drawn attention⁷.

The parboiled and absorbed (PBA) method is the best-studied approach for balancing arsenic removal with nutrient retention¹. The process:

1. Bring a large pot of water to a full boil.
2. Add the rice and parboil it for about five minutes.
3. Drain the parboiling water completely.
4. Add fresh water (enough to be absorbed) and cook on low heat until done.

A 2021 laboratory study tested four home cooking treatments — unwashed and absorbed, washed and absorbed, pre-soaked and absorbed, and parboiled and absorbed — on three types each of brown and white rice. The PBA method removed 73% of inorganic arsenic from white rice and 54% from brown rice, raising the margin of exposure 3.7-fold for white rice and 2.2-fold for brown. The other treatments reduced inorganic arsenic in white rice only. There was no significant loss of zinc with PBA, and losses of phosphorus, potassium, magnesium, and manganese were similar to or smaller than the losses reported for cooking in excess water¹.

By contrast, a laboratory study found that cooking rice in excess water reduced inorganic arsenic by about 40% in long-grain polished white rice, 60% in parboiled rice, and 50% in brown rice, but also reduced iron, folate, thiamin, and niacin by 50–70% in enriched white and parboiled rice, which carry those nutrients on the grain surface. The losses were significantly smaller for brown rice, which is not enriched³.

Rinsing before cooking has a minimal effect on the arsenic in the cooked grain, despite being widely recommended, and it washes enriched nutrients out of polished and parboiled rice³. (A Spanish exposure study did recommend washing rice as well as choosing white or pre-cooked rice⁶, and the 2019 review lists repeated washing among the methods that lower arsenic at some nutrient cost⁷; the evidence for plain rinsing is weaker than for cooking in excess water.)

Who Should Pay the Most Attention

• Infants and toddlers: in a Spanish survey, infants and toddlers had the highest dietary exposure to total arsenic of any age group, and baby cereals were the main source of infants' inorganic arsenic⁶. The FDA ties inorganic arsenic exposure to neurodevelopmental effects and notes that iron-fortified oat, barley, and multigrain infant cereals can be a first or early cereal in place of rice cereal¹¹.
• Pregnant women: the FDA advises eating a variety of grains as part of a well-balanced diet¹¹.
• People eating rice more than once daily: exposure scales with how often and how much rice you eat. Cooking by the PBA method¹ and varying grains (oats, quinoa, barley, millet) reduces the inorganic arsenic you take in.

See our water filtration page for information on arsenic in drinking water, which is a separate and often larger exposure pathway in affected regions.

Carcinogenicity: IARC Classification and Mechanism

Inorganic arsenic is classified as a Group 1 carcinogen — "carcinogenic to humans" — by the International Agency for Research on Cancer. Zhou and Xi (2018, PMID 30223072) reviewed the evidence: epidemiological studies have established a strong association between inorganic arsenic in drinking water and a higher incidence of bladder, liver, lung, prostate, and skin cancer, and inorganic arsenic also raises the risk of cardiovascular disease, hypertension, and diabetes. The molecular mechanisms of carcinogenesis remain poorly defined; proposed ones include genotoxicity, altered cell proliferation, oxidative stress, changes to the epigenome, disturbances of signal transduction pathways, cytotoxicity, and regenerative proliferation⁴.

At the lower exposures of a typical diet (rather than contaminated drinking water), the evidence is more uncertain. Epidemiological data on cancer from rice-derived arsenic alone are limited, in part because it is hard to separate the contribution of rice from total dietary and environmental arsenic exposure.

Cardiovascular Risk at Dietary Exposure Levels: Mixed Evidence

Xu et al. (2020, PMID 32659549) conducted an ecological study of whether estimated inorganic arsenic exposure from rice was associated with cardiovascular disease (CVD) mortality across local authorities in England and Wales. They estimated daily per-capita exposure for each authority using ethnicity as a proxy for the class of rice consumption². After adjustment for confounders including smoking prevalence, education, employment, overweight percentage, PM2.5, and others, the preferred non-linear model showed CVD risk increasing with exposure above about 0.3 µg per person per day. In the linear model, CVD age-standardized mortality in the highest exposure quartile (0.375–2.71 µg/person/day) was 1.06 times that in the lowest (< 0.265 µg/person/day; 95% CI 1.02–1.11; p-trend < 0.001). As the authors acknowledge, this is an ecological study with well-known limitations: it cannot show that rice arsenic caused the difference.

A US cohort gave a different answer. Sobel et al. (2020, PMID 32067593) analyzed 5,050 adults in the Multi-Ethnic Study of Atherosclerosis (MESA) who had no clinical CVD; 13% ate at least one serving of rice a day⁸. Compared with people who ate less than one serving a week, those eating a serving or more a day showed no association with markers of subclinical CVD after adjustment, including inflammation (hsCRP geometric mean ratio 0.98, 95% CI 0.86–1.11), aortic distensibility (0.99, 0.91–1.07), and carotid intima-media thickness (0.98, 0.91–1.06). Associations with urinary arsenic, measured in 310 participants, were similar. The authors call for research that uses urinary arsenic to assess the cardiovascular effects of low-level arsenic exposure. Taken together, the studies at dietary exposure levels are inconsistent.

The PBA Cooking Method: Detailed Evidence

Menon et al. (2021, PMID 33153748) modified the absorption method of cooking and tested it in combination with four home-friendly treatments (UA, unwashed and absorbed; WA, washed and absorbed; PSA, pre-soaked and absorbed; PBA, parboiled and absorbed) on three types each of brown and white rice. Nutrient elements were measured by ICP-MS and arsenic species by LC-ICP-MS¹.

Overall, PBA was the best treatment: it removed 54% of inorganic arsenic from brown rice and 73% from white rice, raising the margin of exposure (MOE) — a risk-based safety metric in which higher values mean a larger margin — by 3.7 for white rice and 2.2 times for brown rice. The other treatments were effective only for white rice. Treatments retained more nutrient elements in brown rice than in white. No significant loss of zinc was observed for either rice type, and losses of phosphorus, potassium, magnesium, and manganese were similar to or lower than the losses reported for rice cooked in excess water. The authors concluded that PBA is a promising technique and that further research is needed with different regional rice types and water quality.

Excess Water Cooking: Nutrient Tradeoffs

Gray et al. (2016, PMID 26515534) studied the effects of rinsing rice and cooking it in different amounts of water on total arsenic, inorganic arsenic, iron, cadmium, manganese, folate, thiamin, and niacin in the cooked grain³. Rinsing before cooking had a minimal effect on arsenic, but washed enriched iron, folate, thiamin, and niacin out of polished and parboiled rice. Cooking in excess water reduced average inorganic arsenic by 40% in long-grain polished rice, 60% in parboiled rice, and 50% in brown rice. Iron, folate, niacin, and thiamin fell by 50–70% in enriched polished and parboiled rice, but significantly less in brown rice, which is not enriched.

Exposure Surveys and Mitigation Reviews

González et al. (2020, PMID 32413457) measured total and inorganic arsenic in rice and rice products in Spain and estimated dietary exposure and health risks for infants and adults⁶. Brown varieties had higher arsenic than white rice (189 vs 132 µg/kg). Toddlers and infants had the highest dietary exposure to total arsenic (4.08 and 3.99 µg/day), but unlike the other groups the main contributor was organic arsenic. For adults, rice was the major contributor to inorganic arsenic exposure; for infants, baby cereals and breakfast cereals were the most important contributors. No population group exceeded the lower limit of the EFSA benchmark dose range (BMDL01, 0.3 to 8.0 µg/kg body weight per day) in any of the three exposure scenarios (high, mean, and low) considered. The authors recommend white rice or pre-cooked rice and washing rice before cooking to minimize exposure.

Kumarathilaka et al. (2019, PMID 30986740) reviewed the causes of high inorganic arsenic in cooked rice, focusing on arsenic-endemic areas⁷. The key factors were cultivation on arsenic-contaminated paddy soils, use of raw grain above 200 µg/kg of inorganic arsenic, and cooking with arsenic-contaminated water. Polishing, sequential washing, and cooking in excess water all lower the arsenic in cooked rice but reduce its nutrient content, and cooking in percolating water has gained attention as another approach. They suggest rainwater harvesting as a sustainable way to avoid contaminated cooking water.

Geographic Variation

Meharg et al. (2009, PMID 19350943) compiled total arsenic analyses for 901 polished (white) rice samples from 10 countries and found about a 7-fold variation in the median, lowest in Egypt and India and highest in the United States and France⁹. In a subset of 63 samples from Bangladesh, China, India, Italy, and the United States analyzed for arsenic species, the relationship between inorganic and total arsenic differed significantly among countries. The estimated internal cancer risk from inorganic arsenic in rice varied 30-fold across the five countries examined, from 0.7 per 10,000 for Italians to 22 per 10,000 for Bangladeshis for a 60 kg person. Zavala et al. (2008, PMID 18546735) analyzed arsenic species in 24 US rice samples that had high arsenic and reported that DMA dominated in high-arsenic US rice, while rice from Asia and Europe was mostly the inorganic type; they caution that the relative toxicity of DMA is not well enough understood to assess the relative risks firmly¹⁰.

Regulatory Context

In August 2020 the FDA finalized guidance identifying an action level of 100 µg/kg (100 ppb) for inorganic arsenic in infant rice cereals, which it said protects public health by reducing infants' dietary exposure and is achievable by industry, because inorganic arsenic exposure is associated with neurodevelopmental effects. Sampling showed 76% of samples at or below 100 ppb in 2018, compared with 47% in 2014 and 36% in 2011–2013¹¹.

Confidence Assessment

The evidence that inorganic arsenic at high doses (primarily via drinking water) causes bladder, lung, and skin cancer is strong and well established — this is the basis for the IARC Group 1 classification⁴. The evidence that rice-derived arsenic at typical dietary intake levels causes meaningful cancer risk in Western populations is more uncertain, because the exposures are much lower. The cardiovascular evidence at dietary levels is mixed: a positive ecological association in England and Wales² and no association in a US cohort⁸. The cooking evidence is solid for the methods tested in the laboratory: the PBA method removed about half to three-quarters of inorganic arsenic in one study¹, and excess-water cooking removed 40–60% in another, at a nutrient cost for enriched rice³. These are single laboratory studies of specific rice types, so the exact percentages will vary with the rice and the method.