Rice Safety: Arsenic Levels and How to Reduce Your Exposure

Why rice accumulates more arsenic than other grains, which types have the most, and evidence-based cooking methods that remove 50–73% of inorganic arsenic

Rice absorbs more arsenic from soil and water than nearly any other staple grain — a consequence of how it is grown in flooded fields, where waterlogged conditions make arsenic more chemically available for uptake by plant roots. Inorganic arsenic, the form concentrated in rice, is classified as a Group 1 carcinogen by the International Agency for Research on Cancer, with strong epidemiological links to bladder, lung, and skin cancer at high long-term doses [4]. For most people eating rice a few times per week, the risk is low, but for high consumers — particularly infants on rice cereal, people eating rice multiple times daily, and pregnant women — exposure adds up. The reassuring part: simple cooking changes can reduce the inorganic arsenic in your rice by 50–73% without losing the nutrients that make rice worth eating [1].

Why Rice Accumulates 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.

This is not a manufacturing or agricultural chemical problem. It is geology. Arsenic is naturally present in bedrock, and historical use of arsenic-based pesticides in certain regions — particularly former cotton-growing areas of the American South — means some soils have elevated baseline levels [5].

Inorganic vs. Organic Arsenic

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

Inorganic arsenic (arsenite and arsenate): the form associated with cancer and cardiovascular harm. This is the form the FDA and EFSA regulate and that toxicologists refer to in risk assessments.
Organic arsenic (dimethylarsinic acid, DMA, and monomethylarsonic acid, MMA): generally considered less toxic, though not entirely benign at high exposures.

Inorganic arsenic constitutes roughly 60–80% of the arsenic in white rice and 80–90% in brown rice, with variation by growing region [4][5].

Which Types of Rice Have the Most

Brown rice consistently shows higher inorganic arsenic than white rice — approximately 40–50% more — because arsenic concentrates in the outer bran layer that is milled away to make white rice. Studies report mean inorganic arsenic levels of 150–200 µg/kg in brown rice versus 100–150 µg/kg in white rice [2][5].

By growing region, U.S. rice (particularly from Arkansas, Louisiana, Mississippi, Missouri, and Texas) tends to have higher arsenic than rice from California, India, Thailand, or Europe. Basmati rice from India and Pakistan typically has among the lowest levels of any variety [5].

Rice products concentrate arsenic relative to the grain: rice cakes, rice crackers, and infant rice cereal often have higher per-serving exposure because they are essentially condensed rice. The FDA has proposed a limit of 100 µg/kg for inorganic arsenic in infant rice cereal specifically because of infants' lower body weight and higher rice product consumption relative to adults [5].

How Cooking Reduces Arsenic

Arsenic in rice is water-soluble. Cooking methods that use more water and discard the cooking water substantially reduce the inorganic arsenic that ends up in the final grain.

The parboiled and absorbed (PBA) method is currently the best-studied approach for balancing arsenic removal with nutrient retention [1]. The process:

Bring a large pot of water to a full boil — use a roughly 5:1 water-to-rice ratio.
Add the rice and parboil for five minutes.
Drain the parboiling water completely.
Add fresh water (enough to absorb) and cook on low heat until done.

A 2021 study from the University of Sheffield tested four cooking approaches across brown and white rice. The PBA method removed 73% of inorganic arsenic from white rice and 54% from brown rice — the highest reduction of any method — without significant loss of zinc, manganese, or phosphorus. By contrast, cooking rice in excess water (6:1 ratio) reduced arsenic by 40–60% but also washed out 50–70% of iron, folate, thiamin, and niacin added to enriched white and parboiled rice [1][3].

What does not work well: Rinsing rice before cooking has minimal effect on inorganic arsenic content, despite being widely recommended. Rinsing does remove some surface starch but does not meaningfully reach the arsenic bound within the grain [3].

Who Should Pay the Most Attention

Infants and toddlers: highest rice-to-bodyweight intake. The FDA advises varying grains and not relying exclusively on rice-based cereals for infants.
Pregnant women: arsenic crosses the placenta; prenatal exposure is associated with infant health outcomes in high-exposure populations.
People eating rice more than once daily: exposure scales directly with serving frequency. Applying the PBA method and varying grains (oats, quinoa, barley, millet) meaningfully reduces cumulative inorganic arsenic intake.
People with high-rice diets who also have high manganese or lead exposures: the cardiovascular effects of arsenic may compound with other heavy metal exposures.

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

Evidence Review

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, with the strongest epidemiological evidence for bladder, lung, and skin cancers from high-dose exposure via contaminated drinking water in Bangladesh, Taiwan, Argentina, and Chile. Zhou and Xi (2018, PMID 30223072) reviewed the molecular mechanisms in detail: inorganic arsenic does not directly damage DNA in the way ionizing radiation does. Instead, it acts primarily through indirect mechanisms: inhibiting DNA repair enzymes, generating reactive oxygen species (ROS) that damage DNA and cell membranes, altering DNA methylation patterns (promoter hypomethylation of oncogenes, hypermethylation of tumor suppressor genes), and disrupting signal transduction pathways including MAPK, PI3K/Akt, and NF-κB. Arsenic also promotes epithelial-mesenchymal transition, a process associated with tumor invasiveness [4].

At population dietary levels (not drinking water levels), the evidence is more uncertain. The epidemiological data for cancer from rice-derived arsenic alone is limited, in part because isolating the contribution of rice from total dietary and environmental arsenic exposure is methodologically difficult.

Cardiovascular Risk at Dietary Exposure Levels

Xu et al. (2020, PMID 32659549) conducted an ecological study examining whether population-level inorganic arsenic exposure from rice was associated with cardiovascular disease (CVD) mortality across 319 local authorities in England and Wales. They used ethnicity as a proxy for rice consumption — British South Asian communities consume rice at significantly higher rates — and estimated per capita inorganic arsenic exposure by local authority.

The study found a statistically significant positive association between estimated inorganic arsenic exposure from rice and age-standardized CVD mortality rates, after adjustment for deprivation, smoking, obesity, and other CVD risk factors. This is an ecological (population-level) association study, which cannot establish causation — confounding is a major limitation — but it adds to a body of research suggesting cardiovascular effects at lower arsenic exposures than previously appreciated. A parallel U.S. study using MESA cohort data (PMID 32067593) similarly found that higher dietary arsenic exposure was associated with greater carotid intima-media thickness, a subclinical marker of atherosclerosis, in a dose-dependent pattern [2].

The PBA Cooking Method: Detailed Evidence

Menon et al. (2021, PMID 33153748) from the University of Sheffield tested four cooking protocols on both brown (long-grain) and white (long-grain) rice across four varieties with differing baseline arsenic levels. The four methods were: unwashed-absorbed (standard method), washed-absorbed, pre-soaked-absorbed, and parboiled-absorbed (PBA).

Results for inorganic arsenic reduction relative to unwashed-absorbed standard:

Washed-absorbed: ~10% reduction (not statistically meaningful)
Pre-soaked-absorbed: ~20% reduction
PBA (white rice): 73% reduction
PBA (brown rice): 54% reduction

Critically, the PBA method showed no significant loss of zinc (Zn) from either rice type. Phosphorus, potassium, magnesium, and manganese losses were similar to or less than those reported for excess water cooking. The margin of exposure (MOE) — a risk-based safety metric where higher values indicate greater safety margin — was raised 3.7-fold for white rice and 2.2-fold for brown rice when using the PBA method, compared to standard cooking [1].

Excess Water Cooking: Nutrient Tradeoffs

Gray et al. (2016, PMID 26515534) published FDA-funded laboratory work testing a 6:1 water-to-rice ratio on four rice types: long grain polished (white), parboiled, brown, and long grain enriched. Inorganic arsenic reductions were 40% (white), 60% (parboiled), and 50% (brown). However, enriched white and parboiled rice lost 50–70% of added iron, folate, thiamin, and niacin in the discarded cooking water — minerals that are added back to enrich nutritionally depleted white rice. Brown rice, which is not enriched, showed lower mineral losses from excess water cooking because its nutrients are intrinsic rather than surface-applied [3]. This study is the primary basis for FDA's stated guidance that cooking methods can reduce arsenic by 40–60%.

Regulatory Context

In 2016, the FDA proposed an action level of 100 µg/kg inorganic arsenic for infant rice cereal, based on a risk assessment using cancer slope factors and dietary exposure modeling across infant consumers. This remains the only proposed U.S. regulatory limit for arsenic in solid rice products; no limit exists for adult rice consumption. The European Food Safety Authority (EFSA) applies a tolerable weekly intake approach and has set maximum levels for inorganic arsenic in various rice product categories under EU Regulation (EC) No 1881/2006 [5].

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 classification. The evidence that rice-derived arsenic at typical dietary intake levels causes meaningful cancer risk in Western populations is more uncertain; the exposures are lower by one to two orders of magnitude compared to the drinking water studies. The cardiovascular evidence at dietary levels is preliminary but biologically plausible. The cooking intervention evidence is solid: the PBA method reliably removes 50–73% of inorganic arsenic across multiple studies and does not compromise key nutrients, making it a practical harm-reduction strategy with a well-characterized risk-benefit profile [1][3].

References

Improved rice cooking approach to maximise arsenic removal while preserving nutrient elementsMenon M, Dong W, Chen X, Hufton J, Rhodes EJ. Science of the Total Environment, 2021. PubMed 33153748 →
Association of low-level inorganic arsenic exposure from rice with age-standardized mortality risk of cardiovascular disease (CVD) in England and WalesXu L, Mondal D, Bhatt M, Bhatt S, Al-Rmalli J, Haris PI. Science of the Total Environment, 2020. PubMed 32659549 →
Cooking rice in excess water reduces both arsenic and enriched vitamins in the cooked grainGray PJ, Conklin SD, Todorov TI, Kasko SM. Food Additives and Contaminants: Part A, 2016. PubMed 26515534 →
A review on arsenic carcinogenesis: Epidemiology, metabolism, genotoxicity and epigenetic changesZhou Q, Xi S. Regulatory Toxicology and Pharmacology, 2018. PubMed 30223072 →
Arsenic in FoodU.S. Food and Drug Administration. FDA, 2024. Source →