Academic journal article Environmental Health Perspectives

In Search of "Just Right": The Challenge of Regulating Arsenic in Rice

Academic journal article Environmental Health Perspectives

In Search of "Just Right": The Challenge of Regulating Arsenic in Rice

Article excerpt

Rice, a dietary staple for millions of people around the world, is often contaminated with arsenic, a naturally occurring element in soils that can cause cancer and other health effects. (1)

Although other foods also contain arsenic, rice is unusually efficient at absorbing this element from soil; it can absorb up to 10 times more arsenic than other crops, such as wheat. (2) Moreover, rice flour and syrup are used in many processed foods, including baby foods, so exposures aren't limited to people eating the grain itself. It's estimated that 95% of the average arsenic intake among Europeans comes from food, and half of that comes from rice and rice products. (3) And in areas with high levels of arsenic in well water, the exposures via water and rice add up to a toxic double whammy. (3)

Mounting worries over arsenic in rice are now prompting calls for regulation. "We need to set strict standards for rice that will be meaningful in terms of reducing arsenic exposure through the diet," says Andrew Meharg, a professor of biological sciences at Queens University Belfast in Ireland. "This is imperative to protect people with high rice consumption, including virtually all children, people living in South Asia, and those who eat a lot of rice for health reasons, such as gluten intolerance."

But regulating a naturally occurring element in such a widely eaten food is no easy task. Arsenic levels can vary widely in rice from different countries and states, and among different rice cultivars, according to Aaron Barchowski, a professor of environmental and occupational health at the University of Pittsburgh. This raises difficult questions about how a regulated standard could be monitored and enforced.

Assessing the Threat

The U.S. Environmental Protection Agency (EPA) currently designates arsenic as a nonthreshold carcinogen, meaning that any dose, no matter how small, carries some cancer risk. (4) Some scientists don't agree--they say doses below a certain threshold won't cause cancer, a debate that has yet to be resolved. (5)

In another area of uncertainty, Michael Crupain, director of food safety testing at the testing group Consumer Reports (CR), notes that scientists have not documented elevated rates of bladder and lung cancer--the more lethal malignancies with which arsenic in well water is most often associated (6) --in countries where rice is commonly eaten in large amounts. "Carefully designed studies investigating this question need to be conducted," he says.

However, studies also reveal associations between arsenic and numerous health effects, including cardiovascular disease, (7) lung disease, (8) and impaired cognitive function, (9) among many others. Barchowski explains that arsenic in small amounts stresses cells, making them prone to maladaptive reactions that promote disease over time.

Children in particular appear to be uniquely sensitive to low doses of arsenic. (10) Investigators in both rural Bangladesh and the United States, for instance, have shown that fetal exposure to arsenic is associated with respiratory infections and diarrhea during infancy and early childhood. (10,11,12) Moreover, cross-sectional epidemiological studies in Bangladesh and in Taiwan have connected early arsenic exposures with neurobehavioral problems in school children and adolescents. (1)

While people can be assumed to drink water from the same well on a consistent basis, the amounts of arsenic ingested from food can be far more difficult to quantify, according to Habibul Ahsan, a professor of health studies, medicine, and human genetics at the University of Chicago. Dietary effects vary by whether the arsenic is organic or inorganic (the latter being more toxic) and by the amounts of arsenic in a given food, he says, and the absorption of arsenic from the gut into the bloodstream also varies by food type.

Barchowsky points out that rice and rice products contain many nutrients-for example, B vitamins and selenium-that can protect against the toxic effects of arsenic. …

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