Rice, a staple in most Asian households, is the biggest food source of inorganic arsenic, the more toxic version of one of the world’s most toxic elements.
While arsenic is present only in small amounts in most food and drinks, prolonged exposure poses serious health risks.
What arsenic is: Arsenic, a naturally occurring metalloid, is a toxin known since ancient times.
- Organic arsenic compounds are typically found in fish and shellfish.
- Inorganic arsenic compounds are present in soils, sediments and groundwater, occurring either naturally or as a consequence of mining, ore smelting or using arsenic for industrial purposes, according to the Centers for Disease Control and Prevention.
- Ingesting unusually large doses of inorganic arsenic can cause nausea, vomiting, diarrhea, dehydration and shock.
- Chronic exposure to inorganic arsenic in drinking water has been linked to skin lesions, cardiovascular disease, neurotoxicity and developmental toxicity, as well as cancers of the skin, urinary bladder and lung.
How arsenic gets into rice: Being naturally present in the environment, arsenic finds ways to enter the food chain.
- Rice is cultivated in paddy fields that require irrigation water, which is often contaminated with arsenic — at least in South and Southeast Asian countries, according to a 2011 study.
- In Bangladesh, researchers found that arsenic accumulates in the soil of paddy fields, which only makes the problem worse.
- Rice also absorbs more arsenic from water and soil compared to other crops such as wheat and barley, according to a 2007 study.
- The CDC notes that people are most likely exposed to inorganic arsenic through drinking water.
- For this reason, contaminated water may also be used to cook rice, without people knowing.
Removing the most arsenic: Researchers from the University of Sheffield’s Institute for Sustainable Food have found a way to cook rice to remove the most arsenic, all while retaining its nutrients.
- The “parboiling with absorption” (PBA) method can cut down 54% of inorganic arsenic in brown rice and 74% in white rice.
- First, boil fresh water (four cups for every cup of raw rice).
- Add rice and boil for another five minutes.
- Drain the water as it now contains arsenic.
- Add fresh water (this time, two cups for every cup of raw rice), then cook with low to medium heat with a lid on.
Brown rice retained more nutrients than white rice through the PBA method. There was no significant loss of zinc in both rice types, while the loss of other nutrients (phosphorus, potassium, magnesium and manganese) was similar or less than compared to losses from rice cooked in excess water in earlier studies.
“Our aim was to optimize the method to remove arsenic while keeping maximum nutrients in the cooked rice. Our newly developed method, PBA, is easy and home-friendly so that everyone can use it,” lead author Dr. Manoj Menon said in a statement.
The study was published in the journal Science of the Total Environment on Oct. 29.
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