Arsenic poisoning and rice: Thorough washing, cooking in excess water may help cut exposure

A recent study said that flood irrigation used to cultivate rice in India leads to longer exposure to contaminated water and soil, increasing the rate of arsenic absorption

Myupchar August 05, 2020 22:27:09 IST
Arsenic poisoning and rice: Thorough washing, cooking in excess water may help cut exposure

Rice is a staple food in several countries across the world. From Japan to India to Mexico, different varieties of rice are grown and consumed as a source for carbohydrates. A recent study has brought into focus a big downside of rice consumption — and no, we’re not referring to weight gain or obesity here.

This study, published in the journal Science of the Total Environment, confirmed that prolonged consumption of rice can lead to chronic exposure to arsenic.

Prolonged arsenic poisoning can, in turn, lead to thousands of avoidable premature deaths every year. The study also highlighted that the consumption of inorganic arsenic-bearing rice is a high-risk factor for cardiovascular diseases and mortality related to it.

This is not the first time concerns about the arsenic in rice have come up. That most rice varieties, no matter where they grow in the world, have some amounts of arsenic in them has been common knowledge for decades.

What is arsenic and how bad is it for health?

According to the British Nutrition Foundation (BNF), concerns over the presence of Arsenic in rice have spiked since the effects of chronic inorganic arsenic poisoning have become more widely known.

The BNF reveals that arsenic is a toxic metal element that’s present in air, soil and water, and is often absorbed by food crops as they grow. Arsenic is found in two forms, organic and inorganic, and the latter is of greater concern where negative health outcomes are concerned.

A study in Frontiers in Physiology in 2012 explains that consuming plant crops which have had significant inorganic arsenic exposure can affect oxidative carbon metabolism, amino acid and protein relationships, nitrogen and sulfur assimilation pathways — all of which make arsenic a carcinogen.

"Soluble inorganic arsenic (found in rocks and soil or dissolved in water) can have immediate and long-term toxic effects,” says Akanksha Mishra, a nutrition and wellness expert associated with myUpchar.

“Among immediate effects, you can see gastrointestinal symptoms such as severe vomiting, abdominal pain, diarrhoea and disruption in blood circulation. Long-term exposure to arsenic from different sources can cause cancer, skin lesions, dementia, cardiovascular disease and diabetes. In early childhood, exposure has been linked to negative impacts on brain development,” adds Mishra.

Many studies, including one in Environmental Health Perspectives in 2009, indicate that exposure to arsenic-contaminated food and water during pregnancy can also lead to miscarriage or low birth-weight and developmental difficulties in babies.

Why does rice have higher arsenic content?

All studies regarding rice and arsenic poisoning indicate that it’s the agricultural method used to cultivate rice that increases arsenic absorption in rice crops. A review article published in Frontiers in Sustainable Food Systems in May 2020 reveals that flood irrigation — the most common rice cultivation method used in India — using rainwater and groundwater is responsible for the arsenic contamination of rice crops. During this method, rice or paddy roots have a longer exposure to contaminated water and soil, increasing the rate of absorption.

The article also points out that the Gangetic basin is one of the largest regions of arsenic contamination in India, and this is where rice cultivation occurs extensively. Inorganic arsenic can persist in the soil indefinitely and can contaminate both rainwater as well as groundwater. The use of biochemical processes, like sprinkling of pesticides, also increases the arsenic content of the same soil and water.

How to avoid getting arsenic poisoning from rice

This article also mentions that India and other countries are examining different agronomic practices to reduce arsenic contamination in rice crops, but adopting these can be time-consuming. Meanwhile, what are rice consumers supposed to do?

Consumer Reports, the American non-profit which came out with an extensive report on the arsenic content in different rice varieties in 2012, reveals that rice varieties which have their husk removed and polished might have lesser arsenic content. It revealed that basmati rice from India and sushi rice grown in the US have the lowest inorganic arsenic content, while arsenic in brown rice, brown basmati rice and black rice (or forbidden rice) is much higher.

However, a 2017 study insists that basmati rice grown in Punjab and northwest parts of India have higher arsenic content and should be screened before consumption.

This is clearly too much of an ask since screening each variety of rice before consumption, or switching completely to bulgur, amaranth, buckwheat, barley, millets, quinoa and farro — all of which have low or no arsenic content — is not possible for all consumers.

Consumer Reports suggests the following two methods to reduce arsenic poisoning from rice, apart from limiting rice consumption:

1. Repeatedly and thoroughly rinse rice with clean water before cooking it. This will remove toxic substances on the skin or husk of the rice.

2. Cook a cup of rice in six cups of water until done, and drain out the excess water. This method, popular in eastern parts of India, is effective in removing all toxic substances from rice. Remember the 1:6 ratio.

For more information, read our article on White rice or brown rice, which is healthier?

Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.

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