About 200 million people worldwide are reported to be affected by the consumption of arsenic via contaminated groundwater and food crops. The health risks to humans include chronic respiratory disease, liver fibrosis, cardiovascular diseases, skin cancer, and lung cancer.
What is arsenic, why does rice take it up?
Arsenic is a natural component found in our earth’s crust. The arsenic concentration of Earth’s crust is just 1 to 1.8 mg/kg. It is toxic in its inorganic form and studies have found inorganic arsenic in many rice varieties and rice-based products.
Though pesticides that contain arsenic are mostly banned now, studies have shown that arsenic can remain in the soil for centuries.
Rice plants have a higher tendency to take up arsenic than other cereals as they are grown under submerged soil conditions. This environment increases the dissolved concentration of the chemical that is readily available for the plant.
A paper published in April suggested that arsenic uptake by rice plants can increase with climate change. They note that “elevated temperature can increase arsenic concentrations in rice tissue, exacerbating an existing threat to rice quality and human health.”
Which rice varieties store more arsenic?
Previous studies from various countries have shown that some rice varieties (EPAGRI 108, TCSY 837 and Kalijira) have a tendency to accumulate less arsenic in grains while others (BRRI dhan 47, BRRI dhan 32 and IIY 416) accumulate a higher amount.
In the recent work, the team tested 15 rice varieties from three distinct groups — local aromatic rice, high yielding varieties and hybrid rice — in a naturally contaminated field following standard cultivation practices.
They studied the shoot, root at three different growth stages and all fractions of grains (polished rice, bran, husk) for arsenic accumulation.
They noticed that the local aromatic rice varieties such as Radhatilak, Gobindabhog, Badsabhog, Dudheswar accumulated the lowest amount of arsenic.
“This study has confirmed worrisome levels of arsenic in some popular high yielding (Swarna masuri, CR dhan, Pratikhya) and hybrid varieties (Pro-agro, CR dhan, Arize, Rajalaxmi, Ajay) in the market,” says the first author of the paper Rubina Khanam, Scientist from the Crop Production Division of the ICAR-National Rice Research Institute, Cuttack. “The good news is to those consuming local aromatic and few high yielding varieties (Satabdi, Swarna) on a regular basis. We recommend that farmers of arsenuc contaminated areas grow these varieties to curb arsenic toxicity to humans.”
How do I know if my rice has arsenic?
“Currently, there are no home tests that you can do. The best way to be safe is to cook rice in the traditional gruel way and discard the water. A major part of grain arsenic will be eliminated. Try not to pressure cook rice,” says Professor Biswapati Mandal, a co-author from the Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi Viswavidyalaya, West Bengal.
The team adds that our government can give incentives and persuade farmers to grow those screened varieties that accumulate less arsenic in the contaminated areas.