A Columbia University study warns that climate change increases arsenic in rice

Climate change could be resulting in higher levels of arsenic in rice, potentially increasing lifetime cancer and health risks for people in Asian countries by 2050, according to a new study published in The Lancet Planetary Health journal.

Researchers from Columbia University, US, explained that an increase in temperatures above 2 degrees Celsius and rising levels of carbon dioxide could be causing changes in soil chemistry, favouring arsenic, which gets more easily absorbed into a rice grain.

Contaminated soil and irrigated water while growing rice are known to increase inorganic arsenic in rice.

An increased exposure to arsenic is known to heighten the risk of cancers of the lung, bladder and skin, among others. Rice can also absorb additional arsenic from water used for cooking.

"Our results suggest that this increase in arsenic levels could significantly elevate the incidence of heart disease, diabetes, and other non-cancer health effects," author Lewis Ziska, associate professor of environmental health sciences, Columbia University, said.

"As rice is a dietary staple in many parts of the world, these changes could lead to a substantial rise in the global burden of cancer, cardiovascular diseases, and other arsenic-related health issues," Ziska said.

Studies have revealed rice consumption to be a major health threat to people in South and Southeast Asian countries, including India, Bangladesh, Nepal, Thailand and Vietnam, where rice is the staple food.

The combined effects of rising CO2 and temperatures on arsenic accumulation in rice have not been studied in detail until now, the team said.

In this study, the researchers measured the effects of rising temperatures and carbon dioxide on 28 rice strains over 10 years in the field. Using models, inorganic arsenic doses and health risks for seven Asian countries -- Bangladesh, China, India, Indonesia, Myanmar, the Philippines, and Vietnam -- were estimated.

"We found that temperature and CO2 act synergistically to increase arsenic concentrations in rice, compounding dietary arsenic exposures for rice consumers and leading to projected cancer cases in the tens of millions among populations of Asian countries in 2050," according to the study.

Projected average cases of bladder and lung cancer in 2050 were found to increase in proportion with exposure to arsenic, with the highest risk projections (44 per cent) seen for rising temperatures and carbon dioxide levels.

China was projected to see 1.34 crore cases of cancer attributable to arsenic in rice in 2050 -- the highest among the seven countries studied.

"Emerging evidence also suggests that arsenic exposure may be linked to diabetes, adverse pregnancy outcomes, neurodevelopmental issues, and immune system effects," Ziska said.

The authors suggested measures to reduce arsenic exposure, including breeding plants to minimise arsenic uptake and improved soil management in rice paddies, along with public health initiatives.