Rising temperatures, carbon could bump up arsenic in rice

Scientists of the Columbia University’s Mailman School of Public Health, in New York/ USA, and the Chinese Academy of Sciences show in a recent study that increased temperatures above two degrees, coupled with rising carbon dioxide levels, lead to higher concentrations of inorganic arsenic in rice.

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 especially for populations in Asia by 2050, according to the study, which was published in The Lancet Planetary Health in April.

“Ingesting rice in regions like southern China and Southeast and South Asia is already a significant source of dietary arsenic and cancer risk,” said Lewis Ziska, an associate professor in environmental health sciences at the Mailman School of Public Health and lead researcher of the study. Ziska explained that the higher arsenic levels are likely due to climate-related changes in soil chemistry that make it more easily absorbed into rice grain.

Long-term field experiments with 28 rice strains in seven Asian countries  

In their study, the researchers measured the effects of rising temperatures and carbon dioxide on 28 rice strains over ten years in the field. They used a method called Free-Air CO₂ Enrichment, which involves elevating levels of CO2 in a specified area, and advanced modelling techniques. This helped them estimate inorganic arsenic doses and health risks, including for cancer, in seven Asian countries: Bangladesh, China, India, Indonesia, Myanmar, the Philippines and Vietnam.

Country estimates of rice availability in 2021, as reported by the UN Food and Agriculture Organization (FAO), were used as the starting point for estimating rice ingestion. The standard deviation of rice ingestion per kilogramme bodyweight from US Environmental Protection Agency data was used to create a normal distribution for each country.

“We found that concurrent increases in temperature and CO₂ can act synergistically to increase inorganic arsenic in multiple rice lines that are grown throughout Southeast Asia, and that this increase will alter the health consequences for rice consuming populations,” Ziska told SciDev.Net.

He noted that until now, the combined effects of rising carbon dioxide and temperatures on arsenic accumulation in rice have not been studied in detail.

Limiting harm

The researchers suggest several actions that could help reduce arsenic exposure in the future. “These include efforts in plant breeding to minimise arsenic uptake, improved soil management in rice paddies and better processing practices,” Ziska said.

“Along with public health initiatives focused on consumer education and exposure monitoring, [these] could play a critical role in mitigating the health impacts of climate change on rice consumption.”

(ScidevNet/Dann Okoith/wi)

Reference:
“Impact of climate change on arsenic concentrations in paddy rice and the associated dietary health risks in Asia: an experimental and modelling study” Lewis H. Ziska et al.; The Lancet Planetary Health, April 2025

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