Arsenic in Rice Could Cause 13.4 Million Cancer Cases, Study Warns

Flooding rice paddies—a traditional method of growing the water-intensive crop—is becoming increasingly hazardous due to rising levels of arsenic, researchers warn.

More than half of the rice samples studied would then exceed China’s proposed arsenic limit of 200 parts per billion.

A study published April 16 in The Lancet Planetary Health estimates that climate-driven increases in arsenic could cause as many as 13.4 million cancer cases by 2050. Ayurella Horn-Muller reported the findings for environmental outlet Grist.

“It's a disaster… and a wake-up call,” said Donming Wang, the doctoral student at the Chinese Academy of Sciences who led the decade-long research project.

The study examined how rising global temperatures and increased atmospheric CO₂ levels interact with arsenic-laden soil and rice crops.

Researchers studied three types of rice—short, medium, and long grain—grown in seven countries: Bangladesh, China, India, Indonesia, Myanmar, the Philippines, and Vietnam.

They found that higher temperatures and CO₂ concentrations stimulate rice root growth, which in turn leads to greater arsenic absorption from the soil. The CO₂ also enhances microbial activity that releases more arsenic into the soil.

Inorganic arsenic, a form not bonded with carbon, is classified by the World Health Organization (WHO) as a “confirmed carcinogen” and is the second-largest source of dietary arsenic globally, after drinking water.

Chronic exposure is linked to lung, bladder, and skin cancers, as well as heart disease, diabetes, developmental issues, and weakened immune systems.

Under a worst-case climate scenario—where global temperatures exceed 2°C (3.6°F) and CO₂ levels increase by another 200 parts per million—the study found inorganic arsenic levels in rice could rise by 44%.

More than half of the rice samples studied would then exceed China’s proposed arsenic limit of 200 parts per billion, with an estimated 13.4 million arsenic-related cancer cases possible by 2050.