Posted on April, 25, 2025 at 09:36 am
An estimated 3.5 billion people around the globe depend on rice as a food staple. According to the Alliance of Bioversity International and the International Center for Tropical Agriculture, these 3.5 billion individuals rely on rice for "more than 20% of their daily calories. By 2035, an additional 116 million tons of rice will be needed to feed the planet's growing population."
It added that rice consumption is growing faster than any other commodity in Africa "because the growing urban population considers it a convenience food." However, a new study published in the journal Lancet Planetary Health has found that rice and access to it may be in serious danger.
In April, researchers from Columbia University published the findings of their study on the impact of climate change on arsenic concentrations in paddy rice in Asia. And the findings are, quite simply, alarming.
To be clear, rice has always contained some level of arsenic, a naturally occurring element found in soil that is toxic to humans, especially in its "inorganic" form, which the National Institute of Environmental Health Sciences (NIEHS) explains can cause a range of health issues, including lung and bladder cancers, heart disease, diabetes, and developmental problems in children. The NIEHS notes, "It is not possible to remove arsenic entirely from the environment or food supply."
The way rice grows in water-filled paddies, along with its porous nature, allows it to easily absorb contaminants like arsenic. However, the researchers who partnered with scientists from China and Johns Hopkins for the report aimed to determine how rice and its contaminants will appear in the future.
To figure this out, the team cultivated 28 popular rice varieties in four open-air paddies in China's Yangtze River Delta from 2014 to 2023. They surrounded each paddy with metal rings to increase the surrounding air's carbon dioxide level by about 200 parts per million during the day, which is approximately the amount scientists believe will rise by the mid-21st century. They also equipped two of the sites with infrared heaters to maintain the water at about 2°C (3.6°F) warmer than usual, again to replicate the anticipated future climate.
The scientists would then periodically harvest grain, stems, and leaves, as well as mud samples, to measure the levels of arsenic and other microorganisms. They found that when carbon dioxide levels rose independently, arsenic levels in the rice kernels barely increased. When measuring the arsenic concentrations with an increase in temperature, arsenic levels rose noticeably higher. However, when heat and extra carbon dioxide were combined, the arsenic levels surged far more than either factor alone, which the authors called a "synergistic increase."
"Previous work has focused on individual responses — some on carbon dioxide and some on temperature, but not both, and not on a wide range of rice genetics," Lewis Ziska, a plant physiologist and associate professor at Columbia University, told Climate News. "We knew that temperature by itself could increase levels, and carbon dioxide by a little bit. But when we put both of them together, then wow, that was really something we were not expecting. You're looking at a crop staple that's consumed by a billion people every day, and any effect on toxicity is going to have a pretty damn large effect."
Additionally, the researchers ran computer models for seven countries where rice is the main dish, including Bangladesh, China, India, Indonesia, Myanmar, the Philippines, and Vietnam. They used current rice consumption figures and projections for the 2050 populations, along with data collected from their sample rice fields. They found that under today's climate, approximately 13.4 million lifetime cancer cases in China can be attributed to arsenic in rice. However, under the warmer, high carbon dioxide scenario, that number will jump to 19.3 million. Across all seven countries, the risks of cancer and other chronic diseases rose by about 44%.
"There is a toxicological effect of climate change relative to one of the most consumed staples in the world," Ziska additionally told Inside Climate News, adding, "and the consumption is one of the hallmarks of whether you're going to be vulnerable to that effect."
There is, however, at least a sliver of hope in this report. The researchers note that techniques like alternating wetting and drying of paddies can introduce bursts of oxygen, which may help keep arsenic levels at bay. They also state that scientists could breed more arsenic-resistant strains of rice for future planting.
There are also steps you can take at home to reduce your arsenic exposure. According to Ohio State University, you can try rinsing rice thoroughly when it's in its raw state and cooking it in extra water that you pour off later. This method has been shown to lower the levels of arsenic in your final dish by as much as 60%.
Of course, none of these address our growing climate crisis. However, perhaps this study is the reminder some need. "Rice has always been a food where arsenic is an issue, and climate change is making it worse," Keeve Nachman, one of the report's authors and a professor at Johns Hopkins University, added. "This is one more reason to intervene — to control people's exposure. The number one thing we can do is everything in our power to slow climate change."
Source: FAW