Rice is one of the most consumed foods worldwide, being the basis of daily food for thousands of millions of people. Its importance goes far beyond cooking, playing an essential role in global food security. However, a new study raises serious concerns: With the advancement of climate change, rice may become more toxic, endangering public health.
A growing risk with global warming
According to a recent study published in The Lancet Planetary Health, quoted by, rice can become more dangerous for human consumption as global temperatures increase and carbon dioxide (CO₂) levels in the atmosphere rise. This combination is being associated with an increase in rice arsenic levels, a toxic and carcinogenic element.
According to the investigation, led by an international team of scientists from the United States and China, this scenario could affect thousands of millions of people, especially in developing countries, where rice is the main source of livelihood.
How the rice absorbs the arsenic
Rice cultivation is in itself a part of the problem. As it is usually cultivated in flooded fields, rice ends up absorbing not only water but all that is in it, including the arsenic, whether of natural origin or result of human activity, becoming more toxic.
“This is a basic culture that is consumed by billions of people every day, and any effect on toxicity will have a very large impact,” says Lewis Ziska, plant physiologist and associate professor at Columbia University.
The impact of climate change
Ziska has been studying rice for over 30 years, with a particular focus on the effects of climate change on the nutritional value of food. In this study, he joined efforts with researchers from various institutions to analyze how temperature increases and CO₂ affects arsenic levels in rice.
The results surprised even the researchers themselves. “We knew that the temperature in itself could increase the levels, and CO₂ a little. But when we put together the two, then, Wow, it was something we weren’t waiting,” admits Ziska.
Field experiences with worrying results
For six years, scientists have cultivated rice in controlled fields, exposed to different levels of CO₂ and temperature, simulating the conditions that are foreseen for the coming decades. The results were clear: when both factors increase, the concentration of arsenic, especially the most dangerous inorganic, also grows in rice grains. This type of arsenic is associated with various health problems, including skin, bladder and lung cancer, cardiovascular disease and neurological damage in babies.
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Submerged cultivation facilitates contamination
The method of cultivation of rice, with flooded fields, prevents the growth of weeds but creates an environment conducive to the accumulation of arsenic in the soil and water. Rice, because it has a highly porous structure, quickly absorbs this water and, with it, the arsenic, becoming more toxic.
“What happens in rice, due to complex biogeochemical processes in the soil, is that when the temperature and CO₂ increase, the inorganic arsenic increases as well,” explains Ziska. “And it is this inorganic arsenium that poses the highest risk to health.”
An old problem that gets worse
“Rice has always been a food in which arsenic is a problem, and climate change is aggravating it,” says Keeve Nachman, a professor at Johns Hopkins University and a specialist on the impacts of food production on health. According to Nachman, this new study reinforces the need to act, both in combating climate change and in the implementation of measures to reduce the exposure of the population to this contaminant.
An invisible threat
Although arsenic naturally occurs in many environments, including soils and groundwater, its presence in rice, a daily consumed food by millions, is especially worrying. In places with high rice consumption, inorganic arsenic exposure has been associated with higher rates of serious diseases.
The solutions pointed out by the researchers include changes in cultivation methods, with less use of water and practices that limit the absorption of arsenic by plants. In addition, they defend more rigorous policies of environmental and food control, as well as the reinforcement of the investigation in this area.
The urgency to act
“This is one more reason to intervene, to control people’s exposure. The first thing we can do is all we can to slow down climate change,” concludes Keeve Nachman.
Given a challenge that affects both public health and global food safety, the answer will have to be rapid, coordinated and based on science. After all, when the most basic food on the planet becomes a possible threat, there is no time to lose.
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