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Throughout the Yangs River Delta, southern China is known for its extensive rice production, with farmers planting slender green stems. The grass plants soaked in muddy pool fields for months before they reached a few feet high and turned golden. Along the submerged plants, the embankment stores and distributes a stable supply of water, which farmers originate from nearby canals.
This traditional flooding practice is almost as old as the domestication of ancient grains. Thousands of years later, agricultural methods continue to dominate rice cultivation practices from low-lying fields in Arkansas to the vast terraces in Vietnam.
As the Earth heats up, the popularity of this popular rice has become increasingly dangerous for millions of people around the world, according to a study published Wednesday in the journal Lancet Planetary Health. After drinking water, rice is the world's second largest dietary source, the world's largest dietary source, and climate change appears to be increasing the amount of highly toxic chemicals in it, researchers say. Without any measures to change the way most of the world’s rice is produced, regulate the consumption of people in it or reduce warming, the authors concluded that communities containing rice diets may start to face an increased risk of cancer and disease in 2050.
“Our results are very scary,” said Wanging Wang, a PhD student in ecology at the Institute of Soil Science, Chinese Academy of Sciences, who led the paper. “It was a disaster…and a wake-up call.”
Back in 2014, Wang and an international team of climate, plant and public health scientists began working on a research project that would eventually bring them nearly a decade. They are trying to wading in large rice fields that wading in 2050, trying to discover how the projected temperature and atmospheric carbon dioxide levels interact with arsenic in the soil and the rice crops grown there. They know from past research that carcinogens are a problem in rice crops, but want to find out how many problems may still be in the warming world. The team not only stares at any rice, but some of the most produced cereal varieties worldwide.
Although there are estimated 40,000 species of rice on this planet, they tend to classify them into three categories depending on the length of the grain. Short-grained rice or sticky ones often used in sushi; long crystals, including aromatic types such as basmati and jasmine; and medium-grained rice, or rice that tends to be used as main courses. Among them, japonica and long-grained indica are two major subspecies that have been eaten in Asia. Wang's study simulates the growth of 28 strains of Japonica, Indica and Hybrid Rice, the core center of the continent's seven largest rice consumption and production countries: Bangladesh, China, India, Indonesia, Myanmar, the Philippines, the Philippines and Vietnam. India, Vietnam and China are one of the groups of eight countries that lead the rest of the world with rice exports.
After nearly a decade of observation and analysis of plant growth, the researchers found that the combination of higher temperatures and carbon dioxide promotes root growth, thereby improving the ability of rice plants to absorb arsenic from the soil. They believe this is because soil chemistry favors arsenic and climate-related changes can be absorbed into the grain more easily. Crops rich in carbon dioxide were found to capture more atmospheric carbon and pump some of them into the soil, stimulating the microorganisms that make arsenic.
The more roots grow, the more carbon there is in the soil, which may be a food source for soil bacteria that reproduce in warm temperatures. When the soil in rice is washed with water, oxygen is exhausted, causing soil bacteria to further rely on arsenic to generate energy. The end result is that more arsenic is built in the rice fields and more roots are incorporated into the developing grains.
The effects of these arsenic contain are related to content growth and carbon capture, which is an ambivalent surprise to Corey Lesk, a postdoctoral climate at Dartmouth College, and crop researchers have nothing to do with the paper. The paradox, Lesker said, is that both results are talked about as potential benefits to rice yields under climate change. “More roots can make rice drier, and cheaper carbon can increase yields overall,” he said. “However, additional arsenic accumulation may make the health benefits from this yield difficult to achieve.”
Arsenic comes in many different forms. Notoriously toxic, inorganic arsenic-compounds that do not contain carbon-the World Health Organization classifies it as “confirmed carcinogens” and “the most important chemical pollutant in drinking water worldwide.” This form of arsenic is often more toxic to humans because they are less stable than their organic counterparts and may allow arsenic to interact with molecules that increase exposure. Long-term exposure is associated with lung, bladder and skin cancer as well as heart disease, diabetes, adverse pregnancy, neurodevelopmental problems, as well as weakened immune system, and other health effects.
Over the years, scientists and public health experts have known that the presence of arsenic in food is an increasingly threatening threat, but dietary exposure has long been considered a less risk compared to contaminated groundwater. Therefore, policy measures to mitigate risks are slowing down. For example, a few existing standards formulated by the EU and China are considered inconsistent and largely unenforceable. No country has formally formulated regulations on exposure to organic arsenic in foods. (In the U.S., the Food and Drug Administration has established a level of action per billion arsenic in infant cereals, but recommendations to manufacturers are not enforceable regulations for arsenic in rice or any other food.)
Wang hopes to see this change. The levels of inorganic arsenic commonly found in rice today fall within China's recommended standards, for example, but her paper shows that lifetime bladder and lung cancer incidents are likely to increase “proportionally” to exposure by 2050. Under a “worst case” climate scenario, where global temperatures rise above 2 degrees Celsius (3.6 degrees Fahrenheit) and are coupled with CO2 levels that increase Another 200 parts per million, the levels of inorganic arsenic in the rice varieties studied are expected to increase by 44%. This means that more than half of the rice samples will exceed the limit currently proposed by China, which will limit every billion parts of inorganic arsenic in rice, with an estimated 13.4 million cancers associated with rice-based arsenic exposure.
Since these health risks are calculated based on weight, infants and young children will face the greatest health burden. In particular, babies may end up with huge risks from eating rice grains, according to researchers.
“You are talking about a crop staple that feeds billions of people, when you think more carbon dioxide and higher temperatures can significantly affect the amount of arsenic in that staple, the number of health consequences associated with numerous words because of the lack of better, huge, huge
But everyone shouldn't stop eating rice suddenly, he added. Although the team found that the amount of inorganic arsenic in rice was higher than that of many other plants, it was still very low overall. The key variable is how much rice a person eats. If you are one of the most regions where you consume rice multiple times a week, this looming health burden may apply to you, but if you do it occasionally, Ziska says you may end up being exposed to inorganic arsenic and you may not be “big.”
In this way, the predictions of this study may also deepen existing global and social inequality, as Rice has long been one of the most swallowed grains on the planet because it is also one of the most affordable grains.
In addition to mitigating global greenhouse gas emissions, what Ziska calls “waving my rainbow, unicorn and sprinkling wand” – adapts to the future efforts to avoid toxic rice, including rice paddie farmers grown earlier in the season to avoid developing seeds, soil management, better soil management and plant reproduction in warm temperatures to minimize the reproduction of rice, thus allowing numerous fuels to reproduce.
Water-saving irrigation techniques, such as alternating wetting and drying, first submerged rice fields and then dried over the cycle, can also be used to reduce these increased health risks. and The huge methane footprint of the cereal. Globally, rice production accounts for about 8% of all methane emissions in human activities – submerged rice fields are ideal for methane-emitting bacteria.
“I know this field is not sexy, it has the same atmosphere as the apocalypse, sea level rise, 10 storms,” Ziska said. “But I'm honest about telling you that it will have the greatest effect on human side because we all eat.”
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