A study by Columbia University’s Mailman School of Public Health and the Chinese Academy of Sciences warns that climate change and rising carbon dioxide may increase toxic inorganic arsenic in paddy rice. Inorganic arsenic forms when arsenic combines with non-carbon elements such as oxygen or sulphur and is more toxic than organic arsenic in seafood. Long-term exposure can cause cancers of the lung, bladder and skin and is linked to heart disease and diabetes.
The researchers found that temperatures above two degrees combined with higher atmospheric CO2 led to higher inorganic arsenic concentrations in rice grain. Lead researcher Lewis Ziska said the rise is likely due to climate-driven changes in soil chemistry that make arsenic easier for rice plants to absorb. The study measured effects on 28 rice strains in field experiments over ten years using Free-Air CO2 Enrichment and modelling to estimate doses and health risks for seven Asian countries.
To reduce harm the team recommends plant breeding to limit uptake, improved soil management, better processing and public health measures. External experts add that washing and careful cooking can lower arsenic and that adding nutrients like silicon, phosphorus and iron during growth can reduce uptake; breeders report progress but wider adoption needs funding.
Difficult words
- inorganic — not containing carbon; made of other elements
- arsenic — a toxic chemical element often in soil and water
- exposure — contact with something harmful over time
- uptake — process of taking a substance into a plant
- breed — produce new plant varieties by controlled crossingbreeding
- model — make a simplified representation to study effectsmodelling
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Discussion questions
- How could plant breeding and soil management reduce arsenic in rice where you live?
- What changes in washing or cooking rice could people use to lower arsenic exposure in their meals?
- What difficulties might prevent farmers from adopting new rice varieties or improved soil methods?
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