Science Snippets: Climate Change Drives Increased Arsenic in Rice

Draft script:

Rice is an important food for billions of people on Earth. Ongoing climate change is the most abrupt in planetary history. Ongoing climate change is also irreversible. The combination of rice as an important staple crop for billions of people and abrupt, irreversible climate change spells disaster when the rice contains a dangerous level of arsenic.

The BBC published an article on 18 April 2025 titled How climate change could affect arsenic in rice. Here’s the lede: “Rice is a staple food for billions of people around the planet, but a new study suggests climate change may increase arsenic levels contained within the grain.” The two sentences comprising the following paragraph point out the danger we face: “Rice is a staple food for more than half of the global population. It is consumed on a daily basis by more people than either wheat or maize, also known as corn.”

The single sentence comprising the next paragraph puts a typically British spin on this horrible news: “So it is with some concern that scientists have unveiled a recent finding: that as carbon emissions rise and the Earth continues to warm, so too will arsenic levels in rice.”

Consumption of arsenic can lead to long-term health issues, including gastrointestinal distress, decreased production of blood, neurological damage, and death. For the BBC, “it is with some concern that as carbon emissions rise and the Earth continues to warm, so too will arsenic levels in rice.”

Were I consuming rice with high levels of arsenic, I suspect concern would not be the first word that would come to mind. I am reasonably comfortable with the thought of my death in the near term. I am not comfortable with my death resulting from arsenic poisoning or any other issue that is preventable. Our society managed to significantly reduce lead as a hazard in paint and in the air. Are we still aiming for a future with preventable deaths from arsenic poisoning? Is this a cause for “some concern”?

Three paragraphs in the story from the BBC provide a reasonable overview of arsenic in rice: “The presence of arsenic in rice has long been known as a problem. Almost all rice contains arsenic. The harmful, naturally occurring chemical can accumulate in the soil of paddy fields, leaching into the grains of rice grown there. But the amounts found in rice grains can vary considerably from well below the recommended limits set by regulatory bodies to several times higher.

Yet, consuming even low amounts of inorganic arsenic through food or drinking water can lead to cancers and a range of other health problems, such as cardiovascular disease and diabetes.

Researchers around the world have been working on ways to reduce the levels of arsenic in rice – and in the meantime, there are ways of cooking it that can extract some of this harmful element from grains (see the box further down the story for more).”

These three paragraphs provide an excellent setup to introduce a peer-reviewed paper: “[A] new study of inorganic arsenic accumulation has found it may become a greater problem due to climate change. The researchers grew 28 different strains of paddy rice at four different locations in China in experimental conditions over a 10-year period.”

The peer-reviewed, open-access paper was published 16 April 2025 in The Lancet Planetary Health. It was created by 30 scholars and titled Impact of climate change on arsenic concentrations in paddy rice and the associated dietary health risks in Asia: an experimental and modelling study.

The peer-reviewed paper begins with a Summary that contains this information: “… Rising global atmospheric carbon dioxide … concentrations and surface temperatures could negatively affect rice yields and nutritional quality; however, their effects on arsenic accumulation in paddy rice have not been assessed concurrently. We aimed to assess the impact of increases in CO₂ and temperature (individually and in combination) on arsenic concentrations in rice, characterise soil properties that might influence arsenic uptake, and model the associated risks of cancer and other health outcomes due to increased arsenic exposure.

… Concomitant increases in CO₂ and temperature resulted in a synergistic increase of inorganic arsenic in rice grain. The observed increase is likely to be related to changes in soil biogeochemistry that favoured reduced arsenic species. Modelled consumption of rice under these conditions resulted in projected increases in inorganic arsenic exposure and lifetime cancer and health risks for multiple Asian countries by 2050. Interpretation Inorganic arsenic exposure and the associated health consequences might increase in rice grain grown in flooded systems with mid-century climate projections. The current assessment reinforces the urgent need for mitigation of arsenic exposure in rice relative to near-term climate change.

… Inorganic arsenic exposure and the associated health consequences might increase in rice grain grown in flooded systems with mid-century climate projections. The current assessment reinforces the urgent need for mitigation of arsenic exposure in rice relative to near-term climate change.”

As you probably know, I strongly suspect “lifetime cancer and health risks … by 2050” is an understatement. I doubt there will be humans on Earth at that late date. Nonetheless, the admission of “lifetime cancer and health risks for multiple Asian countries” is a surprisingly serious concern brought to us from a corporate media outlet and a peer-reviewed paper.

A Discussion section concludes the peer-reviewed paper with more bad news: “policy measures to control dietary arsenic exposures are inconsistent across countries and largely voluntary, inadequately comprehensive, or unenforced. For example, the US Food and Drug Administration has recommended a nonregulatory action level of 100 ppb of inorganic arsenic in infant rice cereal but does not formally regulate arsenic in rice or any other food. The European Union has established an enforceable inorganic arsenic standard of 100 ppb for rice used in foods for infants and children, as well as more tolerant standards for rice and other foods containing rice ranging from 200 to 300 ppb. China has proposed a limit of 200 ppb for inorganic arsenic in paddy rice; under elevated temperature and CO₂ conditions, more than half the rice samples in our study would have exceeded this limit ... To date, no countries or jurisdictions have established regulatory standards or guidance for organic arsenic species in foods.”

That final sentence is astonishing, considering our vast knowledge of arsenic in rice and other foods: “To date, no countries or jurisdictions have established regulatory standards or guidance for organic arsenic species in foods.” What are we waiting for? Even with my dire outlook on our future, I’m a fan of relevant actions that could extend our lives. Even better, we can maintain our health. This will allow us to appreciate the time we have remaining. A long life is only worthy if it is a long, healthy life.