Arsenic in rice: is it an actual problem?

We have had quite a few readers ask us about arsenic in rice and if it is a problem. Well, the answer is both yes and no! To break it down further, however, we need to take a deeper dive into the topic.


Arsenic is one of the most toxic elements in the world, and is found throughout nature in various concentrations (rocks, groundwater, soil, living beings, foods, drinks…). Its presence in nature is mostly unnoteworthy, with our bodies being able to handle certain low levels of this substance. That being said, increased levels of this element in nature can be attributed to human activity, such as agriculture, mining, and various other forms of industry. Arsenic is found in two forms, both of which may be converted to the other; it may be an organic compound, or it may be an inorganic salt. The latter (also known as inorganic arsenic) is more toxic than the organic variety, which is sometimes even used in medicines. Until the discovery of antibiotics in the mid 20th century, organic arsenic (known as salvarzan) was the most effective drug against syphilis! Various arsenic compounds were also used in veterinary medicines, and until fairly recently were used to protect wood.

The biggest problem with arsenic is its presence in drinking water. In some parts of South America and Asia, for example, millions of people are exposed to drinking water that contains large amounts of inorganic arsenic. This is especially problematic as we consume more water than any other substance. Fish and various other sea foods also tend to contain higher levels of arsenic; this is usually the less toxic organic form, but not always!

Recently, a great deal has been written about the arsenic content of rice, especially as rice is a staple food for a large proportion of the world’s population. Most of the arsenic in rice is inorganic (and thus more toxic). Compared to other plant foods, the arsenic content of rice is indeed very high. This is because different plants absorb and accumulate different minerals from soil and water at varying rates. A recent study carried out by members of Hungry Pumpkin team showed this quite well, with yarrow (Achillea millefolium), nettles (Urtica dioca), and narrow-leaved plantain (Plantago lanceolata) each accumulating different metals despite growing in the same contaminated soil. The yarrow had ten times more cadmium than the nettle, and the narrow-leaved plantain had ten times more lead than the other two plants, which had similar amounts. 

In addition to its biological tendency to accumulate arsenic, there is another reason for the high content in rice: the way we produce it. The rice paddies are irrigated with groundwater, which, in some parts of the world, may be strongly polluted with arsenic. Rainwater, on the other hand, is free of arsenic. 


Effects of Arsenic on Health

High doses of arsenic (around 100 mg) are acutely toxic, meaning they rapidly cause a range of health issues and even death. Arsenic in our diets is present in quantities thousands of times smaller and does not cause an immediate poisoning. However, prolonged intake of small amounts of arsenic may also lead to health issues and increase the risk of various chronic health issues such as cancer, cardiovascular disease, diabetes, nervous system conditions, and skin rashes. That being said, we need to be aware that arsenic is naturally present all around us and can never actually be completely avoided.

So, this then brings up an important question: just what sort of arsenic concentration IS acceptable? Regulations for drinking water set maximum acceptable arsenic levels at 10 μg / L, which is 10 parts per billion. This is about as much as dissolving 1 g of arsenic (about a teaspoon) in a swimming pool. Such a low concentration is difficult to detect by chemical analysis. According to the World Health Organisation (WHO), such a limit would cause 6 people out of 10 000 to develop arsenic-related cancers in their lifetime. Is this acceptable? If the norms for arsenic concentration were reduced by a factor of 10 (to 1 μg / L), cancer would occur ten times less frequently, in other words, in 6 people of every 100 000. Is this acceptable?

Experts have acknowledged that the current limits are not the most appropriate and that they should be lowered, as the limits for other contaminants are set as to not cause cancer in more than 1 out of every 100 000 people with lifelong exposure. The permissible concentration of arsenic in water is not reduced due to two practical issues: 1) lower concentrations could not be controlled by most laboratory analysis as the instruments required to measure more precisely are not widely available and 2) a large part of the world’s population would then be left without drinking water as it would be impossible to provide a lower concentration to them. The WHO estimates that 140 million people across 50 countries drink water that does not even meet our current and less stringent standards. In Bangladesh, for example, the soil structure is the main issue, and as many as 20 million people drink water contaminated with arsenic, reaching concentrations as high as 50 μg / L. On the other side of the planet in the USA, often seen as a rich and prosperous nation in the global capitalist paradigm, areas in the west and centre of the country see as much as 12% of drinking water contaminated with levels of arsenic above 20 μg / L.


How much arsenic is in rice?

Various sources place the arsenic content of rice between 10 and 500 μg of arsenic per kg of rice. So, not all rice contains a lot of arsenic, but determining the arsenic content of a [particular rice is virtually impossible for us as consumers. Area of origin for the rice cannot be used as a means of figuring this out, as such contamination occurs worldwide. 

Some websites offer tips on how to reduce the arsenic content of rice, but they are not very effective. The arsenic content of rice can be reduced by washing and cooking the rice in large amounts of clean water, which is then drained and discarded, however, this still leaves about 75% of the arsenic in the rice, while removing many of the nutrients and using a large amount of water. As we also noted, drinking water in many places also contains arsenic, so this washing procedure would not help. All this being said, aromatic rices such as basmati and jasmine tend to contain less arsenic. 

Should we be concerned about arsenic in rice?

There is no doubt that arsenic poses a health risk to humans, especially those eating large quantities of rice every day, meaning it is especially risky for people eating Asian diets, which use rice as an essential core component. Young children may also be more at risk, as there are many rice-based products created for them. This is also true for people on milk- and gluten-free diets. Rice-based baby formulas, rice crackers, puddings, and rice milks often make up large portions of the diets for these individuals. Young children are especially vulnerable due to their small body size.

Though arsenic in rice is indeed a problem, it is not necessary to panic and solely focus on this. There are also many measures much more effective in cutting your arsenic intake than skipping rice. Data shows that the average American consumes 4.2 μg of arsenic per day with drinking water, while with rice they get “only” 1.4 μg. Americans with an Asian diet consume 2.8 μg per day via rice. That being said, a box of cigarettes will put 2.4 μg of arsenic into your body while giving you no nutritional benefit and introducing various other dangerous substances. To remind ourselves of dosing, 100,000 μg of arsenic (though in its organic and less toxic form) was once used for treating syphilis. An interesting study analysed arsenic content in 38 different rices, 195 milk samples, 82 wine samples (among many more) for a total of 3 000 food and beverage samples. Rice was only in fourth place in terms of arsenic content, with 0.5 μg per 100 g portion. Meat contained twice as much, cheese contained ten times as much, and fish contained 100 time more arsenic than rice! Depending on your diet, you need to be wary of different things. For example, a Mediterranean diet will introduce more arsenic through bread and wine than it will through rice due to the frequency and serving size of each. 

So, we can safely say that smokers and those eating meat and cheese do not need to worry about arsenic content in rice, as they are already getting more of it from those sources than they will from the rice!


Additional reading:

https://www.healthline.com/nutrition/arsenic-in-rice

https://www.consumerreports.org/cro/magazine/2012/11/arsenic-in-your-food/index.htm

https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.7907

https://en.wikipedia.org/wiki/Arsenic_poisoning

https://ofmpub.epa.gov/eims/eimscomm.getfile?p_download_id=494843

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