Arsenic is one of the world’s most toxic elements.
Throughout history, it has been infiltrating the food chain and finding its way into our foods.
However, this problem is now getting worse.
Widespread pollution is raising the levels of arsenic in foods, posing a serious health risk.
Recently, studies have detected high levels of arsenic in rice.
This is a major concern, since rice is a staple food for a large part of the world’s population.
What is Arsenic?
Arsenic is a toxic trace element, denoted by the symbol As.
It is not usually found on its own. Rather, it is bound with other elements in chemical compounds.
These compounds can be divided into two broad categories (1):
Organic arsenic: mainly found in plant and animal tissues.
Inorganic arsenic: found in rocks and soil or dissolved in water. This is the more toxic form.
Both forms are naturally present in the environment, but their levels have been increasing due to pollution.
For a number of reasons, rice may accumulate a significant amount of inorganic arsenic (the more toxic form) from the environment.
Dietary Sources of Arsenic
Arsenic is found in nearly all foods and drinks, but is usually only found in small amounts.
In contrast, relatively high levels are found in:
Contaminated drinking water: Millions of people around the world are exposed to drinking water that contains high amounts of inorganic arsenic. This is most common in South America and Asia (2, 3).
Seafood: Fish, shrimp, shellfish and other seafood may contain significant amounts of organic arsenic, the less toxic form. However, mussels and certain types of seaweed may contain inorganic arsenic as well (4, 5, 6).
Rice and rice-based foods: Rice accumulates more arsenic than other food crops. In fact, it is the single biggest food source of inorganic arsenic, which is the more toxic form (7, 8, 9, 10).
High levels of inorganic arsenic have been detected in many rice-based products, such as:
Rice milk (11).
Rice bran (12, 13).
Rice-based breakfast cereals (13).
Rice cereal (baby rice) (14, 15).
Rice crackers (13).
Brown rice syrup (16).
Cereal bars containing rice and/or brown rice syrup.
Bottom Line: Seafood contains arsenic, but mostly the organic form. Rice and rice-based products may contain high levels of the inorganic (more toxic) form.
Why is Arsenic Found in Rice?
White Rice in a Glass Bowl
Arsenic naturally occurs in water, soil and rocks, but its levels may be higher in some areas than others.
It readily enters the food chain and may accumulate in significant amounts in both animals and plants, some of which are eaten by humans.
As a result of human activities, arsenic pollution has been rising.
The main sources of arsenic pollution include certain pesticides and herbicides, wood preservatives, phosphate fertilizers, industrial waste, mining activities, coal burning and smelting (17, 18, 19).
Arsenic often drains into groundwater, which is heavily polluted in certain parts of the world (20, 21).
From groundwater, arsenic finds its way into wells and other water supplies that may be used for crop irrigation and cooking (22).
Paddy rice is particularly susceptible to arsenic contamination, for three reasons:
It is grown in flooded fields (paddy fields) that require high quantities of irrigation water. In many areas, this irrigation water is contaminated with arsenic
Arsenic may accumulate in the soil of paddy fields, worsening the problem.
Rice absorbs more arsenic from water and soil compared to other common food crops .
Using contaminated water for cooking is another concern, because rice grains easily absorb arsenic from cooking water when they are boiled