Arsenic

Updated: October 2024

What is it?

Arsenic (known as As and number 33 on the Periodic Table) is a semi-metallic solid. Arsenic occurs widely in the environment from natural sources, such as deposits in the earth; and from man-made sources such as metal manufacturing, combustion of fossil fuels, and pesticide use with agricultural products.

Where do we find it?

Arsenic is used as a wood preservative, as an integral electronic component, and as an ingredient in foreign pesticides. Arsenic use in the U.S. has dramatically decreased in both pesticides and wood preservatives, though wood preserved with arsenic manufactured prior to 2003 can still be used. In addition to manufactured sources, arsenic leaches from bedrock into soil and water, often as a result of mining and erosion. It also can be found in the air from the combustion of fossil fuels. Both natural and manufactured sources of arsenic contribute to the presence in the food supply either from the environment where foods are processed or from the soil the crops are grown in.

What are the types of Arsenic?

There are two main types of arsenic, organic and inorganic. Organic arsenic (arsenic that is attached to a carbon atom) is generally considered non-toxic as compared to inorganic arsenic. The organic arsenic compound arsenobetaine is the most common form of arsenic in seafood and is considered non-toxic to humans. In July 2024, the European Food Safety Authority (EFSA) published a risk assessment on the dietary exposure to two small organic arsenic species -- dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) – suggested it may be a health concern. Though more extensive studies and methodologies need to be explored to better understand the toxicity and the potential adverse health effects. The FDA is monitoring emerging research on possible health risks from these forms of organic arsenic and plans to continue monitoring both inorganic and organic forms of arsenic in foods.

Inorganic arsenic is known to be more toxic to human health. The main sources in the food supply for these species are found in rice and rice products, grains, fruit juices and drinking water from private wells. Exposure to high levels of inorganic arsenic can result in adverse neurological effects such as learning disabilities and behavior difficulties. Fetuses, infants and children are the most vulnerable due to their small body sizes. In adults, long-term exposure to inorganic arsenic has been associated with various cancers and cardiovascular disease.

How is inorganic arsenic monitored?

The U.S. Food and Drug Administration (FDA) has been measuring arsenic levels in food since the early 1990's through their Total Diet Study program, FDA's Toxic Elements in Food and Foodware, and Radionuclides in Food compliance program, and other surveys. The surveys can be in response to an increase in contaminated levels of inorganic arsenic in food or conducted annually.

How is Inorganic Arsenic being Regulated?

There are no FDA regulations to authorize arsenic for use as a color or food additive. In August 2020, FDA established an action level of 100 ppb for inorganic arsenic in infant rice cereal. In June 2023, FDA established an action level of 10 ppb for inorganic arsenic in apple juice. As a part of FDA's Closer to Zero program, FDA intends to publish draft guidance proposing an action level for arsenic in food intended for babies and young children. For bottled water, FDA has established an allowable limit of 10 ppb for arsenic and aligns with EPA's set the level of arsenic allowed in drinking water at 10 parts per billion (ppb). Lastly, FDA leverages import alerts to prevent potentially contaminated products from being distributed in the United States. FDA has issued import alerts for certain foods and certain manufacturers due to heavy metals, including arsenic. See Import Alert 99-42 on heavy metal (including arsenic) contamination in foods).

What are mitigation strategies?

For growers, there are a few methods to reduce arsenic accumulation in the food supply. Nanoscale sulfur (NS) can be added to soil and has shown to increase rice seed yield by 26% and lower arsenic accumulation by 54% in rice grains. Another method to decrease arsenic uptake in rice is through introducing soil drying during the growing season. This method would need to be done cautiously as Cd levels can be promoted with drying of soil in rice fields. As for the consumer, FDA and others have published studies showing that cooking rice similar to how pasta is cooked reduces the amount of arsenic in rice, though this method does also reduce the nutritional value of enriched polished and parboiled rice.

What's the bottom line?

It is important to consider both the levels of arsenic in foods and the quantity of those foods ingested by consumers; this is usually done in a risk assessment. FDA has conducted a risk assessment for arsenic in rice and rice products that was published in March 2016. In the risk assessment, the cancer risk attributable to lifetime exposure to arsenic in all rice and rice products is small in proportion to the overall incidence of these cancers (lung and bladder). The risk assessment attributes 39 cases per million people due to arsenic exposure from rice and rice products intake which is a small percentage compared to the total number of lung and bladder cancer cases from all causes which is 90,000 per million people over a lifetime. FDA is coordinating with EPA on the evaluation of non-cancer health effect risks associated with arsenic exposure in utero and during infancy and early childhood. FDA recommends that people "consume a variety of foods and beverages and follow a well-balanced diet consistent with the Dietary Guidelines for Americans."