What foods contain high levels of arsenic?

According to the World Health Organization, contaminated water used for drinking, food preparation, and crop irrigation is a major source of dietary arsenic exposure. While many foods contain small, generally harmless amounts, some foods contain high levels of arsenic, with different types of arsenic having different toxicity levels.

Quick Summary

This article explores common foods, such as rice, certain seafood, and some vegetables, that may contain high levels of arsenic, detailing the distinction between less-toxic organic arsenic and more-toxic inorganic arsenic. It also provides practical strategies for reducing arsenic exposure through diet.

Key Points

• Inorganic vs. Organic Arsenic: The inorganic form of arsenic found in foods like rice is much more toxic than the organic form found in most seafood.

• Rice is a Major Contributor: Rice and rice-based products are a primary source of dietary inorganic arsenic, largely because rice plants readily absorb arsenic from water and soil.

• Cooking Reduces Arsenic in Rice: Cooking rice with excess water, then draining it, can significantly reduce its arsenic content. Soaking rice overnight beforehand can further increase this reduction.

• Brown Rice Contains More Arsenic: Because it retains the bran layer, brown rice typically has higher arsenic levels than white rice.

• Seafood is Generally Low-Risk: The arsenic in most fish and shellfish is organic and considered less harmful. However, certain types of seaweed, like hijiki, are exceptions and should be avoided.

• Diversify Your Diet: Limiting consumption of any single food type and incorporating a variety of grains, fruits, and vegetables can help minimize overall arsenic exposure.

• Check Your Water Source: If you have a private well, having your water tested is important, as contaminated water is a major source of inorganic arsenic exposure.

Arsenic is a naturally occurring metalloid found in the earth's crust and is widely distributed throughout the environment. It exists in both inorganic (the more toxic form) and organic (the less toxic form) compounds. Most human exposure to arsenic is through contaminated water, but food is also a significant pathway. Because plants absorb arsenic from the soil and water in which they grow, and animals can accumulate it through their food chain, certain foods tend to have higher concentrations than others.

High-Arsenic Food Sources

Some of the most common food items found to contain higher levels of arsenic include:

• Rice and rice-based products: Rice is a primary concern for dietary inorganic arsenic exposure because it absorbs arsenic from water and soil much more efficiently than other crops. This is largely due to its cultivation in flooded conditions (paddy fields). Studies show brown rice often contains more arsenic than white rice because the arsenic accumulates in the bran layer, which is removed during the processing of white rice. Products like rice milk, infant rice cereal, and brown rice syrup are also of concern.
• Seafood: Fish, shellfish, and seaweed are known to contain arsenic, although it is predominantly in the less harmful organic form, arsenobetaine. However, certain types of seaweed, particularly hijiki, can contain high levels of inorganic arsenic and should be avoided. Some shellfish, especially those harvested from contaminated areas, can also have elevated inorganic arsenic concentrations.
• Vegetables: Leafy and root vegetables absorb arsenic from the soil. Examples include lettuce, broccoli, cabbage, kale, carrots, and radishes. Testing is recommended for home gardeners in high-risk areas, but for most people, regular consumption of a varied diet of fruits and vegetables poses little risk.
• Fruit Juices: Arsenic can be present in some fruit juices, especially apple juice, due to its presence in the soil where the fruit is grown or from past use of arsenic-based pesticides. The FDA has an action level for inorganic arsenic in apple juice.

Factors Influencing Arsenic Levels in Food

Several factors can influence the amount of arsenic found in food products:

• Cultivation Method: For rice, the flooded cultivation method promotes arsenic absorption from the soil and water.
• Location of Growth: The geographical region and local soil and water conditions are major determinants of arsenic concentration. Rice from certain regions, like parts of the US (Louisiana, Texas) and Asia (Bangladesh, China), has been shown to contain higher levels than rice from other areas.
• Processing: For rice, polishing to produce white rice removes the arsenic-rich bran layer, significantly reducing the inorganic arsenic content.
• Cooking Methods: How food, particularly rice, is prepared can impact its arsenic content. Cooking with clean, low-arsenic water and using a high water-to-rice ratio can reduce inorganic arsenic levels.

How to Reduce Dietary Arsenic Exposure

• Vary your diet: Avoid relying heavily on a single food item. Incorporate other grains like quinoa, millet, couscous, and barley as alternatives to rice.
• Properly cook rice: Use the "parboiling with absorption method," which involves parboiling the rice for five minutes, draining the water, and then cooking it in fresh water until it's absorbed. Alternatively, cook rice in a large volume of water (a 6:1 water-to-rice ratio) and drain the excess, similar to cooking pasta.
• Prepare seafood thoughtfully: Avoid eating hijiki seaweed. If you eat shellfish regularly, ensure it's from sources with low levels of contaminants.
• Wash produce thoroughly: Always wash fruits and vegetables to remove surface-level soil and contaminants.
• Test your water: If you use a private well for drinking or cooking, have it tested for arsenic.

Comparison of Arsenic Types in Common Foods

Food Category	Predominant Arsenic Type	Associated Health Risk	Key Takeaway
Rice and Rice Products	Inorganic (especially brown rice)	Higher toxicity, potential long-term risks (cancer, organ damage)	Use proper cooking methods and vary grain consumption.
Seafood (most fish/shellfish)	Organic (arsenobetaine)	Low toxicity to humans, generally not a concern	Keep eating seafood as part of a healthy diet, but be mindful of sourcing.
Hijiki Seaweed	Inorganic	Higher toxicity, significant concern	Avoid this specific type of seaweed.
Leafy Vegetables	Inorganic (from soil)	Generally low risk for most, but dependent on soil conditions	Vary your intake and wash thoroughly.
Fruit Juices	Inorganic	Can be elevated, especially apple juice. Not a major risk with varied intake	Limit intake, especially for young children.

Conclusion

While the presence of arsenic in the food supply is a concern, for most individuals, the risk can be managed through informed dietary choices and preparation methods. Rice and certain seaweeds are the most significant food-based sources of the more toxic inorganic arsenic. By varying your diet and adopting best practices for food preparation, you can effectively minimize your exposure. Awareness and moderate consumption are key to enjoying a healthy and balanced diet without unnecessary risk.

For more detailed information on contaminants in food and reducing exposure, consult the U.S. Food and Drug Administration's 'Closer to Zero' action plan.

Frequently Asked Questions

What is the most common food source of inorganic arsenic?

Rice and rice-based products are the most significant food source of inorganic arsenic. This is because rice is often grown in flooded paddy fields, which facilitates the plant's absorption of arsenic from soil and water.

Why does brown rice have more arsenic than white rice?

Brown rice contains more arsenic than white rice because the arsenic tends to accumulate in the outer bran layer of the grain. This layer is removed during the milling process to produce white rice, which lowers its arsenic content.

Does all seafood contain high levels of arsenic?

No, most seafood contains arsenic primarily in a less toxic organic form called arsenobetaine, which is largely harmless to humans and passed through the body. The exception is certain types of seaweed, like hijiki, and some shellfish from contaminated areas, which can contain higher, more concerning levels of inorganic arsenic.

Can proper cooking reduce the arsenic in rice?

Yes, cooking rice properly can significantly reduce its arsenic content. One effective method is to use a large volume of water (a 6:1 water-to-rice ratio), boiling the rice like pasta, and then draining the excess water.

Are vegetables a major source of arsenic?

Some vegetables, particularly leafy greens and root vegetables, can absorb arsenic from soil, but for most people, the levels are not high enough to pose a significant risk with a varied diet. Testing soil is important for home gardeners in areas with historical contamination.

Are infants and young children more vulnerable to arsenic exposure?

Yes, infants and young children are particularly vulnerable because of their smaller body size and rapid development. Health organizations recommend limiting exposure to high-arsenic foods like infant rice cereals.

Is organic arsenic in food dangerous?

Organic arsenic found in most food, such as seafood, is considered much less toxic and is not typically a health concern. However, the inorganic form found in rice and some other foods is highly toxic and linked to serious long-term health effects.