Arsenic is a naturally occurring element found in the earth's crust, meaning it is present in air, water, and soil globally. Its entry into our food supply is largely unavoidable, but the health implications depend heavily on the type and quantity consumed. This article explores the primary foods that contain small amounts of arsenic, distinguishing between the more toxic inorganic forms and the less harmful organic compounds.
The Difference Between Inorganic and Organic Arsenic
Not all arsenic is created equal. Understanding the distinction between its chemical forms is crucial for assessing risk.
Inorganic Arsenic
This is the most toxic form and is primarily found in contaminated soil and groundwater. It is a human carcinogen and long-term exposure, particularly through contaminated drinking water, has been linked to skin lesions, cancer, cardiovascular disease, and other health issues. Certain plants readily absorb inorganic arsenic from the soil, which is a major pathway for human dietary exposure.
Organic Arsenic
This form is found primarily in marine life, such as fish and shellfish. For the vast majority of people, the organic arsenic present in seafood is considered harmless and is efficiently passed out of the body. Ongoing research continues to explore the toxicity of various organic arsenic compounds.
Rice and Rice-Based Products
Rice is a significant source of dietary arsenic for many populations due to its unique cultivation method. Rice plants are often grown in flooded fields, which mobilizes arsenic in the soil and makes it more available for plant uptake.
- Brown Rice vs. White Rice: The arsenic in rice tends to accumulate in the outer bran layer. As a result, brown rice, which retains its bran, typically contains higher levels of total and inorganic arsenic than white rice, where the bran has been polished away. This presents a dietary trade-off, as brown rice also contains more fiber and nutrients.
- Infant Products: Infants and young children are particularly vulnerable to arsenic exposure due to their smaller body size. Because rice is a common ingredient in infant cereals and other baby foods, regulations have been implemented to set limits on inorganic arsenic in these products. The FDA advises parents to offer a varied diet of different grains like oat, barley, or multigrain cereals.
- Reducing Arsenic in Rice During Cooking: Cooking rice in a "pasta method"—using six parts water to one part rice and draining the excess water afterward—can reduce inorganic arsenic content by up to 50%.
Seafood and Seaweed
While seafood can contain high levels of total arsenic, most of it is the less toxic organic arsenobetaine. However, there are exceptions.
- Shellfish: Some shellfish, particularly from certain contaminated areas, may contain higher inorganic arsenic levels. It is important to be aware of local advisories.
- Seaweed: A specific type of seaweed called hijiki is known to contain very high levels of inorganic arsenic and should be avoided. Other seaweeds typically contain far less.
Vegetables, Fruits, and Juices
Plants can absorb arsenic from the soil, though uptake varies widely depending on the plant type, soil composition, and irrigation water quality.
- Vegetables: Root vegetables like carrots and potatoes tend to hold arsenic in their skins. Peeling them can reduce exposure. Leafy greens like lettuce and kale can also accumulate more arsenic than fruiting plants like tomatoes or squash, which absorb very little.
- Fruit Juices: Some fruit juices, particularly apple, pear, and grape, can contain trace amounts of arsenic. The American Academy of Pediatrics does not recommend juice for children under 12 months and advises limiting intake for older children.
Other Sources of Dietary Arsenic
In addition to food, drinking water is a major potential source of arsenic exposure, especially from contaminated groundwater in private wells. Using contaminated water for cooking or irrigation also transfers arsenic into the food chain.
Comparison of Arsenic Types in Common Foods
| Food Type | Primary Arsenic Form | Relative Toxicity | Comments |
|---|---|---|---|
| Rice | Mostly Inorganic | High | Brown rice typically has more than white. Preparation method can reduce content. |
| Seafood | Mostly Organic (Arsenobetaine) | Low | Most forms are harmless; hijiki seaweed is a major exception. |
| Hijiki Seaweed | Inorganic | High | Should be avoided due to very high inorganic arsenic levels. |
| Root Vegetables | Inorganic | High | Concentrates in skin; peeling can help. Varies by soil quality. |
| Leafy Vegetables | Inorganic | High | Absorbs from soil. Varies by soil quality. |
| Fruiting Plants | Very low absorption | N/A | Tomatoes, peppers, and squash absorb very little. |
Conclusion: Managing Your Exposure
Given that arsenic is present in the environment, eliminating it from your diet is virtually impossible. The key is to manage your intake, especially of the more toxic inorganic form, and not to over-consume any single food known to be a source. Varying your diet, particularly your grain choices, and preparing rice using methods that reduce arsenic are effective strategies. For those with private well water, regular testing is critical, as contaminated water used for cooking can significantly increase your exposure. Making informed, balanced dietary choices is the best way to minimize your risk while still enjoying a nutritious diet. Further guidance is available from the FDA.
