What To Know About Metals in Foods
We all know that eating well is key to staying well, but how do we avoid contaminants in our foods? Arsenic, lead, cadmium, mercury, and chromium might sound like something you'd find in a chemistry lab, but these metals have been detected in many of the everyday foods we eat. And they carry health risks.
"Toxic metals are not just present—they're persistent," says Kathrin Schilling, PhD, a researcher at Columbia University Mailman School of Public Health. "The key is understanding how these metals accumulate in our bodies and figuring out how to prevent exposure," she says.
Dr. Schilling has spent years studying these metals and how they interact with the environment and human health. Her work combines earth sciences and biomedical sciences, using metal isotopes to better understand how to minimize the risks from metals like arsenic, lead, and mercury found in common food items.
Dr. Schilling explains the metals you might find in your food, the health risks they pose, and what you can do about it.
The Most Common Metals in Foods
Dr. Schilling's research has uncovered the often-overlooked presence of metals in everyday consumer products such as tampons and pads. These findings have raised concerns about chronic, low-level exposure to toxic metals through products that come into direct contact with the body.
When it comes to metals found in foods, she explains what you need to know about some of the most common ones:
Mercury
- Health risks: Mercury exposure can lead to serious neurological damage, especially in the form of methylmercury, which accumulates in the brain and nerves. It can cause problems, including cognitive decline and tremors.
- Where it's found: Mercury is most commonly found in larger fish, like tuna, swordfish, and shark, as well as other seafood.
- How to avoid it: Choose smaller fish such as salmon, cod, or sardines, which tend to have lower mercury levels.
Arsenic
- Health risks: Long-term exposure to arsenic can increase the risk of cancer, cardiovascular diseases, and neurological damage.
- Where it's found: Arsenic is often found in rice (especially rice grown in waterlogged fields) and some drinking water sources.
- How to avoid it: Rinse rice thoroughly before cooking. Cook rice with extra water and drain it off. Alternating rice with other grains, like quinoa or oats, can also reduce exposure.
Lead
- Health risks: Lead poisoning is a major concern, both in children and adults. It can affect nearly every organ in the body and lead to developmental delays, high blood pressure, and kidney damage.
- Where it's found: In addition to items like lead paint, lead has been detected in substances we consume, including spices (such as cinnamon and turmeric), some colored foods, and contaminated water. For example, lead chromate, which has been illegally added to turmeric to enhance its yellow color, has been linked to elevated blood lead levels.
- How to avoid it: To reduce the likelihood of consuming adulterated powdered products, buy whole spices—such as cinnamon, turmeric, and chili—and grind them at home. Avoid purchasing loose or unlabeled spice powders in local or online markets; instead look for trusted certifications, such as USDA Organic or those from third-party heavy metal testing programs like ConsumerLab or the Clean Label Project. Avoid storing food or beverages in antique containers or lead crystal, such as Bohemian crystal glassware.
Cadmium
- Health risks: Cadmium is linked to kidney disease and bone damage and can even lead to cancer over time with prolonged exposure.
- Where it's found: Commonly found in leafy greens, root vegetables, and cocoa, particularly in areas with soil contamination due to industrial activities or fertilizers.
- How to avoid it: Wash vegetables thoroughly and limit your intake of processed cocoa products.
Other metals to be aware of include nickel, which can cause allergic reactions and is found in nuts, seeds, and grains. Aluminum, which can leach into food from some cookware and packaging, is another to consider. Though these metals may not always be present in high concentrations, chronic exposure raises concerns.
Who Is Most Vulnerable to Metals in Foods?
Certain groups are more vulnerable to these metals' harmful effects, particularly regarding food exposure.
"Pregnant women, infants, and young children are at the highest risk," Dr. Schilling says. Toxic metals can cross the placenta, affecting fetal development and leading to potential lifelong consequences. Mercury exposure, for example, can impair brain and nervous system development in babies.
Children are especially susceptible because their bodies absorb toxic metals more quickly than adults. Even small amounts of lead can cause developmental delays, learning difficulties, and behavioral problems. As a result, initiatives like the FDA's Closer to Zero focus on reducing toxic metal levels in foods consumed by infants and young children.
Current Regulations
In the U.S., the Food and Drug Administration (FDA) monitors arsenic, lead, cadmium, and mercury levels in food, as these are the metals most commonly associated with health risks. However, many metals, such as aluminum, thallium, and nickel, are not subject to regular testing, even though they pose potential dangers. Dr. Schilling emphasizes the need for expanded testing to include these lesser-studied metals.
Food testing is more rigorous in New York State than in many other areas. The state has routinely tested imported products, such as baby foods and fruit juices, for toxic metal contamination. In one case, New York State removed fruit juices with lead levels exceeding FDA safety limits.
Are Some Metals Good for Our Health?
While metals like lead and mercury are harmful, others are essential for our health. For example, copper, zinc, and iron play vital roles in various bodily functions, such as immune support, oxygen transport, and brain development.
- Copper is crucial for red blood cell production
- Zinc supports cell growth and helps with protein synthesis
- Iron is necessary for oxygen to be transported through the blood
Other essential metals include magnesium, calcium, selenium, and potassium, which support bone health, muscle function, and overall metabolic processes. However, balance is key. Both deficiencies and excesses of these metals can lead to health issues. For example, too much iron can cause liver damage, while too little can lead to anemia.
The Big Picture
While we can take steps to minimize metal exposure in our diets, broader issues like climate change, industrial pollution, and agricultural practices play a large role in the persistence of these metals in our food supply. Rising temperatures, for example, increase arsenic availability in rice, and industrial pollution continues to release toxic metals into the environment.
"The bigger picture is that we need to address these environmental factors," says Dr. Schilling. "We must tackle the root causes like pollution and climate change to ensure long-term food safety."
References
Kathrin Schilling, PhD, is an assistant professor of Environmental Health Sciences and an associate member of the Columbia Center for Environmental Health and Justice in Northern Manhattan.