sunny rice fields

What You Need to Know About Contaminants in Your Food

October 20, 2023
dr. tiffany sanchez

Dr. Tiffany Sanchez, Assistant Professor of Environmental Health Sciences at the Mailman School of Public Health

Food that’s both nutritious and safe is vital to good health. Unsafe food causes sickness and death. Unfortunately, it’s a fact of life. Food can be contaminated with bacteria, chemicals, parasites, poison, and viruses.

Everyone is at risk, but babies and young children are the most vulnerable. Consuming chemicals in food can lead to acute toxicity (emergency-grade poisoning that happens after one exposure or multiple exposures in a short period) and hundreds of serious problems, like cancer and heart disease.

“Children are not just small humans. They have different absorption patterns, especially when they’re under age 3,” says Tiffany Sanchez, PhD, an environmental epidemiologist. She studies the relationship between our environment (nature itself, pollution, chemicals, and more) and our health by looking at patterns of exposure to different contaminants and their impact.

To reduce exposure to toxins in foods eaten by babies and children, the United States Food and Drug Administration has a plan called Closer to Zero. There is no zero. And, exposure depends on the type and amount of contaminants, how much a person consumes, and their body’s ability to process them.

We asked Sanchez about what everyone should know about food contaminants.

What are food contaminants?

Food contaminants are substances found in food at levels that could potentially harm human health.

They can also be called toxicants: substances that can be harmful to humans.

Food can be contaminated with bacteria, chemicals, parasites, poison, and viruses.

Food contaminants can come from various sources, including agricultural practices, food handling and packing, and environmental pollution. It can be hard to minimize exposure, but it’s important to know the most common sources.

The most common and most concerning non-bacterial food contaminants are:

  • Heavy metals, namely arsenic, lead, mercury, and cadmium.
    • These top four food contaminants cause harm during active brain development, from pre-birth through early childhood; also linked to heart disease.
  • Molds, such as aflatoxin
    • Sometimes found in canned foods or peanut butter; linked to cancer.

How do contaminants get into food?

Some contaminants are naturally present in the environment. Others result from pesticides, fertilizers, industrial emissions, and other pollution, additives, and preservatives, diluting or substituting quality ingredients with cheaper alternatives, and leaching from containers, packaging materials, and cooking utensils.

For example, crops like rice may naturally have high arsenic levels. When the rice plant is grown in soils and water with naturally high arsenic levels, the plant mistakenly thinks arsenic is a nutrient because of chemical similarities. So, it absorbs arsenic all the way from the root to the grain as part of the natural growing process.

Alternatively, some spices may be tampered with (artificially). Turmeric, for example, is a vibrant yellow color. However, ground turmeric may be mixed with lead chromate to make it even brighter yellow.

What are the health risks associated with consuming contaminated foods?

Eating contaminated or toxic food or water can result in foodborne illness and often does. Food and waterborne illness symptoms range from nausea, cramps, low fever, or headaches to vomiting and diarrhea, and further to high fever, severe dehydration, severe diarrhea (lasting two days or more), difficulty seeing or speaking, blood in urine, kidney or liver damage, miscarriage, and seizures. Many of these symptoms can be life-threatening.

The symptoms of heavy metal illness (also know as toxicity) can be similar. They can lead to numbness, tingling hands and feet, lack of coordination, brain fog, memory problems, depression, constant fatigue, joint pain, weakness, and more.

Who is most at risk?

It depends on the contaminants. Overall, children are most at risk. Lead and arsenic are known neurotoxicants.

The FDA’s Closer to Zero program prioritized babies and young children because their metabolism makes them more vulnerable to the harmful effects of contaminants.

How can someone outside of a lab determine if food is contaminated?

This is the hard part. As a consumer, you really can’t. It’s hard to tell, especially with heavy metals: you cannot see, taste, or smell. There needs to be a transparent relationship between producer and consumer. That’s why regulations are in place to protect consumers.

Are organic foods less likely to contain contaminants compared to conventionally grown foods?

Scientifically speaking…Maybe. If you are not testing, you do not know. You have to look at the history of the soil and its use before organic practices. In addition, chemical and pesticide drift from nearby conventional farms can invade an organic farm’s air, soil, and water.

Theoretically, organic foods have lower levels of toxicants, including heavy metals, synthetic fertilizers, and pesticide residues. But there is no guarantee.

How can someone minimize exposure to food contaminants?

A varied diet is our best defense. Cut back on processed foods; eliminate ultra-processed foods. Eat more whole grains and greens, and vary your diet regularly.

Can cooking food eliminate contaminants effectively?

Yes and no. Cooking meat, poultry, and seafood can destroy certain contaminants—namely bacteria—and make food safe for consumption.

It can be different with heavy metals. You can reduce exposure if you rinse the rice in low-arsenic water and cook it in low-arsenic water. On the other hand, you could inadvertently enrich arsenic levels in rice if you have arsenic in your water, like from a well.

To learn more about contaminants, check out the FDA’s website.


Tiffany Sanchez, PhD, is director of Columbia’s Environmental Health Data Science MS program, and an assistant professor of environmental health sciences at Columbia University Irving Medical Center. She is also on the faculty at the Columbia Center for Environmental Health and Justice in Northern Manhattan. She’s currently studying the relationship between arsenic exposure through eating rice and cardiovascular disease.