Formaldehyde in Food: What You Need to Know

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When the media breaks news about formaldehyde in the food supply, it sounds scary and threatening to your health. But many news stories on formaldehyde in food include foods that have been banned from entering the United States due to their unusually high levels of formaldehyde.

Although formaldehyde is a dangerous chemical in high doses, the small amount in foods is generally harmless. The compound is found naturally in minimal amounts in food and is even produced by your own body at the cellular level. Learn more about foods that contain formaldehyde, including the possible risks of ingestion or inhalation.

What Is Formaldehyde?

Formaldehyde is a colorless gas with a strong smell. It is most commonly known for its use in building materials and is also a consequence of some environmental pollutants. In fact, formaldehyde occurs naturally in all forms of life.

Other sources of formaldehyde include:

  • Manufacturing facilities that use formaldehyde in processing
  • Wood products with formaldehyde resins
  • Exhaust from cars, buses, and trucks
  • Cigarette smoke
  • Chemicals in new carpets
  • Paints, sealants, and stains

When formaldehyde is dissolved in water it becomes formalin, which is commonly used as a disinfectant as well as a preservative in funeral homes and medical labs. Formalin is also used as a preservative for food, though it is also produced during the cooking and smoking process.

Why Is Formaldehyde In Food?

Living creatures, including humans, produce formaldehyde through normal metabolic functions. For example, a process called the “one-carbon cycle” uses folate to enable the synthesis of amino acids and DNA precursors. One byproduct of this process is formaldehyde.

Similarly, plants and animals (including those you eat for food) may produce formaldehyde as part of their metabolic processes. It is also found naturally in the environment related to plant decomposition and breaks down quickly in the air.

Most of the time, formaldehyde in food is a completely natural occurrence. It’s simply the byproduct of the processes going on inside a living, breathing organism—be it a plant or animal.

Formaldehyde is also approved as an indirect food additive. This means it’s used in certain materials that have contact with food. Currently, the Food and Drug Administration (FDA) lists it as approved for use in defoaming agents, which are used to prevent foam on certain liquids and other foods.

The FDA has also approved liquid formalin for use in the fishing industry. It is used as an anti-parasitic water treatment for certain types of fish you might eat, including salmon and catfish. It’s also used as an antifungal treatment on fish eggs.

There is no withdrawal time between the use of formalin on fish and its entry into the food system, which causes concern among some people. However, formalin does not accumulate in the bodies of fish. There are also specific guidelines in the U.S. as far as percentages of formalin used in these products and the length of time for application.

Fish from other countries may be more concerning, though. While it is prohibited, some fisheries abroad will use formaldehyde treatment as a preservative on their fish to extend the time to spoilage.

Theoretically, fish containing high levels of formaldehyde should not be accepted into the U.S. food supply, but there have been occasional media reports of imported fish testing for higher-than-normal levels of formaldehyde.

What Foods Contain Formaldehyde?

The European Food Safety Authority (EFSA) noted that natural levels of formaldehyde in food vary widely depending on the type of product. Here are some common examples, listed in milligrams (mg) to kilograms (kg) of the food product (i.e. 6 mg/kg means there would be 6 mg of formaldehyde in 1 kg of the food):

  • Meat and poultry: 5.7 to 20 mg/kg
  • Milk: 0.01 to 0.8 mg/kg
  • Fish: 6.4 to 293 mg/kg
  • Sugar: 0.75 mg/kg
  • Produce: 6 to 35 mg/kg
  • Coffee: 3.4 to 16 mg/kg

What Happens to Formaldehyde in the Human Body?

With minimal exposure, the body is actually quite efficient at enacting several lines of defense. When you breathe in formaldehyde, the cells lining your respiratory tract work quickly to break it down. If you’re only breathing in small amounts from everyday environmental exposure, your body usually breaks it down so quickly that little to none reaches the bloodstream.

When you ingest formaldehyde in food, it is rapidly absorbed and metabolized in the gastrointestinal tract. Most formaldehyde in food is also bound in a way that makes it unusable and unlikely to cause any side effects.

Is Formaldehyde Toxic?

In large amounts, formaldehyde can be toxic. While most people are not at risk for formaldehyde exposure, toxicity may occur in indoor settings where the gas was released by products containing formaldehyde. However, the trace amount of formaldehyde in food is unlikely to cause formaldehyde poisoning.

In fact, formaldehyde poisoning is rare, but it can occur if a person was exposed to high levels of the substance. Extreme cases of formaldehyde poisoning may cause low blood pressure, abnormal heart rhythm, irregular breathing, restlessness, unconsciousness, coma, and in rare cases, death. Additionally, some reports indicate that patients using dialysis machines that were cleaned with formaldehyde had experienced a loss of red blood cells.

In the U.S., the minimal risk level for humans is set at 0.2 mg/kg/day of chronic exposure, which is a conservative estimate of the daily human exposure that is considered to be safe. In addition, the EFSA states that food intake would be unlikely to exceed 100 mg/day at a maximum level, which would still only equate to around 1.5 mg/kg for a 150-pound person.

Risk of Formaldehyde Exposure

The World Health Organization (WHO) states that the greatest risk of formaldehyde exposure comes from frequent, high concentration inhalation, rather than ingestion of food. Here's a look at the different ways a person could potentially be at risk for formaldehyde exposure.

Inhalation

The most common way to be exposed to formaldehyde is by inhaling air that contains it. Some factory workers can be exposed to formaldehyde through the treatment of textiles and the production of resins. Other at-risk groups may include healthcare workers, medical lab technicians, and mortuary workers. In addition, some teachers and students who work with biological specimens preserved with formalin are at risk for exposure.

Research is mixed on the degree of risk, however. For instance, a study in the American Journal of Epidemiology examined data from a large group of chemical workers who had various degrees of exposure to formaldehyde. They concluded that there was no risk of excess death from nasopharyngeal cancer or myeloid leukemia at typical occupational exposure levels. At the highest exposure category, however, a small risk for myeloid leukemia was observed.

In addition, a 2015 review published in BMC Cancer found significant connections between formaldehyde exposure and sinonasal cancer, among both the cohort and case-control studies examined.

In response to a review of the evidence, however, the National Cancer Institute (NCI) concluded that "based on data from studies in people and from lab research, exposure to formaldehyde may cause leukemia, particularly myeloid leukemia, in humans." Still, it's important to keep in mind that this warning refers to high levels of occupational risk via inhalation—not the levels of formaldehyde you might naturally breathe through the air in your home.

The average person is unlikely to find themself exposed to toxic amounts of airborne formaldehyde.

Ingestion

The risk of ingesting a poisonous amount of formaldehyde is unlikely. When it comes to ingestion of formaldehyde, side effects and risks are only evident at high doses. 

The Agency for Toxic Substance and Disease Registry notes that excessive ingestion could cause reduced food intake, kidney and liver side effects, gastrointestinal lesions, and (in extreme cases) increased risk of death. However, the Agency for Toxic Substance and Disease Registry notes that toxic effects are thought to begin at high levels of 50–100 mg/kg/day of ingested formaldehyde. 

The WHO estimates a person’s average intake of formaldehyde via food at 1.5–14 mg/day for an average adult. At the highest end of this range for a 150-pound person, that would be about 0.2 mg/kg, which is well below the levels related to side effects.

The EFSA estimates your body’s total formaldehyde turnover rate at 874-1310 mg/kg of body weight per day, which is quite high compared to the minimal amount you take in via food.

How to Minimize Formaldehyde Exposure

There is very little risk associated with the natural formaldehyde occurring in the food you eat. But if you’re still concerned about the amount of formaldehyde in your food, follow these simple guidelines to help minimize your exposure.

  • Wash your produce. Formaldehyde is water-soluble, so rinsing fruits and vegetables under cold running water will help reduce the total amount. This is good practice from a food safety perspective to help rinse off any dirt or bacterial remnants.
  • Cook food like meats and fish to their proper temperature. This can reduce the amount of formaldehyde and is also a critical food safety measure to prevent foodborne illness.
  • Buy local fish. If you’re concerned about the use of formalin, look for fish that were caught locally or regionally. Some research shows that fish imported from outside of the U.S. may contain higher amounts of formaldehyde than domestic fish. Additionally, consumers are advised to avoid purchasing fish that have stiffened or emit an unusual smell, as this may indicate that it has been treated with formaldehyde. While some reports state that formaldehyde has been found in frozen fish in certain parts of the U.S., the amounts were too low to cause concern.

If you're concerned about formalin in farm-raised fish, it's important to note that it's used as a disinfectant in aquaculture practices around the world, including the U.S. Research shows that formalin may produce fish toxicity, but the implications for human health are not fully understood.

Because the greatest risk from formaldehyde comes from inhalation, you may wish to focus on reducing that type of exposure instead. Here are a few things you can do:

  • Inquire about the formaldehyde content of wood products for home use. These include cabinets and building materials. You may also want to avoid stockpiling antique furniture and wood building materials in your home, which may contain formaldehyde and other volatile organic compounds (VOCs).
  • Limit the use of pressed wood products. Exterior-grade pressed wood products typically contain lower formaldehyde amounts because they use a different type of resin.
  • Ventilate your home regularly. This helps to ensure better indoor air quality, and especially if you're painting or remodeling.
  • Monitor the air in your home. You'll want to be sure the air doesn't become too humid.
  • Quit smoking. And don’t allow others to smoke inside your home.
  • Wash new clothes. Before you wear any new clothes for the first time, give them a good wash.
  • Skip keratin hair treatments. These contain or release formaldehyde during the smoothing process.

Frequently Asked Questions

Which countries have banned the use of formaldehyde in foods?

In 2016, the use of formalin as a food preservative was banned in the European Union due to its potential as a carcinogen. Elsewhere, formaldehyde is illegal in foods beyond trace amounts. Many foods like fruits, vegetables, meats, and milk that contain naturally occurring formaldehyde are legal around the world.

How much formaldehyde is in fast food?

Like other food manufacturers, formalin may be used as a food preservative by certain fast-food chains. However, the toxic food packaging used by some fast food restaurants is likely more hazardous to your health than any trace amounts of formaldehyde found in these foods.

A Word From Verywell

Naturally occurring formaldehyde in food is generally safe and relatively common. It is produced naturally by living organisms and is unlikely to cause formaldehyde poisoning. Most foods that have been preserved with formalin should be safe for consumption in the U.S.

The only time to really be concerned about formaldehyde exposure is when excessive amounts are inhaled over time. But most people shouldn't have to worry about inhaling or ingesting dangerous amounts of formaldehyde from the foods they eat or the air they breathe.

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