Formaldehyde in Food: What You Need to Know

Person filling their plate at a barbecue

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When the media breaks news about formaldehyde in our food supply, it sounds scary and threatening to your health. Rest assured – even though formaldehyde is a dangerous chemical in high doses, the 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.

What is Formaldehyde?

Formaldehyde is a colorless gas with a strong smell. It’s most commonly known for its use in building materials and is also a consequence of some environmental pollutants.

The most common sources of exposure are:

  • 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

Living creatures, including humans, also produce formaldehyde through normal metabolic functions. For example, a process called the “one-carbon cycle” uses the vitamin 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.

Additionally, there is a related substance called formalin, a solution of formaldehyde in water. This is commonly used as a disinfectant, as well as a preservative in funeral homes and medical labs.

Why is Formaldehyde in Food?

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.

The European Food Safety Authority noted that natural levels of formaldehyde in food vary widely depending on the type of product. Here are some common examples, listed in mg/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

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

Liquid formalin is also used in the fishing industry. The FDA has approved it for use 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 concerns some people. However, formalin does not accumulate in the body of the fish. There are also specific guidelines in the United States 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, these fish should not be accepted into the United States food supply, but there have been occasional media reports of imported fish testing for higher-than-normal levels of formaldehyde.

What Happens to Formaldehyde in Your Body?

With minimal exposures, the body is actually quite efficient at enacting several lines of defense.

When you breathe in formaldehyde, the cells lining your respiratory tract work to quickly break it down. If you’re only breathing in small amounts that are simply from 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.

Risk of Formaldehyde Exposure

In large amounts, formaldehyde can be toxic. The World Health Organization has concluded that the greatest risk of formaldehyde exposure comes from frequent, high concentration inhalation - rather than ingestion of food.

Inhalation

Some studies exposed animals (like rats) to high ambient formaldehyde concentrations. They found increased rates of - and deaths from - nasopharyngeal cancer. Similarly, early studies found connections between workers with high formaldehyde exposure and higher rates of nasopharyngeal cancer or leukemia.

There is still some mixed evidence on the degree of risk. For example, a study in the American Journal of Epidemiology examined data from a large group of chemical workers who had various exposures 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, though, there was small risk identified for myeloid leukemia. In addition, another systematic review in BMC Cancer did find significant connections between formaldehyde exposure and sinonasal cancer, among both cohort and case-control studies examined.

In response to a review of all the evidence, the National Cancer Institute concluded: “that exposure to formaldehyde may cause leukemia, particularly myeloid leukemia, in humans.”

Remember, though, this refers to high levels of occupational risk via inhalation – not the levels of formaldehyde you might naturally breathe in the air at your house.

This is also completely different than oral ingestion via food.

Ingestion

When it comes to ingestion of formaldehyde, there can be side effects as well but this occurs at quite 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 scenarios) increased risk of death.

Don’t be alarmed, though. To give perspective, the Agency for Toxic Substance and Disease Registry notes these effects are thought to begin at levels of 50-100 mg/kg/day of ingested formaldehyde. You can compare that to two major estimates of current intake:

1) The World Health Organization estimates a person’s average intake via food at 1.5–14 mg/day for an average adult, most of it in a bound and unavailable form. At the highest end of this range for a 150-pound person, that would be about 0.2 mg/kg – well below the levels related to side effects.

In fact, in the United States the “MRL” – 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 likely to be safe.

2) The European Food Safety Authority 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.

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. If you’re worried about it, though, here are a few simple steps to take:

  • 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. Again, not only will this reduce the amount of formaldehyde but it's also a critical food safety measure to prevent foodborne illness.
  • Buy fish from the United States. If you’re concerned about the use of formalin, look for a local fisherman from whom you can purchase fresh wild-caught fish.

Because the greatest risk from formaldehyde comes from inhalation, your time may be better spent focusing on steps to reduce that exposure. You can:

  • Inquire about the formaldehyde content of wood products for use in the home (like cabinets and and building materials).
  • Limit the use of pressed wood products, or use exterior grade pressed wood products which typically contain lower formaldehyde amounts because they use a different type of resin.
  • Ventilate your home regularly for better indoor air quality, and especially if doing painting or remodeling projects.
  • Keep your home from becoming too humid.
  • Quit smoking. Also, don’t allow others to smoke inside your home.
  • Wash new clothes before wearing them.
  • Skip keratin hair treatments, which contain or release formaldehyde during the smoothing process.
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