Can Formaldehyde Exposure Cause Leukemia?

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Formaldehyde is a colorless, strong chemically-smelling compound that may conjure up images of high school frog dissections and bottled organs, perhaps due to its prominent early use as an embalming agent. When combined in water, the substance becomes formalin, a chemical variation of formaldehyde.

Formalin is an agent commonly found in medical laboratories around the world, as it “fixes” tissue samples; such biologic samples are said to be “formalin fixed, paraffin embedded” when formalin makes cross-links in the tissues that preserve the sample, and then the paraffin embedding of the tissue is used to impart enough firmness and strength to allow the sample to be sliced thinly and placed on a slide for microscopic viewing.

The use of formaldehyde and formalin is not limited to medicine, however, and formaldehyde is much more common in the environment than one might think. A brief list of products that contain or are made with formaldehyde follows:

  • Certain building materials, including pressed-wood products, such as particleboard, plywood, and fiberboard
  • Some glues and adhesives
  • Permanent-press fabrics
  • Paper product coatings
  • Certain insulation materials
  • Industrial fungicides, germicides, and disinfectants
  • Preservatives in mortuaries and medical laboratories

Formaldehyde also occurs naturally in the environment. In fact, it is produced in small amounts by living organisms as part of normal metabolism.

When Was It First Used?

Formaldehyde was first commercially produced in Germany in the 1880s, then later in Belgium, France, and the United States. Historically, formaldehyde was at first used primarily as a medical preservative, or an embalming agent.

Today, such uses represent less than one percent of the pie. Use in particleboard, which began in 1940 in Germany was one of the early industrial demands for the chemical.

What Is It Used for Today?

Estimates are that over 3.6 million metric tons of formaldehyde per year are produced by European manufacturers alone, for use in a number of different industries including construction, automotive, aircraft and healthcare.

In 2012, China was the biggest producer, followed by the U.S. and other countries. World formaldehyde production was estimated to exceed 52 million metric tons in 2017.

Formaldehyde has excellent abrasion and heat resistant qualities, so it is used in the production of many important aircraft parts including landing gear components, brake pads, door and window insulation and as an ingredient in engine lubricant. Small amounts of formaldehyde-based resins are used in the textiles industry to help dyes set in the fabrics and prevent the colors from running when clothing is washed.

How Are People Exposed to Formaldehyde?

According to the American Cancer Society, the main way in which people are exposed to formaldehyde is through inhalation, however it is also possible to become exposed through the skin or by eating foods or drinking liquids that contain formaldehyde. Formaldehyde that comes in contact with the so-called respiratory mucosa, the cells lining the mouth, nose throat and airways, can be broken down by enzymes such that less than a third of it enters the bloodstream.

Both indoor air and outdoor air contain small amounts of formaldehyde normally. These amounts are generally less than 0.03 parts per million.

Car exhaust is a major source of formaldehyde in outside air, whereas indoor formaldehyde levels receive contributions from things like pressed wood products that contain formaldehyde resins, indoor unvented stoves, and kerosene heaters. Tobacco smoke is also a source of formaldehyde, and at least one study has found higher levels of formaldehyde bound to DNA in white blood cells of smokers compared with nonsmokers.

How Can Formaldehyde Affect General Health?

People who have been exposed through inhalation to levels at 0.0 to 0.5 ppm have been reported to have nasal and eye irritation, neurological effects, and increased risk of asthma and/or allergy.

Eczema and changes in lung function have been observed at levels in the range of 0.6 to 1.9 ppm. Decreased body weight, gastrointestinal ulcers, liver and kidney damage were observed in animals orally exposed to 50–100 milligrams/kilogram/day (mg/kg/day) formaldehyde.

Can Formaldehyde Exposure Cause Cancer?

Unfortunately, the answer to this question seems to be “yes” at the moment. That is, various groups recognize that there may be some risk of cancer development due to formaldehyde exposure, but the magnitude or extent of this risk is not clear. The Department of Health and Human Services (HHS) determined in 2011 that formaldehyde is a known human carcinogen based on human and animal inhalation studies.

Is Formaldehyde Exposure Linked to Leukemia and Other Blood Cancers?

While the same caveat seems to apply specifically to blood cancers—that the precise cancer risk from formaldehyde exposure is unknown—leukemia, and specifically a category of leukemia known as myeloid leukemia, has been mentioned by more than a few organizations in conjunction with formaldehyde exposure. Here is a summary statement about the risk from formaldehyde from the American Cancer Society:

"Exposure to formaldehyde has been shown to cause cancer in laboratory test animals. Exposure to relatively high amounts of formaldehyde in medical and occupational settings has been linked to some types of cancer in humans, but the effect of exposure to small amounts is less clear."

The ACS also reports that several studies have found that embalmers and medical professionals that use formaldehyde have an increased risk of leukemia, and particularly myeloid leukemia: “Some studies of industrial workers exposed to formaldehyde have also found increased risks of leukemia, but not all studies have shown an increased risk.”

National Cancer Institute researchers have concluded that, based on data from studies in people and from lab research, exposure to formaldehyde may cause leukemia, particularly myeloid leukemia, in humans.

The US EPA states: “Formaldehyde can cause irritation of the skin, eyes, nose, and throat. High levels of exposure may cause some types of cancers.” The agency does offer some specific levels and measurements regarding formaldehyde levels and risk:

  • The US EPA has determined that exposure to formaldehyde in drinking water at concentrations of 10 milligrams/liter (mg/L) for 1 day or 5 mg/L for 10 days is not expected to cause any adverse effects in children.
  • The EPA has also determined that a lifetime exposure to 1 mg/L of formaldehyde in drinking water is not expected to cause any adverse health effects.

Other agencies have also ruled on formaldehyde exposure:

  • The Occupational Health and Safety Administration (OSHA) has limited workers’ exposure to an average of 0.75 ppm for an 8-hour workday, 40-hour workweek.
  • The U.S. Department of Housing and Urban Development (HUD) has set standards for formaldehyde emissions in manufactured housing of less than 0.2 ppm for plywood and 0.3 ppm for particle board. The HUD standards are designed to provide an ambient air level of 0.4 ppm or less in manufactured housing.

Studies Attempt to Characterize Impact Blood Cells

If indeed it is the case that formaldehyde contributes to the risk of leukemia, then there is presumably a mechanism by which this happens that scientists can observe. That was the premise leading to a study published in the May 2017 issue of Critical Reviews in Toxicology which examined the effect of formaldehyde exposure on the health of workers exposed to formaldehyde at one of two factories using or producing formaldehyde-melamine resins in China.

Previous studies had found that such exposure causes damage to blood-forming cells in the bone marrow. In the present study, the investigators tried to establish the presence of certain cellular changes in white blood cells in response to formaldehyde exposure. They were unable to show differences in white blood cell, granulocyte, platelet, and red blood cell counts that depended on levels of formaldehyde exposure. Among formaldehyde-exposed workers, no association was observed between individual average formaldehyde exposure estimates and frequency of an abnormal number of chromosomes in the cells. This study did not prove that formaldehyde is safe, but rather that any harmful effects of formaldehyde did not seem to be caused by a change in chromosome number, at least not at the doses tested.

A Word From Verywell

While scientists continue to try to understand the risks involved with formaldehyde exposure, there are some things you can do at home to try to limit your exposure. The EPA recommends using "exterior-grade" pressed-wood products even indoors. Apparently, these products emit less formaldehyde because of the chemical composition of the adhesives used.

You can also ask about formaldehyde content at the point of purchase—when buying pressed-wood products including building materials, cabinetry, and furniture, etc.

Home formaldehyde levels can be reduced by not allowing smoking indoors. You also want to ensure good ventilation. And something to think about when fine tuning your thermostat is that moderate temperatures and reduced humidity levels are encouraged. Some people save money by not cooling the house when away, but you don’t want to allow home temperatures to become too extreme.

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