1. What is formaldehyde?

Formaldehyde is a colorless, flammable, strong-smelling chemical that is used in building materials and to produce many household products. It is used in pressed-wood products, such as particleboard, plywood, and fiberboard; glues and adhesives; permanent-press fabrics; paper product coatings; and certain insulation materials. In addition, formaldehyde is commonly used as an industrial fungicide, germicide, and disinfectant, and as a preservative in mortuaries and medical laboratories. Formaldehyde also occurs naturally in the environment. It is produced in small amounts by most living organisms as part of normal metabolic processes.

2. How is the general population exposed to formaldehyde?

According to a 1997 report by the U.S. Consumer Product Safety Commission, formaldehyde is normally present in both indoor and outdoor air at low levels, usually less than 0.03 parts of formaldehyde per million parts of air (ppm). Materials containing formaldehyde can release formaldehyde gas or vapor into the air. One source of formaldehyde exposure in the air is automobile tailpipe emissions.

During the 1970s, urea-formaldehyde foam insulation (UFFI) was used in many homes. However, few homes are now insulated with UFFI. Homes in which UFFI was installed many years ago are not likely to have high formaldehyde levels now. Pressed-wood products containing formaldehyde resins are often a significant source of formaldehyde in homes. Other potential indoor sources of formaldehyde include cigarette smoke and the use of unvented fuel-burning appliances, such as gas stoves, wood-burning stoves, and kerosene heaters.

Industrial workers who produce formaldehyde or formaldehyde-containing products, laboratory technicians, certain health care professionals, and mortuary employees may be exposed to higher levels of formaldehyde than the general public. Exposure occurs primarily by inhaling formaldehyde gas or vapor from the air or by absorbing liquids containing formaldehyde through the skin.

3. What are the short-term health effects of formaldehyde exposure?

When formaldehyde is present in the air at levels exceeding 0.1 ppm, some individuals may experience adverse effects such as watery eyes; burning sensations in the eyes, nose, and throat; coughing; wheezing; nausea; and skin irritation. Some people are very sensitive to formaldehyde, whereas others have no reaction to the same level of exposure.

4. Can formaldehyde cause cancer?

Although the short-term health effects of formaldehyde exposure are well known, less is known about its potential long-term health effects. In 1980, laboratory studies showed that exposure to formaldehyde could cause nasal cancer in rats. This finding raised the question of whether formaldehyde exposure could also cause cancer in humans. In 1987, the U.S. Environmental Protection Agency (EPA) classified formaldehyde as a probable human carcinogen under conditions of unusually high or prolonged exposure (1). Since that time, some studies of humans have suggested that formaldehyde exposure is associated with certain types of cancer. The International Agency for Research on Cancer (IARC) classifies formaldehyde as a human carcinogen (2).

5. What have scientists learned about the relationship between formaldehyde and cancer?

Since the 1980s, the National Cancer Institute (NCI), a component of the National Institutes of Health, has conducted studies to determine whether there is an association between occupational exposure to formaldehyde and an increase in the risk of cancer. The results of this research have provided EPA and the Occupational Safety and Health Administration (OSHA) with information to evaluate the potential health effects of workplace exposure to formaldehyde.

The long-term effects of formaldehyde exposure have been evaluated in epidemiologic studies (studies that attempt to uncover the patterns and causes of disease in groups of people). One type of epidemiologic study is called a cohort study. A cohort is a group of people who may vary in their exposure to a particular factor, such as formaldehyde, and are followed over time to see whether they develop a disease. Another kind of epidemiologic study is called a case-control study. Case-control studies begin with people who are diagnosed as having a disease (cases) and compare them to people without the disease (controls), trying to identify differences in factors, such as exposure to formaldehyde, that might explain why the cases developed the disease but the controls did not.

Several NCI surveys of professionals who are potentially exposed to formaldehyde in their work, such as anatomists and embalmers, have suggested that these individuals are at an increased risk of leukemia and brain cancer compared with the general population. However, specific work practices and exposures were not characterized in these studies. An NCI case-control study among funeral industry workers that characterized exposure to formaldehyde also found an association between increasing formaldehyde exposure and mortality from myeloid leukemia (3). For this study, carried out among funeral industry workers who had died between 1960 and 1986, researchers compared those who had died from hematopoietic and lymphatic cancers and brain tumors with those who died from other causes. (Hematopoietic or hematologic cancers such as leukemia develop in the blood or bone marrow. Lymphatic cancers develop in the tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases.) This analysis showed that those who had performed the most embalming and those with the highest estimated formaldehyde exposure had the greatest risk of myeloid leukemia. There was no association with other cancers of the hematopoietic and lymphatic systems or with brain cancer.

A number of cohort studies involving workers exposed to formaldehyde have recently been completed. One study, conducted by NCI, looked at 25,619 workers in industries with the potential for occupational formaldehyde exposure and estimated each worker's exposure to the chemical while at work (4). The results showed an increased risk of death due to leukemia, particularly myeloid leukemia, among workers exposed to formaldehyde. This risk was associated with increasing peak and average levels of exposure, as well as with the duration of exposure, but it was not associated with cumulative exposure. An additional 10 years of data on the same workers were used in a follow-up study published in 2009 (5). This analysis continued to show a possible link between formaldehyde exposure and cancers of the hematopoietic and lymphatic systems, particularly myeloid leukemia. As in the initial study, the risk was highest earlier in the follow-up period. Risks declined steadily over time, such that the cumulative excess risk of myeloid leukemia was no longer statistically significant at the end of the follow-up period. The researchers noted that similar patterns of risks over time had been seen for other agents known to cause leukemia.

A cohort study of 11,039 textile workers performed by the National Institute for Occupational Safety and Health (NIOSH) also found an association between the duration of exposure to formaldehyde and leukemia deaths (6). However, the evidence remains mixed because a cohort study of 14,014 British industry workers found no association between formaldehyde exposure and leukemia deaths (7).

Formaldehyde undergoes rapid chemical changes immediately after absorption. Therefore, some scientists think that formaldehyde is unlikely to have effects at sites other than the upper respiratory tract. However, some laboratory studies suggest that formaldehyde may affect the lymphatic and hematopoietic systems. Based on both the epidemiologic data from cohort and case-control studies and the experimental data from laboratory research, NCI investigators have concluded that exposure to formaldehyde may cause leukemia, particularly myeloid leukemia, in humans.

In addition, several case-control studies, as well as analysis of the large NCI industrial cohort (5), have found an association between formaldehyde exposure and nasopharyngeal cancer, although some other studies have not. Data from extended follow-up of the NCI cohort found that the excess of nasopharyngeal cancer observed in the earlier report persisted (8).

Earlier analysis of the NCI cohort found increased lung cancer deaths among industrial workers compared with the general U.S. population. However, the rate of lung cancer deaths did not increase with higher levels of formaldehyde exposure. This observation led the researchers to conclude that factors other than formaldehyde exposure might have caused the increased deaths. The most recent data on lung cancer from the cohort study did not find any relationship between formaldehyde exposure and lung cancer mortality.

6. What has been done to protect workers from formaldehyde?

In 1987, OSHA established a Federal standard that reduced the amount of formaldehyde to which workers can be exposed over an 8-hour work day from 3 ppm to 1 ppm. In May 1992, the standard was amended, and the formaldehyde exposure limit was further reduced to 0.75 ppm.

7. How can people limit formaldehyde exposure in their homes?

The EPA recommends the use of "exterior-grade" pressed-wood products to limit formaldehyde exposure in the home. Before purchasing pressed-wood products, including building materials, cabinetry, and furniture, buyers should ask about the formaldehyde content of these products. Formaldehyde levels in homes can also be reduced by ensuring adequate ventilation, moderate temperatures, and reduced humidity levels through the use of air conditioners and dehumidifiers.

8. Where can people find more information about formaldehyde?

The following organizations can provide additional resources that readers may find helpful:

The U.S. Consumer Product Safety Commission (CPSC) has information about household products that contain formaldehyde. CPSC can be contacted at:

Address:	U.S. Consumer Product Safety Commission 4330 East West Highway Bethesda, MD 20814
Telephone:	1–800–638–2772 (1–800–638–CPSC)
TTY:	301–595–7054
Web site:	http://www.cpsc.gov

The U.S. Food and Drug Administration (FDA) maintains information about cosmetics and drugs that contain formaldehyde. FDA can be contacted at:

Address:	U.S. Food and Drug Administration 10903 New Hampshire Avenue Silver Spring, MD 20993–0002
Telephone:	1–888–463–6332 (1–888–INFO–FDA)
Web site:	http://www.fda.gov

The Federal Emergency Management Agency (FEMA) has information about formaldehyde exposure levels in mobile homes and trailers supplied by FEMA after Hurricane Katrina. FEMA can be contacted at:

Address:	Federal Emergency Management Agency Post Office Box 10055 Hyattsville, MD 20782–7055
Telephone:	1–800–621–3362 (1–800–621–FEMA)
E-mail:	FEMA-Correspondence-Unit@dhs.gov
Web site:	http://www.fema.gov

The Occupational Safety and Health Administration (OSHA) has information about occupational exposure limits for formaldehyde. OSHA can be contacted at:

Address:	U.S. Department of Labor Occupational Safety and Health Administration 200 Constitution Avenue Washington, DC 20210
Telephone:	1–800–321–6742 (1–800–321–OSHA)
Web site:	http://www.osha.gov

Selected References

1. U.S. Environmental Protection Agency, Office of Air and Radiation. Report to Congress on Indoor Air Quality, Volume II: Assessment and Control of Indoor Air Pollution, 1989.
2. International Agency for Research on Cancer (June 2004). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 88 (2006): Formaldehyde, 2-Butoxyethanol and 1-tert-Butoxypropan-2-ol. Retrieved May 4, 2009, from: http://monographs.iarc.fr/ENG/Monographs/vol88/index.php.

3. Hauptmann M, Stewart PA, Lubin JH, et al. Mortality from lymphohematopoietic malignancies and brain cancer among embalmers exposed to formaldehyde. Journal of the National Cancer Institute 2009; 101(24). Published online ahead of print November 20, 2009.

4. Hauptmann M, Lubin JH, Stewart PA, Hayes RB, Blair A. Mortality from lymphohematopoietic malignancies among workers in formaldehyde industries. Journal of the National Cancer Institute 2003; 95(21):1615–1623.

5. Beane Freeman L, Blair A, Lubin JH, et al. Mortality from lymphohematopoietic malignancies among workers in formaldehyde industries: The National Cancer Institute cohort. Journal of the National Cancer Institute 2009; 101(10):751–761.

6. Pinkerton LE, Hein MJ, Stayner LT. Mortality among a cohort of garment workers exposed to formaldehyde: An update. Occupational Environmental Medicine 2004; 61:193–200.

7. Coggon D, Harris EC, Poole J, Palmer KT. Extended follow-up of a cohort of British chemical workers exposed to formaldehyde. Journal of the National Cancer Institute 2003; 95(21):1608–1615.

8. Hauptmann M, Lubin JH, Stewart PA, Hayes RB, Blair A. Mortality from solid cancers among workers in formaldehyde industries. American Journal of Epidemiology 2004; 159(12):1117–1130.

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Glossary Terms

The process of taking nutrients from the digestive system into the blood so they can be used in the body.

An unexpected medical problem that happens during treatment with a drug or other therapy. Adverse effects do not have to be caused by the drug or therapy, and they may be mild, moderate, or severe. Also called adverse event.

A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.

The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.

The growth of abnormal cells in the tissues of the brain. Brain tumors can be benign (not cancer) or malignant (cancer).

A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is a cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is a cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is a cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord. Also called malignancy.

Any substance that causes cancer.

A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls). Researchers study the medical and lifestyle histories of the people in each group to learn what factors may be associated with the disease or condition. For example, one group may have been exposed to a particular substance that the other was not. Also called retrospective study.

A group of individuals who share a common trait, such as birth year. In medicine, a cohort is a group that is part of a clinical trial or study and is observed over a period of time.

A research study that compares a particular outcome (such as lung cancer) in groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke compared with those who do not smoke).

The total amount of a substance or radiation that a person is exposed to over time. Cumulative exposure to a harmful substance or radiation may increase the risk of certain diseases or conditions.

The process of identifying a disease, such as cancer, from its signs and symptoms.

Any substance or process that is used primarily on non-living objects to kill germs, such as viruses, bacteria, and other microorganisms that can cause infection and disease. Most disinfectants are harsh chemicals but sometimes heat or radiation may be used.

Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic.

In clinical trials, refers to a drug (including a new drug, dose, combination, or route of administration) or procedure that has undergone basic laboratory testing and received approval from the U.S. Food and Drug Administration (FDA) to be tested in human subjects. A drug or procedure may be approved by the FDA for use in one disease or condition, but be considered experimental in other diseases or conditions. Also called investigational.

An agency in the U.S. federal government whose mission is to protect public health by making sure that food, cosmetics, and nutritional supplements are safe to use and truthfully labeled. The Food and Drug Administration also makes sure that drugs, medical devices, and equipment are safe and effective, and that blood for transfusions and transplant tissue are safe. Also called FDA.

A chemical used in manufacturing and chemical industries, and as a preservative by anatomists, embalmers, and pathologists. Being exposed to formaldehyde may increase the risk of developing leukemia and brain cancer.

Any substance used to kill fungi (plant-like organisms that do not make chlorophyll), such as yeast and molds.

Any substance or process that kills germs (bacteria, viruses, and other microorganisms that can cause infection and disease). Also called microbicide.

A cancer of the blood or bone marrow, such as leukemia or lymphoma.

Tissue in which new blood cells are formed.

Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body’s natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.

In medicine, refers to the act of taking a substance into the body by breathing.

Research done in a laboratory. These studies may use test tubes or animals to find out if a drug, procedure, or treatment is likely to be useful. Laboratory studies take place before any testing is done in humans.

Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of blood cells to be produced and enter the bloodstream.

Cancer that forms in tissues of the lung, usually in the cells lining air passages. The two main types are small cell lung cancer and non-small cell lung cancer. These types are diagnosed based on how the cells look under a microscope.

Having to do with metabolism (the total of all chemical changes that take place in a cell or an organism to produce energy and basic materials needed for important life processes).

The state of being mortal (destined to die). Mortality also refers to the death rate, or the number of deaths in a certain group of people in a certain period of time. Mortality may be reported for people who have a certain disease, live in one area of the country, or who are of a certain gender, age, or ethnic group.

Having to do with or resembling the bone marrow. May also refer to certain types of hematopoietic (blood-forming) cells found in the bone marrow. Sometimes used as a synonym for myelogenous; for example, acute myeloid leukemia and acute myelogenous leukemia are the same disease.

By or having to do with the nose.

Cancer that forms in tissues of the nasopharynx (upper part of the throat behind the nose). Most nasopharyngeal cancers are squamous cell carcinomas (cancer that begins in flat cells lining the nasopharynx).

The National Cancer Institute, part of the National Institutes of Health of the United States Department of Health and Human Services, is the Federal Government's principal agency for cancer research. The National Cancer Institute conducts, coordinates, and funds cancer research, training, health information dissemination, and other programs with respect to the cause, diagnosis, prevention, and treatment of cancer. Access the National Cancer Institute Web site at http://www.cancer.gov. Also called NCI.

A federal agency in the U.S. that conducts biomedical research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the National Institutes of Health Web site at http://www.nih.gov. Also called NIH.

A feeling of sickness or discomfort in the stomach that may come with an urge to vomit. Nausea is a side effect of some types of cancer therapy.

A part of the body that performs a specific function. For example, the heart is an organ.

The organs that are involved in breathing. These include the nose, throat, larynx, trachea, bronchi, and lungs. Also called respiratory system.

A person who has studied science, especially one who is active in a particular field of investigation.

Describes a mathematical measure of difference between groups. The difference is said to be statistically significant if it is greater than what might be expected to happen by chance alone. Also called significant.

The hollow tube inside the neck that starts behind the nose and ends at the top of the trachea (windpipe) and esophagus (the tube that goes to the stomach). The throat is about 5 inches long, depending on body size. Also called pharynx.

A group or layer of cells that work together to perform a specific function.

A type of immune cell. Most white blood cells are made in the bone marrow and are found in the blood and lymph tissue. White blood cells help the body fight infections and other diseases. Granulocytes, monocytes, and lymphocytes are white blood cells. Also called leukocyte and WBC.