Formaldehyde is a colorless, flammable gas at room temperature. It has a pungent, distinct odor and may cause a burning sensation to the eyes, nose, and lungs at high concentrations. Formaldehyde is also known as methanal, methylene oxide, oxymethylene, methylaldehyde, and oxomethane. Formaldehyde can react with many other chemicals, and it will break down into methanol (wood alcohol) and carbon monoxide at very high temperatures.
Formaldehyde is naturally produced in very small amounts in our bodies as a part of our normal, everyday metabolism and causes us no harm. It can also be found in the air that we breathe at home and at work, in the food we eat, and in some products that we put on our skin. A major source of formaldehyde that we breathe every day is found in smog in the lower atmosphere. Automobile exhaust from cars without catalytic converters or those using oxygenated gasoline also contain formaldehyde. At home, formaldehyde is produced by cigarettes and other tobacco products, gas cookers, and open fireplaces. It is also used as a preservative in some foods, such as some types of Italian cheeses, dried foods, and fish. Formaldehyde is found in many products used every day around the house, such as antiseptics, medicines, cosmetics, dish-washing liquids, fabric softeners, shoe-care agents, carpet cleaners, glues and adhesives, lacquers, paper, plastics, and some types of wood products. Some people are exposed to higher levels of formaldehyde if they live in a new mobile home, as formaldehyde is given off as a gas from the manufactured wood products used in these homes.
Formaldehyde is used in many industries. It is used in the production of fertilizer, paper, plywood, and urea-formaldehyde resins. It is present in the air in iron foundries. It is also used in the production of cosmetics and sugar, in well-drilling fluids, in agriculture as a preservative for grains and seed dressings, in the rubber industry in the production of latex, in leather tanning, in wood preservation, and in photographic film production. Formaldehyde is combined with methanol and buffers to make embalming fluid. Formaldehyde is also used in many hospitals and laboratories to preserve tissue specimens.
Pathways for formaldehyde in the environment
Most of the formaldehyde you are exposed to in the environment is in the air. Formaldehyde dissolves easily in water, but it does not last a long time in water and is not commonly found in drinking water supplies. Most formaldehyde in the air also breaks down during the day. The breakdown products of formaldehyde in air include formic acid and carbon monoxide. Formaldehyde does not seem to build up in plants and animals, and although formaldehyde is found in some food, it is not found in large amounts.
Exposure to formaldehyde
You are exposed to small amounts of formaldehyde in the air. It occurs from both natural and man made sources although combustion is the largest source. If you live in an unpopulated area, you may be exposed to about 0.2 parts per billion (ppb) of formaldehyde in the air outdoors. In suburban areas, you may be exposed to about 2–6 ppb of formaldehyde. If you live in a heavily populated area or near some industries, you may be exposed to 10–20 ppb. You may also be exposed to higher levels of formaldehyde during rush hour commutes in highly populated areas because it is formed in automobile and truck exhaust.
There is usually more formaldehyde present indoors than outdoors. Formaldehyde is released to the air from many home products and you may breath in formaldehyde while using these products. Latex paint, fingernail hardener, and fingernail polish release a large amount of formaldehyde to the air. Plywood and particle board, as well as furniture and cabinets made from them, fiberglass products, new carpets, decorative laminates, and some permanent press fabrics give off a moderate amount of formaldehyde. Some paper products, such as grocery bags and paper towels, give off small amounts of formaldehyde. Because these products contain formaldehyde, you may also be exposed on the skin by touching or coming in direct contact with them. You may also be exposed to small amounts of formaldehyde in the food you eat. You are not likely to be exposed to formaldehyde in the water you drink because it does not last a long time in water.
Many other home products contain and give off formaldehyde although the amount has not been carefully measured. These products include household cleaners, carpet cleaners, disinfectants, cosmetics, medicines, fabric softeners, glues, lacquers, and antiseptics. You may also breathe formaldehyde if you use unvented gas or kerosene heaters indoors or if you or someone else smokes a cigar, cigarette, or pipe indoors. The amount of formaldehyde in mobile homes is usually higher than it is in conventional homes because of their lower air turnover.
People who work at or near chemical plants that make or use formaldehyde can be exposed to higher than normal amounts of formaldehyde. Doctors, nurses, dentists, veterinarians, pathologists, embalmers, workers in the clothing industry or in furniture factories, and teachers and students who handle preserved specimens in laboratories also might be exposed to higher amounts of formaldehyde. The National Institute for Occupational Safety and Health (NIOSH) estimates that 1,329,332 individuals in the United States have had the potential for occupational exposure to formaldehyde.
Pathways for formaldehyde in the body
Formaldehyde can enter your body after you breath it in, drink or eat it, or when it comes in contact with your skin. Formaldehyde is quickly absorbed from the nose and the upper part of your lungs. When formaldehyde is eaten and drunk, it is also very quickly absorbed. Very small amounts are probably absorbed from formaldehyde that comes in contact with your skin. Once absorbed, formaldehyde is very quickly broken down. Almost every tissue in the body has the ability to break down formaldehyde. It is usually converted to a non-toxic chemical called formate, which is excreted in the urine. Formaldehyde can also be converted to carbon dioxide and breathed out of the body. It can also be broken down so the body can use it to make larger molecules needed in your tissues, or it can attach to deoxyribonucleic acid (DNA) or to protein in your body. Formaldehyde is not stored in fat.
Health effects of formaldehyde
Formaldehyde is irritating to tissues when it comes into direct contact with them. Some people are more sensitive to the effects of formaldehyde than others. The most common symptoms include irritation of the eyes, nose, and throat, along with increased tearing, which occurs at air concentrations of about 0.4–3 parts per million (ppm). NIOSH states that formaldehyde is immediately dangerous to life and health at 20 ppm. One large study of people with asthma found that they may be more sensitive to the effects of inhaled formaldehyde than other people; however, many studies show that they are not more sensitive. Severe pain, vomiting, coma, and possible death can occur after drinking large amounts of formaldehyde. Skin can become irritated if it comes into contact with a strong solution of formaldehyde.
To protect the public from the harmful effects of toxic chemicals and to find ways to treat people who have been harmed, scientists use many tests.
You should know that one way to learn whether a chemical will harm people is to determine how the body absorbs, uses, and releases the chemical. For some chemicals, animal testing may be necessary. Animal testing may also help identify such health effects as cancer or birth defects. Without laboratory animals, scientists would lose a basic method for getting information needed to make wise decisions that protect public health. Scientists have the responsibility to treat research animals with care and compassion. Scientists must comply with strict animal care guidelines because laws today protect the welfare of research animals.
Additionally, there are vigorous national and international efforts to develop alternatives to animal testing. The efforts focus on both in vitro and in silico approaches and methods. For example, the National Toxicology Program (NTP) at the National Institute of Environmental Health Sciences (NIEHS) created the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) in 1998. The role of NICEATM is to serve the needs of high quality, credible science by facilitating development and validation—and regulatory and public acceptance—of innovative, revised test methods that reduce, refine, and replace the use of animals in testing while strengthening protection of human health, animal health and welfare, and the environment. In Europe, similar efforts at developing alternatives to animal based testing are taking place under the aegis of the European Centre for the Validation of Alternative Methods (ECVAM).
Several studies of laboratory rats exposed for life to high amounts of formaldehyde in air found that the rats developed nose cancer. Some studies of humans exposed to lower amounts of formaldehyde in workplace air found more cases of cancer of the nose and throat (nasopharyngeal cancer) than expected, but other studies have not found nasopharyngeal cancer in other groups of workers exposed to formaldehyde in air. The Department of Health and Human Services (DHHS) has determined that formaldehyde may reasonably be anticipated to be a human carcinogen (NTP). The International Agency for Research on Cancer (IARC) has determined that formaldehyde is probably carcinogenic to humans. This determination was based on specific judgments that there is limited evidence in humans and sufficient evidence in laboratory animals that formaldehyde can cause cancer. The Environmental Protection Agency (EPA) has determined that formaldehyde is a probable human carcinogen based on limited evidence in humans and sufficient evidence in laboratory animals.
Health effects in children
Children and adults are likely to be exposed to formaldehyde in the same way. The most common way for children to be exposed to formaldehyde is by breathing it. Children may also be exposed by wearing some types of new clothes or cosmetics. A small number of studies have looked at the health effects of formaldehyde in children. It is very likely that breathing formaldehyde will result in nose and eye irritation (burning feeling, itchy, tearing, and sore throat). We do not know if the irritation would occur at lower concentrations in children than in adults. Studies in animals suggest that formaldehyde will not cause birth defects in humans. Inhaled formaldehyde or formaldehyde applied to the skin is not likely to be transferred from mother to child in breast milk or to reach the developing fetus.
Reducing risk of exposure to formaldehyde
If your doctor finds that you have been exposed to significant amounts of formaldehyde, ask if children may also be exposed. When necessary your doctor may need to ask your state department of public health to investigate.
Formaldehyde is usually found in the air. Formaldehyde levels are also higher indoors than outdoors. Opening windows or using a fan to bring in fresh air is the easiest way to lower formaldehyde levels in the home and reduce the risk of exposure to your family.
Removing formaldehyde sources from the house will also reduce the risk of exposure. Since formaldehyde is found in tobacco smoke, not smoking or smoking outside will reduce exposure to formaldehyde. Unvented heaters, such as portable kerosene heaters, also produce formaldehyde. If you do not use these heaters in your home or shop, you help to prevent the build up of formaldehyde indoors.
Formaldehyde is found in small amounts in many consumer products including antiseptics, medicines, dish-washing liquids, fabric softeners, shoe-care agents, carpet cleaners, glues, adhesives, and lacquers. If you or a member of your family uses these products, providing fresh outdoor air when you use them. This will reduce your exposure to formaldehyde. Some cosmetics, such as nail hardeners, have very high levels of formaldehyde. If you do not use these products in a small room, or if you have plenty of ventilation when you use them, you will reduce your exposure to formaldehyde. If your children are not in the room when you use these products, you will also reduce their exposure to formaldehyde.
Formaldehyde is emitted from some wood products such as plywood and particle board, especially when they are new. The amount of formaldehyde released from them decreases slowly over a few months. If you put these materials in your house, or buy furniture or cabinets made from them, opening a window will lower formaldehyde in the house. The amount of formaldehyde emitted to the house will be less if the wood product is covered with plastic laminate or coated on all sides. If it is not, sealing the unfinished sides will help to lower the amount of formaldehyde that is given off.
Some permanent press fabrics emit formaldehyde. Washing these new clothes before use will usually lower the amount of formaldehyde and reduce your family's risk of exposure.
Medical tests for exposure to formaldehyde
We have no reliable test to determine how much formaldehyde you have been exposed to or whether you will experience any harmful health effects.
Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Agency for Toxic Substances and Disease Registry. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Agency for Toxic Substances and Disease Registry should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.