- What is formaldehyde?
Formaldehyde is a colorless, flammable, strong-smelling chemical that is
used to manufacture 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.
- 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 example of formaldehyde exposure in the air is through 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, 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.
- 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 health effects, such as watery eyes; burning sensations
of 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.
- 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 industrial workers have suggested that formaldehyde
exposure is associated with nasal sinus cancer and nasopharyngeal cancer,
and possibly with leukemia. In 1995, the International Agency for Research
on Cancer (IARC) concluded that formaldehyde is a probable human carcinogen.
In June 2004, after evaluating all existing data, the IARC reclassified formaldehyde
as a known human carcinogen (2).
- 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.
Long-term effects of formaldehyde 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 studies have found that anatomists and embalmers, people who
are potentially exposed to formaldehyde in their professions, are at an increased
risk of leukemia and brain cancer compared with the general population. In
2003, a number of cohort studies were completed among workers exposed to formaldehyde.
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 (3). 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 not with cumulative exposure. Using an additional 10 years
of data, a follow-up study published in 2009 continued to show a possible
link between formaldehyde exposure and cancers of the hematopoietic
and lymphatic
systems, particularly myeloid leukemia, as was previously reported (4).
As in the previous study, the risk was highest earlier in the follow-up period
and declined steadily over time, such that the cumulative excess risk of myeloid
leukemia was no longer statistically
significant. The researchers noted that similar patterns of risks over
time had been seen for other agents known to cause leukemia.
A separate 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 (5).
However, the evidence remains mixed because a cohort study of 14,014 British
industry workers found no association between cumulative formaldehyde exposure
and leukemia deaths (6).
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 studies and the
experimental data from laboratory research, NCI investigators have concluded
that exposure to formaldehyde may cause leukemia, particularly myeloid leukemia,
in humans. However, inconsistent results from other studies suggest that further
research is needed before definite conclusions can be drawn.
Several case-control studies and cohort studies, including analysis of the
large NCI cohort, have reported an association between formaldehyde exposure
and nasopharyngeal cancer, although some other studies have not. Data from
extended follow-up of the NCI study found that the excess of nasopharyngeal
cancer observed in the earlier report persisted (7).
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. New data
on lung cancer from the extended follow-up did not find any relationship between
formaldehyde exposure and lung cancer mortality.
- 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.
- 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.
- 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 20814–4408 |
| Telephone: |
1–800–638–2772 (1–800–638–CPSC) |
| TTY: |
1–800–638–8270 |
| 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 20903 |
| 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:
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 |
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