The International Agency for Research on Cancer (IARC) has classified formaldehyde as carcinogenic to humans.
“Twenty-six scientists from 10 countries evaluated the available evidence on the carcinogenicity of formaldehyde, a widely used chemical,” said Dr. Peter Boyle, the Director of the Agency, which is part of the World Health Organization.
Previous evaluations, based on the smaller number of studies available at that time, had concluded that formaldehyde was probably carcinogenic to humans, but new information from studies of persons exposed to formaldehyde increased the overall weight of the evidence, Dr. Boyle noted in a news release.
Based on the new information, the expert working group determined that there is now sufficient evidence that formaldehyde causes nasopharyngeal cancer in humans.
“Their conclusion that there is adequate data available from humans for an increased risk of a relatively rare form of cancer—nasopharyngeal cancer—and a supporting mechanism, demonstrates the value and strengths of the Monographs Programme [which convened the working group],” he said.
The working group also found limited evidence for cancers of the nasal cavity and paranasal sinuses and “strong but not sufficient evidence” for leukemia.
The finding for leukemia reflects the epidemiologists' finding of strong evidence in human studies coupled with an inability to identify a mechanism for induction of leukemia, based on the available data.
“By signaling the degree of evidence for leukemia and cancer of the nasal cavity and paranasal sinuses, the working group identified areas where further clarification through research is needed,” Dr. Boyle said. “This represents a service to Public Health.”
According to IARC information, formaldehyde is produced worldwide on a large scale, used mainly in the production of resins that are used as adhesives and binders for wood products, pulp, paper, as well as in the production of plastics and coatings, in textile finishing and in the manufacture of industrial chemicals. It is used as a disinfectant and preservative (formalin) in many applications.
Previous evaluations, based on the smaller number of studies available at that time, had concluded that formaldehyde was probably carcinogenic to humans, but new information from studies of persons exposed to formaldehyde increased the overall weight of the evidence.
Common sources of exposure include vehicle emissions, particle boards, and similar building materials, carpets, paints and varnishes, foods and cooking, tobacco smoke, and the use of formaldehyde as a disinfectant. Levels of formaldehyde in outdoor air are generally low but higher levels can be found in the indoor air of homes.
Occupational exposure occurs in a wide variety of occupations and industries—for example, it is estimated that more than one million workers are exposed to some degree across the European Union, according to the IARC.
Short-term exposures to high levels have been reported for embalmers, pathologists, and paper workers; and lower levels have usually been encountered during the manufacture of man-made vitreous fibers, abrasives, and rubber and in formaldehyde-production industries.