The International Agency for Research on Cancer has determined that formaldehyde is carcinogenic to humans.

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 has increased the overall weight of the evidence.

Based on this new information, the expert working group has determined that there is now sufficient evidence that formaldehyde causes nasopharyngeal cancer in humans, a rare cancer in developed countries.

IARC is the gold standard international body evaluating chemical carcinogens. They operate under the World Health Organization, and call the best scientists from all over the world to serve on evaluation working groups.

The OSHA Permissible Exposure Limit for formaldehyde in the workplace 0.75 parts formaldehyde per million parts of air (0.75 ppm) measured as an 8-hour time-weighted average (TWA). The standard includes a second PEL in the form of a short-term exposure limit (STEL) of 2 ppm that which means a workers average exposure during any 15-minute period must not exceed 2 ppm.
NIOSH has a Recommended Exposure Limit ceiling of 0.1 ppm, which means that a worker’s exposure should never exceed 0.1 ppm even for an instant.

Formaldehyde is a very widely used chemical.

Formaldehyde is produced worldwide on a large scale. It is used mainly in the production of resins that are used as adhesives and binders for wood products, pulp, paper, glasswool and rockwool. Formaldehyde is also used extensively 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.

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 to formaldehyde 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. Short-term exposures to high levels have been reported for embalmers, pathologists and paper workers. Lower levels have usually been encountered during the manufacture of man-made vitreous fibres, abrasives and rubber and in formaldehyde production industries. A very wide range of exposure levels has been observed in the production of resins and plastic products. The development of resins that release less formaldehyde and improved ventilation has resulted in decreased exposure levels in many industrial settings in recent decades.