Formaldehyde is a colorless, strong-smelling gas often found in aqueous (water-based) solutions. Formaldehyde in the United States is used for many industrial applications – including in plastics and resin manufacture (e.g., particle board), in adhesives, and in resins used in a variety of applications where they can replace metals in mechanical working parts (e.g., automobiles, trucks, consumer articles, plumbing, industrial machinery, and appliances).

Recently, several groups have announced links between formaldehyde exposure and cancer.  For example, in June 2012, IARC announced that it would classify diesel engine exhaust as Group 1, carcinogenic to humans. Diesel engine exhaust contains a number of compounds, including formaldehyde.

Despite the weaknesses in the analyses classifying formaldehyde as a carcinogen, it seems likely that the current climate will intensify, which could bring even stricter scrutiny with respect to potential occupational exposure to formaldehyde and additional adverse publicity regarding formaldehyde-containing products. Companies with products that utilize or contain ormaldehyde can likely expect that litigation related to allegations of injury from formaldehyde exposure will only increase in the future.

Formaldehyde is also a normal metabolite of the human body. An adult human body normally produces and metabolizes (detoxifies or utilizes) over 50,000 milligrams of endogenous formaldehyde per day. Because free formaldehyde can diffuse from tissues in the upper respiratory tract into exhaled air, minute amounts of formaldehyde can also be detected in the breath. Formaldehyde exposure can occur dermally, through inhalation, or by ingestion.

In the 1980s and 1990s, a number of epidemiological studies were conducted on industrial workers and other professionals occupationally exposed to formaldehyde over the course of their careers. Several of these studies found a link between formaldehyde exposure and certain kinds of cancer, including nasopharyngeal and nasal cancer. Several recent studies also have found increased risks for leukemia among groups exposed to formaldehyde. Criticisms of these studies have been extensive and include, but are not limited to, the following:

• Limited information about subjects’ exposure levels and few measurements taken to assess their exposure levels;
• Comparison between high and low level formaldehyde exposure groups, rather than exposed and unexposed (control) groups;
• Limited information about leukemia subtypes;
• Failure to conclude whether the outcome was the result of a causal relationship between formaldehyde exposure and cancer or whether it was the result of chance; and
• Utilizing studies with a wide range of formaldehyde exposure levels and a corresponding wide range of risk  estimates in conducting a meta-analysis, resulting in a potentially unreliable summary risk estimate for the meta-analysis.

These publications appear to have influenced recent assessments of the carcinogenicity of formaldehyde. On June 2, 2010, the EPA released a 1043-page draft of its Integrated Risk Information System (IRIS) assessment entitled Toxicological Review of Formaldehyde Inhalation Toxicity ("IRIS Formaldehyde Draft"). The IRIS Formaldehyde Draft concluded that "the human epidemiologic evidence is sufficient to conclude that there is a causal association between formaldehyde exposure and mortality from myeloid leukemia."

In June 2011, the National Toxicology Program (NTP) 12th Report on Carcinogens (ROC) was published classifying formaldehyde as Group 1, carcinogenic to humans. The ROC lists nasopharyngeal cancer, sinonasal cancer, and lymphohematopoietic (LHP) cancer as being causally linked to formaldehyde exposure and states that links between formaldehyde exposure and certain types of cancers, including nasopharyngeal cancer, sinonasal cancer, and LHP cancers, "cannot be explained by chance, bias, or confounding." However, the ROC observes that "[t]he mechanisms by which formaldehyde causes toxicity at distal sites are unknown" but refers to the recent publications linking cancer with formaldehyde exposure.

The International Agency for Research on Cancer (IARC) monograph for formaldehyde, published in Volume 100F (2012), classifies formaldehyde as Group 1, carcinogenic to humans.  Prior to October 2009, formaldehyde had been classified as Group 2A, meaning that it was a probable human carcinogen. 

However, these classifications of formaldehyde have been subject to widespread scrutiny based on weaknesses in the studies upon which they base their conclusions. For example, the American Chemistry Council has observed that the EPA’s proposed cancer risk value of 0.008 parts per billion for formaldehyde in the IRIS would suggest that human breath (which contains