Formaldehyde is one part of the larger 'VOC' (volatile organic compound) family, where 'volatile' means that compounds become a gas at normal room temperature.
• Formaldehyde, discovered in 1867 and isolated in 1892, is called methanal and is formed by oxidising methanol.
• It is an organic compound with the formula CH2O
• Pure formaldehyde is extremely reactive. For this reason, it is often mixed into chemical compounds to form a stable substance.
• Formaldehyde naturally exists in the atmosphere as a byproduct of combustion (eg forest fires, car exhausts) as well as that of atmospheric reactions - particularly in the production of one of the components of smog.
• At room temperature it is a colourless, pungent smelling and flammable gas.
• Formaldehyde breaks down rapidly in the environment through action with sunlight and bacteria.
• Equally it metabolises quickly to formic acid in the human body and does not accumulate.
What is it used for?
Formaldehyde is used in a wide spectrum of products. Examples include shampoo, lipstick, nail polish, some glues, ink, paint and wrinkle-free fabrics. In construction, formaldehyde is still widely used as a binder in insulation products as well as commonly as an adhesive in wood panel products.
Concern about the health effects of exposure to formaldehyde emissions from materials and furniture was first expressed in the 1970s as buildings became more air-tight as the result of then energy crisis. Concern was also extended to workers exposed to formaldehyde.
The US Environmental Protection Agency (EPA) describes formaldehyde as causing '…watery eyes, burning sensations in the eyes and throat, nausea, and difficulty in breathing in some humans exposed at elevated levels (above 0.1 parts per million). High concentrations may trigger attacks in people with asthma. There is evidence that some people can develop a sensitivity to formaldehyde. It has also been shown to cause cancer in animals and may cause cancer in humans. Health effects include eye, nose, and throat irritation; wheezing and coughing; fatigue; skin rash; severe allergic reactions.' 1
Formaldehyde and cancer
Though there is little dispute about irritation and allergic reactions to Formaldehyde, debate continues concerning its status as a carcinogen - though consensus appears to be approaching.
One particularly significant study of a possible link between formaldehyde and cancer comes from two studies conducted by the US National Cancer Institute (NCI). The first (cohort) study examined deaths amongst a group of 25,619 workers who were employed, prior to 1966, in the production of formaldehyde, formaldehyde resin or in processes that included the use of formaldehyde such as moulded-plastic and plywood.
In the first report using data up until 1994, the risks showed an increased risk of death due to leukaemia amongst workers. The risk was associated with increasing peak and average levels of exposure, as well as duration, but it was not associated with cumulative exposure. 2
The second report, published in 2009, and based on a further 10 years of data continued to show a possible link between exposure and cancer. 3
Though in many ways persuasive, the evidence is a little mixed. For example a British cohort study of textile workers could not provide conclusive evidence of a causal association between formaldehyde exposure and leukaemia. 4
On balance though, and in concluding analysis of the various studies, the NCI maintains that '…exposure to formaldehyde may cause leukemia, particularly myeloid leukemia, in humans.' 5
In addition to suggesting the link between formaldehyde and leukaemia, the NCI studies also suggested a link with nasopharyngeal cancer ( a rare form of cancer of the nose). Again, this association agreed with some similar studies but in other studies no such link could be identified. Furthermore, in most modern studies, a previously suggested link with lung cancer has not been upheld.
Formaldehyde industry response
Concern about possible linkage between formaldehyde and cancer, not surprisingly stirred the formaldehyde industry into a defence of its production and use.
The main target of industry criticism has been the NCI report (cited above), particularly concerning claims of occurrence of nasopharyngeal cancer. Critics of the study claim that the cancer was due to other causes - a claim that was backed by a University of Pittsburgh study in 2007.
The industry disputes that formaldehyde is capable of causing leukemia, saying it is “biologically implausible.” They state that since formaldehyde is so reactive, it will only act on tissues of first contact, and its rapid metabolism prevents its distribution throughout the organism.
The main objection to the disapprobation of formaldehyde is that of the likelihood of human exposure to emissions of sufficient concentration to pose a risk. At a 2007 International Formaldehyde Science Conference organised by the European Formaldehyde Industry Association, it was resolved that '… the common use of formaldehyde in consumer products and other applications does not pose a risk to human health'
• The International Agency for Research on Cancer (IARC) classifies formaldehyde as 'carcinogenic to humans'. 6
• EU Classification. The EU Risk Phrase 7 is 'Toxic by inhalation, in contact with skin and if swallowed. Causes burns. Limited evidence of a carcinogenic effect. May cause sensitisation by skin contact. [R:23/24/25-34-40-43]'
• The Environment Agency categorises formaldehyde as a hazardous Volatile Organic Compound (VOC)
• Formaldehyde is not considered a 'substance of very high concern' (SVHC) under REACH regulations, but it is listed as a SVHC on the ETUC 'Trade Union Priority List for REACH Authorisation' (Version 2.0, June 2010)
Domestic exposure to formaldehyde
'Indoor air levels of formaldehyde are not generally the subject of official regulations. However the generally accepted guideline figure for the amount of formaldehyde that should not be exceeded in ambient air from all formaldehyde emitting sources is 0.1 milligramme per cubic metre of air (equivalent to about 0.08ppm) measured over a 30 minute reference period (WHO, 2000).' 8
In a recent survey of English homes, it was found that the geometric mean concentration of formaldehyde from all sources was 0.022 mg m -39
However when concentrations were associated with the age of the house, there was a correlation between age and concentration. Houses built before 1919 showed considerably less concentrations than those homes built in the period 1991 - 1998.
A second factor that was shown to determine concentration was the presence of particleboard in the home. A 'significant difference' was found between homes with and without particleboard.
The overall conclusion of the survey was that formaldehyde exposure in the home is likely to be of concern only in new homes but where after a year following construction, concentration reduced considerably. 'Even so, there are clear implications for mitigation of exposure and these are consistent with current thinking derived from other work' including: 'use (of) low-emission materials in the construction and furnishing of homes, and ensur(ing) good ventilation, especially during construction and the first year of occupancy;'
Formaldehyde, Indoor Air Qualilty (IAQ) and ventilation
One significant omission from the homes survey was a measure of ventilation rate. Whilst probably not of overwhelming importance at the time of the survey, the link between indoor air quality and controlled ventilation has become much more important as airtightness standards have become a feature of regulations.
IAQ is influenced by both ventilation (the amount of air getting in) and the indoor sources of pollutant emissions. As previously noted there are a number of possible sources of formaldehyde off-gassing, which might include construction materials as well as furniture and other household materials.
Ventilation acts by diluting the concentration of the pollutant and removes some of the pollutant from the internal to the external environment. Where ventilation is reduced, so is the ability to remove pollutants. Whereas a combination of weak air tightness and ventilation rates required by the Building Regulations up to and including those of 2006 were usually adequate to control pollutant concentrations, Part F (2010) now calls for a minimum average controlled ventilation rate of 0.3 l/s m-2 of floor area (Passivhaus rate by comparison is even tighter at 0.2 l/s m-2).
• Controlling IAQ through ventilation is becoming increasingly difficult.
Specify materials to reduce formaldehyde off-gassing
As the ability to control IAQ through ventilation becomes more difficult, so it becomes equally more important to control the sources of indoor air pollution.
• Select materials and products that off-gas less formaldehyde or or use safer substitutes,.
1 EPA website www.epa.gov/iaq/formalde.html
2 Hauptmann M, Lubin JH, Stewart PA, Hayes RB, Blair A. Mortality from lymphohematopoietic malignancies among workers in formaldehyde industries. Journal of the National Cancer Institute 2003; 95(21):1615-1623
3 Beane Freeman L, Blair A, Lubin JH, et al. Mortality from lymphohematopoietic malignancies among workers in formaldehyde industries: The National Cancer Institute cohort. Journal of the National Cancer Institute 2009; 101(10):751-761
4 Coggon D, Harris EC, Poole J, Palmer KT. Extended follow-up of a cohort of British chemical workers exposed to formaldehyde. Journal of the National Cancer Institute 2003; 95(21):1608-1615.
6 (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Volume 88 (2006) Formaldehyde, 2-Butoxyethanol and 1-tert-Butoxypropan-2-ol)
7 Defined in Annex II of EU Directive 67/548/EEC as amended by EU Directive 2001/59/EC
8 PanelGuide, WPIF, 2008
9 Raw G, Coward S, Brown V and Crump D. Exposure to air pollutants in English homes. Journal of Exposure Analysis and Environmental Epidemiology, 14, S85-S94, 2004.