Known for its irritant effects, formaldehyde is a substance found mainly in indoor environments where it has multiple sources: construction products, furnishings, detergents, etc. It is also emitted naturally during combustion phenomena (fires, cigarette smoking) and anthropogenic activities (cooking food, using a wood burning stove). Formaldehyde has been classified as "carcinogenic to humans" (Group 1) by the International Agency for Research on Cancer (IARC) since 2004. Following this classification, ANSES conducted a series of expert assessments concerning the general and occupational populations. In 2011, it also submitted a proposal to the European Chemicals Agency (ECHA), which led to formaldehyde’s European classification being revised to that of Category 1B carcinogen (presumed to have carcinogenic potential for humans) and Category 2 mutagen.
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Updated on 03/08/2018
Assessment of the health risks associated with the presence of formaldehyde
Presentation of the Agency’s work
Keywords : Formaldehyde, Hazardous chemical substance substitution, Indoor air, Chemical risks, REACh (regulation), Volatile organic compounds (VOCs), Reference values (RVs), Occupational exposure limits (OELs), Toxicity reference values (TRVs)
Known for its irritant effects, formaldehyde is a substance found mainly in indoor environments where it has multiple sources: construction products, furnishings, detergents, etc. Because of its physico-chemical properties, formaldehyde has many applications as a biocide, preservative or fixing agent. It is also emitted naturally during combustion phenomena (fires, cigarette smoking) and anthropogenic activities (cooking food, using a wood burning stove).
In June 2004, the International Agency for Research on Cancer (IARC) changed the classification of formaldehyde from the category of substances that are “probably carcinogenic to humans” (Group 2A) to “carcinogenic to humans” (Group 1) for nasopharyngeal cancers by inhalation, on the basis of epidemiological studies in the workplace.
Following an ECHA opinion in November 2012 and ANSES's 2011 proposal to revise its classification, formaldehyde was classified as a Category 1B carcinogen and Category 2 mutagen at European level by Commission Regulation (EU) No 605/2014 of 5 June 2014.
In France, the Ministry of Labour had anticipated this revised harmonised classification by issuing an Order in July 2006 classifying “Work involving exposure to formaldehyde” in the list of activities involving carcinogenic substances, preparations and processes, as defined by the Labour Code. The implementation of this Order was effective as of 1 January 2007 and involves measures for identifying substitutes for formaldehyde as a priority.
As a result of the classification of formaldehyde by the IARC in June 2004, ANSES was asked by the Ministries of Health, Ecology and Labour in November and December 2004 to conduct an assessment of the health risks associated with the presence of formaldehyde in indoor and outdoor environments. The objectives of this request were:
- to analyse toxicological data on formaldehyde;
- to identify products affected by the presence of formaldehyde;
- to analyse and quantify routes of exposure by specifying direct and indirect sources of formaldehyde;
- to assess the health risks for the general and occupational population for any type of effect, with particular attention to children;
- to draw up a list of possible existing substitute products or processes.
To complete this work successfully, a Working Group reporting to several of the Agency’s Expert Committees was formed. At the same time, work was initiated with various organisations between 2004 and 2009 (Ineris, INRS, CSTB, poison control centres, etc.) to respond to the various points in the request.
On this basis, two reports were published:
- In May 2008: “Toxicity of formaldehyde. State of knowledge on the characterisation of hazards and selection of toxicity reference values (TRVs)” and “Assessment of the health risks for the general population”;
- In May 2009: “Study of industrial sectors”, “Health risks associated with the presence of formaldehyde in occupational environments” and “Relationship by composition and emission”.
Analysis of toxicological data
By air, the critical effects of formaldehyde in humans are irritation of the eyes and respiratory tract, observed for acute and chronic exposure. Formaldehyde also causes nasopharyngeal cancers by air in humans, according to epidemiological studies conducted in the workplace.
Analysis of the mechanism of action indicates that irritant effects, which occur at lower concentrations than those capable of inducing cancer, are considered to be precursor effects of the induction of tumours observed at higher concentrations. This finding supports the hypothesis of a threshold dose carcinogenic mechanism and the choice of irritant effects as the critical effects.
Concerning the relationship between exposure to formaldehyde by inhalation and the onset of leukaemia, the expert appraisal did not reach any conclusion on this point, mainly due to the failure to identify a mechanism of action supporting a relationship. It should also be noted that in 2009 the IARC considered the causal link to be confirmed in humans.
Study of industrial sectors
The study of industrial sectors emphasises the ubiquitous use of formaldehyde in multiple occupational sectors and many consumer products. It is still difficult at present to rank sources of formaldehyde in indoor environments and to evaluate their respective contribution to the exposure of the general population. This ranking is even more difficult because emissions may come from the formaldehyde itself contained in products, from formaldehyde releasers and also from phenomena of chemical reactivity leading to the secondary formation of formaldehyde. The lack of relationship between the composition of the products and their formaldehyde emissions illustrates these difficulties.
Risks for the general population
Based on the results of the assessments of health risks for the general population, housing is a major contributor to formaldehyde exposure in indoor environments. According to the data available in 2008, the risk of cancer can be excluded for both adults and children. However, in order to reduce exposure and in light of the uncertainties and lack of knowledge on the share attributable to each source, it seems appropriate to limit the presence of formaldehyde in products intended for the general public with, for example, labelling that provides information on formaldehyde emissions. More broadly, the Agency recommends reducing exposure by advocating better ventilation of indoor environments.
Risks for the occupational population
According to the results of the assessment of occupational risks, the risk of nasopharyngeal cancers cannot be excluded in a certain number of sectors with repeated high exposure. Management actions should prioritise workers for whom levels of exposure at certain work stations can sometimes be 100 times higher than the maximum concentrations recorded in housing. In order to reduce the exposure of these workers, binding legal instruments, in this case, the Order of 13 July 2006, already require that the employer change existing industrial processes as a matter of priority.
Identification of substitute products
Numerous avenues were listed by sector. However, the review was not exhaustive and the alternative substances identified have not been analysed as to their safety and effectiveness. This additional study is being conducted as part of the work carried out by ANSES on the substitution of formaldehyde for its uses in pathological anatomy and cytology, embalming, human food and animal feed, and also in fish farming.
ANSES's other work on formaldehyde
Following on from this work, ANSES – as the agency responsible for providing support to the French authorities for the implementation of European regulations on the labelling of chemicals – prepared and submitted, on behalf of the French authorities, a proposal to revise formaldehyde’s classification in order to place it in a more stringent category at the European level. ECHA’s Risk Assessment Committee examined the proposal with respect to the European classification criteria and the scientific evidence, and issued an opinion in November 2012 recommending that the carcinogen category of formaldehyde be changed from Category 2 to Category 1B and adding a Category 2 classification for mutagenicity. This final opinion was sent to the European Commission for updating of the CLP Regulation on 5 June 2014.
Moreover, in 2013, at the European level, ANSES and the RIVM (National Institute for Public Health and the Environment of the Netherlands) jointly took charge of the assessment of formaldehyde in the framework of the REACh Regulation. The main objective of this procedure was to resolve the remaining uncertainties on the risk assessment of this substance. In 2017, as part of work to assess occupational exposure, France identified the need to conduct a risk management option analysis.
Lastly, in 2017, ANSES updated its reference values for formaldehyde in light of new data published: occupational exposure limits (OELs), occupational derived no effect levels (DNELs), toxicity reference values (TRVs) by inhalation, and indoor air quality guidelines (IAQGs).