Known for its irritant effects, formaldehyde is a substance found mainly in indoor environments where it has multiple sources, e.g. building and decorating products, detergents, etc. It is also emitted naturally during combustion phenomena (fires, cigarette smoking) and anthropogenic activities (cooking food, using a wood stove). Formaldehyde has been classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer (IARC) since 2004. Based on this classification, the Agency conducted a series of expert assessments concerned with the general and occupational populations. In 2011, it also submitted to the European Chemicals Agency (ECHA) its proposal to revise formaldehyde’s classification with a view to giving it a more stringent carcinogenic classification at the European level.
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Updated on 03/08/2016
Assessment of the health risks associated with the presence of formaldehyde
Presentation of the Agency’s work
Known for its irritant effects, formaldehyde is a substance found mainly in indoor environments where it has multiple sources: building and decorating products, detergents, etc. Because of its physico-chemical properties, formaldehyde has many industrial applications as a biocide, preservative or fixing agent, as examples. 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.
In Europe, formaldehyde is classified as a category 2 carcinogen according to the CLP Regulation (Former Category 3 according to Directive 67/548/EEC). In Europe, formaldehyde is classified as a category 2B carcinogen according to the CLP Regulation while the ECHA opinion of November 2012 recommends a modification of this classification, making it a category 1B carcinogen and a category 2 mutagen.
In France, the Ministry of Labour issued 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, the Agency received a solicited request in November and December 2004 by the Ministries of Health, Ecology and Labour 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:
- analysis of toxicological data on formaldehyde;
- identification of products affected by the presence of formaldehyde;
- analysis and quantification of routes of exposure by specifying direct and indirect sources of formaldehyde;
- assessment of the health risks for the general and occupational population for any type of effect, with particular attention to children;
- establishment of 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 (CES Chemicals, CES Air environments, Committee on expert appraisal for recommending occupational exposure limits for chemical agents [OELs]) was formed. Concurrently, work was initiated with various organisations between 2004 and 2009 (the French National Institute for Industrial Environment and Risks [INERIS], National Research and Safety Institute [INRS], French Scientific and Technical Centre for Building [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 exposures. Formaldehyde is also the cause of 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 that those capable of inducing cancer, are considered to be precursor effects of the induction of tumours observed at higher concentrations. This finding supports that hypothesis of a threshold dose carcinogenic mechanism and the designation of irritant effects as being critical.
Concerning the relationship between exposure to formaldehyde by inhalation and the onset of leukaemia, the expert appraisals did not reach any conclusion on this point, notably 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, formaldehyde releasers but also 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. The risks of eye and respiratory irritation cannot be excluded. It should be taken into consideration in discussions on a policy of isolation and containment of housing. From the available data 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 the emission of formaldehyde. 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 address as a priority workers for whom levels of exposure at certain workplaces are on occasion 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 will be carried out as part of the work conducted by ANSES on the substitution of carcinogenic, mutagenic and reprotoxic (CMR) substances, particularly in connection with formaldehyde releasers.
In this context, 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. The European Chemicals Agency (ECHA) put the French proposal forward for consultation with the other Member States the stakeholders in November 2011. Following this consultation phase, which ended on 15 December 2011, ECHA’s Risk Assessment Committee examined the proposal with respect to the European classification criteria as well as the scientific evidence, and issued an opinion in November 2012 recommending to change the carcinogen category of formaldehyde 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.
Moreover, in 2013 on the European level ANSES in conjunction with the RIVM (National Institute for Public Health and the Environment of the Netherlands) took charge of the assessment of formaldehyde in the framework of the REACh regulation. The main objective of this procedure is to resolve the remaining uncertainties on the risk assessment of this substance. Its initial conclusions will be published in 2015.