Update on the formaldehyde release from wood-based panels 

The acceptable levels of formaldehyde emission from wood panel products have 

been continuously reduced over the last decades. The driving forces have been the 

increased public awareness and the consumer demand for non-hazardous products 

as well as the corresponding governmental regulations. The recent re-classification 

of formaldehyde by the International Agency for Research on Cancer as 

“carcinogenic to humans”, has triggered further concern and reactions by worker and 

consumer associations, “green” organisations, regulatory authorities and the industry 

itself. New studies on formaldehyde health effects were initiated since 2005 in both 

the USA and Europe and corresponding regulatory decisions on reclassification have 

been postponed until the results are available. 

The issue of formaldehyde release from composite wood panels is mainly related to 

the use of urea-formaldehyde (UF) resins as bonding adhesives for their production. 

These high reactivity and low cost polymers are contributing to the panel 

formaldehyde emission by their low resistance to hydrolysis and the presence of free 

non-reacted formaldehyde. Resin copolymers produced with the use of melamine 

either at low (urea-melamine-formaldehyde resins, UMF) or at high levels (melamineurea-formaldehyde resins, MUF) have improved hydrolytic stability but yet 

questionable performance in regard to very low formaldehyde emission levels. 

Urea-formaldehyde resins have traditionally been used in the production of woodbased panels (mainly particleboard, fibreboard, plywood) and related products for 

decades. Indoor air quality and formaldehyde emissions from composite wood 

products first became subject to broad public and governmental concern in the late 

1970s, when the energy crisis encouraged heat conservation through tight sealing of 

homes. This reduced the rate of outdoor air infiltration and overall ventilation rates 

leading to the entrapment of gaseous pollutants inside home air atmosphere. With 

Europe, North America and Japan as pioneers, test methods to accurately measure 

formaldehyde emissions from panels were developed and product emission 

guidelines were established. These were combined with work place exposure limits 

for formaldehyde. A total change in the formulation of UF resins was made by the 

resin industries to meet the low panel emission guidelines. Moreover, competitive 

bonding systems such as phenol-formaldehyde resins or polymeric diphenyl methane 

diisocyanate (PMDI) binders were proposed. 

Formaldehyde classification 

Until recently, formaldehyde was classified by the World Health Organization (WHO) 

as probably carcinogenic to humans (Group 2A). In 2004, the International Agency 

for Research on Cancer (IARC) of WHO, decided to recommend the reclassification 

of formaldehyde as “carcinogenic to humans (Group 1)”, on the basis of available 

scientific data (IARC 2004). This recommendation, although not legally binding, was 

received with concern and immediate reactions from worker and consumer 

associations, “green” organisations, regulatory authorities and the industry 

(producers and users of formaldehyde) associations (FormaCare and European 

Panel Federation in Europe, Formaldehyde Council and Composite Panel 

Association in N. America). The latter indicated that the decision of IARC had been 

based on studies regarding the exposure in 30-60 years ago, while the work place 

emission levels have declined dramatically the past three decades due to the 

technological progress made (Composite Panel Association 2004, Formaldehyde 

1
Council 2004). Moreover, they stressed that the IARC classification was a “hazard 

identification” and not a full risk assessment. 

In 2005, new toxicological and cancer studies were initiated by FormaCare and the 

Formaldehyde Council, involving various independent research institutes in Europe 

and the USA. In the meantime, there were proposals to reclassify formaldehyde in 

Europe by the French institute for occupational risk prevention (INRS) and the 

German Federal Institute for Risk Assessment (BfR). However, the European 

Chemicals Bureau (ECB) postponed its decision on the reclassification of 

formaldehyde until the results of the new studies were available (FormaCare 2006). 

Also the U.S. Environmental Protection Agency (EPA) delayed formaldehyde 

reclassification until the completion of the follow-up study of the National Cancer 

Institute. 

The IARC recommendation was finally published in December 2006 through its 

monograph series Volume Number 88. In this report, it is stated that “there is 

sufficient evidence in humans and in experimental animals for the carcinogenicity of 

formaldehyde” and that “formaldehyde is carcinogenic to humans (Group 1)” (IARC 

2006). It is further mentioned that the highest occupational exposure to 

formaldehyde were measured in varnishing, production of textiles, garments, furs, in 

certain jobs in board mills and foundries. Lower exposure levels have been 

encountered in formaldehyde production (mean concentration < 1ppm). A wide 

range of exposure levels has been observed in the production of resins production 

(all data were derived from the 1980s). In wood products manufacture, exposure 

occurs during glue mix preparation, laying of mat, hot pressing and sanding – all data 

were derived from the 1960s-70s-80s. The reported mean concentrations in the air 

were greater than 1ppm in particleboard mills and approximately 2ppm in plywood, 

however, recent studies reported concentrations lower than 0.4ppm in plywood and 

less than 0.16ppm in OSB and fibreboard plants. 

In September 2007, an International Formaldehyde Science Conference took place 

in Barcelona, Spain, organized by FormaCare (the European Formaldehyde Industry 

Association, sector group of CEFIC, the European Chemical Industry Council). The 

results of newly available scientific studies on the epidemiology and toxicology of 

formaldehyde were presented and discussed by representatives of institutes from 

Europe, the USA and Brazil, European Commission representatives and industry 

scientists (FormaCare 2007, Press Release). Main conclusions include the following 

points: a) the evidence for NasoPharyngealCancer formation is highly ambiguous, b) 

the leukemia formation related to formaldehyde exposure is highly improbable, c) no 

mutagenic effects were observed in experiments and d) in the normal living 

environment or at the workplace, formaldehyde exposure is not expected to lead to 

sensory irritation. The threshold for sensory irritation is clearly lower than that leading 

to cell death. Concentrations of 0.5 ppm or 0.3 ppm with peaks of 0.6 ppm will not 

lead to objective signs of sensory irritation. The bottom line of the conference was 

that “the common use of formaldehyde in consumer products and other applications 

does not pose a risk to human health”. The IARC recommendation was challenged 

by presenting the weak points of the studies on which it was based (old data, lack of 

statistical robustness of data analysis, no consideration of confounding effects) (also 

in FormaCare 2007, Scientific fact sheet). Such weak points and the newly available 

data suggest that there is no clear connection between formaldehyde exposure at 

current levels of exposure and cancer in humans. 

In October 2007, a study on the “Socio-Economic Benefits of Formaldehyde to the 

European Union (EU 25) and Norway” was released by FormaCare, quantifying the 

value of formaldehyde to society and the contribution of the formaldehyde industry to 

2
the economies of these countries (Global Insight 2007). The study indicated that 

“consumers would have to spend an additional €29.4 billion per year if formaldehydebased products were replaced by substitute chemicals” and that alternative products 

are of inferior quality and often of higher cost than the formaldehyde-based products, 

leading to a pronounced consumer preference for these latter products. Prior to this 

European study a report had been released on the “The Economic Benefits of 

Formaldehyde to the United States and Canadian Economies”, showing even higher 

economic benefits from the use of formaldehyde products (Global Insight 2005). It 

was found that “people use products that contain formaldehyde every day, and that 

formaldehyde and the products made from it provide an enormous contribution to the 

U.S. and Canadian economies”. 

Within the EU, formaldehyde is currently classified as a Category 3-R40 substance 

(“limited evidence of carcinogenic effect”), which is the lowest available EU category 

for suspected carcinogens. According to the findings of the Barcelona conference 

this category is still appropriate (Gelbke 2008). The classification of formaldehyde in 

the EU will be reviewed under the new REACH regulation on chemicals and their 

safe use. In the U.S. the current classification by EPA is that of a probable human 

carcinogen. 

Occupational Exposure Limits 

The Occupational Exposure Limits (OELs) for formaldehyde are presented in Table 

1. In countries with higher limits there are discussions to lower them following the 

recommendation of IARC (e.g. in Australia, the OEL of 1.0ppm will be set to 0.3ppm 

in 2008). 

Table 1: Occupational Exposure Limits (OELs) for formaldehyde (IARC 2006, 

FormaCare 2007, Q&A on formaldehyde) 

Country Concentration, ppm Typea

Australia 1.0 TWA 

Austria 0.3 TWA 

Belgium 0.3 Ceiling 

Brazil 1.6 Ceiling 

Canada-Alberta 2.0 Ceiling 

Canada-Ontario 0.3 Ceiling 

Canada-Quebec 2.0 Ceiling 

Denmark 0.3 TWA & STEL 

Finland 0.3 TWA 

France 0.5 TWA 

Germany 0.3 TWA 

Greece 2.0 TWA 

Hong Kong 0.3 Ceiling 

Ireland 2.0 TWA 

Italy 0.3 Ceiling 

Japan 0.5 TWA 

Malaysia 0.3 Ceiling 

Mexico 2.0 Ceiling 

Netherlands 1.0 TWA 

New Zealand 1.0 Ceiling 

Norway 0.5 TWA 

South Africa 2.0 TWA 

Spain 0.3 STEL 

Sweden 0.5 TWA 

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Switzerland 0.3 TWA 

United Kingdom 2.0 TWA 

USA-ACGIHb 0.3 Ceiling 

USA-NIOSHb 0.016 TWA 

USA-OSHAb 0.75 TWA a

TWA: time-weighted average, STEL: short-term exposure limit. 

Formaldehyde emission standards for wood-based panels 

In Table 2, the classification of wood-based panels in respect to formaldehyde 

emission according to the European, Australian, U.S.A. (also valid in Canada) and 

Japanese standards is given. 

Table 2: Formaldehyde emission standards for wood-based panels in Europe, 

Australia, the U.S.A. and Japan 

Country Standard Test method Board classa Limit value 

Europe EN 13986 Chamber EN 717-1 

Perforator EN 120 

Chamber EN 717-1 

Gas analysis EN 717-2 

Chamber EN 717-1 

Perforator EN 120 

Chamber EN 717-1 

Gas analysis EN 717-2 

E1-PB, MDF, 

OSB 

E1-PW 

E2-PB, MDF, 

OSB 

E2-PW 

≤0.1ppm 

≤8mg/100g 

≤ 0.1ppm 

≤ 3.5mg/h*m2

>0.1ppm 

>8 - ≤30mg/100g 

> 0.1ppm 

> 3.5 ≤÷

8.0mg/h*m2

Australia AS/NZS 

1859-1 & 2 

Desiccator AS/NZS 

4266.16 

E0-PB, MDF 

E1-PB 

E1-MDF 

E2-PB, MDF 

≤0.5mg/L 

≤1.5mg/L 

≤1.0mg/L 

≤4.5mg/L 

U.S.A. ANSI 

A208.1 & 2 

(PB & MDF) 

Large chamber ASTM 

E1333 

Large chamber ASTM 

E1333 

Large chamber ASTM 

E1333 

PB, MDF 

Industrial PW 

PW wall 

panels 

≤0.3ppm 

≤0.3ppm 

≤0.2ppm 

Japan JIS A 5908 

& 5905 (PB 

& MDF) 

Desiccator JIS A 1460 F** 

F***/E0 

F /SE0 

≤1.5mg/L 

≤0.5mg/L 

≤0.3mg/L a

PB: particleboard, MDF: medium density fibreboard, OSB: oriented strand board, 

PW: plywood 

In Europe, Germany pioneered in issuing regulations as well as in reducing panel 

formaldehyde emissions in actual industrial practice. Currently the German 

regulation requires compliance with E1 emission limits of 6.5mg/100g for 

particleboard and 7.0mg/100g for fibreboard (tested by the perforator method) 

(Roffael 2006). Also other European countries like Austria, Denmark and Sweden 

4
followed Germany in producing boards of only these E1 levels. However, most 

European countries still have legislation allowing the production and distribution of E2 

boards (according to EN 13986). Recently, the members of EPF agreed to only 

produce E1 boards and that compliance should be monitored through a system of 

internal and external checks (EUWID 2007). At the same time, the members firmed 

up the E1 limit values for ongoing production monitoring. 

The emission limit of the Japanese F**  class is more or less equivalent to European 

E1-class according to the German regulations, while the F*** and F  emission 

limits are much lower than the E1-class. The emission of F** ** boards is close to the 

emission of solid untreated wood (e.g. between 0.008-0.01ppm or 0.5-2.0mg/100g 

for spruce wood flakes, Marutzky et al. 2004). 

The Air Resources Board of California (CARB) adopted a new regulation in April 

2007 to reduce the formaldehyde emissions from composite wood products, 

including particleboard, MDF and hardwood plywood (Airborne Toxic Control 

measure, ATCM, CARB 2007). The final approval of its modified version is due by 

late April 2008. This regulation proposes the reduction of formaldehyde emission 

standards in two phases (Figure 1). Phase 1 limits (effective from January 2009) are 

roughly equivalent to the European E1 emission class that is the Japanese F** class 

(Figure 2). Phase 2 limits (effective from January 2010 and January 2011) are 

comparable to the Japanese F*** limits, the so-called E0 levels in Europe. The new 

regulation will establish the most stringent formaldehyde emission limits on wood 

products in the United States. The measure requires that wood panels and products 

manufactured from wood panels be certified by a “third party” laboratory (Third Party 

Certifier, TPC) approved by the CARB. The emission standards of Table 1 apply to 

panels sold, supplied, offered for sale, or manufactured for sale in California, also to 

panels used in finished goods and there are special provisions for manufacturers 

using NAF (No-Added Formaldehyde) & ULEF (Ultra-Low-Emitting Formaldehyde) 

resins. 

Figure 1: The California Air Resources Board new standards (CARB 2008) 

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Figure 2: CARB versus European and Japanese standards (CARB 2008, h) 

Discussions on a new emission class are currently under way in Europe. Industry 

insiders believe that the limit will be similar to that of the Blue Angel certification for 

environmentally-friendly products and services (EUWID 2007). Wood-based panels 

meeting this certification have to remain at least 50% below a formaldehyde emission 

value of 0.1ppm set out in class E1 and thus produce emissions of less than 

0.05ppm. This new emission value should be fixed as a voluntary guideline outside 

of standardisation. It may, however, serve as the basis for a future standard. 

The Industry response 

Facing the developments in formaldehyde re-classification and new emission 

standards, the wood panel manufacturers provided products with reduced 

formaldehyde release (Figure 3). 

Figure 3: Formaldehyde reduction for particleboards between 1978-2006 

(Marutzky 2008) 

6
This was mainly the result of applying adhesive resins with improved formaldehyde 

performance, a problem solved by the resin industry through either of the following: 

• New formulation urea-formaldehyde resins (with/without melamine). 

• Alternative gluing systems (PF, PMDI). 

• Resins based on biomass products or by-products (e.g. soy, tannin, lignin).

Such efforts and products aimed to meet the new demands for very low 

formaldehyde emission from composite panel products without any deterioration in 

panel performance or significant modification of manufacturing plant operating 

conditions and above all with due respect to production costs. Lately, formaldehydebased resin products providing panels with formaldehyde emission values at the 

level of natural wood were offered (Athanassiadou et al 2007, Kantner 2008).

As in the case of all chemicals, the wise use of formaldehyde together with the 

respect of formaldehyde emission standards and exposure limits are the means for 

safeguarding the worker and consumer health and quality of life levels. 

7
References 

Athanassiadou E. (2000) Formaldehyde free aminoplastic bonded composites. In: 

Proceedings of the 5th International Conference on Environmental Pollution, 

Aristotelian University, pp. 770. Thessaloniki, Greece. 

Athanassiadou E., Tsiantzi, S., Markessini, C. (2007) Towards composites with 

formaldehyde emission at natural wood levels, Proceedings of the 2nd Conference of 

COST Action E49, Measurement and Control of VOC Emissions from Wood-Based 

Panels, 28-29 November 2007, Braunschweig, Germany. 

CARB (2007) http://www.arb.ca.gov/toxics/compwood/compwood.htm 

CARB (2008) http://www.arb.ca.gov/regact/2007/compwood07/fro-final.pdf 

CARB (2008, h) http://www.arb.ca.gov/regact/2007/compwood07/apph.pdf 

Composite Panel Association (2004) IARC Decision on Formaldehyde 

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21_FormaCare_Press_Release_english_ final.doc 

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http://www.inrs.fr/ 

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