What is Formaldehyde?
Formaldehyde is a naturally occurring, simple chemical compound composed of hydrogen, carbon and oxygen. At room temperature formaldehyde is a colourless gas. All organic life forms including bacteria, plants, fish, animals and humans, produce formaldehyde that is emitted at various low levels. Formaldehyde does not accumulate in the atmosphere because it is quickly broken down by sunlight, through a process called photo-oxidation. The human body is also able to quickly metabolise, or break down, formaldehyde so it does not accumulate in our bodies. Because formaldehyde has many useful chemical properties, it is also manufactured industrially and serves as a key building block in a wide range of applications. Commercially manufactured formaldehyde is usually sold in liquid form as formalin, a solution that is most commonly 37% formaldehyde.
How is formaldehyde made?
Formaldehyde is generally produced commercially via the metal oxide process or the silver process. The diagram below illustrated the metal oxide process from Formox. A catalyst is used to create a reaction between methanol and oxygen at a high temperature which creates formaldehyde and water. The reaction between methanol and oxygen generates heat which is used to produce steam. CH3OH + ½ O2 → H2CO + H2O + heat. The gas mixture (air, formaldehyde and steam) is then cooled down and sent to an absorber where the formaldehyde is absorbed by water to produce an aqueous solution.
Health and Safety
Like most chemicals, either naturally occurring or man-made, very high concentrations of formaldehyde can be toxic. However its natural presence in our bodies at low levels means that human beings have the right metabolic processes to ensure that it is broken down quickly and does not build up in the body. On average, it is estimated that the human body produces as much as 7g of formaldehyde a day.
In March 2012, Formacare and the European Panel Federation (EPF) commissioned an independent study to TNO Triskelion and Risk & Policy Analysts Limited (RPA) to assess the safety of formaldehyde at the workplace and in homes. The Risk Assessment, based on recent workplace exposure measurements in the EU, showed safe use for worker exposure for the manufacture and major uses of formaldehyde, compared to a then occupational exposure limit of 0.4 ppm. For workers in some industries, particular tasks require the use of risk management measures, such as half masks, to meet safe levels.
Likewise, today’s indoor levels of formaldehyde in houses are shown to be safe, based on studies with large numbers of measurements in real homes in the EU over the past 20 years. Formaldehyde concentrations in homes are well below the safe level of 0.1 mg/m3 recommended by the WHO.
More information can be found here.
Like many substances, formaldehyde should be handled with care and the appropriate precautions should be taken when working with the substance in an industrial setting. Occupational exposure can occur in industries that use formaldehyde, including the manufacture of formaldehyde or formaldehyde-based resins. A wide array of safety measures can be implemented to limit exposure to formaldehyde process emissions and formacare recommends the highest level of protection in occupational settings, including the use of closed systems and high standard ventilation units.
As of 2019, the European Commission’s Scientific Committee on Occupational Exposure Limits (SCOEL) has recommended an Occupational Exposure Limit of 0.3ppm for 8H Time Weighted Average (TWA). A recommendation for an OEL could be derived since the substance is known to have a threshold mode of action. It is also aligned with the DNEL (Derived No Effect Level) developed by the lead registrant for the CSR and Extended Safety Data Sheets.
In 2018 the European Commission included formaldehyde in its proposal for a third amendment to the Carcinogens and Mutagens Directive (Directive 2004/37/EC on the protection of workers from the risks related to exposure to carcinogens or mutagens at work) and following the ordinary legislative procedure, the European Parliament voted the CMD3 in March 2019. While Council vote is pending, the CMD3 brings a Binding Occupational Exposure Limit that through a harmonized regulation that is protective for the European workers and enables industry to strive in Europe. Following its transposition into national law, CMD3 will also facilitate the creation of a level playing field at European level for formaldehyde production.
CMD 3 will bring the following value as a maximum level for workers exposure in the EU:
- 0.3 ppm Time Weighted Average (TWA)
- 0.6 ppm Short-Term Exposure Limits (STEL)
As usual with the ordinary legislative procedure (formerly known as codecision), the law foresees 2 years of transition before the Member States should comply with the values. Users of formalin for embalming and medical purposes (such as anatomopathology) were granted an extra 3 years of transition period.
Formacare is committed to even tighter standards for workers safety. A voluntary agreement is under preparation to cut the transition period and make the 0,3ppm BOEL applicable immediately.
Because industrially produced formaldehyde is used mainly as an intermediate, consumers rarely come into direct contact with formaldehyde. Formaldehyde is used in many applications in full compliance with specific European regulations to ensure consumers benefit from the properties of formaldehyde in a safe and comfortable way.
Consumers may be exposed to trace amounts of formaldehyde in indoor air. A recent study by Salthammer et al estimates that 10-50% of the formaldehyde found in indoor air comes from organic uses such as candles, incense, cooking, gas heaters, cigarette smoke or natural wood itself. The rest stems from emissions from materials produced from formaldehyde like resins, or glues.
Because formaldehyde-based resins are used in many construction and decorative products, these products can also emit very low levels of formaldehyde into the indoor air. Industry innovation has led to a steady decrease in formaldehyde indoor air levels over the last 40 years, to levels that are often so low, they are difficult to detect.
A study by the World Health Organisation proposed an indoor air quality guideline of 0.1 mg/m³. The average levels of formaldehyde in homes are already well below the recommended guidelines. Indeed, instances where formaldehyde levels exceed the WHO recommended indoor guidelines are extremely rare. The WHO 2010 guidelines for formaldehyde also concluded that formaldehyde does not present a greater risk to vulnerable populations such as children and the elderly.
Prof. Tunga Salthammer – A critical review of indoor formaldehyde concentrations and guideline values
Prof. Gunnar Nielsen – WHO (2010) Guideline value on formaldehyde and recent scientific studies
Safety of Construction & Decoration products
Wood naturally emits formaldehyde therefore it is not possible to achieve zero formaldehyde emissions from wood and wood-based products.
Through technical progress and innovation, the wood panel industry has, however, developed a voluntary European standard (E1) based on the WHO recommendation for indoor air levels of formaldehyde.
Although wood products still emit formaldehyde, the E1 label ensures that these products remain significantly below the WHO guideline, and thus allow consumers to safely benefit from all the properties of formaldehyde-based wood products.
The voluntary efforts of the wood panel industry have helped lower the concentration of formaldehyde in resins from around 100 mg/100g of panels in 1975, to less than 8mg/100g nowadays; that is from 0.1% to 0.008%.
Safety in other applications
Formaldehyde as an aqueous solution is a very effective disinfectant that can kill bacteria and fungi.
Also, because of this beneficial property, formaldehyde is sometimes used in certain vaccines and other healthcare applications such as in anti-infective drugs and in gel capsules to promote maximum absorption. In vaccines where the product is injected into the body, the amounts of formaldehyde are too low to affect the levels that naturally occur in the body. The development and use of vaccines is governed by the European Medicines Agency (EMEA).
EU-wide legislation strictly regulates the use of chemical substances in cosmetics to guarantee consumer safety via the Cosmetics Directive (76/768). Under this directive, formaldehyde is listed as a safe substance that can be used as an ingredient for cosmetics at a maximum level of 0.2%. All finished products containing formaldehyde or substances which release formaldehyde must be labelled with the warning “contains formaldehyde” where the concentration of formaldehyde in the finished product exceeds 0.05%. Formacare condemns the manufacture or use of any cosmetics product that does not comply with EU law.
Best practice for formaldehyde measurement
Best practice for determining free formaldehyde in aminoplast resins
Formacare recommends that free formaldehyde in liquid adhesives should be performed in accordance with EN 1243:2011. The recommendation is valid only for aminoplast resins (for example wood glues and impregnating resins) containing formaldehyde, and/or urea and/or melamine, but excluding etherified adhesives. The EN 1243:2011 standard, and recommendations for best practice, can be downloaded via the links below:
- Standard EN 1243:2011 can be purchased from the BSI Group: EN 1243:2011
- Formacare’s recommended best practice: Best practice for free formaldehyde measurement
Best practice for determining the free formaldehyde content in alkylated amino resins
The Solvent Resin Manufacturer (SRM) recommends to use the Industry Standard DIN EN ISO 11402 4.3 Sulphite Method. The purpose of this document is to describe the best practice procedure according to the Industry Standard. The procedure itself (as written in the Standard) is the basis for this document.
Formaldehyde air monitoring
A wide range of test methods and devices are available on the market for measuring formaldehyde in the working environment or in indoor air. In order to clarify which methods are capable of providing accurate measurements, Formacare experts performed a review of existing methods. A summary of the findings can be downloaded via the link below:
- Overview of test methods: “Occupational Hygiene Monitoring of Formaldehyde”
Formacare recommends as best practice the use of a procedure that samples air using a 2,4-DNPH and then determines the formaldehyde concentration by HPLC. The full procedure is provided in the link below:
- Recommended test method: “Determination of volatile aldehydes in ambient air”