Health risk assessment of indoor exposure to emissions from wood and wood products
In recent years, air quality and its effect on human health was mainly focused on outdoor air. However, most people spend the majority of their time indoors. Especially modern airtight constructions together with low ventilation rates can result in an accumulation of emissions of building materials and furniture. This might have an impact on human health.
Wood and wood-based products are widely used as construction material and for furniture due to its good material properties. As organic material wood-based products emit a variety of volatile organic compounds (VOC) which are among others responsible for the characteristic odour of wood products. The extent to which these substances may affect human health is the topic of controversial discussion. Toxicological threshold values exist for a series of substances for which precautionary hygienic values for indoor air quality have been derived. Wood products commonly emit mixtures of different substances. There is little knowledge about the effect of mixtures of these substances on human health (irritations of the skin and the mucous membranes in the eyes and respiratory tract, allergenic as well as immunotoxic potential, but also positive effects such as increased performance). Therefore, the emissions released during the use of wooden products should be analysed and toxicologically evaluated. The aim was to provide a comprehensive picture of possible health effects of emissions from wood.
The results of the project ensure more safety when utilizing wood and wood-based products for indoor applications. This benefits consumers and players in the construction sector.
Starting point was a literature review in which the current state of knowledge was reflected by the working groups involved in the project. Regulatory aspects were discussed as well as possible health-promoting and adverse effects of emissions from wooden products. The focus of the Thünen Institute of Wood Research was the characterization of the emission behaviour of wood and wood-based products. The quantitative and qualitative composition of the emissions was of particular interest. In addition, the factors influencing the emission performance were discussed.
On the basis of the literature review, cell biological, immunological and allergological experiments were conducted. Thereby the potential hazard of wood emissions (toxicity of mixtures) and single emission components (lead compounds) were investigated. The focus was on pine wood which is characterized by comparatively high terpene emissions. In addition, OSB (oriented strand board) was examined due to its mixture of terpene as well as aldehyde emissions. Our task was to design suitable exposure scenarios in emission test chambers (according to EN ISO 16000). Furthermore, we provided the wood technological expertise to support the project partners with their experiments.
Wood is a natural product that is characterised by a complex and heterogeneous emission behaviour. The quantitative and qualitative composition of the emissions depend on the wood specie and the type of wood-based panel. Additionally, the emissions are subject to temporal dynamics. Until now it is not possible to predict exactly enough the indoor concentrations of VOC from single product emission tests.
Based on the results of the project an adjustment of the TVOC concept is recommended. The TVOC value corresponds to the sum of the concentrations of the single VOC and works as an indicator regarding indoor air quality. Even though the concept is practicable, it is too simplified to fulfil the complexity of the emissions of wood-based products. The main criticism is the missing weighting of the different toxicity of the single compounds. Under identical experimental conditions terpenes are for example much less toxic than aldehydes. An evaluation based on sums of VOC which belong just to the same group of substances might be an alternative to the TVOC concept. Furthermore, the results show that hygienical critical or even inacceptable concentrations (“worst case” scenario) of pine and OSB emissions induce no adverse health effects in allergen-sensitized mice.
The results of the cell biological, immunological and allergological experiments are difficult to transform to the real indoor situation. Extensive epidemiological studies or experimental exposition studies with volunteers would be necessary for that. However, it is questionable if emissions of wooden products make a relevant contribution to health-impairing effects. A wide range of other factors exist to which humans are exposed indoors (e.g. particulates, microbial contaminants, VOC of other materials) that might have a higher impact. Moreover, some VOC of wooden products could even have health-promoting effects. Further research is necessary in this topic. Especially lower concentrations of VOC are of interest as they might influence the psyche (e.g. pleasant smell perception).
The final report and the literature study can be downloaded from the following address: www.fnr-server.de/ftp/pdf/reports/22011015.pdf
5.2016 - 12.2019