Volatil organic compounds : a way to detect fungal development in indoor environments

Background : Fungi are common biocontaminants in closed environments able to induce respiratory diseases and degradation of substrates they colonize.However, as soon as they start to grow, fungi emit VOCs which arise from their metabolism or from the degradation of materials. Unlike spores, VOCs are dispersed in the environment and are not retained by substrates. Consequently, measuring these specific compounds should enable both the detection of early and hidden proliferations. However, until now, the use of VOCs as a fungal tracer has been limited by their low levels compared with those from materials and also by the lack of specificity of most of the VOCs emitted. Aims :The aim of this study consists on determining if there are specific chemical emissions of fungal growth. To achieve this, chemical emissions from sterile products and those contaminated artificially by molds were analyzed using a descriptive statistical method. Methods :Three fungal strains frequently isolated in indoor environments were employed.Two types of products were used as growth substrates: a control substrate consists on fiberglass and five commercial materials frequently encountered in indoor environments. The VOC are sampled on adsorbent tube and analyzed by GC/MS. Results : The statistical analysis used, Principal Component Analysis, considers the chromatograms of each type of substrate without prejudging compounds. This analysis, applied to each product’s emissions, enabled to differentiate contaminated substrates from sterile ones. Furthermore comparison of ion fragments from chemical emissions between contaminated and sterile products enabled to determinate 59 ion fragments responsible of the discrimination.This VOC fingerprint of fungal growth has been tested on samples from 12 dwellings and permitted to detect the 7 contaminated ones. Conclusions :Despite the low emission rates, this study proves that the emission of specific VOC enables to detect the presence of an active fungal development in indoor environments even in the case of hidden contamination.