Induction of sister chromatid exchanges (SCE) in human tracheal epithelial cells by the fractions PM-10 and PM-2.5 of airborne particulates.

Recent epidemiological studies in the United States and in Europe indicate, that the coarse fraction (PM-10) of airborne particulates, smaller than 10 microm and particularly the fine fraction (PM-2.5) smaller than 2.5 microm are responsible for adverse health effects, causing an increasing morbidity and mortality. Furthermore, an association was reported between air pollution, especially the levels of the fine respirable particles and death from lung cancer. The epithelium of the respiratory tract is the major target of airborne particulates and the location of the most common cancer in man, bronchogenic carcinoma. The genotoxic activity of the coarse (PM-10) and the fine fraction (PM-2.5) of airborne particulates leading to mutation and cancer can be analyzed using in vitro models of human bronchoepithelial cells. In our study collection of the coarse (PM-10) and the fine fraction (PM-2.5) of airborne particulates was conducted in the winter of 1996 in the highly industrialized Rhine-Ruhr region (Germany). For collection we selected an urban area (Düsseldorf), an industrialized area Duisburg and a rural area (Borken). Airborne particulates were collected with a Low Volume M-10 dichotomous sampler (Graseby-Andersen) equipped with glass fiber filters. Chemical substances were extracted from filters with di-chloromethane and quantitatively transferred to dimethylsulfoxide (DMSO). As target cells for testing the genotoxic activity we used cultures of the human bronchioepithelial cell line (BEAS-2B). As a sensitive cytogenetic endpoint for evaluation of the genotoxic activity of extracts of airborne particulates we utilized the induction of 'sister chromatid exchanges' (SCE). The coarse fraction PM-10 and especially the fine fraction PM-2.5 of airborne particulates from all three locations caused a strong dose-related induction of 'sister chromatid exchanges'. The fine fractions PM-2.5 from the three locations exerted a stronger genotoxic activity than the corresponding coarse fractions PM-10. While airborne particulates from Düsseldorf and Duisburg revealed a comparable genotoxic activity, the samples from Borken disclosed a lower genotoxicity. It is important that especially the fine fraction PM-2.5, exerted a strong genotoxicity equivalent to substances of airborne particulates from less than 0.5 m3 of air. Results of this study and earlier reports demonstrate that the human tracheobronchial epithelial cell line (BEAS-2B) in vitro offer a reliable and sensitive in vitro model for genotoxicity testing of airborne particulates, especially of the coarse (PM-10) and fine fraction (PM-2.5).

[Encasing evaluation: studies of dust retention and water permeability]. / Encasing-Bezüge: Untersuchungen zum Staubrückhaltevermögen und zur Wasserdampfdurchlässigkeit.

The use of allergenproof mattress casings for those allergic to house-dust mite is a vital component of therapeutic concepts concerning the avoidance of allergens. Encasings of different materials are available from a variety of manufacturers on the German market. The goal of this study was to investigate different encasing materials to test for their impermeability to dust and permeability to water vapour ("breathability"). Material samples from nine different manufacturers as well as one additional samples were tested by two independent institutes. The samples were coded with serial numbers and the product names and manufacturers were unknown to the testers. The degree to which particles could penetrate the materials (as a measure of dust penetration) was tested in two series of experiments using the naturally available ambient air and fine coaldust. A thermo-regulation model ("skin model") was used to test the materials for water vapour permeability. The results of three of the nine samples tested for particle penetration have to be considered unsatisfactory due to the number and size of the particles allowed to enter. Overall an additional synthetic layer appears to improve the materials capacity to prevent dust penetration. The water vapour permeability of three of the nine samples of encasing material must be classified as unsatisfactory with the consequence of possible sleep disturbance. From an allergological point of view, minimal particle penetration is an essential criteria. On the other hand, low water vapour transport properties can diminish the patients willingness to comply. The present study cannot be substituted for a clinical study of effectiveness but nonetheless reveals, in some cases, considerable differences in the physical properties of the various materials. It would be desirable for the individual product packaging to feature a declaration of the relevant test data, thus providing decision-making for those buying or prescribing.