Adsorption of polycyclic aromatic hydrocarbons on to asbestos and man-made mineral fibres in the gas phase.

The adsorption of the aromatic hydrocarbons naphthalene and phenanthrene on to 4 types of asbestos and 2 types of man-made mineral fibres in the gas phase was studied. The asbestos types were chrysotile, anthophyllite, amosite, and crocidolite and the man-made mineral fibres were rock wool and glass wool. The influence of the gas humidity on this adsorption was also studied. The experiments were performed in an open system with the continuous generation of a gas stream of constant flow rate, humidity and hydrocarbon concentration. The results show that chrysotile asbestos is an extremely good adsorbent of polycyclic aromatic hydrocarbons (PAHs) in dry gas. This material adsorbs about 100,000 times more PAH than does glass wool, which has the lowest capacity of the fibres tested. The amphibolic asbestos types lie in the upper half and the rock wool sample in the lower half of the range. However, if the gas phase is humidified to typical ambient air values, there is a dramatic decrease in the adsorption on to the highly adsorbing materials. This means that, at relevant gas-phase humidities, there will be a fairly weak adsorption of PAH of about the same order of magnitude for all the materials tested. Any enhanced biological effect of inhalation of PAH adsorbed on fibres is thus likely to be connected with properties of the fibres other than the mere amounts of PAH adsorbed.