ASSESSING TOXIC POTENCY OF AMBIENT AIR USING BIO-ANALYTICAL METHODS: A CASE STUDY USING PASSIVE AIR SAMPLING

Hazardous air pollutants are present in ambient air as components of complex mixtures a large proportion of which remains uncharacterised in terms of exposure or effect. Current regulatory approaches however focus on relatively few individual components of this mixture, which are sufficiently characterised, for monitoring and potential regulation. Bio-analytical assessments may be undertaken for complex mixtures for specific mechanisms of toxicity. These assessments would provide a screening tool for overall toxic potency. A framework is outlined for the application of a mode of action test battery for these assessments. Passive air samplers which may be deployed over wide spatial scales simultaneously are particularly suited as a screening tool for assessing exposure. A preliminary field study was conducted at five sites in Queensland using semipermeable membrane devices, a type of passive air sampler. These samples were then assessed for overall toxic potency using the umuC assay (genotoxicity) and analysed for polycyclic aromatic hydrocarbons. Both toxicity units and maximum induction ratios were determined as overall potency estimates. The sum of benzo[a]pyrene equivalents (ΣBaP Eq) was determined for co-deployed samplers. Significant differences were found between some sites using overall potency estimates. A significant correlation was found between toxicity units and the ΣBaP Eq. However, this parameter does not appear to identify the most potent site as assessed bio-analytically suggesting that other non-quantified components may be responsible for observed effect in certain cases