Evaluating in vitro inhalation bioaccessibility of potentially harmful elements in active and passive air sampling media

This study evaluated the use of Quartz Fibre (QF) and Polyurethane Foam (PUF) filter materials, commonly used in active and passive airborne particulate matter (APM) sampling respectively, in terms of their ability to capture statistically similar observations of in vitro inhalation bioaccessibility to better inform human health risk assessment from inhalation exposure to PHEs. The results indicated that both filter media can provide comparable inhalation bioaccessibility data at the lowest solid-to-liquid ratio (S/L 500) tested in this study, i.e. the largest amount of material deposited on the filter relative to the volume of extractant used. There was no statistical difference in the solid to liquid ratio, with the exception of Sr in the PUF and Cu for the QF. It is recommended that passive dust deposition samplers are either deployed for longer periods of time (in the order of months) to allow for sufficient sample material to be retained, or the extraction is scaled up to use larger filter portions. Further work is required to understand the impact of the increased porosity of the PUF on this recommendation, as the possibility of particle resuspension is greatly reduced compared to the densely woven surface of QF filters. This method of APM capture represents a cost-effective approach for application in the field with minimal risk of loss of equipment, no need for infrastructure (power and security) and their relatively low cost in the region of $200 per filter unit and $10 per filter. The lung bioaccessibility method provides a robust means of additional interpretation for human health risk assessment with context specific exposure.