Association between particulate compositional changes during filter extraction and the interpretation of filter-based PM2.5 toxicology

摘要

Ambient fine particulate matter (PM2.5) is a global public health concern as it has well-established adverse respiratory and cardiovascular outcomes. Additionally, health effects have been shown to vary based on PM2.5 composition highlighting the importance of the contribution of metallic and organic species. To better understand the biological plausibility of epidemiology associations to PM2.5, ambient filter-based toxicology studies are routinely performed. These studies require extraction of ambient PM2.5 from a filter and the methods for this extraction vary between research groups and differences in extraction methods utilized have been shown to result in differential toxicology outcomes. udThis study compared characterization data for both ambient filter-based and corresponding extraction solutions prepared for toxicology research to identify compositional changes that occur due to the extraction methods. PM2.5 was characterized for concentration, metals, and organic compounds present in both ambient and extracted samples. While total PM2.5 mass recovery was high following extraction, there were significant and near complete losses of health relevant compounds. Following these findings, a study to assess the impact these compositional changes have on the interpretation of associations to inflammatory responses was designed.udThe release of a pro-inflammatory cytokine, interleukin (IL)-6, was measured in an alveolar macrophage cell line and associations were made between IL-6 release and PM2.5 constituents in both ambient and extracted samples. When using ambient composition data, significant positive associations were made between IL-6 and a number of organic constituents, however these constituents were not detected in the extraction solution. Additionally, use of ambient composition values displayed significant negative associations to several health relevant metals, these associations were found to be positive when using the extracted values. This research established compositional changes from ambient PM2.5 due to extraction procedures and these changes led to a misinterpretation of associations between constituents and the release of a pro-inflammatory mediator udThe public health significance of PM2.5 exposure is evident as it is a ubiquitous exposure with established adverse health outcomes. Further developing toxicology studies that accurately assess ambient exposures of PM2.5 are essential to ultimately create constituent specific regulations to protect human health. ud