Ambient fine particulate matters (PMs), which can be characterized by their particle size &lt;2.5 µm (PM2.5), have been suggested to be a prominent risk factor associated with human morbidity and mortality. Among other chemical components of PM2.5, metal constituents are often statistically correlated to human disease outcomes in epidemiological studies or to biological endpoints measured in toxicological investigations. Although there is a perceived role of PM-bound metals in human health, there is, to date, no quantitatively deterministic understanding on the extent that metals can contribute to the combined effects of PM2.5 containing a multitude of known and unknown chemical components. It is critical, from a mixture toxicity perspective, to address the unknown effect of such a complex, unresolved chemical cocktail, and to understand the contributing metals in a quantitative risk assessment. In this study, we aim to evaluate the in vitro cytotoxic effects of PM2.5 collected from several megacities in China using A549 human alveolar basal epithelial cells. Preliminary data showed that the assay was able to capture the mixture effect and distinguish spatiotemporal patterns of urban PMs. The samples collected in winter episode days from Shanghai and Guangzhou triggered cytotoxic effects twice higher than those from Nanjing. The PM2.5 samples collected in summer clean days were generally an order of magnitude lower than those collected in winter air pollution episode days. Our ongoing work involves measuring the bioavailable fractions of trace elements in the PM samples, and profiling the toxic potency of individual elements and of their defined mixtures at the concentration of bioavailable fractions. We will employ mixture toxicity models to calculate the contribution of trace elements to the overall cytotoxicity triggered by PM2.5 and associated metals. The anticipated results would answer the critical question whether metals are dominant toxicity drivers in urban PM2.5.

Toxicity of airborne particulate matter in urban China: Quantitative contribution of metals to mixture effects

251st National Meeting (2016)

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