Investigating the Oxidative Potential and In Vitro Toxicity of Ambient Water-Soluble PM10 in an Eastern Mediterranean Site

Abstract

In this study, the acellular dithiothreitol (DTT) assay, the in vitro cellular DCFH-DA assay on human lung epithelial cells, and gene expression measurements were used to assess the toxicity of water-soluble (WS) PM₁₀ relating to reactive oxygen species (ROS) in summer at an Eastern Mediterranean urban site. Large influences from anthropogenic sources on health risks were observed with acellular and cellular assays. Anthropogenic biomass burning (BB) and natural dust events increased human pulmonary exposure to the oxidative potential (OP_dose,T) of WS-PM₁₀ by 209 and 47%, respectively, compared to regular periods. OP_v^DTT and ROS_v results were positively correlated in anthropogenic-dominant samples, while showed no significant correlation in the remaining samples. As a result, the BB and dust event had higher and lower levels of cellular ROS_v compared with the nonevent period, respectively. Source apportionment results suggest that specific organic contents (e.g., PAHs) had relatively low contents in samples less influenced by anthropogenic sources, possibly explaining the divergence in acellular and cellular results. Heavy metals were dominant contributors of OP_v^DTT throughout the campaign, and a Chelex method is recommended over a EDTA method for quantification of their summed OP_v^DTT.

Water-soluble particulate matter from anthropogenic biomass burning has a greater potential to induce oxidative stress than mineral dust storms when the human body is exposed to polluted air.