[Toxicity of PM_2.5 Based on a Battery of Bioassays]

To accurately evaluate the biotoxicity of PM_2.5, PM_2.5 samples from winter fog-haze days, winter normal days, and summer days in Changzhou were selected for evaluation based on the acute toxicity of luminescent bacteria and zebrafish embryos and the cytotoxicity of human lung adenocarcinoma cells in vitro (A549). The three atmospheric conditions and the physical and chemical indicators were also evaluated using correlation analysis. The PM_2.5 samples showed either acute or developmental toxicity during all three periods. The toxicity unit (TU) of the luminescent bacteria for the winter fog-haze days, winter normal days, and summer days were 1.74 (toxic), 1.19 (toxic), and 0.92 (slightly toxic), respectively. The maximum TU of the zebrafish embryos was for winter normal days (TU=1.14, toxic) followed by winter fog-haze days (TU=0.79, slightly toxic), and summer days (TU=0, non-toxic). The highest TU of A549 was for winter fog-haze days (TU=0.61, toxic) followed by summer days (TU=0.38, toxic) and winter normal days (TU=0.31, toxic). With respect to developmental toxicity, with the exception of summer day samples, the PM_2.5 samples from the other two periods had detrimental effects on the development of zebrafish embryos, mainly showing pericardial edema, a bent notochord, and tail deformity. The average toxicity (AvTx), toxic print (TxPr), and most sensitive test (MST) indices showed that the PM_2.5 samples from winter fog-haze days and winter normal days exhibited toxicity, while samples from the summer days showed slight toxicity; PM_2.5 samples from winter fog-haze days had the highest level of comprehensive toxicity. In addition, luminescent bacteria were the most sensitive to PM_2.5 samples, followed by zebrafish embryos and A549. The results of chemical analysis and biological toxicity tests show that the pollutants contained in PM_2.5 have a biological toxicity effect, which can provide a basis for the comprehensive assessment of PM_2.5 biological toxicity and human health risks.