Toxicological analysis and organ damages of rats injected with soluble ambient particulate matter from 31 cities in China

Abstract

Efforts to reduce particulate matter (PM) mass concentrations often overlook the variability in PM components and associated health effects across cities. Here, we conducted PM toxicity experiments by injecting 228 Wistar rats with water-soluble PM suspensions (filtered through 0.45 μm membrane) (PMSF) of equal mass (6 mg/kg body weight), collected from automobile air filter in 31 major Chinese cities. Results revealed that PMs from thirty-one sources resulted in statistically significant differences in organ damages (heart, lung and liver), protein biomarkers and four microRNA expressions (miR-21, miR-125b, miR-146a, and miR-155). Nonetheless, these same measurements exhibited a statistical similarity for neighboring cities. Dimensionality reduction and machine learning algorithm revealed a strong link between specific metal components in PMSF and PM-related health risks. For example, reducing 6.20% of metal elements in PMSF was estimated to result in a 23.74% reduction in health risk. Additionally, Polycyclic Aromatic Hydrocarbons (PAHs) levels per unit PM mass was also observed to vary substantially across the 31 cities, thus further explaining the health disparity. Until this work, most studies involve limited number of city PM sources, thus developing a biased understanding of PM toxicity and health impacts for a country or the world. The results here provide a state-of-the-art mechanistic understanding of the health effects of PMs of diverse city sources, while formulating the theoretical basis and reference for city- and component-specific PM control.