Ambient polycyclic aromatic hydrocarbons and cardiovascular disease in China

Polycyclic aromatic hydrocarbons (PAHs) are a prominent category of ambient air pollutants worldwide, but our understanding of their potential health effects at ambient concentrations is severely limited. Our goal was to investigate the relation between ambient PAHs and daily hospitalizations for cardiovascular disease and explore its potential mechanism. This research included both observational and experimental studies. For population-based study, we collected data on daily hospitalizations for cardiovascular events in 184 major Chinese cities, which cover a population of 280 million individuals, for period of 2014-2017. We utilized a time-series quasi-Poisson regression model to assess the city-specific relations between PAHs and hospitalizations, and then employed a random-effects meta-analysis to aggregate the effect estimates across the cities. We also employed meta-regression models and stratified analyses to explore possible effect modifiers. For animal study, mice were exposed to varying doses of PAHs via tracheal instillation to evaluate the cardiac damage induced by PAHs. Potential mechanisms were elucidated through transcriptomic and proteomic sequencing. On the national scale, each interquartile range (IQR) increase in PAHs concentrations at 0-7 days was related to a 5.18 % (3.27 %-7.12 %) increase in hospital admissions for cardiovascular disease, 5.72 % (3.83 %-7.65 %) for ischemic heart disease, and 6.08 % (3.37 %-8.87 %) for ischemic stroke. The cardiovascular impacts of PAHs remained even after controlling for PM_2.5. The associations were more pronounced in cities with lower socioeconomic level, or higher temperatures and relative humidity, as well as in subpopulations with elder age (P < 0.05). We also found consistent associations between each of the seven individual PAHs and cardiovascular outcomes. In animal models, PAHs exposure induces cardiac injury via inflammation and oxidative stress, potentially linked to the PI3K/AKT and MAPK signaling pathways. This nationwide study indicated that ambient PAHs could represent a distinct risk factor for cardiovascular disease. They may contribute to cardiac damage through the regulation of inflammation and oxidative stress.