External and internal exposure to PM_2.5-bound PAHs from household solid fuel combustion: health effects mediated by...

This study investigated the personal exposure (PE) characteristics and metabolic patterns of polycyclic aromatic hydrocarbons (PAHs), as well as their effects on inflammatory and oxidative stress biomarkers in housewives exposed to household solid fuels combustion. Compared with raw coal users, biomass users showed significantly elevated levels of biomarkers IL-6 and IL-10 (p < 0.05), indicating obvious health damage. PM_2.5-bound PAHs exposure was dominated by parent (p)-PAHs in each fuel group (clean coal, raw coal and biomass), followed by the oxidized and nitrated PAHs. Clean coal group exhibited a certain reduction effect on p-PAHs exposure compared to the biomass group (p < 0.01), but only limited reduction was observed for PAH derivatives (p > 0.05). The raw coal and biomass fuel groups showed higher PAHs exposure during daytime than at night, while no significant diurnal variation was found in the clean coal group (p > 0.05). Additives in the clean coal production process may affect the formation of PAH derivatives. Urinary hydroxylated (OH)-PAHs levels in the participants aligned with the concentration orders of inhalation PAHs in PM_2.5 across the fuel groups. Most OH-PAHs showed significant correlations with inflammatory and oxidative stress biomarkers (p < 0.05), clearly superior to their p-PAHs. Mediation analysis indicated that hydroxynaphthalene (OHN) and hydroxyfluorene (OHF) played key roles in the association between PAHs respiratory exposure and inflammation factors (IL-6, IL-10). 1- Hydroxypyrene (1-OHP) mediated the effect of pyrene (PYR) on the oxidative stress biomarker 8-OHdG. This study can provide scientific basis for accurate health risk assessment of PAHs exposure from solid fuel combustion and regional rural energy structure optimization.