Personal exposure to fine particulate matter and benzo[a]pyrene from indoor air pollution and leukocyte mitochondrial DNA copy number in rural China

Households in Xuanwei and Fuyuan, China, possess hazardous levels of fine particulate matter with an aerodynamic diameter < 2.5 microns (PM_2.5) and polycyclic aromatic hydrocarbons (PAHs) from coal combustion. Previous studies found that increased exposure to PM_2.5 and benzo[a]pyrene (BaP; a PAH) were associated with decreased mitochondrial DNA copy number (mtDNAcn), a marker of oxidative stress. We further evaluated these associations in a cross-sectional study of 148 healthy non-smoking women from Xuanwei and Fuyuan. Personal exposure to PM_2.5 and BaP was measured using portable devices. MtDNAcn was measured using qPCR amplification of leukocyte DNA that was collected after air measurements. Linear regression models were used to estimate the associations between personal exposure to PM_2.5 and BaP, and mtDNAcn adjusted for age, body mass index (BMI) and fuel type. We found inverse associations between exposure to PM_2.5 and BaP, and mtDNAcn. Each incremental log-μg/m³ increase in PM_2.5 was associated with a significant decrease in mtDNAcn of -10.3 copies per cell [95% confidence interval (95% CI): -18.6, -2.0; P = 0.02]. Additionally, each log-ng/m³ increase in BaP was associated with a significant decrease in mtDNAcn of -5.4 copies per cell (95% CI: -9.9, -0.8, P = 0.02). Age, BMI, fuel type and coal mine type were not significantly associated with mtDNAcn. Exposure to PM_2.5 and BaP may alter mitochondrial dynamics in non-smoking Chinese women. MtDNAcn may be a potential mediator of indoor air pollution on chronic disease development.