Objective To evaluate the effects of single and mixed exposure to polycyclic aromatic hydrocarbons (PAHs) on oxidative stress markers in healthy elderly individuals, and to identify the key PAHs that affect oxidative stress markers.

Methods A panel of 76 healthy elderly individuals aged 60-69 years was recruited in Jinan, Shandong Province, China to participate in five epidemiological surveys from September 2018 to January 2019. The participants' basic information was gathered using a questionnaire, and their urine and blood samples were collected. The urine samples were examined by gas chromatography-tandem mass spectrometry for six PAHs, including 1-hydroxynaphthalene (1-NAP), 2-hydroxynaphthalene (2-NAP), 2-hydroxyfluorene (2-FLUO), 3-hydroxyfluorene (3-FLUO), 2-hydroxyphenanthrene (2-PHEN), and 1-hydroxypyrene (1-PYR). The levels of oxidative stress markers, including 8-hydroxyguanosine (8-OHG) and 8-hydroxydeoxyguanosine (8-OHdG), were determined by high-performance liquid chromatography-tandem mass spectrometry. The relationship between the PAHs and the oxidative stress markers was assessed by using a linear mixed-effects model, quantile g-computation (qgcomp) regression model, and Bayesian kernel machine regression (BKMR) model.

Results For the 76 included individuals (half male and half female), the mean age was 65±3 years, and the mean body mass index was 25.12±2.49 kg/m². The median concentrations of 1-NAP, 2-NAP, 2-FLUO, 3-FLUO, 2-PHEN, and 1-PYR were 1.16, 0.83, 0.24, 0.08, 0.06, and 0.10 μg/L, respectively. The median concentrations of 8-OHG and 8-OHdG were 5.66 and 4.50 ng/mL, respectively. For every 10-fold increase in the six PAHs, the percent changes in 8-OHG and 8-OHdG levels were 20.88% to 72.67% and 13.32% to 70.19%, respectively. The qgcomp and BKMR models showed mixed PAHs exposure was significantly positively associated with the total effects on 8-OHG and 8-OHdG levels, with 2-FLUO contributing most to oxidative stress.

Conclusion Exposure to PAHs, either individually or as a mixture, is associated with oxidative stress levels in healthy elderly individuals, in which 2-FLUO has the most significant effects on oxidative stress markers.