Fig. 1

Restricted cubic splines representing the associations of urinary OH-PAHs with 8-OHdG (a) and 8-iso-PGF2α (b), with adjustment for age (continuous variable), gender (male/female), height (continuous variable), weight (continuous variable), smoking amounts (continuous variable), passive smoking status (yes/no), drinking status (yes/no), education level (categorical variable), annual family income (categorical variable), regular physical activity (yes/no), cooking meals at home (yes/no), sleep duration at night (continuous variable), eating smoked food (< 1/≥1 time/week), eating vegetables or fruits (< 1/≥1 time/day), eating aquatic products (< 1/≥1 time/day) and city (Wuhan/Zhuhai). Knots were placed at the 5th, 35th, 65th 95th percentiles of the independent variables distributions, and the reference value was set at the 5th percentile. Abbreviations: ƩHMW OH-PAH, sum of urinary high-molecular-weight monohydroxy polycyclic aromatic hydrocarbon, including 1-hydroxypyrene; ƩLMW OH-PAHs, sum of urinary low-molecular-weight monohydroxy polycyclic aromatic hydrocarbon, including 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyfluorene, 9-hydroxyfluorene, 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, 3-hydroxyphenanthrene, 4-hydroxyphenanthrene and 9-hydroxyphenanthrene; ƩOH-PAHs, sum of urinary monohydroxy polycyclic aromatic hydrocarbons; 8-iso-PGF2α, 8-isoprostane; 8-OHdG, 8-hydroxy-2′-deoxyguanosine; OH-PAHs, urinary monohydroxy polycyclic aromatic hydrocarbons