Abstract:

Polycyclic aromatic hydrocarbons （PAHs） are organic pollutants that are ubiquitous in nature and in environments affected by anthropogenic activities. PAHs enter the human body through inhalation， ingestion， or skin contact， and consequently threaten human health. Urban areas are mostly affected by PAHs pollution， which is ascribable to dense population， heavy traffic， and limited air-pollutant diffusion. In this study， we assessed the current status of PAHs exposure among non-occupationally exposed urban residents using isotope dilution combined with liquid-liquid extraction-gas chromatography-high resolution dual-focus magnetic mass spectrometry （GC-HRMS）. The burden of PAHs of 92 permanent residents aged 2 to 80 years in Beijing was investigated. Ten monohydroxypolycyclic aromatic hydrocarbons （OH-PAHs） were measured in urine samples， namely hydroxynaphthalene （OHNap， including 1-OHNap and 2-OHNap）， hydroxyfluorene （OHFlu， including 2-OHFlu， 3-OHFlu， and 9-OHFlu）， hydroxyphenanthrene （OHPhe， including 1-OHPhe， 2-OHPhe， 3-OHPhe， and 4-OHPhe）， and 1-hydroxypyrene （1-OHPyr）. The OH-PAH levels were corrected with urinary creatinine， with results below LODs replaced with half the value of LODs. Correlations between OH-PAHs were assessed using Spearman’s rank correlation analysis （two-tailed）. The nonparametric Mann-Whitney U test and the Kruskal-Wallis H test were used to compare the distribution of OH-PAH levels in different populations. The results showed that six OH-PAHs （1-OHNap， 2-OHNap， 2-OHFlu， 9-OHFlu， 1-OHPhe， and 2-OHPhe） were detected in all the urine samples. The total contents （ΣOH-PAHs） of the 10 OH-PAHs ranged from 661 to 33 782 ng/g， with an overall geometric mean （GM） of 2 775 ng/g and significant inter-individual differences. The following content-distribution trend was observed： OHNap>OHFlu>OHPhe>1-OHPyr， with a significant negative correlation with molecular size recorded. OHNap was mainly observed， accounting for 62.2% of the total. Complex correlations were found to existed between the OH-PAHs， with 9-OHFlu exhibiting unique exposure patterns. Urinary OH-PAH levels were found to correlate with gender and age， and smoking was also observed to be a significant influencing factor. ΣOH-PAHs peaked in the youth group （0‒15 years）， with a GM of 3 940 ng/g. Levels of ΣOH-PAHs were similar in the working-age group （16‒59 years， GM： 2 598 ng/g） and in the elderly group （≥60 years， GM： 2 639 ng/g）. These suggest that age is a key PAH-exposure factor. Habitual smoking was found to consistently and significantly affect OH-PAH levels， with smokers generally having higher levels of OH-PAH than non-smokers. While males exhibited higher overall exposure levels than females， females exhibited significantly higher levels of 1-OHPyr than males （p=0.03） when smoking was excluded， which suggests that metabolic and behavioral differences between genders impact PAHs exposure. This study revealed the exposure and distribution characteristics of OH-PAHs in Beijing residents. It provides a scientific basis for studying PAHs pollution and its health effect， as well as epidemiological investigations， disease-burden assessments， and policy formulation.

Key words: polycyclic aromatic hydrocarbons （PAHs）, gas chromatography-high resolution dual-focus magnetic mass spectrometry （GC-HRMS）, monohydroxypolycyclic aromatic hydrocarbons （OH-PAHs）, exposure characteristics, influencing factors