Air quality impact on hair and urine element levels and oxidative stress in university students

Exposure to air pollution has been consistently linked to oxidative stress and inflammation in humans, contributing to adverse health outcomes. This study aimed to assess the effects of air pollution on hair and urinary concentrations of 40 elements and changes in biomarkers of oxidative stress (8-oxo-7,8-dihydroguanine (8-oxoGua), 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) 8-oxo-7,8-dihydroguanosine (8-oxoGuo), 3-nitrotyrosine (3NO₂Tyr) and 5-methylcytidine (5-MeCyt)) in university students from Rome, Italy, and Santiago, Chile. Particulate matter (PM₁₀) samples from both cities were analyzed for elements and oxidative potential (OP) via acellular assays with dithiothreitol (DTT), ascorbic acid (AA) and 2',7'-dichlorofluorescin (DCFH). The average PM₁₀ concentration was 26 μg m^-3 in Rome (March-April 2022) and 71 μg m^-3 in Santiago (May-July 2022), reflecting significant differences in exposure. Generally, higher concentrations were observed in Chilean students than Italian students, except for Mo, Sr, and Tl in urine and Bi, Hg, K, Mg, Rb, and Zn in hair. Females generally presented higher levels of all the elements than males did. The OP of PM₁₀ was higher in Santiago and positively correlated with both oxidative stress biomarkers and elemental bioaccumulation. Multivariable linear regression models revealed that oxidative biomarkers were significantly associated with city of residence, smoking status, and selected elements including La, Mo, Rb, and Se. These findings suggest that oxidative stress is influenced by a combination of environmental exposure, lifestyle, and individual metal burden. This study highlights the importance of integrated biomonitoring approaches to better understand health risks related to local air pollution.