Airborne microplastic exposure and urinary oxidative damage biomarkers in populations living in traffic-congested areas

Airborne microplastics (MP) have emerged as a growing environmental and human health concern globally. This study aimed to investigate associations between exposure to traffic-related airborne MP and oxidative damage among residents living in different traffic-congested areas in Bangkok, Thailand. Ambient and personal air samples were collected from low-, medium-, and high-traffic areas. From pyrolysis-GC-MS analyses, airborne MP concentrations significantly increased ( p < 0.01) in locations with higher traffic density, measuring 1.25, 2.25 and 2.75 µg/m 3 for low-, medium- and high-traffic locations, respectively. In line with traffic-related airborne MP, personal exposure was highest in the high-exposed group (2.82 µg/m 3 ), which was significantly higher than the medium- and low-exposed groups by 1.50- and 2.32-fold, respectively. Urinary MP concentrations, a potential internal MP exposure indicator, also increased in an exposure-dependent manner. The high-exposed group (4.63 mg/g creatinine) had MP concentrations that were 1.36- and 1.8-fold higher than the medium- and low-exposed groups, respectively. MP polymers for airborne and personal exposure showed similar profiles. Polyethylene (PE) was the most predominant polymer, followed by polyvinyl chloride (PVC), nylon (N66), and styrene-butadiene rubber (SBR). Additionally, urinary oxidative damage to DNA (8-hydroxydeoxyguanosine, 8-OHdG, and ethenodeoxyadenosine (1,N6-ƐdA), lipid (8-isoprostane, 8-iso-PGF2α), and protein (dityrosine) were significantly increased in medium- and high traffic-exposed groups. Significant positive associations were found between personal exposure to airborne MP, urinary MP, and oxidative damage. This integrative study revealed that exposure to traffic-related airborne MP was associated with oxidative damage, highlighting its potential biological relevance and possible negative impacts on individuals and public health.