Organic UV Filter Exposure in Children of Indonesia, Thailand, and Saudi Arabia – Urinary Concentrations, Risks, and Potential Sources

Public health concerns about organic UV filters are increasing, yet exposure levels among children remain poorly characterized. In particular, the contribution of non-sunscreen sources is still unclear. To address this gap, we recruited 301 children aged 6–11 years with limited sunscreen use from Indonesia, Thailand, and Saudi Arabia during 2017–2018. Human biomonitoring of octocrylene (OC), 2-ethylhexyl salicylate (EHS), and homosalate (HMS) was conducted by analyzing eight novel urinary biomarkers using online-SPE-LC-MS/MS. Daily intakes were estimated by reverse dosimetry. Our results demonstrated widespread exposure to OC and EHS in children, whereas HMS exposure was rare. Significant inter-country differences were observed, with the highest concentrations of CPAA (biomarker for OC) in Thai children (92.3% > LOQ) and of 5cx-EPS (for EHS) in Indonesian children (76.4% >LOQ). Reported sunscreen use was not associated with urinary metabolite concentrations. None of the metabolites exceeded the HBM-I value; however, the maximum 5cx-EPS concentration (6.26 µg/L) approached this threshold. Among the children, OC and EHS exposures were not associated with reported sunscreen use, but were significantly associated with other potential sources, including antimicrobial soap use and fish consumption. Several country-specific sources were also identified: OC exposure was associated with recent wardrobe replacement (Indonesia), and frequent use of toilet detergents (Thailand), while EHS exposure was associated with the use of bath products in Indonesia and paper-based food storage containers (Saudi Arabia). These findings establish baseline exposure levels of major organic UV filters in children and highlight the importance of non-sunscreen sources in shaping exposure pathways.