Elevated Consumer Exposure to Volatile Organic Compounds During Do-It-Yourself Painting Oil-Based Wood Stain Evidenced by Passive Air Sampling and Urinary Metabolites

Consumer products are significant contributors to indoor volatile organic compound (VOC) emissions, with oil-based wood stains, commonly used in do-it-yourself (DIY) projects, being particularly notable sources. This study was aimed at evaluating personal exposure to VOCs during DIY application of oil-based wood stains by integrating passive sampling, dermal exposure assessment, and urinary biomonitoring. Twenty-two volunteers wore a validated expanded polytetrafluoroethylene passive sampler (ePTFE PS) during indoor painting activities in naturally ventilated residential settings. Despite open-window ventilation, benzene concentrations increased from 4.5 to 5100 μg/m³—a 1100-fold rise. Toluene, ethylbenzene, xylenes, and styrene showed similar increases ranging from 160 to 710 times. Limonene and α-pinene concentrations rose by 440% and 600%, respectively. A statistically significant correlation was observed between inhalation exposure to m-xylene and its urinary metabolites (p- and o-methylhippuric acids), with metabolite concentrations reaching up to 57.2 μg/mg creatinine. Inhalation exposure was calculated to be 630–1100 times higher than dermal exposure. These findings highlight the dominance of the inhalation route and demonstrate that passive sampling is an effective and practical approach for assessing VOC exposure from consumer products in real-world environments.