Unravelling airborne complexities: the role of spider webs and indoor dust in assessing human exposure to indoor organic micropollutants.

Indoor environments serve as critical exposure pathways for airborne micropollutants, yet traditional sampling methods often face limitations in representing dynamic air quality. Alternative, non-invasive techniques for indoor pollutant monitoring are gaining attention. This study evaluates the use of spider webs as innovative biomonitoring tools for assessing airborne micropollutants across various indoor environments, in comparison with conventional indoor dust sampling. Spider webs and indoor dust samples were collected from a range of indoor microenvironments, including electronic shops, textile stores, daycare centers, and décor shops. Non-target screening of micropollutants was carried out using Gas Chromatography-Mass Spectrometry (GC-MS). Quantification of targeted phthalates (Di-butyl phthalate (DBP), Di-ethyl phthalate (DEP), Di-methyl phthalate (DMP), Mono-butyl phthalate (MBP), Mono-methyl phthalate (MMP), and Mono-ethyl phthalate (MEP)) and bisphenol A (BPA) was performed using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). Structural distortions in spider silk due to pollutant exposure were monitored using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, focusing on alterations in the amide regions. Among the compounds detected, several were exclusive to either web or dust samples, while others were common to both. Esters and carboxylic acids were dominant in web-specific compounds, whereas esters and phenols were prevalent in both matrices. Dust samples recorded higher concentrations of DBP (mean: 10,434 ng/g) and BPA (mean: 2240 ng/g) than web samples (DBP mean: 2352 ng/g; BPA mean: 777 ng/g). ATR-FTIR analysis revealed significant shifts in amide I and II bands in spider silk collected from high-exposure areas, indicating distortion in silk protein structures in response to micropollutant accumulation. This study highlights the novelty of using spider webs as sensitive, non-invasive bioindicators for indoor air quality. By employing advanced analytical techniques (GC-MS, LC-MS/MS, and ATR-FTIR), we demonstrate that spider webs effectively capture and reflect the presence of airborne micropollutants. Beyond their analytical relevance, spider webs offer a cost-effective, passive, and easily deployable monitoring tool, making them particularly valuable for routine air quality assessments in high-risk microenvironments such as electronics shops and plastics/decor outlets. These findings establish spider web analysis as a promising complement to conventional indoor air monitoring approaches.