Exploring overlooked bisphenol exposure sources through a comprehensive 7-day investigation using time-activity diaries and urinary biomonitoring

Bisphenols (BPs), widely used in polycarbonate plastics and epoxy resins, are associated with potential health risks, yet many exposure sources remain inadequately characterized. This study employed a novel approach by integrating 7-day time-activity diaries with individualized urinary biomonitoring to capture overlooked BP exposure sources. Twelve adult participants meticulously documented their daily activities, including food intake, across seven consecutive days, while providing all urine voids for analysis. A total of 401 urine samples were collected and analyzed individually (without pooling) to assess temporal variations and exposure associations. Among the eight analyzed BPs, Bisphenol A (BPA) and Bisphenol S (BPS) were detected in over 70 %, with median concentrations ranging from below the limit of quantification (LOQ) to 1.46 ng/mL for BPA and <LOQ to 0.85 ng/mL for BPS, highlighting widespread exposure. While general questionnaires provided limited insight, the multi-day diaries successfully linked BP exposure to both well-known sources-such as food containers, personal care products, detergents, and receipts-and previously underexplored sources, including ointments, medical plasters, sheer tights, wallpapering, vinyl flooring installation, crop cultivation, and food preparation with gloves. These findings demonstrate the power of combining detailed, multi-day activity tracking with individualized biomonitoring to uncover subtle and unconventional chemical exposure routes. Future investigations in larger populations are warranted to refine exposure assessment strategies and better understand BP exposure dynamics.