Bisphenol A leaching from epoxy resins in the drinking water distribution networks as human health risk determinant

Monitoring and management of drinking water distribution networks (DWDNs), including possible leaching from materials in contact with drinking water, have been stressed as crucial to avoid re-contamination of drinking water leading to a potential increase of human health risk. Recent scientific studies and regulations clearly highlighted the leaching of bisphenol A (BPA) from plastic materials used to renovate DWDNs pipelines as one of the major hazardous source, resulting in severe consequences for human health. In this study, lab migration tests were performed on three commercial epoxy resins, designed with the Design of Experiments (DoE) method in order to build a BPA migration model as a function of water chemical stability, evaluated as aggressivity index (AI), and residual chlorine concentration. Tests lasted about 170 days to account for both short and long-term leaching. BPA migration over time was well described by a combination of two 1st-order kinetic models with an initial peak of leaching, a decrease and, then, a second increase due to resins' deterioration. Initial BPA concentration in the contact water and BPA integral migration over time showed inverse proportionality with both chlorine concentration and AI values. However, measurements of free BPA content in epoxy resins proved that this is due to BPA transformation, not to a reduced leaching. The validated BPA migration model was combined with the hydraulic model of the DWDN in an urban area, through EPANET-MSX software. The model allowed to simulate the propagation of BPA in the DWDN, after the execution of a relining intervention, identifying the most vulnerable areas and permitting to customize a site-specific monitoring and intervention plan to minimize the health risk for final consumers.