CAS-MNP: Impact of Disinfectants on Release and Transformation of Microplastics and Additives from Drinking Water Pipes

Johns Hopkins University, Baltimore MD

Investigators

Abstract

With support from the Environmental Chemical Sciences program in the Division of Chemistry, Professors Howard Fairbrother and Carsten Prasse at Johns Hopkins University, Professor James Ranville at the Colorado School of Mines, and their students will investigate the effects of free chlorine, a common disinfectant used in drinking water distribution systems, on plastic pipes. Plastic pipes are replacing traditional metal pipes in distribution systems due to the well-documented health and safety issues caused by leached toxic metals during aging. However, the safety of these replacement plastic pipes is unclear. One unintended consequence of using plastic pipes is their susceptibility to degradation, a process that has been shown to result in the formation of microplastics (MPs). Additionally, organic chemicals, frequently incorporated as additives into pipes to enhance their properties, can leach from plastic pipes during the degradation caused by free chlorine. Moreover, these organic chemicals can react with free chlorine once they have been leached to produce new chemicals that can be more toxic than the additives themselves. The potential health risks associated with MPs and chemical additives in drinking water have raised increasing concerns. Through this study, we intend to holistically evaluate the safety of plastic pipes in the presence of chlorinated drinking water. Students involved in this research will acquire skills in materials chemistry, environmental chemistry, and environmental engineering. Students at the K-12 and university level will participate in educational activities, such as hands-on experiences with model drinking water and pipe materials to demonstrate the breakdown over time. This project aims to develop a safety profile of polyvinyl chloride (PVC) and polyethylene (PE) under the oxidizing conditions presented by free chlorine in drinking water. This will be accomplished by synthesizing model pipe materials containing a metal tag and exposing them to model drinking water; any microplastics formed will be quantified by measuring the embedded metal tag via single particle inductively coupled mass spectrometry (spICP-MS). Additives leached from PVC and PE synthesized with known concentrations of additives will be probed via liquid chromatography- and gas chromatography-high resolution mass spectrometry, including the identification of transformation products formed from the reaction of leached chemical additives with free chlorine. These results will help to inform the health and safety impacts of plastic pipes in drinking water distribution systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.