Collaborative Research: Drinking Water Safety: Occurrence, Formation, and Genotoxicity of New Halocyclopentadiene Disinfection By-Products

Abstract Access to water disinfection globally and in the United States significantly reduced occurrence of water-borne pathogens. However, chemical disinfection has also raised a public health issue: the potential for cancer induction and reproductive/developmental effects associated with chemical disinfection by-products (DBPs) that are formed by the reaction of disinfectants with organic matter, bromide, and iodide. Out of the 11 DBPs currently regulated in the U.S., none of them produce the same adverse health effects in in vivo animal studies that are observed in human epidemiology studies. Thus, there is a need to identify toxicity drivers within the poorly characterized DBPs, which includes DBPs with higher-molecular-weight (>2 carbon atom). A new class of higher molecular weight DBPs – halocyclopentadienes (HCPDs) containing 5 carbons, was discovered recently in chlorinated and chloraminated drinking water at levels up to 257 ng/L total (sum of 6 HCPDs) and one of those DBPs showed the highest cytotoxicity level compared to the known regulated DBPs. Thus, it is critical to screen for the occurrence of these novel HCPDs in different source of drinking water. In addition, while the cytotoxicity of three halocyclopentadienes was recently conducted, their genotoxicity is currently unknown. This proposed interdisciplinary research seeks to fill these knowledge gaps through an assessment of HCPD occurrence in U.S. drinking water, determination of important factors influencing their formation, and investigation of their genotoxicity in vitro and in vivo. Additionally, the HCPD with the highest genotoxicity level will be also evaluated for the potential to induce of transgenerational toxicity in a model nematode. Results from this research will generate data to better understand the potential risks of this new class of DBPs and enable long-term engineering solutions to enhance drinking water safety and sustainability. .