Date of Award

Summer 2020

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Susan D. Richardson

Abstract

Water disinfection was cited as the greatest public health achievement of the 20th Century. By inactivating pathogens, disinfection has significantly reduced waterborne diseases in drinking water and swimming pools. However, chemical disinfection has also raised a public health issue: the potential for cancer induction, reproductive and developmental effects, and asthma-related risks associated with exposure to chemical disinfection byproducts (DBPs), which are formed by the reaction of disinfectants with organic matter (natural or anthropogenic), bromide, and iodide. In the U.S., four trihalomethanes (THMs) and five haloacetic acids (HAAs) are currently regulated in drinking water, although no DBPs are regulated in pools, and these DBPs are commonly used as the metric for DBP exposure in epidemiology studies. However, these DBPs do not produce the same adverse health effects in animal studies that are observed in humans, and most scientists believe the critical DBPs driving toxicity in disinfected waters are not adequately identified, regulated, or controlled.

Three studies presented here integrate newly developed analytical methods for the quantification of over 70 DBPs, total organic halogen (TOX), and mammalian cell cytotoxicity for representative whole water mixtures for the first time in drinking water and swimming pools to better understand DBP drivers of toxicity. Nitrogenous DBPs, including haloacetamides, haloacetonitriles, and halonitromethanes, were found to be important drivers of toxicity in both drinking water and pools, and iodinated DBPs were drivers of toxicity in drinking water plants utilizing chloramine disinfection. Some highly toxic, unregulated DBPs were reported for the first time in U.S. drinking water, including chloroiodoacetamide and iodoacetonitrile. Chloroacetaldehyde, which is the most cytotoxic haloacetaldehyde, was quantified for the first time in swimming pools, and this DBP was largely responsible for the observed cytotoxicity of the whole water mixture.

We found that advanced water treatment strategies, particularly granular activated carbon, can effectively limit DBP formation and resulting cytotoxicity in wastewater- and halide-impacted drinking waters by removing DBP precursors and other contaminants. Further, the use of secondary copper/silver ionization with lower chlorine levels helped reduced DBP formation and cytotoxicity in swimming pools and is a promising approach for limiting DBP exposure while swimming.

Rights

© 2020, Joshua M. Allen

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