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Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Civil Engineering

Year Degree Awarded

2017

Month Degree Awarded

February

First Advisor

David A. Reckhow

Second Advisor

John E. Tobiason

Third Advisor

Krystal Pollitt

Subject Categories

Environmental Engineering | Environmental Health | Environmental Public Health | Toxicology

Abstract

The focus of this work has been placed is on iodinated DBPs (I-DBPs), measured using total organic iodine (TOI), a surrogate measure of iodinated organics. This is due to the growing toxicity literature that places I-DBPs among the most toxic of all DBPs. To measure TOI in water, a new method was developed. This method combines adsorption, combustion, and trapping of combustion products, with an offline inductively coupled plasma/mass spectrometer (ICP-MS) for iodide detection. Three factors were varied across two levels each in order to optimize the method. The chosen method used a sample pH of less than 1 prior to adsorption, a solution of 2% tetramethyl ammonium hydroxide (TMAH) in the trap solution, and a TMAH wash solution for the ICP-MS.

The method was then used to quantify TOI in raw and treated waters in three water treatment plants in the Northeast US over a period of fifteen months across different treatment plants and in different locations within the same systems. The results showed that there was substantial inter-monthly variability in TOI where values cluster high or low for months at a time. There was no change in TOI concentration upon treatment, suggesting that the TOI components may have shifted between the raw and treated waters. The results of a multivariate regression showed that dissolved organic carbon, specific UV254 absorbance, combined residual chlorine, and pH were all correlated with TOI concentration. These parameters were then used to fit a predictive model for TOI formation in water.

Expanding on the current literature on the toxicological profile of I-DBPs, the impact of six I-DBPs on healthy human colon epithelial cells, CCD 841 CoN, was tested. The rank order for cytotoxicity of the I-DBPs was found to be iodoacetic acid >iodoacetamide >bromoiodoacetamide >chloroiodoacetamide> bromoiodoacetic acid ≈ diiodoacetic acid. Iodoacetamide was 3.5 times more cytotoxic than bromoiodoacetamide, which in turn was 2.7 times more cytotoxic than chloroiodoacetamide. For both dihaloacids, the cytotoxicity was less than 1% of that of the monohaloacid. Apart from iodoacetic acid, the nitrogenous I-DBPs evaluated in this study proved to be more cytotoxic than the carbonaceous I-DBPs.

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