Sleight, Trevor, W
(2021)
Prediction and Hazard Estimation of Polycyclic Aromatic Hydrocarbon Transformation Products.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Polycyclic Aromatic Hydrocarbons (PAHs) are a group of compounds containing at least two aromatic rings. Generated from natural or industrial processes, their degradation half-lives can range from weeks to months, as they undergo numerous environmental reactions resulting in diverse transformation products (TPs). While some PAHs possess known hazardous properties, relatively little is known about the hazards of their TPs. An increase in mutagenicity (the ability to cause genetic errors) has been observed as PAHs biodegrade. Since numerous TPs can be generated from each original PAH, evaluating which structures contribute to a potential increase in mutagenicity becomes a complex problem for remediators and regulators. The objective of this work was to build tools utilizing new and existing approaches to predict the most likely PAH TPs, identify which contributed to mutagenicity, and test the tools via an empirical experiment.
To achieve this objective, a network-based tool was developed to refine datasets of over 20,000 predicted PAH TPs to less than 200, for the parent PAHs acenaphthene, anthracene, fluorene, and phenanthrene, creating a manageable number of the highest likelihood compounds. Within this subset, the tool predicted up to 48% of PAH TPs found by previous empirical studies, aiding in the first step, predicting likely TPs. To address the second step of PAH degradation risk assessment, a method to predict the hazard – here mutagenicity - of the most likely TPs was needed, as available tools were not designed for biodegradation-induced mutagenicity. A QSAR for PAH TP mutagenicity was developed which outperformed the best available QSARs when evaluating for biodegradation-induced mutagenicity and suggested that certain structural features corresponded to mutagenic mechanisms. Finally, the predictive tools were tested in an empirical study, aiming to identify the approximate time in a PAH’s degradation that mutagens emerge. Biodegradation cultures with phenanthrene and fluorene suggested that the networks tool and the QSAR together could help target the occurrence of mutagenicity in a PAH’s degradation timeline. Overall, this work provided two computational tools, the networks model for predicting the likely TPs, and the QSAR for estimating the mutagenicity of actively degrading PAHs and demonstrated their utility in biodegradation experiments.
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Details
| Item Type: |
University of Pittsburgh ETD
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| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
3 September 2021 |
| Date Type: |
Publication |
| Defense Date: |
21 June 2021 |
| Approval Date: |
3 September 2021 |
| Submission Date: |
6 July 2021 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
100 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Civil and Environmental Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
PAH, mutagen, networks, biodegradation, risk |
| Related URLs: |
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| Date Deposited: |
03 Sep 2021 17:26 |
| Last Modified: |
03 Sep 2022 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/41371 |
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