Unregulated Heavy Metals in United States Public Water Systems: An Assessment of Contaminant Co-Occurrence and Human Health Risk 公开
Thompson, Alesha (Spring 2019)
Abstract
Background: The United States Environmental Protection Agency monitors unregulated contaminants in drinking water and consolidates these results in the National Contaminant Occurrence Database. Our objective was to assess contaminant co-occurrence and human health risk of unregulated metals (chromium, chromium-6, molybdenum, vanadium, cobalt and strontium) over 2013-2015.
Methods: Multilevel Tobit regressions with state and water system random intercepts were used to estimate geometric means of each contaminant in public water systems. Human health risk was assessed by using the Environmental Protection Agency Regional Screening Level calculator. Co-occuring contaminant gene interactions were examined by using the Comparative Toxicogenomics Database and the Database for Annotation, Visualization and Integrated Discovery.
Results: Public water supplies’ geometric means of vanadium and chromium were positively associated in the water samples recorded (r = 0.45, p < 0.01), and these contaminants co-occurred in individual water samples. The geospatial maps of these contaminants in the top 5 cm of soil in the contiguous United States are similar. There were 24 overlapping genes that interact with these chemicals, and the most affected pathway was the HIF-1 pathway.
Conclusion: This assessment is a preliminary step in toward understanding the potential health implications of unregulated contaminants in United States drinking water. Certain public water system samples returned values that represented potentially negative health effects and they should be examined further to understand what is causing the high values. Further research needs to address the cumulative human health risk of ingesting more than one contaminant in the drinking water.
Table of Contents
TABLE OF CONTENTS
1. INTRODUCTION.....................................................................................................1
2. METHODS..............................................................................................................2
Data.............................................................................................................................2
Summary of Individual Contaminant Reported Values......................................................3
Assessment of Contaminant Co-Occurrence....................................................................3
Non-carcinogenic and Carcinogenic Health Risk Calculations..........................................4
Toxicogenomic Pathway Investigation............................................................................6
Mapping of Co-Occurring Contaminants.........................................................................7
3. RESULTS................................................................................................................7
4. DISCUSSION..........................................................................................................9
5. CONCLUSION.......................................................................................................12
REFERENCES...............................................................................................................13
TABLES AND FIGURES..................................................................................................17
About this Master's Thesis
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Primary PDF
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Unregulated Heavy Metals in United States Public Water Systems: An Assessment of Contaminant Co-Occurrence and Human Health Risk () | 2019-04-24 12:48:51 -0400 |
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Supplemental Files
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Modified UCMR Dataset (Thesis Dataset) | 2019-04-24 12:49:14 -0400 |
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