The effect of perfluorooctanoic acid (PFOA) on health outcomes in an exposed community Open Access

Barry, Vaughn (2014)

Permanent URL: https://etd.library.emory.edu/concern/etds/r494vk76p?locale=en
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Abstract

Perfluorooctanoic acid (PFOA) is a synthetic chemical used in manufacturing processes. It is found at low levels in the serum of most people in the U.S. with higher levels often observed in occupationally exposed workers. Animal studies suggest PFOA can cause adverse health events - including liver, testicular, and pancreatic tumors - but human health effects are unclear.

DuPont chemical plant in Washington West Virginia released PFOA into the Ohio River and air over a fifty year period. Residents living near the plant filed a class action lawsuit in 2001 alleging health damage due to PFOA contaminated drinking water. A pretrial settlement required DuPont to provide funding for several health surveys conducted among community residents and DuPont workers during 2005-2011.

This dissertation assessed whether PFOA was associated with certain health outcomes in this mid-Ohio valley population and explored how results could be impacted by diseases with different survival patterns.

Three manuscripts were developed from the work conducted in this dissertation. The first manuscript describes the association between estimated lifetime PFOA exposure and cancer incidence in this population. The second manuscript describes conditions for bias in exposure-disease estimates in this survivor cohort. The third manuscript describes whether PFOA exposure in early life was associated with overweight and obesity risk in adulthood.

Results suggest that PFOA may cause kidney and testicular cancer. The hazard ratios and 95% confidence intervals for incident kidney and testicular cancers were 1.10 (0.98 - 1.25) and 1.34 (1.00 - 1.79) for each 1-unit increase in ln-transformed estimated serum PFOA. Simulated data indicated that survivor bias existed when time to death after disease differed between those with low and high exposure. In this situation, bias was greatest when the disease of interest was highly fatal. High levels of PFOA exposure experienced during the first three years of life were not associated with overweight and obesity risk in adulthood and results did not vary by sex. Findings suggest that PFOA may be associated with particular adverse health events.

Table of Contents

Chapter 1: Overview and Motivation

1

Chapter 2: Background and Literature Review

4

Chapter 3: Study Population

12

Chapter 4: Methods

17

Chapter 5: Perfluorooctanoic Acid (PFOA) and Incident Cancers Among Adults Living Near a Chemical Plant

21

Chapter 6: How Diseases with Different Survival Patterns Impact the Magnitude of Survivor Bias in the Context of this Study

42

Chapter 7: Early Life Perfluorooctanoic Acid (PFOA) Exposure and Overweight and Obesity Risk in Adulthood in a Community with Elevated Exposure

61

Chapter 8: Conclusions and Future Directions

86

References

88

Appendix

100

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