Exposure to per- and polyfluoroalkyl substances in Australian communities affected by environmental contamination

Abstract

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals associated with environmental contamination events worldwide. From 2013 to 2017, the Australian Government Department of Defence identified PFAS contamination surrounding Defence Force bases in Katherine (Northern Territory), Williamtown (New South Wales) and Oakey (Queensland). In this thesis, I investigate human exposure to PFAS in Katherine, Oakey and Williamtown to inform future public health responses. I address three key research objectives. 1. To measure and describe human exposure to PFAS in Australian communities affected by PFAS contamination surrounding Defence Force bases. 2. To identify exposure pathways and risk factors for exposure to PFAS in the communities. 3. To examine perceptions and experiences of blood testing for PFAS in the communities. From 2016 to 2019, the Australian Government conducted the Voluntary Blood Testing Program (VBTP) for PFAS in Katherine, Oakey and Williamtown. Participants of the VBTP were recruited for the PFAS Health Study. I compared blood serum concentrations of perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS) and perfluorooctanoic acid (PFOA) in 2,587 residents and workers from Katherine, Oakey and Williamtown and 702 residents of comparison communities. I investigated risk factors for elevated serum PFAS concentrations (defined as a concentration above the 95th percentile in the comparison population) in residents from Katherine, Oakey and Williamtown. In addition, I examined community perceptions and experiences of blood testing for PFAS. Geometric means of serum concentrations for participants from Katherine, Oakey and Williamtown ranged from 4.9-6.6 nanograms per millilitre (ng/mL) for PFOS and from 2.9-3.7 ng/mL for PFHxS. In total, 29-42% of participants had an elevated serum PFOS concentration and 48-55% had an elevated serum PFHxS concentration. Geometric means of serum PFOA concentrations ranged from 1.3-1.8 ng/mL for participants from Katherine, Oakey and Williamtown, equivalent to that observed in the comparison communities. I observed a higher odds of elevated serum PFOS and PFHxS concentrations associated with ingestion of bore water in Oakey, consumption of high-risk local produce and occupational exposure in Williamtown and length of residence in Katherine and Williamtown. Participants from Katherine, Oakey and Williamtown reported following public health precautions to limit their use of bore water and consumption of local produce. Participants who reported that the blood test results were helpful indicated that the results confirmed their exposure to PFAS. Some participants assumed that the test results could be used to make inferences about their health or that levels within reference values could be considered safe. Participants who indicated that the test results were not helpful or were unsure reflected on the uncertainty of exposure to PFAS and health effects and had unanswered questions. Evidence of elevated blood serum PFAS concentrations in Katherine, Oakey and Williamtown warrants continued public health precautions. Examination of serum PFAS concentrations over time could assess the effectiveness of precautionary measures. However, investigating PFAS exposure in communities affected by environmental contamination also requires robust evidence of serum PFAS concentrations in the general population. Both need tailored strategies to report results to individuals, communities and clinicians. Show more