We kicked off the Lab on September 29th with a presentation by NatuRE Policy Lab co-coordinator Will Troske, who presented joint work with Laura Alcocer Quinones and Jeffrey Hadachek (UW-Madison) entitled "Behavioral Responses to PFAS in Drinking Water." 

Per- and Polyfluoroalkyl Substances (PFAS) are a family of man-made chemicals detrimental to human health. A primary exposure pathway is drinking water. In the most recent Unregulated Contaminant Monitoring Rule data collection, the Environmental Protection Agency found contamination in 8 to 15% of tested public water systems. Despite widespread exposure to PFAS, evidence of avoidance behavior remains limited. Will's paper estimates the effect of information provisions on the avoidance of PFAS exposure. Past research quantified how individuals avoid exposure when notified by measuring additional bottled water purchases (Allaire et al., 2019; Zivinet al., 2011; Hadachek, 2024). The case of PFAS is unique, however, for two primary reasons. First, the emerging nature of PFAS creates uncertainty around the full health impacts of exposure, especially compared to more common contaminants like lead, nitrates, or bacteria (e.g. E-Coli). Second, PFAS differs from common contaminants because it deteriorates more slowly than E-Colior nitrates and passes through filters, unlike lead. This work informs the literature by addressing how affected individuals respond to information about emerging PFAS contamination and by estimating the extent to which people remain exposed to PFAS in their drinking water, even after being informed.

Will and his coauthors leverage variation in PFAS Maximum Contaminant Level (MCL) violations across nine states to quantify these impacts. We employ a two-way fixed effects design, pairing detailed violation data at the weekly level with Nielsen retail scanner data, including bottled water and water filter purchases per store. Preliminary results show water filter purchases increase by 6% in the week following a violation and no significant increase for bottled water. This increase represents a community-level cost of approximately $60,000 for each violation and $11.5 million in aggregate over our sample. These results show that consumers spend significantly more on durable filters to protect themselves in anticipation of exposure over the long run, rather than investing in short-run solutions, like bottled water.