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Multigenerational PFOS exposure in zebrafish (Danio rerio)
Citation:
Gust, K., D. Moore, N. Vinas, M. Wilbanks, E. Mylroie, A. Kimble, K. Jensen, R. Erickson, G. Ankley, AND J. Conder. Multigenerational PFOS exposure in zebrafish (Danio rerio). Tri-Services Virtual Meeting, Duluth, MN, February 09 - 10, 2021.
Impact/Purpose:
Relatively little is known as to the chronic effects of PFOS in fish, which leads to uncertainty in criteria derivation for the chemical. This presentation will describe the status of an ongoing, multigenerational study conducted with zebrafish to better define the adverse biological effects of PFOS.
Description:
A zebrafish multi-generational PFOS exposure is currently underway to provide answers to questions outstanding from equivocal results generated in a previous Australian study reported by Keiter et al (2012), the results of which have influenced PFOS regulatory limits worldwide. A consortium of US federal and industry scientists convened to identify opportunities to build upon the Australian study to provide critical tests of endpoints that remain in question. The consortium has sought to repeat the multi-generation zebrafish exposure, but including an expanded and more carefully determined dosing range, greatly increased replication base on statistical power-analysis, expanded analytical chemistry which includes external validation, as well as an expanded suite of endpoint to improve overall toxicological context. The 180d parental generation (P1) fish exposure was recently completed (January 2021), and the current presentation will focus on the methods, and results of that work while also providing overall context for the full multi-generational exposure. Briefly, sublethal PFOS exposure concentrations of 0, 0.1, 0.6, 3.2, 20, 100 µg/L were targeted in a flow-through fish exposure system including 5 replicate exposure tanks per treatment with each including a final target of 30 fish per replicate. Mean analytical chemistry results closely matched PFOS targets, remained stable over time, and were matched within 20% of external chemistry results, except for the lowest PFOS exposure concentration which was within 50% of external measurements. A trend of increased, but not statistically significant mortality was observed at the highest PFOS exposure concentration. Growth endpoints measured at days 30, 60, 90, and 180 days indicated significant negative effects on body weight at day 60, only in the highest exposure. First pass examination of 8 weekly breeding trials executed near the completion of the 180d exposure have indicated increased egg production through time, slight but significant decreases in egg viability through time, however pairwise comparisons against controls did not identify significant negative effects of PFOS exposure on egg production or viability. The first familial generation (F1) PFOS exposure has been successfully launched and will proceed through another 180d exposure where survival, growth and reproduction will again be assessed (as well as a host of additional endpoints not described herein). Finally, the second familial generation will be produced and exposed for two weeks to round out the full multi-generational exposure.