Toxicokinetics and toxic effects of a Chinese PFOS alternative F-53B in adult zebrafish.

6:2 chlorinated polyfluorinated ether sulfonate (F-53B), a Chinese PFOS alternative, has recently been identified in river water, sewage sludge, wildlife and humans, causing great concerns about its potential toxic effects. Here, we report the first investigation of the toxicokinetics and oxidative stress of F-53B in adult zebrafish. Adult male and female zebrafish were exposed to 10 and 100 μg/L of F-53B for 7 days followed by a 5-d depuration period to examine bioaccumulation, distribution, and depuration of F-53B in fish. The results showed that F-53B was readily accumulated in fish tissues with log BCF values of 2.36-3.65, but was eliminated slowly (t = 152.4-358.5 h). F-53B accumulation was greater in males than in females and the concentration in tissues decreased in the following order: gonad ≈ liver ≫ gill ≫ brain in females and liver ≈ gill ≫ gonad ≫ brain in males, showing sex- and tissue- specific accumulation of F-53B in fish. After chronic exposure to F-53B for 28 days, a significant dose-dependent increase in histopathological changes in the liver were mainly manifested by vacuolation. Furthermore, F-53B also significantly reduced the enzyme activity (or content) of most of the measured oxidative stress-related markers (e.g., SOD, CAT and MDA) except for an increase in GSH-Px activity, indicating that oxidative stress was induced in zebrafish after treatment with F-53B. The results of this study provide important information on the toxicokinetics and toxic effects of F-53B, which will contribute to the ecological risk assessments of F-53B released into surface waters.