Thyroid endocrine disruption effects of perfluoroalkyl phosphinic acids on zebrafish at early development.

Perfluoroalkyl phosphinic acids (PFPiAs, including 6:6, 6:8 and 8:8 PFPiAs) are one kind of emerging perfluoroalkyl substances and usually used as leveling and wetting agents in household cleaning products and pesticide formulations. In this study, zebrafish embryos (6 h post-fertilization [hpf]) were exposed to 6:6, 6:8 and 8:8 PFPiAs individually (0.5, 5 and 50 nM) for 168 hpf. 8:8 PFPiA at 5 and 50 nM reduced the body length, while all treatments of 6:8 and 8:8 PFPiA depressed the heartbeat of the zebrafish larvae. 8:8 PFPiA at 50 nM distinctly enhanced the thyroxine (T4) and triiodothyronine (T3) contents. In a negative feedback mechanism, the three PFPiAs remarkably suppressed the genes responsible for THs regulation (corticotropin-releasing hormone, crh ; thyroid stimulating hormone, tshβ), and 8:8 PFPiA displayed the strongest effect. In addition, 8:8 PFPiA significantly promoted the gene expressions corresponding to THs transport, metabolism and action (transthyretin, ttr ; uridine diphosphate glucuronosyltransferase, ugt1ab ; deiodinases, dio1 and dio2 ; thyroid hormone receptors, trα and trβ). As a result, 8:8 PFPiA displayed the strongest thyroid endocrine disrupting effect and significantly affected the growth of zebrafish larvae among the three PFPiAs in the present study. Unlabelled Image • 8:8 PFPiA inhibited the growth of zebrafish larvae. • 8:8 PFPiA significantly increased T4 and T3 contents and altered genes in the HPT axis. • Three PFPiAs suppressed genes regulating THs levels in negative feedback mechanism. • 8:8 PFPiA displayed the strongest thyroid endocrine disruption than 6:6 and 6:8 PFPiA. [ABSTRACT FROM AUTHOR]