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

ABSTRACT

Perfluoroalkyl phosphinic acids (PFPiAs, including 66, 68 and 88 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 66, 68 and 88 PFPiAs individually (0.5, 5 and 50 nM) for 168 hpf. 88 PFPiA at 5 and 50 nM reduced the body length, while all treatments of 68 and 88 PFPiA depressed the heartbeat of the zebrafish larvae. 88 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, tshß), and 88 PFPiA displayed the strongest effect. In addition, 88 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 trß). As a result, 88 PFPiA displayed the strongest thyroid endocrine disrupting effect and significantly affected the growth of zebrafish larvae among the three PFPiAs in the present study.