Comparative analysis of four PFAS regarding their toxicity to zebrafish development

Area of Science:

• Environmental Science
• Toxicology
• Developmental Biology

Background:

• Poly- and perfluoroalkyl substances (PFAS) are prevalent environmental contaminants.
• Legacy PFAS (PFOS, PFOA) use is declining, but replacement PFAS (PFHxA, 6:2 FTS) are increasingly detected in water systems.
• The toxicity of replacement PFAS is not well understood.

Purpose of the Study:

• To investigate the developmental toxicity of legacy PFAS (PFOS, PFOA) and replacement PFAS (PFHxA, 6:2 FTS) in zebrafish embryos.
• To assess the impact of these PFAS on zebrafish embryonic development, vessel formation, and organ size (liver, pancreas).

Main Methods:

• Zebrafish embryos (wild-type and transgenic) were exposed to environmentally relevant and higher concentrations of PFOS, PFOA, PFHxA, and 6:2 FTS.
• Developmental endpoints, intersegmental vessel formation, and organ sizes (liver, pancreas) were analyzed.
• Exposure durations ranged from 1 to 120 hours post-fertilization (hpf).

Main Results:

• No adverse effects on zebrafish development were observed at environmental concentrations (5 ng/L) for any of the four PFAS.
• Higher concentrations of all tested PFAS led to shortened intersegmental vessels.
• PFOS, PFOA, and 6:2 FTS caused liver enlargement at specific concentrations.
• PFOS and PFOA exposure resulted in pancreatic development defects.

Conclusions:

• Both legacy (PFOS, PFOA) and replacement (PFHxA, 6:2 FTS) PFAS exhibit developmental toxicity in zebrafish embryos.
• PFAS exposure can lead to vascular, liver, and pancreas abnormalities.
• Further research is needed to understand the long-term implications of replacement PFAS exposure.