Enhanced Ecological Risk of PFOA Degradation Products: Insights from Concentration-Dependent Transcriptomics, Adverse...

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Environmental Science

Background:

• Perfluorooctanoic acid (PFOA) degradation aims to meet water quality standards.
• Environmental risks of PFOA degradation products remain understudied.
• Photocatalytic degradation of PFOA yields perfluoroalkyl carboxylic acids (PFCAs) and fluoride ions.

Purpose of the Study:

• Investigate bioaccumulation and trophic transfer of PFOA degradation products (PFCAs).
• Assess the toxicity of PFOA degradation products in a model aquatic food web.
• Elucidate the mechanisms of toxicity in zebrafish (Danio rerio) exposed to degradation products.

Main Methods:

• Photocatalytic degradation of PFOA using N-CQDs/TiO2.
• Bioaccumulation and trophic transfer studies in Chlorella sp., Daphnia magna, and Danio rerio.
• Transcriptomics, adverse outcome pathway (AOP) analysis, and biomarker tests in zebrafish.

Main Results:

• Degradation-induced acidification increased bioaccumulation of PFOA and PFCAs; long-chain PFCAs (C6-C8) underwent trophic transfer.
• PFOA degradation products exhibited higher acute toxicity than PFOA, with zebrafish being most sensitive.
• Mechanisms included lipid metabolism disorders (PPAR/LXR activation), skeletal toxicity, oxidative stress (fluoride ion binding), and neurotoxicity (acidification, neuronal impairment).

Conclusions:

• PFOA degradation does not eliminate risk; incomplete degradation can increase ecological toxicity and health risks.
• PFCAs, fluoride ions, and acidic pH contribute to the toxicity of degradation products.
• The nervous system is particularly susceptible, with degradation products impairing neuronal development and neurotransmitter signaling.