Meta-analysis evaluates toxicity of PFAS to microalgae: Mechanisms and ecological risks

As emerging contaminants, perfluoroalkyl and polyfluoroalkyl substances (PFAS) are widely distributed across the environment. Concerns have been increasingly raised about their bioaccumulation in living organisms and the associated toxic effects. As important primary producers in aquatic ecosystems and ideal biological indicators for assessing water quality, microalgae inevitably coexist with PFAS in the aquatic environment. Gaining insight into the impacts and underlying mechanisms of PFAS on microalgae is essential for developing effective strategies for risk management and mitigation. This study extracted 1681 datapoints from 45 papers for meta-analysis. The results indicated that PFAS significantly inhibit microalgal growth and photosynthesis, while increasing oxidative stress and cell membrane damage, which potentially poses a greater risk of algal toxin release. Chlorophyta experience more membrane damage compared to cyanobacteria. There is a negative correlation between microalgal biomass and PFAS concentration; however, the impact of PFAS diminishes over time. Additionally, a complex nonlinear relationship, exhibiting a quadratic pattern, exists between the length of fluorocarbon chains and the biomass of microalgae. At the same fluorocarbon chain length, PFAS with -COOH functional groups show greater toxicity than PFAS containing other functional groups. Relying solely on microalgae for PFAS removal may be inadequate due to their limited efficiency in the removal process. These findings enhance our comprehension of microalgae behavior under various PFAS conditions, offering a theoretical basis for PFAS distribution management and ecological risk assessment, though future research should address current limitations by investigating long-term exposure effects and species-specific responses across broader taxonomic groups.