A margin of safety approach for the assessment of environmentally realistic chemical mixtures in the marine environment based on combined passive sampling and ecotoxicity testing

Methodological advances and future directions of microalgal bioassays for evaluation of potential toxicity in environmental samples: A review

Microalgal bioassays are widely applied to evaluate the potential toxicity of various persistent toxic substances in environmental samples due to multiple advantages, including high sensitivity, short test duration, and cost-effectiveness. Microalgal bioassay is gradually developing in method, and the scope of application to environmental samples is also expanding. Here, we reviewed the published literature on microalgal bioassays for environmental assessments, focusing on types of samples, sample preparation methods, and endpoints, and highlighted key scientific advancements. Bibliographic analysis was performed with the keywords 'microalgae' and 'toxicity' or 'bioassay', and 'microalgal toxicity'; 89 research articles were selected and reviewed. Traditionally, most studies implementing microalgal bioassays focused on water samples (44%) with passive samplers (38%). Studies using the direct exposure method (41%) of injecting microalgae into sampled water mainly evaluated toxic effects by growth inhibition (63%). Recently, various automated sampling techniques, in situ bioanalytical methods with multiple endpoints, and targeted and non-targeted chemical analyses have been applied. More research is needed to identify causative toxicants affecting microalgae and to quantify the cause-effect relationships. This study provides the first comprehensive overview of recent advances in microalgal bioassays performed with environmental samples, suggesting future research directions based on current understanding and limitations.

Substances of emerging concern in Baltic Sea water: Review on methodological advances for the environmental assessment and proposal for future monitoring

The Baltic Sea is among the most polluted seas worldwide. Anthropogenic contaminants are mainly introduced via riverine discharge and atmospheric deposition. Regional and international measures have successfully been employed to reduce concentrations of several legacy contaminants. However, current Baltic Sea monitoring programs do not address compounds of emerging concern. Hence, potentially harmful pharmaceuticals, UV filters, polar pesticides, estrogenic compounds, per- and polyfluoroalkyl substances, or naturally produced algal toxins are not taken into account during the assessment of the state of the Baltic Sea. Herein, we conducted literature searches based on systematic approaches and compiled reported data on these substances in Baltic Sea surface water and on methodological advances for sample processing and chemical as well as effect-based analysis of these analytically challenging marine pollutants. Finally, we provide recommendations for improvement of future contaminant and risk assessment in the Baltic Sea, which revolve around a combination of both chemical and effect-based analyses.

Persistence and Recovery of ZIF-8 and ZIF-67 Phytotoxicity

Zeolitic imidazolate frameworks (ZIFs) have been developed quickly and have attracted considerable attention for use in the detection and removal of various pollutants. Understanding the environmental risks of ZIFs is a prerequisite to their safe application by industry and new chemical registration by governments; however, the persistence and recovery of toxicity induced by ZIFs remain largely unclear. This study finds that typical ZIFs (e.g., ZIF-8 and ZIF-67) at a concentration of 0.01-1 mg/L induce significant algal growth inhibition, plasmolysis, membrane permeability, chloroplast damage, and chlorophyll biosynthesis, and the above alterations are recoverable. Unexpectedly, a persistent decrease in reactive oxygen species (ROS) is observed due to the quenching of hydroxyl free radicals. The adverse effects of ZIF-8 are weak and easily alleviated compared with those of ZIF-67. ZIF-8 is internalized mainly by caveolae-mediated endocytosis, while ZIF-67 is internalized mainly by clathrin-mediated endocytosis. Omics studies reveal that the downregulation of mRNA associated with oxidative phosphorylation and the inhibition of chlorophyll and adenosine triphosphate (ATP) synthesis in mitochondria are related to the persistence of phytotoxicity. These findings highlight the phenomena and mechanisms of the persistence and recovery of phytotoxicity, indicating the need to reconsider the environmental risk assessments of ZIFs.