No abstract

Cylindrospermopsin (CYN), a cyanotoxin produced by harmful algal blooms, has been reported worldwide; however, there remains limited understanding of its potential risks to surface water quality. In the present study, we reviewed available literature regarding the global occurrence, bioaccumulation, and toxicity of CYN in aquatic systems with a particular focus on fresh water. We subsequently developed environmental exposure distributions (EEDs) for CYN in surface waters and performed probabilistic environmental hazard assessments (PEHAs) using guideline values (GVs). PEHAs were performed by geographic region, type of aquatic system, and matrix. CYN was prevalent in North America, Europe, and Asia/Pacific, with lakes being the most common system. Many global whole water EEDs exceeded guideline values (GV) previously developed for drinking water (e.g., 0.5 μg L −1 ) and recreational water (e.g., 1 μg L −1 ). GV exceedances were higher in the Asia/Pacific region, and in rivers and reservoirs. Rivers in Asia/ Pacific region exceeded the lowest drinking water GV 73.2% of the time. However, the lack of standardized protocols used for analyses was alarming, which warrants improvement in future studies. In addition, bioaccumulation of CYN has been reported in mollusks, crustaceans, and fish, but such exposure information remains limited. Though several publications have reported aquatic toxicity of CYN, there is a lack of chronic aquatic toxicity data especially for higher trophic level organisms. Most aquatic toxicity studies have not employed standardized experimental designs, *

Surface water contamination from the neurotoxic cyanotoxin anatoxin-a and its analogues present risks to global public health and the environment. Understanding aquatic hazards is critical for cyanobacterial blooms increasing in magnitude, frequency and duration. We examined published data to identify exceedances of guideline values (GVs) globally in various aquatic systems to understand hazards when exposure occurs. Environmental exposure distributions of surface water data (intra- and extracellular toxins) from recreational and potable source waters exceeded common GVs of 0.1, 1 and 300µgL–1 when blooms occur 79.62, 48.37 and 1.42% of the time respectively. In total, 66% of occurrences were from lacustrine ecosystems compared with reservoir, river, coastal and other systems, with almost all data from Asia–Pacific, Europe and North America, highlighting the need for more monitoring efforts in diverse systems and in developing regions. Reservoirs had greatest exceedances of the highest GV compared with other systems, especially in Europe, where an exceedance of 19.92% was observed. Aquatic toxicity and bioaccumulation data were examined and compared to these environmentally relevant concentrations, though a lack of high-quality data highlights major research needs. This study further identifies the utility of probabilistic cyanotoxins assessments to support identification of where environmental monitoring and research may be more effectively focused.