Global scanning of anatoxins in aquatic systems: environment and health hazards, and research needs

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 300 mu g L-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.