A spatiotemporal study of a recreational freshwater lake: UPLC-MS/MS profiling of cyanotoxins and the dermal toxicity assessment

Cyanotoxins are toxic secondary metabolites produced by cyanobacteria with significant health risks to both aquatic ecosystems and humans. In this study, spatiotemporal profiling of cyanotoxins from a recreational freshwater lake were determined by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), across six months at three different study sites. Their toxicity on were examined on human skin keratinocytes because dermal exposure to recreational freshwater is an understudied route of exposure compared to ingestion. A network toxicology framework was constructed to predict and reveal the possible mechanistic insights of the cyanotoxins induce dermal toxicity. Our findings showed that, significant levels of cyanotoxins were identified through ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), with microcystin-RR being the most prevalent cyanotoxins present in the freshwater. Microcystins-enriched water samples significantly reduced the viability of human skin keratinocytes, nonetheless, membrane permeabilisation may not be the primary mechanisms of dermal toxicity. Network toxicology predicted significant enrichment of pathways involved in skin homeostasis and development. The findings suggest potential risks of dermal toxicity upon exposure to cyanotoxins-contaminated recreational freshwater, indicating the necessity for ongoing monitoring and immediate actions in evidence-based water management policies to protect the ecosystem and public health.