A spatiotemporal study of a recreational freshwater lake: ultraperformance liquid chromatography–tandem mass spectrometry profiling of cyanotoxins and the dermal toxicity assessment

Cyanotoxins are toxic secondary metabolites produced by cyanobacteria with significant health risks to aquatic ecosystems and humans. In this study, spatiotemporal profiling of cyanotoxins from a recreational freshwater lake were determined by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) across 6 months at three study sites. Their toxicity on human skin keratinocytes were examined because dermal exposure to recreational freshwater is an understudied route of exposure as compared with ingestion. A network toxicology framework was constructed to predict and reveal the possible mechanistic insights of how the cyanotoxins induce dermal toxicity. Our findings showed that significant levels of cyanotoxins were identified through UPLC-MS/MS, with microcystin-RR being the most prevalent cyanotoxin present in the freshwater. Microcystin-enriched water samples significantly reduced the viability of human skin keratinocytes; nonetheless, membrane permeabilization 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 cyanotoxin-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.