Peracetic acid as a low-cytotoxicity disinfectant in simulated swimming pool water

Disinfection is important for swimming pool water (SPW) microbial safety, yet disinfectants reacting with swimmer-derived organics during long residence times raises SPW cytotoxicity. This work aimed to determine whether peracetic acid (PAA) is capable of controlling SPW cytotoxicity under various scenarios benchmarking against sodium hypochlorite (SH) at concentrations that satisfy prescribed disinfection efficacy. We conducted bench-scale experiments using synthetic body fluid analogues to simulate real SPW scenarios. The novelty stems from the fact that this work represents the first multi-scenario bench-scale application of PAA specifically for SPW disinfection, with PAA-disinfected SPW showing at most 8.9 % of the SH-disinfected SPW cytotoxicity, potentially reducing chemical exposure risks from SPW chemical constituents. PAA-disinfected SPW demonstrated much lower thiol-reactivity than SH-disinfection, correlating with reduced cytotoxicity. The adjustment of the disinfectant exposure (Ct values) for cytotoxicity control on top of similar microbial inactivation was more applicable to SH disinfection than to PAA disinfection. For low-cytotoxicity SPW disinfection, PAA could be prioritized over SH and operated at dosages meeting microbial inactivation, without special considerations for concentration and contact time combinations. If disinfection by SH is mandatory, high disinfectant concentrations with short contact times are advised to achieve microbial inactivation goals while minimizing potential adverse effects.