Multigeneration responses of the springtail folsomia candida to short-chain per- and polyfluorinated substances (PFAS).

Abstract

Short-chain per- and polyfluorinated substances (PFAS) are widely distributed in the environment, but their chronic effects on soil organisms exposed over multiple generations remain largely unknown. The present study therefore aimed to investigate the toxicity of perfluorobutane sulfonic acid (PFBS) and its precursor perfluorobutane sulfonamide (FBSA) to the springtail Folsomia candida during five successive generations, with adult survival (LC50), reproduction (EC50_repro), and population growth rate (EC50_r) as endpoints. The LC50 and EC50_r of PFBS were above the highest test concentration (1300 mg/kg dry soil) for all generations, while the EC50_repro was 1260 and 762 mg/kg dry soil in F2 and F4, respectively, though the difference was not significant owing to wide 95% confidence intervals. In contrast, FBSA exhibited significant reproductive toxicity and thereby affected population growth rate, with LC50, EC50_repro and EC50_r values of 10.3, 1.14, and 1.67 mg/kg dry soil in F0, respectively. The extinction of the populations exposed to the two highest FBSA concentrations (8.85 and 88.3 mg/kg dry soil) in F0 hindered toxicity assessment in subsequent generations, with only an EC50_repro of 0.965 mg/kg dry soil determined in F1. Although the effect concentrations were above environmental levels, the more pronounced reproductive toxicity made FBSA over 1140 and 1350 times more toxic to F. candida reproduction than PFBS in F0 and F1, respectively. These findings reveal that understudied PFAS may pose hidden risks, and emphasize the need to expand the currently limited spectrum of PFAS considered in environmental risk assessment. This study also highlights the value of long-term hazard assessment of PFAS in multigeneration scenarios, which could better capture the potential risks posed by these very persistent chemicals.