Toxicity Of Perfluorobutane Sulfonate As A Substitute For Perfluorooctane Sulfonate On Caenorhabditis Elegans

Due to the potential toxicity for environment and human health,perfluorooctane sulfonate(PFOS)is being replaced by perfluorobutane sulfonate(PFBS).Nowadays,the extensive use of PFBS has resulted in its ubiquity in various environment mediums,raising the wide concerns about the hazards of PFBS to eco-environment and human health.However,few study has done to evaluate the toxicity of PFBS.Owing to its ease of manipulation,genetic manipulability,prolific reproduction and low cost,Caenorhabditis elegans(C.elegans)is considered as very good model for toxicological evaluation.Therefore,C.elegans was used in this study to evaluate the ecotoxicity of PFBS.The bioaccumulation ability,lethality,growth,reproductive capacity,apoptosis,reactive oxygen species,antioxidant enzyme activity and stress-related gene expression were accessed,and the following results were obtained:(1)After 48 h exposure,we found that PFBS was less easy to accumulate in C.elegans when compared with PFOS by HPLC-MS,and PFBS had much higher LC50(median lethal concentration)than PFOS,which is relatively low in toxicity and bioaccumulation of PFBS compared with PFOS;Besides,the body length,brood amount and brood size of C.elegans were inhibited by 0.1 μM PFOS,1000 μM and 1500 μM PFBS,specially,0.1 μM PFOS and 1500 μM PFBS cause barely and 100% reduction of brood amount.(2)After 48 h exposure,we found that 0.1 μM PFOS,500 μM and 1000 μM PFBS induced cell apoptosis in the germline,while both 2 μM PFOS and 1000 μM PFBS exposure increased the levels of reactive oxygen species in C.elegans;Furthermore,2 μM PFOS and1500 μM PFBS can cause changes in catalase activity(CAT),and 1500 μM PFBS can also decrease the glutathione peroxidase activity(GPx).(3)After 48 h exposure,we found that the expression of vitellogenin-associated gene(vit-6)down-regulation and the estrogen receptor-related gene(nhr-14)up-regulation in C.elegans compared with control,the results indicated the endocrine disruption effect of the two compounds;In addition,0.1μM PFOS and 1500 μM PFBS exposure significantly increased the expression of pro-apoptotic genes(egl-1 and ced-13)in C.elegans compared with controls,verifying the ability of PFOS and PFBS to cause germ cell apoptosis;Besides,the antioxidant enzyme genes(sod-3,ctl-2 and gst-4)levels were also significantly up-regulated in 2 μM PFOS and 1000,1500 μM PFBS exposure groups compared with control,implying the increased reactive oxygen species followed PFOS and PFBS treatment.In conclusion,we have systematically evaluated the toxicity of PFBS in this paper,and proved that developmental toxicity and reproductive toxicity of PFOS is greater than PFBS.These results also indicated PFBS as the substitute of PFOS had lower hazard to the eco-environment and human health.