Study On The Aquatic Toxicology Effects Of Two Typic Perfluoro Chemical To Zebrafish Embryos

Perfluororinated Compounds (PFCs) are posing a serious threat on natural environment and human health due to their large scale and long-time of industrial use. With their unique physicochemical properties and environmental persistence, many of these compounds are globally distributed and are routinely measured in various environmental matrices as well as in wildlife and humans. The study on toxicology of PFCs is one of the most important issues in environmental science. But study on toxicology of PFCs is far from enough, specifically on the aquatic toxicological study.Perfluorooctyl Sulfonates (PFOS) and Perfluorooctane Acid (PFOA) are two of major fluorochemical produced. In this study, a bio-toxicological testing method based on zebrafish (Brachydanio rerio) embryos, which is one of the most commonly used species in aquatic toxicological test is developed, PFOS and PFOA are chose to assess the aquatic toxicity of PFCs. According to acute toxicological test result, an additional test with lower concentration, longer exposure time is tried out. Lethal, sublethal, teratological and histological endpoints are used in this study. The acute toxicological test indicate that the LC₅₀(48h) values for PFOA are 1005 mg·L^-1, 107 mg·L^-1 for PFOS, while the LC₅₀ (96h)values are 499 mg·L^-1 for PFOA, 71 mg·L^-1 for PFOS. PFOS is more embryotoxical than PFOA.Both PFOS and PFOA cause sublethal and teratological effects to the zebrafish embryos and larval. The sublethal effects observed in this study including: edema, circulation system defect, growth retarded, hatching-delay, while teratological effects observed including: spinal column malformation, tail malformation, ventral and dorsal fin malformation et al. The most sensitive endpoints for PFOS exposure is spinal column malformation, the EC₅₀ values is 9.14 mg·L^-1 while for PFOA hatching (96h) is most sensitive, the EC₅₀ values is 328.0 mg·L^-1.Histological evaluation of hematoxylin/eosin-stained sections, as well as embryo test, is employed to assess organ toxicity of PFOS and PFOA. Liver and gill pathology is observed. The major finding of the present study was that exposure to 10mg·L^-1 PFOA, and 1 mg·L^-1 PFOS 8 days post-hatch caused liver damage in zebrafish larval, specifically cytoplasmic vacuoles, pycnotic nucleus. High concentration (100mg·L^-1) exposure to PFOA for 10 days caused branchial epithelium damage. Gill pathology does not be observed in the group exposure to PFOS in this study.