Modeling Toxicity of Mixtures of Perfluorooctanoic Acid and Triazoles (Triadimefon and Paclobutrazol) to the Benthic Cladoceran Chydorus sphaericus

• Published in: Environmental science & technology Vol. 47; no. 12; pp. 6621 - 6629
• Main Authors: Le, T. T. Yen, Peijnenburg, Willie J. G. M.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 18.06.2013
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Caprylates - toxicity; Chemical compounds; Chydorus sphaericus; Cladocera; Cladocera - drug effects; Crustaceans; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Fluorocarbons - toxicity; Fundamental and applied biological sciences. Psychology; Marine ecology; Perfluoroalkyl & polyfluoroalkyl substances; Toxicity; Triazoles - toxicity; Detergent; Organic perhalocompound; Toxicity; Cladocera; Chydorus sphaericus; Modeling; Toxic association; Crustacea; Persistent organic pollutant; Anionic surfactant; Paclobutrazol; Perfluorooctanoic acid; Carboxylic acid; Arthropoda; Organic fluorine compounds; Triazole derivatives; Fluorine Organic compounds; Invertebrata; Triadimefon; Branchiopoda; Organic compounds; Benthic zone
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es4001104

Toxicity of perfluorooctanoic acid (PFOA) and triazoles, that is, paclobutrazol (PBZ) and triadimefon (TDF), singly and in binary mixtures was assessed on the benthic cladoceran Chydorus sphaericus. Following single exposure, toxicity of PBZ was not significantly different from that of TDF as shown by the overlapping 95% confidence intervals of their median effective concentrations: EC50PBZ = 0.07–0.09 mM; EC50TDF = 0.066–0.078 mM. PFOA was far less toxic than these triazoles: EC50PFOA = 0.20–0.24 mM. Assuming no interactions between PFOA and the triazoles, the toxicity of PFOA in mixtures with the triazoles estimated by the concentration addition (CA) and independent action (IA) models was significantly lower than its toxicity in single exposure. This contrasted with the results for PBZ and TDF. Based on the assumption that PFOA may interact with the triazoles, different predictions were obtained by the two models. Significant alleviation of PBZ and TDF on the toxicity of PFOA was found by the extended CA model only. According to the extended IA model, PFOA had nonsignificant effects on the toxicity of PBZ while significantly increasing the toxicity of TDF. This difference is possibly related to different modes of actions for various functional groups in PBZ and TDF.