Laboratory for Ecological Risk Assessment, National Institute for Public Health and the Environment, Bilthoven 3720 BA, The Netherlands.
Environ Sci Technol. 2013 Jun 18;47(12):6621-9. doi: 10.1021/es4001104. Epub 2013 May 28.
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: EC50(PBZ) = 0.07-0.09 mM; EC50(TDF) = 0.066-0.078 mM. PFOA was far less toxic than these triazoles: EC50(PFOA) = 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.
全氟辛酸（PFOA）和三唑类化合物，即多效唑（PBZ）和三唑酮（TDF），单独及二元混合物对底栖桡足类 Chydorus sphaericus 的毒性进行了评估。单一暴露后，PBZ 的毒性与 TDF 没有显著差异，因为它们的中效浓度的 95%置信区间重叠：EC50（PBZ）=0.07-0.09mM；EC50（TDF）=0.066-0.078mM。PFOA 的毒性远低于这些三唑类化合物：EC50（PFOA）=0.20-0.24mM。假设 PFOA 与三唑类化合物之间没有相互作用，那么通过浓度加和（CA）和独立作用（IA）模型估算的混合物中 PFOA 的毒性明显低于单一暴露时的毒性。这与 PBZ 和 TDF 的结果形成对比。基于 PFOA 可能与三唑类化合物相互作用的假设，这两种模型得出了不同的预测结果。仅通过扩展 CA 模型发现 PBZ 和 TDF 对 PFOA 毒性有明显缓解作用。根据扩展 IA 模型，PFOA 对 PBZ 的毒性没有显著影响，而显著增加了 TDF 的毒性。这种差异可能与 PBZ 和 TDF 中各种官能团的不同作用模式有关。
