Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China.
Key Laboratory of Pollution Process and Environmental Criteria of Ministry of Education and Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China.
Chemosphere. 2019 May;223:599-607. doi: 10.1016/j.chemosphere.2019.02.102. Epub 2019 Feb 18.
Aquatic organisms are often exposed to time-varied concentrations of contaminants due to pulsed inputs in natural water. Traditional toxicology experiments are usually carried out in a constant exposure pattern, which is inconsistent with the actual environment. In this study, a refined toxicokinetic-toxicodynamic (TK-TD) model was used to study the toxic effects of Pb and Cd on zebrafish larvae under three pulse exposures with 2, 4, and 6 h, respectively. The parameter sensitivity analysis showed that J had the greatest impact on the output of the model. Cd or Pb pulse exposure resulted in less death than constant exposure at the same time-weighted average (TWA) concentrations. Survival fraction in larvae under 6 h interval between two pulses of Pb or Cd was larger than that under 2 h and 4 h interval. Toxicity under constant exposure of Cd or Pb was greater than that under 2, 4, and 6 h interval pulse exposure because the cumulative Cd or Pb concentration in the body under constant exposure was greater than that under pulse exposure. The results also showed that the stochastic death (SD) model was more suitable than the individual tolerance (IT) model for predicting the survival fraction of larvae under pulse exposure to Pb and Cd, which was indicated by higher R (0.670-0.940) in SD model than that (0.588-0.861) in IT model. Our model provides approaches for laboratory toxicity testing and modeling approaches for addressing the toxicity of heavy metal pulsed exposure.
水生生物经常由于天然水中的脉冲输入而暴露于随时间变化的污染物浓度中。传统的毒理学实验通常在恒定暴露模式下进行，这与实际环境不一致。在这项研究中，使用改良的毒代动力学-毒效动力学（TK-TD）模型来研究 Pb 和 Cd 对斑马鱼幼虫在分别为 2、4 和 6 h 的三个脉冲暴露下的毒性作用。参数敏感性分析表明，J 对模型的输出影响最大。与相同时间加权平均（TWA）浓度的恒态暴露相比，Cd 或 Pb 脉冲暴露导致的死亡较少。在 Pb 或 Cd 的两个脉冲之间间隔 6 h 的幼虫的存活分数大于间隔 2 h 和 4 h 的幼虫。由于在恒态暴露下体内累积的 Cd 或 Pb 浓度大于脉冲暴露下的浓度，因此 Cd 或 Pb 的恒态暴露毒性大于 2、4 和 6 h 脉冲暴露毒性。结果还表明，与个体耐受（IT）模型相比，随机死亡（SD）模型更适合预测 Pb 和 Cd 脉冲暴露下幼虫的存活分数，因为 SD 模型的 R 值（0.670-0.940）高于 IT 模型的 R 值（0.588-0.861）。我们的模型为实验室毒性测试提供了方法，并为解决重金属脉冲暴露的毒性提供了建模方法。
