Golder Associates Limited, Burnaby, British Columbia, Canada.
Integr Environ Assess Manag. 2013 Apr;9(2):196-210. doi: 10.1002/ieam.1388. Epub 2013 Feb 20.
This theoretical and case study review of dynamic exposures of aquatic organisms to organic contaminants examines variables important for interpreting exposure and therefore toxicity. The timing and magnitude of the absorbed dose change when the dynamics of exposure change. Thus, the dose metric for interpreting toxic responses observed during such exposure conditions is generally limited to the specific experiment and cannot be extrapolated to either other experiments with different exposure dynamics or to field exposures where exposure dynamics usually are different. This is particularly true for mixture exposures, for which the concentration and composition and, therefore, the timing and magnitude of exposure to individual components of different potency and potentially different mechanisms of action can vary. Aquatic toxicology needs studies that develop temporal thresholds for absorbed toxicant doses to allow for better extrapolation between conditions of dynamic exposure. Improved experimental designs are required that include high-quality temporal measures of both the exposure and the absorbed dose to allow better interpretation of data. For the short term, initial water concentration can be considered a conservative measure of exposure, although the extent to which this is true cannot be estimated specifically unless the dynamics of exposure as well as the toxicokinetics of the chemicals in the exposure scenario for the organism of interest are known. A better, but still limited, metric for interpreting the exposure and, therefore, toxicity is the peak absorbed dose, although this neglects toxicodynamics, requires appropriate temporal measures of accumulated dose to determine the peak concentration, and requires temporal thresholds for critical body residue for each component of the mixture.
本研究通过理论和案例回顾了水生生物暴露于有机污染物的动态过程，考察了用于解释暴露和毒性的重要变量。当暴露动态发生变化时，吸收剂量的时间和幅度会发生变化。因此，解释此类暴露条件下观察到的毒性反应的剂量指标通常仅限于特定实验，不能外推到具有不同暴露动态的其他实验，也不能外推到暴露动态通常不同的野外暴露。对于混合物暴露情况尤其如此，因为在不同浓度、组成的情况下，即不同效力和潜在不同作用机制的个别成分的暴露时间和幅度会有所不同。水生毒理学需要研究开发吸收毒物剂量的时间阈值，以便更好地在动态暴露条件之间进行推断。需要改进实验设计，包括高质量的暴露和吸收剂量的时间测量，以便更好地解释数据。短期内，初始水浓度可以被认为是暴露的保守衡量标准，尽管除非了解暴露动态以及感兴趣生物体的暴露情景中化学物质的毒代动力学，否则无法具体估计这种情况的真实性。一个更好但仍有限的解释暴露和毒性的指标是吸收的峰值剂量，尽管这忽略了毒代动力学，需要适当的时间累积剂量测量来确定峰值浓度，并需要为混合物的每个成分确定关键身体残留的时间阈值。
