A New Concept for the Environmental Risk Assessment of Poorly Water Soluble Compounds and Its Application to Consumer Products
A New Concept for the Environmental Risk Assessment of Poorly Water Soluble Compounds and Its Application to Consumer Products
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DOI：
10.1897/ieam_2008-067.1
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发表时间：
2009-07-01
影响因子：
3.1
通讯作者：
Steber, Josef
中科院分区：
文献类型：
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作者：
Tolls, Johannes;Mueller, Martin;Steber, Josef
许多消费品含有亲脂性、难溶性成分，这些成分代表大量物质，由于多种原因无法用标准方法充分测定其水生毒性。在这种情况下，可以使用最近开发的方法来定义无需关注的水生暴露阈值（ETNCaq；即低于该浓度预计不会对环境产生不利影响）。可以通过将 ETNCaq 值与难溶物质的水生暴露水平进行比较来进行风险评估。因此，水溶性低于 ETNCaq 的物质的水生暴露水平不会超过生态毒理学无影响浓度；因此，他们的风险可以被评估为可以忽略不计。与具有麻醉作用方式的物质相关的 ETNCaq 值为 1.9 μg/L。为了应用上述风险评估策略，需要知道在水中的溶解度。最常见的是，该参数是通过基于对数辛醇-水分配系数 (log K-ow) 的定量结构/活性关系来估计的。通过该方法，利用亲脂性化合物的最新实验溶解度数据，研究了几种水溶性计算模型的预测价值。线性回归模型被证明最适合提供正确的预测，而不会低估实际的水溶性。为了定义适合可靠预测小于 1.9 μg/L 的水溶性的 log K-ow 阈值，通过对实验溶解度数据与其 log Kow 进行统计比较来建立置信限。结果发现，log K-ow = 7 的阈值通常可以区分溶解度大于和小于 1.9 μg/L 的物质。因此，具有基线毒性且 log K-ow > 7 的有机物质不需要进一步测试来证明其环境风险较低。在应用这个概念时，可以考虑水溶性预测的不确定性。如果预测的水中溶解度低于 ETNCaq 的概率为 95%，则相应的 log K-ow 值为 8。
Many consumer products contain lipophilic, poorly soluble ingredients representing large-volume substances whose aquatic toxicity cannot be adequately determined with standard methods for a number of reasons. In such cases, a recently developed approach can be used to define an aquatic exposure threshold of no concern (ETNCaq; i.e., a concentration below which no adverse affects on the environment are to be expected). A risk assessment can be performed by comparing the ETNCaq value with the aquatic exposure levels of poorly soluble substances. Accordingly, the aquatic exposure levels of substances with water solubility below the ETNCaq will not exceed the ecotoxicological no-effect concentration; therefore, their risk can be assessed as being negligible. The ETNCaq value relevant for substances with a narcotic mode of action is 1.9 mu g/L. To apply the above risk assessment strategy, the solubility in water needs to be known. Most frequently, this parameter is estimated by means of quantitative structure/activity relationships based on the log octanol-water partition coefficient (log K-ow). The predictive value of several calculation models for water solubility has been investigated by this method with the use of more recent experimental solubility data for lipophilic compounds. A linear regression model was shown to be the most suitable for providing correct predictions without underestimation of real water solubility. To define a log K-ow threshold suitable for reliably predicting a water solubility of less than 1.9 mu g/L, a confidence limit was established by statistical comparison of the experimental solubility data with their log Kow. It was found that a threshold of log K-ow = 7 generally allows discrimination between substances with solubility greater than and less than 1.9 mu g/L. Accordingly, organic substances with a baseline toxicity and log K-ow > 7 do not require further testing to prove that they have low environmental risk. In applying this concept, the uncertainty of the prediction of water solubility can be accounted for. If the predicted solubility in water is to be below ETNCaq with a probability of 95%, the corresponding log K-ow value is 8.