The assessment of long-range transport potential (LRTP) is enshrined in several frameworks for chemical regulation such as the Stockholm Convention. Screening for LRTP is commonly done with the OECD Pov and LRTP Screening Tool employing two metrics, characteristic travel distance (CTD) and transfer efficiency (TE). Here we introduce a set of three alternative metrics and implement them in the Tool’s model. Each metric is expressed as a fraction of the emissions in a source region. The three metrics quantify the extent to which the chemical (i) reaches a remote region (dispersion, ϕ1), (ii) is transferred to surface media in the remote region (transfer, ϕ2), and (iii) accumulates in these surface media (accumulation, ϕ3). In contrast to CTD and TE, the emissions fractions metrics can integrate transport via water and air, enabling comprehensive LRTP assessment. Furthermore, since there is a coherent relationship between the three metrics, the new approach provides quantitative mechanistic insight into different phenomena determining LRTP. Finally, the accumulation metric, ϕ3, allows assessment of LRTP in the context of the Stockholm Convention, where the ability of a chemical to elicit adverse effects in surface media is decisive. We conclude that the emission fractions approach has the potential to reduce the risk of false positives/negatives in LRTP assessments.

中文翻译：

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评估有机化学品远距离迁移潜力的排放分数方法

远距离迁移潜力 (LRTP) 的评估包含在多个化学品监管框架中，例如斯德哥尔摩公约。LRTP 筛选通常使用 OECD Pov 和 LRTP 筛选工具完成，该工具采用两个指标，即特征行驶距离 (CTD) 和传输效率 (TE)。在这里，我们介绍一组三个替代指标，并在工具模型中实现它们。每个指标都表示为源区域排放量的一部分。这三个指标量化了化学物质 (i) 到达偏远地区（分散，φ1），（ii）转移到偏远地区的地表介质（转移，φ2）和（iii）在这些地表介质中积累的程度（累积，φ3）。与 CTD 和 TE 相比，排放分数指标可以整合通过水和空气的运输，实现全面的 LRTP 评估。此外，由于这三个指标之间存在连贯的关系，新方法提供了对决定 LRTP 的不同现象的定量机制洞察。最后，累积度量 φ3 允许在斯德哥尔摩公约的背景下评估 LRTP，其中化学品在地表介质中引起不利影响的能力是决定性的。我们得出结论，排放分数方法有可能降低 LRTP 评估中误报/误报的风险。其中化学物质在表面介质中引起不利影响的能力是决定性的。我们得出结论，排放分数方法有可能降低 LRTP 评估中误报/误报的风险。其中化学物质在表面介质中引起不利影响的能力是决定性的。我们得出结论，排放分数方法有可能降低 LRTP 评估中误报/误报的风险。