RWTH Aachen University, Institute for Environmental Research, Worringerweg 1, 52074 Aachen, Germany.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, 163 Xianling Road, 210023 Nanjing, China.
Environ Sci Process Impacts. 2022 Aug 17;24(8):1104-1109. doi: 10.1039/d2em00213b.
Characterizing the degradation behavior of chemicals in the environment is a key component of chemical hazard and risk assessment. Persistence has been successfully characterized for readily and for slowly degradable chemicals using standardized tests, but for the third group of chemicals with intermediate degradability ("middle group"), the assessment is less straightforward. Whether chemicals of this group behave as persistent or not in a given environment depends on environmental factors such as the presence of sorbents that can limit the bioavailability of chemicals. Uncertainties associated with current persistence assessments of chemicals in the middle group do not imply that persistence assessment is generally inconsistent, too ambiguous for regulatory use, and not useful in chemical hazard and risk assessment. Given the complexity of the environmental factors influencing chemical degradation, and the diversity of commercial chemicals, it has to be accepted though that for chemicals in the middle group even improved testing methods will not remove all of the immanent heterogeneity in their persistence data. For cases with widely different but technically valid persistence data, a weight-of-evidence approach is necessary and the "benefit of the doubt" should follow the precautionary principle in order to protect human and ecosystem health. We maintain that technically valid persistence data, although they might be considered dissatisfying from a scientific point of view because of high variability or even inconclusiveness, can well be sufficient for regulatory purposes. As with anything, also in persistence assessment, the scientific logic aims for a mechanistic description of the processes involved, low uncertainty, and a comprehensive understanding derived from a broad empirical basis. If the scientific logic is used as a benchmark in the regulatory context, this may easily lead to "paralysis by analysis". While regulatory decisions should be based on sound science, discrepancies between scientific goals and regulatory needs and, consequently, different levels of requirements (must-have nice-to-have) for degradation studies need to be recognized and appreciated. We further advocate for enhancing consistency between regulatory persistence assessments ("one substance-one assessment"), which is currently not the case.
描述化学物质在环境中的降解行为是化学危害和风险评估的关键组成部分。对于易于降解和缓慢降解的化学物质，已经成功使用标准化测试对其持久性进行了特征描述，但对于降解性处于中间水平的第三组化学物质（“中间组”），评估则不那么直接。在给定的环境中，这些化学物质是否表现为持久性，取决于环境因素，如是否存在可以限制化学物质生物利用度的吸附剂。当前对中间组化学物质持久性评估的不确定性并不意味着持久性评估通常不一致，对监管用途过于模糊，并且在化学危害和风险评估中没有用。考虑到影响化学物质降解的环境因素的复杂性，以及商业化学物质的多样性，必须接受这样一个事实，即即使对于中间组的化学物质，即使改进了测试方法，也无法消除其持久性数据中固有的异质性。对于具有广泛差异但技术上有效的持久性数据的情况，需要采用证据权重方法，并且应根据预防原则，对“有疑问的好处”进行权衡，以保护人类和生态系统健康。我们认为，尽管从科学角度来看，技术上有效的持久性数据可能由于高度变异性甚至不明确性而被认为不满意，但它们完全可以满足监管目的。与任何事物一样，在持久性评估中，科学逻辑旨在对涉及的过程进行机制描述，降低不确定性，并从广泛的经验基础中获得全面的理解。如果将科学逻辑用作监管背景下的基准，这可能很容易导致“分析瘫痪”。虽然监管决策应基于可靠的科学，但需要认识到并重视科学目标与监管需求之间的差异，以及降解研究的不同要求水平（必须具备-最好具备）。我们进一步提倡增强监管持久性评估之间的一致性（“一种物质-一种评估”），而目前并非如此。
