Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany.
Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands.
Part Fibre Toxicol. 2024 Nov 29;21(1):48. doi: 10.1186/s12989-024-00602-9.
Human exposure to micro- and nanoplastic particles (MNPs) is inevitable but human health risk assessment remains challenging for several reasons. MNPs are complex mixtures of particles derived from different polymer types, which may contain plenty of additives and/or contaminants. MNPs cover broad size distributions and often have irregular shapes and morphologies. Moreover, several of their properties change over time due to aging/ weathering. Case-by-case assessment of each MNP type does not seem feasible, more straightforward methodologies are needed. However, conceptual approaches for human health risk assessment are rare, reliable methods for exposure and hazard assessment are largely missing, and meaningful data is scarce.
Here we reviewed the state-of-the-art concerning risk assessment of chemicals with a specific focus on polymers as well as on (nano-)particles and fibres. For this purpose, we broadly screened relevant knowledge including guidance documents, standards, scientific publications, publicly available reports. We identified several suitable concepts such as: (i) polymers of low concern (PLC), (ii) poorly soluble low toxicity particles (PSLT) and (iii) fibre pathogenicity paradigm (FPP). We also aimed to identify promising methods, which may serve as a reasonable starting point for a test strategy.
Here, we propose a state-of-the-art modular risk assessment framework for MNPs, focusing primarily on inhalation as a key exposure route for humans that combines several integrated approaches to testing and assessment (IATAs). The framework starts with basic physicochemical characterisation (step 1), followed by assessing the potential for inhalative exposure (step 2) and includes several modules for toxicological assessment (step 3). We provide guidance on how to apply the framework and suggest suitable methods for characterization of physicochemical properties, exposure and hazard assessment. We put special emphasis on new approach methodologies (NAMs) and included grouping, where adequate. The framework has been improved in several iterative cycles by taking into account expert feedback and is currently being tested in several case studies. Overall, it can be regarded as an important step forward to tackle human health risk assessment.
人类接触微塑料和纳米塑料颗粒（MNPs）是不可避免的，但由于以下几个原因，对其进行人类健康风险评估仍然具有挑战性。MNPs 是由不同聚合物类型衍生而来的颗粒的复杂混合物，其中可能含有大量添加剂和/或污染物。MNPs 的粒径分布范围很广，通常形状不规则且形态各异。此外，由于老化/风化，它们的许多特性会随时间发生变化。对每种 MNP 类型进行个案评估似乎不可行，需要更直接的方法。然而，用于人类健康风险评估的概念方法很少，暴露和危害评估的可靠方法在很大程度上缺失，有意义的数据也很稀缺。
在这里，我们综述了化学物质风险评估的最新进展，特别关注聚合物以及（纳米）颗粒和纤维。为此，我们广泛筛选了相关知识，包括指导文件、标准、科学出版物和公开报告。我们确定了几个合适的概念，如：（i）低关注聚合物（PLC），（ii）低溶解度低毒性颗粒（PSLT）和（iii）纤维致病性范例（FPP）。我们还旨在确定有前途的方法，这些方法可能成为测试策略的合理起点。
在这里，我们提出了一个针对 MNPs 的最先进的模块化风险评估框架，主要侧重于人类暴露的关键途径——吸入，并结合了几种综合的测试和评估方法（IATAs）。该框架从基本的物理化学特性描述开始（步骤 1），随后评估吸入暴露的可能性（步骤 2），并包括几个毒理学评估模块（步骤 3）。我们提供了应用该框架的指导，并建议了用于描述物理化学特性、暴露和危害评估的合适方法。我们特别强调了新方法策略（NAMs），并在适当的情况下进行了分组。该框架在几个迭代周期中得到了改进，考虑了专家反馈，目前正在几个案例研究中进行测试。总的来说，这是解决人类健康风险评估的重要一步。
