Research

Substance mapping: A first step towards developing a better assessment strategy for UVCBs

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Abstract

Science Risk assessment of complex substances (e.g., multi-constituent substances (MCs), and substances of Unknown or Variable Composition, Complex Reaction Products, and Biological Materials (UVCBs)) presents numerous challenges. International regulatory programs (specifically REACH, Canada’s Chemicals Management Plan, and USEPA’s PMN process) have highlighted the complexities of characterizing fate and exposure, risk assessment, and registration of these types of substances. A new HESI Project Committee was started in early 2018, with the goal of developing a tiered approach to assess ecological risks of MCs / UVCBs, and meet regulatory needs. The Committee determined that mapping the vast and complex universe of UVCB substances by chemical and/or functional classes should be the foundation of all work performed on this project, as a key to better understand the nature of these substances and their sector of use, and provide insight on which of them present the largest regulatory challenges. This exercise will also help identify UVCBs of most concern to the environment and human health. The classification of UVCBs according to criteria such as chemistry similarities and use patterns could ultimately help the development of strategies and streamline the risk assessment of these substances. Examples of UVCB mapping by participating regulatory agencies will be presented and some of the most common categories of UVCBs will be highlighted along with the technical challenges associated with risk assessment of these classes. Depending on the identified classes of UVCBs, it may be possible to apply many of the existing analytical and assessment methods to characterize UVCBs and evaluate their hazard potential. An important starting point, however, is to have the most accurate information to identify and characterize the MCs and UVCBs to ensure that their chemical classification is accurate. [The views of the authors of this presentation are those of the authors and do not represent the views of their respective organizations]