Unknown confidence in chemical characterization identification levels: When tentative identifications are adequate for toxicological risk assessment of medical devices

Identifying chemicals is critical to chemical characterization and toxicological risk assessments (TRAs) for evaluating patient safety risks posed from medical devices. The burden to accurately identify substances with limited information is high. There is lack of consensus on the confidence needed for compound identifications to conduct a TRA. To address this gap, chemical characterization reports and TRAs were evaluated, and many tentatively identified compounds were grouped into chemical classes, which may consist of all tentative identifications or a mixture of identifications, then treated as one compound. By using this approach, the confidence level of each group member was not used to modulate the outcome of the risk assessment, obviating the need for confirmed identification of each group member. By understanding the downstream confidence level utilization, the burden involved in determining confident identification for all compounds detected during chemical characterization can be reduced to aspects of compound identification that may pose higher toxicological importance. A decision tree was developed to focus the identification process on compounds of interest as well as a method to assign confidence levels. This tool can be used to reduce the burden in identifying individual confidence levels without compromising the reliability of the conclusion of the TRA.