Comparative Analysis Framework for Non-Detects in TSCA Evaluations

This technical report presents a comparative analysis and decision framework for handling non-detects (NDs) in TSCA risk evaluations. It outlines the challenges posed by NDs, which occur when measured concentrations fall below an instrument’s detection limit, complicating exposure assessments in occupational data sets. The report details various statistical approaches for managing NDs, each with distinct strengths and limitations based on factors such as percent censoring and sample size. A scoping literature review confirmed the lack of universally accepted guidelines, leading to inconsistent practices among professionals. The report also describes a simulation study that generated synthetic data sets to evaluate the performance of different ND-handling methods under varying levels of censoring. A decision framework is developed to assist practitioners in selecting the most appropriate ND-handling method based on specific data set characteristics. The findings aim to enhance the accuracy of exposure estimates and support regulatory compliance in occupational health assessments.