Current status and challenges of difficult-to-test substances such as cationic surfactants under the Chemical Substances Control Law

Abstract

We review the current challenges in the ecological risk assessment of ethylenediaminetetraacetic acid (EDTA) and cationic surfactants under Japan’s Chemical Substances Control Law. The complexity of EDTA toxicity assessment arises from its chelating properties, which influence metal bioavailability and ecological toxicity, making conventional assessment methods inadequate. Meanwhile, the toxicity of cationic surfactants is significantly affected by environmental factors, particularly organic matter content and water quality parameters. These variations pose substantial difficulties in achieving reliable toxicity assessments. While the Biotic Ligand Model (BLM) has been applied to address similar challenges in metal toxicity assessment, its effectiveness in evaluating EDTA and cationic surfactants has yet to be fully demonstrated. This paper examines existing evaluation methods, identifies their limitations, and proposes potential approaches for improving the reliability of risk assessments for these difficult-to-test substances.