Utilization of chemical substance transfer and release notification data system for screening assessments in preparation for water source quality accidents

The Water Supply Act mandates individual water suppliers to regularly monitor for contaminants in the water. However, a wide variety of chemical substances are released by industries, so self-monitoring may not be sufficient. This study aimed to develop a framework for identifying chemical substances harmful to human health and ecosystems and with a high risk of causing water pollution accidents based on the amount handled at water sources. A case study was also conducted on a water purification plant with ozonation and granular activated carbon (GAC) treatment. Data on 462 Pollutant Release and Transfer Register (PRTR) Class 1 designated chemical substances in FY2020 were used to create a risk matrix based on the ‘transfer and release amount’ and ‘extent of impact when water quality accident occurs’. This matrix was used to extract and prioritize chemical substances with a high risk of water quality accidents. This screening assessment can be used to identify precursor substances with high priority in addition to conducting regular monitoring, under normal circumstances, as well as in the possible event of a water quality accident, and conducting detailed risk assessments through water purification experiments.