Developing a regional environmental risk assessment model for biocides manufactured in South Korea

The Humidifier Disinfectant Case in South Korea caused 1533 deaths in 2011. To prevent such accidents, the South Korean government implemented the Consumer Chemical Products and Biocides Safety Control Act in 2019, introducing an approval system for biocidal substances and products. The law established an environmental risk assessment based on exposure to these substances and products. We conducted an environmental risk assessment for 11 cities in South Korea to determine the degree of risk to the surrounding area that may occur during biocidal substance manufacturing. In our research, we derived predicted no-effect concentrations (PNEC) based on toxicity values for each organism for microorganisms in sewage treatment plants (STP), freshwater, sediment, and terrestrial compartments for the biocides such as 2-propanol, zinc oxide, calcium oxide, imidacloprid, sodium hypochlorite, and peracetic acid. The predicted environmental concentrations (PEC) of the six biocides were calculated based on the discharge from 11 manufacturing facilities. Local PECs were as high as 1000 mg/L for 2-propanol in STP and 3–90 mg/L for zinc oxide and calcium oxide in STP, while regional PECs were as low as 0.03 mg/L for 2-propanol in surface water. The hazard quotient (HQ) for the six substances shows that 2-propanol, zinc oxide, calcium oxide, and peracetic acid exceed the hazard at STP in Tier 1. However, we found no risk in Tier 2, which considers the characteristics of the actual substances and their behavior in the sewer system. We developed a model that reflects the regional characteristics of each environmental medium through predicted emissions and PECs that may occur during the manufacture of biocidal substances. The model provides a valuable tool for tiered evaluation and control for environmental risk assessment of biocidal substances.