DBP-Biozide – Consideration of Disinfection By-products in the Environmental Risk Assessment of Biocidal Products – Inventory & Development of Recommendations for Assessment

The application of disinfectants and protective agents in different fields results in a large number of reaction products (disinfection by-products, DBPs). The aim of the project is to describe the significance and prioritisation of these metabolites, degradation and reaction products on the basis of an inventory. To this, there are recommendations on what role DBPs play in the environmental risk assessment of biocides. The Institute for Environmental Engineering of the RWTH Aachen University,ISA for the short, works together with the Fraunhofer Institute for Molecular Biology and Applied Ecology, IME for the short, and initially compiles the current state of knowledge on the formation of DBPs. Of particular interest are biocides that form metabolites by reaction with other organic and inorganic substances. These are systematically recorded under consideration of the reaction conditions such as pH value, matrix, biocide dosage and temperature. This enables the differentiation of biocides according to their relevance.
ISA's high-performance environmental analytical laboratory, equipped with state-of-the-art technology, enables the analysis of samples from substances and environmental matrices containing volatile and non-volatile organic and inorganic components. The equipment includes high-performance chromatography systems with UV detectors and MS detectors. In addition, a high-resolution gas chromatograph, GC for the short, with a mass spectrometer, MS for the short, GCMS is available at the ISA and covers the analysis of halogenated hydrocarbons. An exact determination of the mass and the fragmentation processes increases the identification reliability of the individual DBPs. The ISA also has a screening procedure (Suspect Screening) that can search specifically for reaction products from the oxidative degradation of organic compounds. Depending on the disinfectant and protective means and the type of application, some samples must be obtained from professional users. For this purpose, the ISA uses two current projects (DemO3AC and AdOx Köln) to investigate the ozonation of municipal wastewater. In addition, contact with the Aachen University Hospital and drinking water producers is helpful.
The testing and environmental assessment of disinfectants base on worst-case assumptions for the maximum formation rates of DBPs to ensure critical consideration. In addition to the general reactivity of an active substance, there is an examination of the matrix present during the application, e.g. the presence of organic material, and the environmental conditions, e.g. radiation. The "worst case" assumptions lead to a derivation of framework conditions for the experimental testing of active substances/products with regard to the environmental risk.