Sammendrag
In this study the ready biodegradabilities of 10 selected nitrosamines in water were examined. Biodegradability was determined by the standard OECD 301D method, determining the biological oxygen demand in a closed bottle method. This method is recommended as a first step in the assessment of degradability of compounds in water. Nitrosamine concentrations in samples at the start and end of the test period were also measured by chemical analyses. None of the tested nitrosamines were ready biodegradable (i.e. showed biodegradability > 60 %). Both biological oxygen demand and chemical analyses showed that only one of the nitrosamines (nitrosodiethanolamine) was moderate biodegradability at the tested concentrations (2 mg/L), and that most of the chemicals seemed to inhibit the biological oxygen demand at these concentrations. A literature survey showed that nitrosamines are biodegradable in environmental samples, but that the degradability is dependent on concentrations. Thus, it is expected that these compounds may be biodegradable at low concentrations. Nitrosamines are also rapidly degradable in water by photochemical reactions. Based on the results from this study it is recommended to perform additional biodegradation studies with low concentrations of nitrosamines. We also recommended that biodegradation studies should be conducted with water temperatures relevant for Norwegian coastal climate.