Testing The Biodegradability of Priority And Emerging Contaminants As A Mixture

Abstract

Currently about 110,000 chemical substances are present in the European market. The fate of most of those chemicals in the environment is not known. However, biodegradability of those chemicals should be tested before they are registered to the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) System. Current protocols offered by The Organisation for Economic Co-operation and Development (OECD) for testing the biodegradability of the chemicals are limited mainly due to they are low throughput and do not reflect real-world conditions. In OECD protocols, the biodegradability of a single chemical is tested. However, many chemicals coexist in the environment. In addition, experiments are set at a very high initial chemical concentration that is not expected in the environment. Both limitations are due to the lack of an analytical method which can measure multiple compounds simultaneously at very low concentrations. In this study, we coupled OECD 314 Simulation Tests to Assess the Biodegradability of Chemicals Discharged in Wastewater protocol with a powerful liquid chromatography mass spectrometry with scheduled multiple reaction monitoring and tested the biodegradability of 32 priority substances and chemicals with emerging concern. Only seven chemicals were degraded in the test within 28 days. The biodegradation half-lives of those degradable chemicals ranged between 0.6 to 18 days. Acetaminophen was degraded the fastest whereas biodegradation of sulfamethoxazole took longer than the rest of the biodegradable chemicals tested. The novel methodology described here can be applied to test biodegradability of different chemicals as a mixture and adopted as a standard protocol.