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Ring testing ECO 55: assessing the impact of sample collection on microbial population and validity criteria in the OECD 309 surface water mineralisation test.

By July 1, 2024No Comments

The purpose of the OECD 309 test is to measure the time course of biodegradation of a test substance at low concentration in aerobic natural water and to quantify the observations in the form of kinetic rate expressions. Biodegradation is crucial for the removal of environmental organic contaminants and affects chemical persistence and exposure. Regulatory guidelines require quantitative evaluation of chemical degradation half-lives.

The OECD 309 method is a high-tier test for the aerobic biodegradation of chemicals in surface waters (OECD, 2004). The ECO 55 project aims to improve biodegradation testing by assessing inoculum quality, identifying relevant reference substances, and refining test procedures. It will provide guidelines for surface water sample collection and storage, ensuring test robustness and validity at specified temperatures. The focus is on understanding the relationship between inoculum diversity, viability, and biodegradation performance. This will enhance the accuracy and reliability of biodegradation assessments.

Within the ring test IES was in charge of testing three candidate reference substances – benzoic acid, caffeine and 2,4-Dichlorophenoxyacetic acid at 12 ┬░C in the dark over a course of 60 days, results will be published by Ricardo.