A test to assess chemical persistence in the natural environment

The intention of the European Commission to include persistent & mobile chemicals among substances of very high concern is one example of the increasing importance of persistence in chemical regulation.

Currently persistence assessment tests focus on evaluating persistence in WWTPs; there is no regulatory test capable of assessing persistence in the aquatic environment.

Recently we overcame this barrier, showing that a modified OECD 309 test yields the same attenuation rates as in the environment. Hence, there is now a path forward for including environmental persistence in persistence assessment.

However, to pursue this path one must specify where in the environment to collect water for the test, which requires an understanding of spatial variability of persistence. Furthermore, one must be able to translate attenuation rates measured in the lab test into environmental half-lives.

To address these needs, we apply the lab test to measure persistence in water bodies with diverse characteristics from 4 regions on 3 continents.

With these data we explore different proxies to explain spatial variability including cell count, microbial community composition and functional gene counts, employing chemical grouping and benchmarking.

Furthermore, we conduct field measurements of persistence and compare these with the laboratory tests to derive translation factors. Finally, we prepare guidance on how the laboratory test could be used to assess persistence in a regulatory context.