Applying the one concentration approach in fish bioaccumulation studies

Fish bioconcentration studies are carried out to determine whether substances have the potential to bioaccumulate. These studies are required for both plant protection products (PPPs) and industrial chemicals under various global regulations, and therefore result in the use of an extensive number of fish.

Historically, these studies have been carried out using three dose groups (two different active substance concentrations, plus one control group). However a revision to the OECD Test Guideline (TG 305: Bioaccumulation in Fish) in 2012 means that one active substance concentration can now be tested in these studies rather than two, providing there is scientific justification. This has the potential to decrease the numbers of fish used in these tests by one third (ca. 50 fish per study). In collaboration with scientists from Syngenta, BASF and Dow AgroSciences, we have generated an evidence base which supports the one concentration approach in fish bioaccumulation studies for both PPPs and industrial chemicals. A summary of the findings can be found in [1].

Following publication of the analysis, we conducted a survey to assess the barriers to the uptake of the one concentration approach in practice. This revealed that the main reason for not applying the appoach, given by 64% of respondents, is due to lack of regulatory acceptance and/or differing regional requirements related to this type of test. This is despite the revision to the OECD guideline and the supporting scientific evidence base. The survey results were published in 2016. In 2020, the US EPA published a supplement to the US Fish BCF Test Guideline (OCSPP Test Guideline 850.1730) - now allowing for one concentration to be tested under specified conditions, and citing our data analysis publications [2].