A large number of tests in fish, invertebrates and amphibians have been proposed to explore (potential) endocrine activity in aquatic organisms. Some of these tests have already been incorporated in new and/or existing regulatory requirements. However, since no agreed testing strategy exists, it is unclear how these tests will be used in the overall evaluation of a substance.
This RfP aims to generate knowledge to promote a tiered approach and support the optimisation of assays and a testing strategy to investigate potential endocrine activity. This includes
- considering the likelihood of exposure in the environment
- maximising available information whilst minimising resource required (animals, endpoints and cost) and avoiding redundant testing
- provide data on the natural variability of proposed parameters
As appropriate, this RfP may be conducted as a whole by one applicant or be divided into subprojects handled by different groups. However, it is indispensable to finally deliver a joint report tackling all parts of the project.
- Development of a ”Threshold of Toxicological Concern (TTC)”-concept for ecotoxicology analogous to the mammalian approach. Potency, e-fate and exposure of a substance are considered to establish environmental'negligible risk' levels.
- Comparison of modes of action covered by and sensitivity of the proposed test methods for the evaluation of endocrine activity
- Investigations into control variability of fish reproduction - what change is clearly a biological adverse effect?
- Review literature and available data to develop criteria which allow for the allocation of a substance to ”potency groups”
- Include e-fate into the concept
- Develop thresholds (concentrations) for the groups below which there is a very low probability of an appreciable risk to the environment
- Include external parties in the discussion of the concept Comparison of test methods
- Collect available data for model substances which have been tested in more than one of the proposed methods for the assessment of endocrine activity
- Analyse results in order to compare the sensitivity of several methods and endpoints to ascertain their capability to detect different modes of action.
- Fill gaps by conducting ”missing” studies if necessary
- Identify overlaps in the scope of the methods and potential for replacement
- Develop a proposal for a testing strategy (based on data collected) that may be optimised by mode of action (if known) Variability in fish reproduction
- Review literature data on control fish reproduction data
- Conduct control experiments under different laboratory conditions and assess the impact of relevant parameters on reproductive outcome of fish.
- Determine the extent of intra- as well as inter-experimental variation
Short interim reports on progress are required at 3 to 6-monthly intervals. It is expected that the findings will developed into a peer reviewed publication, following presentation at a suitable scientific conference.