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Abstract: The development of a chronic mollusc toxicity test is a current work item on the agenda of the OECD. The freshwater pond snail Lymnaea stagnalis is one of the candidate snail species for such a test. This paper presents a 21-day chronic toxicity test with L. stagnalis, focussing on embryonic development. Eggs were collected from freshly laid egg masses and exposed individually until hatching. The endpoints were hatching success and mean hatching time. Tributyltin (TBT), added as TBT-chloride, was chosen as model substance. The selected exposure concentrations ranged from 0.03 to 10μgTBT/L (all as nominal values) and induced the full range of responses. The embryos were sensitive to TBT (the NOEC for mean hatching time was 0.03μgTBT/L and the NOEC for hatching success was 0.1μgTBT/L). In addition, data on maximum limit concentrations of seven common solvents, recommended in OECD aquatic toxicity testing guidelines, are presented. Among the results, further findings as average embryonic growth and mean hatching time of control groups are provided. In conclusion, the test presented here could easily be standardised and is considered useful as a potential trigger to judge if further studies, e.g. a (partial) life‐cycle study with molluscs, should be conducted. [Copyright &y& Elsevier]

Selecting an appropriate invertebrate assay has been a primary goal of national and international testing programs for endocrine disrupting chemicals. The available information on the endocrine system, its hormones and their modes of action in controlling physiological processes in invertebrates is limited and the selection of appropriate test species still presents a challenge. This paper outlines the development of a higher-tier full life cycle (FLC) test for pesticides with the non-biting midge Chironomus riparius (Insecta, Diptera, Chironomidae). As an insect, C. riparius represents the species' richest and ecologically one of the most important groups of invertebrates. In addition, the endocrine system of insects is one of the best studied among the invertebrates. Acute and chronic tests with Chironomus spp. are commonly used for testing and risk assessment of agrochemicals. A chironomid FLC test protocol has been developed and its suitability investigated in an inter-laboratory comparison. The protocol used is based on existing OECD and US-EPA test methods. To verify the suitability of the test to generate endpoints that encompass adverse effects on the arthropod endocrine system, a juvenile hormone analog was selected as positive control substance. Results have demonstrated that the proposed chironomid FLC can be performed in separate laboratories and that the selected arthropod juvenile hormone mimic causes effects. However, the observed toxicity is not proof of an endocrine disruptive mechanism and could equally be evoked by other compounds. Contrary to a screening assay, which aims at revealing a substance's mode-of-action, the FLC test generates robust, population-relevant endpoints that can be used in the risk assessment of agrochemicals. Since the initial results presented in this paper are encouraging we propose to complete the validation of this assay under OECD with high priority. [ABSTRACT FROM AUTHOR]