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Long-term toxicity to aquatic invertebrates

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No reliable data are available for the long-term toxicity of bismuth to aquatic invertebrates and the requirement for new test results is waived.

Section 2 of Annex XI of Regulation (EC) 1907/2006 states that testing for a specific endpoint may be omitted if it is technically not possible to conduct the study as a consequence of the properties of the substance. The physico-chemical characteristics of a chemical may limit the possibility for performing certain (eco)toxicity assays such as low solubility. A stock solution at a loading rate of 100 mg bismuth/L was prepared by dissolving 2.74 g of bismuth subnitrate in 20 L of the medium used for the acute invertebrate test, according to the guidance on transformation dissolution of metals and metal compounds (OECD, 2001). After agitation for seven days by using a horizontal laboratory shaker (100 rpm) at ambient temperature in the dark to keep the test item in permanent suspension, the Bi concentration in the water accommodated fraction (filtered through 0.6 µm glass fibre filter) was below detection limit (0.0375 mg Bi/L, Egeler et al., 2010). Therefore it can be concluded that it may neither be possible nor relevant to try and conduct certain ecotoxicological tests, as it is difficult to maintain a high enough and constant concentration of bismuth in the water.

Column 2 of Annex IX of Regulation (EC) 1907/2006 also states that "Long-term (aquatic) toxicity studies shall be proposed by the registrant if the CSA according to Annex I indicates the need to investigate further the effect to aquatic organisms". Because all acute tests show the absence of toxic effects and therefore the absence of a classification for the environment for bismuth, there is no need for further investigation of effects to aquatic organisms.

Conclusively, it is proposed to waive further chronic testing with aquatic invertebrates based on the following arguments:

- Significantly higher solubility of bismuth between acute and chronic test set-ups is not expected to occur.

- All of the acute toxicity tests with invertebrate, fish and algae resulted in the absence of any ecotoxicological signal at the largest dose tested (NOEC and L(E)C50 ≥ 100 mg/L).

OECD (2001). Guidance Document on Transformation/Dissolution of Metals and Metal Compounds in Aqueous Media. OECD Series on Testing and Assessment Number 29. ENV/JM/MONO(2001)9. Organisation for Economic Co-Operation and Development, Paris.