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Toxicity to microorganisms

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Description of key information

Key value for chemical safety assessment

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No studies specifically on the toxicity to microorganisms for lead bis(tetrafluoroborate) exist. However, since lead salts are well-examined and also one study for tetrafluoroborate salts exists which results in a EC50of 550mg/L, it was decided to read across from a soluble lead salt and a tetrafluoroborate salt in the forefront of the lead bis(tetrafluoroborate) dossier preparation for reasons already stated in the HH section.

Lead bis(tetrafluoroborate) is a soluble metal salt (> 500 g/L at 20°C; for more detailed information please refer to section 4.8 of this dossier). Read across is performed to the lead dichloride dossier (water solubility 10g/L at 20°C) and potassium tetrafluoroborate (approx. 1.3g/L at 20°C). It is explicitly noted here that the submitter of this dossier has obtained formal access to the lead dichloride dossier.

As stated above, the EC50value for the toxicity testing in bacteria of potassium tetrafluoroborate was determined to 550 mg/L.

Toxicity data to bacteria (heterotrophs and nitrifiers) and different protozoan species for a soluble lead compound were extracted from literature. 2 different no-effect levels for lead, between 1.06 and 2.92 mg/L (depending on the exposure time), were compiled for heterotrophic bacteria. For nitrifiers, 2 different no-effect concentrations, between 2.79 and 9.59 mg/L, were observed. 14 different short-term toxicity data were selected for protozoan species/communities. No-effect concentrations for protozoan communities varied between 1.0 and 7.0 mg Pb/L, while LC50 values for protozoan varied between <1.5 and >250.0 mg/L.

By using the lowest value of all these data, it can be concluded that for lead bis(tetrafluoroborate) the NOEC for acute toxicity to bacteria is ca. 1.8 mg/L (worst case consideration).