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Toxicity to microorganisms

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Description of key information

Magnesium methanolate hydrolyses rapedly in contact with moisture or water into methanol and magnesium hydroxide (detailed description in section 5.1.2). Both hydrolysis products are natural occuring substances and according to the available data are not dangerous for aquatic organisms and no classification is required.

Hydrolysis product methanol:

Bringmann and Kuehn (1978) determined a toxic treshold value (TGK) of 530 mg/L in a 192h test with Microcystis aeruginosa. The same authors report a further toxic treshold value resulting from a cell multiplication test for 16 hours, using two Pseudomonas species, at 6600 mg/L (Bringmann and Kuehn 1977). Other test results reported are an EC50 of 20000 mg/L for activated sluge and an IC50 value of 880 mg/L for Nitrosamonas (Blum and Speece 1991). An IC50 value >1000 mg/L for activated sludge is reported by Klecka et al. (1985). This test was performed according to the OECD Guideline 209 (activated sludge, respiration inhibition test)

According to the available data, the hydrolysis product methanol can be considered as not harmful to microorganisms.

Hydrolysis product magnesium hydroxide:

According to the key study, Magnesium hydroxide was not toxic to waste water (activated sludge) bacteria at a loading rate of 100 mg/l. The 3-hour EC50 of magnesium hydroxide exceeded a loading rate of 100 mg/l.In the supporting study, acute tests showed magnesuim sulfate to be the least toxic substance of the six salt solutions tested.

According to the available data, the hydrolysis product magnesium hydroxide can be considered as not harmful to microorganisms.

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