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Short-term toxicity to aquatic invertebrates

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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:

Valid information from acute toxicity testing with Daphnia magnaaccording to OECD guideline 202 is available (Dom et al., 2012). At test termination after 96 h an EC50 of 18260 mg/L was determined.

In a reliable supporting standard static test withDaphnia magnano adverse effects were reported at 10000 mg/L after 48-h exposure (Kuehn, 1989). Toxicity values well above 10000 mg/L reported also forDaphnia magnain other studies support this finding: 22200 mg/L(EC50, 48h) (Rossini and Ronco 1996), 20803 mg/L (EC50, 24h) (Lilius et al. 1995), and 22910 mg/L (LC50, 24h) (Reiff 1976). Aditionally short-term toxicity data are available from tests conducted with other test organism:Mytilus edulis, LC50 (96h) = 15900 mg/L (Helmstetter et al. 1996) andMoina micrura, LC50 (96h) = 4820 mg/L. Although the lowest toxicity was reported forMoina micrura,the study is considered less relevant due to poor documentation on test procedures and conditions. Nevertheless the LC50 -value supports the indication for very low acute toxicity of methanol towards invertebrates.

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

Hydrolysis product magnesium hydroxide:

The recalculated LC50 (96h) for D. Magna in the key study was determined as 170.86 mg/L with pure, 100% Magnesium hydroxide concentration. In two of the supporting studies, Magnesium chloride was shown to have low toxicity to Daphnia magna with the threshold for Magnesium chloride toxicity to D. magna found to be 0.0078 molar and an LC50 of 3391 mg/l in 25 hours. Magnesium ion was also shown to have low toxicity to Daphnia magna with one supporting study concluding that the EC50 for the Magnesium ion for Daphnia magna was found to be 405.98 mg/l at 24 hours and 343.56 mg/l at 48 hours. Magnesium chloride was also proven to have low toxicity to Daphnia hyaline, having a 48 hour LC50 of 32.0 mg/L, a low toxicity to Cyclops abyssorum, with a 48 hour LC50 of 280 mg/L and Magnesium chloride also has a low toxicity to Eudiaptomus padanus with a 48 hour LC 50 of 180 mg/L. The LC50 for Magnesium chloride on Austropotamobius pallipes pallipes was found to be 480 mg/l in a 96 hr test and 30 day LC50 values of 270 mg/L and 360 mg/L, without and with food, respectively. These values show that Magnesium chloride has low toxicity on Austropotamobius pallipes pallipes. Magnesium sulphate also has a low toxicity for Daphnia magna with an LC50 of 963 mg/l in 24 hours, measured in university lake water. In another supporting study, on the short term toxicity of Magnesium chloride and Magnesium sulphate to Ceriodaphnia dubia, again the conclusion was that Magnesium chloride and Magnesium sulphate, and hence the Magnesium ion, had low toxicity to Ceriodaphnia dubia with the LC50 for Magnesium chloride found to be 880 mg/l after 48 hours and Magnesium sulphate was found to be 1770 mg/l. Magnesium sulphate was found to have a very low toxicity for Lymnaea sp. Eggs with an LC50 of 10530 mg/l in 24hours.

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

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