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Short-term toxicity to fish

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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:

In continuous flow-through systems LC50 (96 h) values for freshwater fish were 29400 mg/L (Pimephales promelas), 20100 mg/L (Salmo gairdneri), 15400 mg/L (Lepomis macrochirus) (Poirer, 1986), 20100 mg/L (Salmo gairdneri) and 28100 mg/L (Pimephales promelas) (Call, 1983). Reiff found in a study conducted under static conditions comparable toxicity values for rainbow trout (11850 mg/L). Since this result is based on nominal concentration, the value from the study of Poirer for Lepomis macrochirus (based on analytical measurements and conducted under flow-trough conditions) is taken as the lowest toxic concentration for freshwater fish. Toxicity and sublethal effects of methanol on swimming performance of the marine fish Florida pompano (Trachinotus carolinus) were investigated in a short-term experiment (24 h), resulting in LC50 > 10000 mg/L. The very low toxicity towards fish has been confirmed by the results of several studies investigating methanol as common cryoprotectant agent in early-life stages of fish (embryos, fish eggs, oocytes): Danio rerio (fish embryo toxicity test), EC50(48 h): 22100 mg/L (Lammer et al.); Danio rerio (OECD 212), NOEC(96h): 3950 mg/L (Chromcova et al.); Danio rerio (oocytes)NOEC (30 min): 64000 mg/L (Plachinta et al.).

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

Hydrolysis product magnesium hydroxide:

Five studies were carried out on the short-term toxicity to fish. The supporting studies all concluded that Magnesium has no short-term toxicity to fish. The first study, on the effect of magnesium cation on survival of brown trout at low pH, concluded that the magnesium ion does not affect the survival rate of brown trout at low pH. The second supporting study, on the acute toxicity of magnesium sulphate to bluegillfish, concludes that magnesium sulphate has a very low toxicity to Lepomis macrochirus. The final supporting study, on the short-term toxicity of magnesium chloride and magnesium sulphate to Pimephales promelas, concluded that magnesium sulphate and magnesium chloride, and hence the magnesium ion, have a very low toxicity to Pimephales promelas.

From the key studies, the recalculated LC50 (96h) of P.Promelas was determined to be 306.79 mg/L for freshwater fish.

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

Key value for chemical safety assessment

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