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Acute toxicity test of monomethylamine were conducted for all three trophic levels (fish, daphnids, and algae). According to the obtained results, the hazard assessment of monomethylamine reveals neither a need to classify the substance as dangerous to the environment, nor is it a PBT or vPvB substance; nor there are any further indications that the substance may be hazardous to the environment. In acccordance with REACH regulation in this tonnage band no long-term toxicity tests for either fish or daphnids have to be conducted.

The short-term toxicity to fish was tested by different scientists. Leuciscus idus was exposed to neutralized as well as non-neutralized monomethylamine in an experiment according to OECD guideline 203 (Bayrisches Landesamt für Wasserwirtschaft, 1986). There was a great difference in the obtained LC50 values, depending if the substance was neutralized (970 mg/L) or not (16 mg/L). BASF AG (1997) has found a LC50 (48 h) > 500 mg/L for this species after 48 hours and a QSAR performed by BASF (2019) came to the result of an LC50 (96h) of ray-finned fish (Actinopterygii) of 398 mg/L.

Furthermore, Tonogai et al. investigated 1982 Oryzias latipes according to JIS K0102 (methylamine was neutralized using HCl) and found a LC50 (48h) of 1000 mg/L.

Embryogenesis of Brachydanio rerio after exposure to methylamine was investigated by Groth et.al. (1993; NOEC = 93 mg/L, LC50 = 711 mg/L) and Kronauer et.al. (1990; rate of embryonic mortality: 60 % at 2 mg/mL test substance).

The acute toxicity of monomethylamine to aquatic invertebrates (Daphnia magna) has been tested according to DIN 38412, part 11 (Kuehn, R. et.al., 1989). Using non-neutralized test substance the following results are shown: EC0 = 95 mg/L, EC50 = 163 mg/L, and EC100 = 260 mg/L, whereas a neutralized sample resulted in LC50 = 702 mg/L.

Two different algae species were used for experiments regarding toxicity to aquatic algae of monomethylamine. Pseudokirchnerella subcapitata showed 21 % growth inhibition at 31 mg/L (Andreozzi et.al., 2000). Scenedesmus obliquus was used to investigate the effects on assimilation rate in dependence of the ambient pH. 35 % increase was shown at pH 7.9, whereas a pH values of 8.3 and 9.0 results in a decrease of assimilation (Azov, A., 1974).

For the hazard assessment for the water compartment (PNECaqua-freshwater) the most critical short-term effect parameter obtained is applied to a assessment factor of 1000 (i.e. EC50 of 16 mg/L, examined in toxicity study regarding fish; BASF AG, 1997). For details please refer to ECHA (2008) “Guidance of Information Requirements and Chemical Safety Assessment, Chapter R.10: Characterisation of dose-response for environment”.

Experimental data regarding inhibition of oxygen consumption by activated sludge is available from BASF AG (1990) Two tests were conducted with different test substance concentrations. The experiments were conducted according to ISO 8192, whereas an EC20 of 240 mg/L and EC20 > 1007 mg/L was reported.

For the hazard assessment for sewage treatment plant (PNECstp) the worst-case extrapolation has to be concluded, thus utilize EC20 = 240 mg/L (instead of EC50) with an assessment factor of 100. For details please refer to ECHA (2008) “Guidance of Information Requirements and Chemical Safety Assessment, Chapter R.10: Characterisation of dose-response for environment”.