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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Link to relevant study record(s)

Description of key information

With high probability acutely not harmful to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:
202.5 mg/L
EC10 or NOEC for freshwater algae:
119.4 mg/L

Additional information

The toxicity of 1-methyl-1H-imidazole (CAS 616-47-7) on the aquatic green algae Desmodesmus subspicatus was investigated in a study conducted similar to OECD 201 (BASF AG, 1990; report no.: 2/204389/t72). The results were recalculated using ToxRatPro v3.3.0 (BASF SE, 2021). After 72 h, the ErC10 was found to be 119.4 mg/L based on nominal concentrations; the 72 h ErC50 was determined to be 202.5 mg/L.

Even though no analytical verification of the test substance concentration was assessed, the test item can be considered as stable under test and storage conditions according to results of biodegradation and adsorption as well as physico-chemical properties such as water solubility and volatility: 1-methylimidazole is considered not readily biodegradable (according to OECD criteria), and only inherently biodegradable after a prolonged test duration (60 days, BASF, 2011, 29G0492/11G077). Additionally, adsorption of 1-methylimidazole to the solid soil phase is not expected (BASF, 2021, Franco&Trapp 2008/2009/2010; BASF, 2018, KOCWIN v2.00). Furthermore, the substance is completely miscible at 20°C (1000g/L; see IUCLID Ch. 4.7) and has a low vapour pressure of 0.3514 hPa at 20 °C and 0.5166 hPa at 25 °C (see IUCLID Ch. 4.6).

Therefore, the substance can be regarded as stable during the 72h test period and tested concentrations can be regarded as nominal test concentrations.


1-methyl-1H-imidazole (CAS 616-47-7) is considered to be with high probability acutely not harmful to aquatic algae.