2,2'-methyliminodiethanol

Short-term toxicity to aquatic invertebrates

Description of key information

With high probability acutely not harmful to freshwater invertebrates. However, the substance is acutely harmful to marine invertebrates.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

233 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

45 mg/L

Additional information

The results as presented by BASF AG in 1988 indicate that methyldiethanolamine is probably acutely not harmful to freshwater daphnids. The 48 -h EC₅₀ based on mobility was determined to be 233 mg a.i./L and was based on nominal test item concentrations. The test solutions were not neutralised and the pH measured at the highest test item concentration of 500 mg/L was 9.67 at test initiation. Therefore, immobilisation might have been caused by the high pH.

In two additional BASF studies the toxicity of the test substance on the marine copepod Acartia tonsa was tested. One study was performed according to ISO 14669 as an acute toxicity study over a period of 48 h, while the other study was performed similar to ISO 14669 but with an extension of the study period to 96 h. In addition, the effects on reproduction were measured. As the exposure period is too short compared to the requirements of a reproduction study with invertebrates (exposure starting with neonates, at least 3 broods), the data on reproduction were ignored. The basic setup of both studies was similar, nevertheless, while the acute toxicity test used 8 -d old copepodids of undetermined sex, the reproduction study was performed with 12 -d old adult females. The number of test animals in the studies did not follow the ISO 14669. The ISO prescribes at least 20 animals per concentration while in both studies only 10 animals per test concentration were used. Therefore, the results on the acute toxicity to marine invertebrates are possibly less reliable.

In the acute toxicity test, the 48 -h LC₅₀ was determined to be 45 mg/L, indicating that the test substance is acutely harmful to marine invertebrate species. The animals in the reproduction test showed a lower sensitivity (48 -h LC50 > 100 mg/L; 96 -h LC50 > 100 mg/L). The deviation in sensitivity could be caused by the difference in age or sex of the test animals. In addition, this could also mirror a natural variation in sensitivity.