2,2'-methyliminodiethanol

Endpoint summary

Additional information

Short-term toxicity to fish: With high probability acutely not harmful to fish

Two acute fish studies were performed according to German Industrial Standards DIN 38412, part 15 using Leuciscus idus as test species (BASF AG, 1990, report no. 10F0990/885214; BASF AG, 1987, report no. 10F0333/875143). The results indicate that the test substance is probably acutely not harmful to fish. The 96-hour LC50 was determined to be >1000 and <2200 mg/L for not neutralized test solutions. In pelagic toxicity testing a pH of 6.5 to 9.0 is generally accepted (REACH Guidance, R.7B). This value was exceeded in the initial phase of all test item solutions. The pH remained above the critical value of pH 9.0 in the test item solutions of >= 2150 mg/L, which could have caused the high mortality in these test solutions. It should be noted that the mortality was not reduced after pH-adjustment of the highest concentration level (10000 mg/l). However, mortality was delayed. The observed mortalities were at least partly due to the pH-shift in the higher test item concentrations.

An additional acute toxicity study using juvenile sheepshead minnows in a semi-static approach resulted in a 96-h LC50 of >1000 mg/L, therefore demonstrating comparable endpoints between freshwater and marine fish species. The test solutions were not neutralised prior to use (BASF AG, 2002; report no. V2489/03).

 

Long-term toxicity to fish: A long-term study on fish was waived based on REACH Annex XI, chapter 3 (SUBSTANCE-TAILORED EXPOSURE-DRIVEN TESTING)

 

According to REACH Annex XI, chapter 3 (SUBSTANCE-TAILORED EXPOSURE-DRIVEN TESTING), testing in accordance with Sections 8.6 and 8.7 of Annex VIII and in accordance with Annex IX and Annex X may be omitted, based on the exposure scenario(s) developed in the Chemical Safety Report. For 2,2'-methyliminodiethanol there is a risk assessment available and submitted with the registration dossier, which includes all life cycle steps of the substance. This risk assessment demonstrates, taking into account the appropriate safety factors, the safe use of the substance throughout its entire life cycle. For none of the protection goals, the use of the substance creates an unacceptable risk. The resulting RCR determined for all compartments demonstrate no significant exposure in all scenarios of the manufacture and all identified uses as referred to in Annex VI section 3.5. with a maximum RCR of 0.02. Therefore, it is concluded that 2,2'-methyliminodiethanol does not pose a risk to the environment.

 

Short-term toxicity to aquatic invertebrates: With high probability acutely not harmful to freshwater invertebrates. However, the substance is acutely harmful to marine invertebrates

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.

 

Long-term toxicity to aquatic invertebrates: The 21 -d NOEC was determined to be 13.9 mg/L (BASF SE, 2021)

 

The assessment was performed with the QSAR Toolbox v4.4 calculation model. The 21 -d NOEC was determined to be 13.9 mg/L (BASF SE, 2021). The substance was within the applicability domain of the model. The calculation was performed with the trend analysis method and the substance was within the applicability domain of the calculation models.

Overall, it can be concluded, that that long-term effects are not to be expected.

Furthermore, a 96 -hour reproduction test on the marine copepod Acartia tonsa was performed (TNO Chemistry, 2002). The 96 -h NOEC was determined to be >= 100 mg/L. The 96 -h LC50 for parental mortality was > 100 mg/L. Although this study aimed to test the effect of MDEA on Acartia tonsa, there are several shortcomings of the test design to yield valid information on reproduction. A valid reproduction test should start with the exposure of newly hatched larvae, which should have sufficient time to reach adulthood and produce 2 to 3 broods of offspring in the control assays. As this study used 12 -d old females and information on the number of broods is missing, information regarding reproduction should not be considered in the risk assessment of MDEA. The data on mortality are discussed in IUCLID Ch. 6.1.3 Short-term toxicity to aquatic invertebrates. 

 

Toxicity to aquatic algae and cyanobacteria: With high probability acutely not harmful to algae

 

The key study was performed with Demodesmus subspicatus. It resulted in an EC50 based on the growth rate of > 100 mg/L (statistical evaluation of the measured fluorescence data resulted in an extrapolated ErC50 of 176 mg/L; BASF AG, 1988, report no. 2/0518/88). The 72h ErC10 was 19 mg/L. Another study by BASF AG using Desmodesmus subspicatus was performed as a range finding study which was not conducted according to current guidelines (deviations for example spacing factor, concentration range tested etc.). Further, the test results were not statistically evaluated and the EC50 of 45.2 mg/L refers to fluorescence values. Hence, this range finding test was disregarded.

A study on the marine alga Skeletonema costata resulted in a 72 -h ErC50 of 410 mg/L and a 72 -h ErC10 of 89 mg/L (BASF AG, 2002, report no. V2489/04). This result is supported by Eide-Haugmo et al. (2009) who performed a study with the same species. The 72 -h ErC50 was determined to be 141 mg/L.

It can be concluded that the substance is with high probability not acutely harmful to algae in freshwater and marine systems.

 

Toxicity to microorganisms: The inhibition of the degradation activity of activated sludge is not anticipated when introduced in appropriate low concentrations

Two short term respiration inhibition tests conducted by BASF (1988, 1993) demonstrate the effect on domestic and industrial activated sludge. The EC20 values were > 1000 mg/L in both studies. In a study exposing Pseudomonas putida to not neutralised test solutions an EC10 of 274 mg/L was observed.

Although supporting chemical analysis was not performed in any of the ecotoxicity studies, the test item concentrations can be assumed to have been stable over the exposure periods of the tests for several reasons:

MDEA is highly soluble in water; therefore, undissolved residues are not to be expected and were also not observed in the tests. In combination with the low vapour pressure (0.0031 hPa at 20 °C, see IUCLID Ch. 4.6) and the low Henry's Law constant (pH 5 to 9: 1.82E-09 to 5.90E-06 Pa m³/mol, see IUCLID Ch. 5.4.2) volatilisation is not to be expected. The low adsorption potential (pH 5 to 8: Koc = 38 to 43, see IUCLID Ch. 5.4.1) indicates that MDEA will not adsorb to the testing equipment or the test animals. Based on the abiotic control of the key biodegradation study, the maximum removal was 6% by day 7 (see IUCLID Ch. 5.2.1, BASF AG, 1993). Although the substance is readily biodegradable, the lag phase in the biodegradation studies was long compared to the exposure periods of the aquatic toxicity tests. In the OECD 301A test (IUCLID Ch. 5.2.1, key study, BASF AG, 1993), the lag phase was > 3 to < 7 days. In seawater, 5% removal was observed after 7d based on BOD (IUCLID Ch. 5.2.1, supp. study, BASF SE, 2011: OECD 306). In the MITI test removal after 28 d was low (7% ThOD, 23 TOC, 25% test material). Regarding the short exposure period (48 to 96 h), a relevant decrease of the test item concentrations (> 20%) is not to be expected.

Based on the properties of MDEA, it can be concluded that the test item concentrations remained within acceptable limits in the ecotoxicity studies.