2,2'-[(4-methylphenyl)imino]bisethanol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Refer to the analogue approach justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

Based on the available read-across data, it is concluded that the target substance does not cause growth inhiibtion to aquatic algae. The retained key values for the toxicity of the target substance to aquatic algae are a NOEC (72 h) of 100 mg/L and an ErC50 (72 h) of greater than 100 mg/L based on growth rate.

Executive summary:

The toxicity of the source substance Accelerator (PT 25E or PT 25E/2) was assessed according to OECD guideline 201. Pseudokirchneriella subcapitata were exposed to the nominal concentrations of 0 (blank-control), 0.1, 1, 10 and 100 mg/L for 72 h.

Both the EC50 for growth rate reduction (72h-ErC50) and the EC50 for yield inhibition (72h-EyC50) exceeded the analytically confirmed concentration of 100 mg/L. The 72h-NOEC for growth rate reduction was 100 mg/L. For yield, the 72h-NOEC was between analytically confirmed concentrations of 10 and 100 mg/L. The study is considered to be reliable without restrictions.

The target substance is expected to have a similar ecotoxicological profile as the source substance based on the high degree of structural and chemical similarity between the source and the target substances. Therefore, it is concluded that the key value for the toxicity of the target substance to aquatic algae is a NOEC (72 h) of ≥ 100 mg/L and an ErC50 (72 h) of > 100 mg/L.

Description of key information

ErC50 (72 h) > 100 mg/L (nominal, OECD 201, P. subcapitata); read-across

NOEC (72 h) ≥ 100 mg/L (nominal, OECD 201, P. subcapitata); read-across

Additional information

There is no study available, in which the toxicity of the target substance N,N-Dihydroxyethyl-p-toluidine (CAS 3077-12-1) to aquatic algae was assessed. Therefore, read-across to the structurally and chemically closely related source substance Reaction mass of 2,2'-[(4-methylphenyl)imino]bisethanol and Ethanol 2-[[2-(2-hydroxyethoxy)ethyl](4-methylphenyl)amino]- (EC 911-490-9) was performed in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5 in order to meet the standard information requirements laid down in Annex VIII of REACh Regulation (EC) No 1907/2006. Based on the high degree of physico-chemical similarity between the target and source substances, the selected source substance is considered a suitable representative for the assessment of the toxicity of the target substance to aquatic algae. A detailed read-across approach justification is provided in IUCLID section 13.

In the available study with the source substance, the freshwater alga (Pseudokirchneriella subcapitata) was exposed to the nominal concentrations of 0.1, 1, 10 and 100 mg/L, including a negative control for 72 h. The test item concentrations in the test vessels were analytically verified and it was shown that the substance concentration was stable throughout the exposure.

After 72 h, no effects on growth rate were recorded, resulting in a NOEC (72 h) of ≥ 100 mg/L and an ErC50 (72 h) of > 100 mg/L

Based on the high degree of structural and chemical similarity between the target and the source substance and since the target substance is the main constituent of the source substance, the target substance is expected to exhibit a similar ecotoxicological profile as the selected source substance. Therefore, it is concluded that the target substance N,N-Dihydroxyethyl-p-toluidine (CAS 3077-12-1) does not cause toxic effects to aquatic algae up to a nominal concentration of 100 mg/L.