Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

No effects were observed in an alga toxicity study performed with the read-across substance 6-(isononanoylamino)hexanoic acid, compound with 2,2’,2’’-nitrilotriethanol up to a concentration of 99.6 mg/L. The ErC50 has been determined to be > 100mg/L. 

Key value for chemical safety assessment

Additional information

In a reliable study (reliability category 1) on growth inhibition of the unicellular freshwater green alga Pseudokirchneriella subcapitata with the read-across substance 6-(isononanoylamino)hexanoic acid, compound with 2,2’,2’’-nitrilotriethanol no inhibitory effects on growth rate or yield and no adverse effects on morphology were observed up to a concentration of 99.6 mg/L. The ErC50 has been determined to be > 100 mg/L. The study was performed according to OECD 201 and compliant to GLP. Stability of the test item concentration in the static test was analytically confirmed by LC-MS/MS. Taking the difference in molecular weight into account an ErC50 > 64.2mg/L is derived for the registration substance. As no effects have been found up to this concentration the value is of no further relevance.

 

Additionally, a non-reliable study (reliability category 3) on the marine alga Skeletonema costatum with 6-(isononanoylamino)hexanoic acid, compound with 2,2’,2’’-nitrilotriethanol is available. The study was performed according to EN ISO 10253 : 1998 and compliant to GLP. The following effect concentrations were determined:

EC50 (72 hours, growht rate) = 133.2 mg/L (95% CI: 130.6-136.3)

EC10 (72 hours, growht rate) = 78.1 mg/L

LOEC (72 hours, growht rate) <= 100 mg/L (lowest tested concentration).

In contrast, in the pre-test after 72 hours no effects were observed at 100 mg/L. These conflicting results of pre-test and definitive study raise doubts in the validity of the study and analytical monitoring of test item concentrations were not performed. In the microscopic evaluation no unusual cell growth or deformity was observed at any of the test concentrations. At the lowest tested concentration (100 mg/L), growth rate reduction was highest from 0 to 24 hours (86.9%) and declined to 21.5 % (0 to 48 hours) and finally 12.6% (0-72 hours). The study authors do not comment on that.

In conclusion, applying read-across between the similar substances 6-(isononanoylamino)hexanoic acid, compound with 2,2’,2’’-nitrilotriethanol and 6-(isononanoylamino)hexanoic acid , these substances may be regarded as non-toxic to freshwater algae at least up to 100 mg/L. Slightly inhibitory effects were observed in a non-reliable test on marine algae with an EC10 (72 h, growth rate) of 78.1 mg/L.