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Toxicity to aquatic algae and cyanobacteria

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Description of key information

A reliable toxicity study to aquatic algae and cyanobacteria (reliability 2) with read-across substance Isostearic acid, esters with methyl α-D-glucoside is available. The NOEC of 100 mg/L, which was above the solubility limit of the test substance and 72 h-ErC50 of > 100 mg/L (nominal) were determined in a study performed according to OECD guideline 201.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

Based on the structural analogue approach to Stearic acid, esters with methyl α-D-glucoside read across from Isostearic acid, esters with methyl α-D-glucoside is considered acceptable.

The structural analogue approach is scientifically justified by close similarities with regard to structural aspects and physico-chemical, environmental toxicological as well as toxicological properties.

With regard to Physical and chemical properties this approach is based on meting and boiling tests, vapour pressure studies and water solubility studies. Similar environmental toxicological properties were observed in standard biodegradation studies and studies on toxicity to microorganisms. Furthermore, comparable data on Acute Oral Toxicity in rats can be considered.

Toxicity to aquatic algae and cyanobacteria

In a 72 h acute toxicity study according to OECD guideline 201, the cultures of Pseudokirchnerella subcapitata NIVA CHL 1 were exposed to Isostearic acid, esters with methyl α-D-glucoside at a nominal concentration of 100 mg/L under static conditions in accordance to OECD Guideline 201. No analytical control was performed, and the test substance could not be completely dissolved in test medium at the loading rate tested.

The NOEC value was 100 mg/L, which was above the solubility limit of the test substance. 72 h-ErC50 for growth inhibition rate and the 72 h-EyC50 for yield inhibition exceeded the maximum input concentration of 100 mg/L of the test substance. The % growth inhibition in the treated algal culture compared to the control was slightly reduced (8.5%). The reduction was not considered to be of biological significance, as it was less than 10%. The total yield was inhibited by 36% when compared to the control. Hence, a 50% effect level could not be reached at the maximum input concentration of the test substance.

There were no abnormalities noted.

Results Synopsis

 

Test Organism: Pseudokirchnerella subcapitata NIVA CHL 1

Test Type: static

72 hr ErC50for growth rate:  >100 mg/L  (nominal)

72 hr EyC50for yield: >100 mg/L (nominal)

72 hr NOEC for growth rate: 100 mg/L (nominal)