Isostearic acid, esters with methyl α-D-glucoside

Short-term toxicity to fish

Description of key information

A reliable Short-term toxicity study to fish reliability 2) according to OECD TG 203 with read-across substance Stearic acid, esters with methyl α-D-glucoside is available. 96 h LC50 for Leuciscus idus is > 10.000 mg/l.

Additional information

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

The structural analogue approach is scientifically justified by close similarities with regard to physico-chemical properties and structural aspects. With regard to the environmental fate side this approach is based on standard biodegradation studies. Furthermore, comparable data on Acute Oral Toxicity in rats can be considered.

Animal welfare aspects also justify the structural analogue approach.

Stearic acid, esters with methyl α-D-glucoside is a reaction product of methyl glucoside with stearic acid, a linear saturated C18 fatty acid.

Isostearic acid, esters with methyl α-D-glucoside is a reaction product of methyl glucoside with the branched isostearic acid (100% UVCB substance).

Due to its esterification with the branched isostearic acid, Isostearic acid, esters with methyl α-D-glucoside is more hydrophobic than the Stearic acid, esters with methyl α-D-glucoside.

For Isostearic acid, esters with methyl α-D-glucoside and for Stearic acid, esters with methyl α-D-glucoside the reaction leads to a fatty acid ester in which the four OH-groups of glucoside are partially esterified.

In the case of Isostearic acid, esters with methyl α-D-glucoside the product is composed of methylglucoside (4 %), methyl glucoside ester (approx. 83 % mono-, di-, and triester (mainly diester)) and of approx. 13 % free fatty acids. More than 90% of the fatty acids have a carbon number of 18, with some chain length distribution between C16 and C20. The main components are mono- and poly branched C18 fatty acids, in which the branching occurs mainly medium-chained, mostly methylenic, which accounts for its good biodegradability (Haase et al., 1989). However, a precise structure of isostearic acid does not exist.

 

Biodegradation studies performed on Isostearic acid, esters with methyl α-D-glucoside and Stearic acid, esters with methyl α-D-glucoside indicate a ready biodegradation within 28 days for both substances.

 

Comparing the results of acute oral toxicity both substances are practically non toxic to male and female Wistar rats. The oral LD50 males and females for both Isostearic acid, esters with methyl α-D-glucoside and Stearic acid, esters with methyl α-D-glucoside were > 2000 mg/kg bw. It is assumed that the metabolic pathways of both substances are similar. In animal and human methyl branched fatty acids can be degraded by alpha oxidation. It is suggested that this metabolic pathway is also active in fish.

 

Short-term toxicity to fish

In a 96-h acute toxicity study according to OECD TG 203, Leuciscus idus were exposed to Stearic acid, esters with methyl α-D-glucoside (according to producer information 100 % a.i.) at nominal concentrations of 0 (control) and 10000 mg test substance/l under static conditions. The test substance was pestled and was directly transferred into the dilution water without stirring or ultrasonic dispersion. The test substance was not dissolved in the test medium and no analytical control was performed. The test meets the validity criteria of the guideline.
The test substance was non-toxic to Leuciscus idus. The 96-h LC₅₀ is > 10000 mg test substance/l because Stearic acid, esters with methyl α-D-glucoside was not dissolved in water.