Stearic acid, esters with methyl α-D-glucoside

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.1 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

no data: aquatic toxicity unlikely

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

1 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Sediment (marine water)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no exposure of soil expected

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Justification for read across

The structural analogue approach using the substance Isostearic acid, esters with methyl α-D-glucoside for read-across is scientifically justified by close similarities with regard to structural aspects and physico-chemical, ecotoxicological as well as toxicological properties.

There is some difference in stereochemistry of both substances that affects some of their chemical properties: the source substance Isostearic acid, esters with methyl α-D-glucoside is a liquid, has in average a higher molecular weight, higher vapour pressure and higher solubility. Unlike Stearic acid, esters with methyl α-D-glucoside ,Isostearic acid, esters with methyl α-D-glucoside, as a branched chain, is believed to be less easily metabolized and can be understood as a worst case in this analogue approach. Both substances are readily biodegradable. With regard to the ecological information the results obtained for source and target substances in testing on microorganisms, invertebrates, algae and fishshow coherent trends in their ecotoxicity. Furthermore, closely similar data on acute oral toxicity, skin and eye irritation, sensitisation can be considered.

Apart from some physical-chemical differences, caused by the difference in stereochemistry, human health, environmental toxicological and environmental fate properties are proved to be similar and follow a regular pattern as a result of structural similarity.

In the sense of Article 13 of REACH Regulation and in the line with animal welfare aspects it is possible to extend the use of obtained data of Isostearic acid, esters with methyl α-D-glucoside to the similar target chemicalStearic acid, esters with methyl α-D-glucoside. Thus, reliable estimates that are adequate for risk assessment can be made without further testing.

Discussion

The short term aquatic toxicity results of Stearic acid, esters with methyl α-D-glucoside are covering four trophic levels.

 

Short-term toxicity study to fish performed according to OECD TG 203 in 1990 and test to microorganisms performed according to DIN 38412 part 27 with Stearic acid, esters with methyl α-D-glucoside are available.There are reliable short-term toxicity studies to aquatic invertebrates, algae and cyanobacteria and microorganisms (reliability 2) with read-across substance Isostearic acid, esters with methyl α-D-glucoside.

 

The most sensitive species was found to be the algae Pseudokirchnerella subcapitata with a 72 h ErC50 of > 100 mg/L (nominal) in a study performed to the read across substance Isostearic acid, esters with methyl α-D-glucoside.

 

The 48 h-EC50 of Daphina magna was determined to be > 100 mg/L (nominal, limit test) in a study performed with the read across substance Isostearic acid, esters with methyl α-D-glucoside.

 

A short-term toxicity study to fish with Stearic acid, esters with methyl α-D-glucoside is available; the 96 h acute toxicity of Leuciscus idusis >10000 mg/L, the test substance was not completely dissolved in water.

In the test performed according to DIN 38412 part 27 (Bacteria Respiration test, preliminary draft) no inhibition of oxygen consumption of Pseudomonas putida was observed, therefore the EC 50 is higher than 10000 mg/L.

The effects are likely to be similar to those found for read across substance Isostearic acid, esters with methyl α-D-glucoside. In an Activated Sludge, Respiration Inhibition Test according to OECD TG 209 no significant inhibitory effects of Isostearic acid, esters with methyl α-D-glucoside were observed at 100 mg/L (3 h EC50 > 100 mg/L, nominal).

 

No data on long-term toxicity to fish is available. As the test substance is readily biodegradable (89% in 28 days, see chapter 5.2.1) a long-term toxicity study to fish, as recommended in REACH Annex VIII 9.1.3, will not deliver any additional information. Presumably Stearic acid, esters with methyl α-D-glucoside will be completely degraded in the environment.

Besides this a long-term toxicity test is difficult to perform because of the low water solubility and the difficulty of maintaining stable test concentrations.

 

Additionally, no toxic effects were observed in vivo studies performed to other species. Both substances are proved to be practically non toxic to Wistar rats in oral test. The oral LD50 males and females for both Stearic acid, esters with methyl α-D-glucoside and Isostearic acid, esters with methyl α-D-glucoside were > 2000 mg/kg bw, showing coherent trends in their toxicological properties.

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. Possibly the metabolic pathways of rat can be transferred to fish.

 

No data on sediment or terrestrial toxicity is available.

Short term toxicity to fish

In a 96-h acute toxicity study according to OECD TG 203, Leuciscus iduswere 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.
Stearic acid, esters with methyl α-D-glucoside was non-toxic to Leuciscus idus. The 96-h LC₅₀is > 10000 mg/L.

Short term toxicity to aquatic invertebrates

The 48–hr-acute toxicity study with Isostearic acid, esters with methyl α-D-glucoside conducted according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test) is available. Under static conditions Daphnia magna were exposed to control, reference substance (potassium dichromate) and the test chemical at a loading rate of 100 mg/L (limit test) for 48 h. Isostearic acid, esters with methyl α-D-glucoside could not be completely dissolved in the test medium at the loading rate tested because the water solubility was visually assessed to be less than 1 mg/L. No analytical control was performed. Immobilization was observed after 24 and 48 h.

The 24 h EC₅₀was > 100 mg/L (nominal, limit test)

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. 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 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-ErC50 for growth rate: >100 mg/L (nominal) 72 hr-EyC50 for yield: >100 mg/L (nominal) 72 hr NOEC for growth rate: 100 mg/L (nominal).

 

Toxicity to microorganisms

The toxic effects of Stearic acid, esters with methyl α-D-glucoside (according to producer infromation 100% a.i.) on Pseudomonas putida according to DIN 38412 part 27 (Bacteria Respiration test, preliminary draft) was assessed by measuring the respiration rate after 1 hour at 0 and 10000 mg/L (nominal). No analytical control was performed.

Based on the study results Stearic acid, esters with methyl α-D-glucoside showed no inhibition of oxygen consumption of Pseudomonas putida. Therefore, the 1 h-EC 50 of the test substance is higher than 10000 mg/L.

 

The absence of toxic effects of the substance on microorganisms was also determined in a 3 hour toxicity study conducted according to OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test) and EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test), the cultures of activated sludge of a predominantly domestic sewage treatment plant were exposed to Isostearic acid, esters with methyl α-D-glucoside at a nominal concentration of 100 mg/L under static conditions. No analytical control was performed.

Conclusion on classification

Results from existing aquatic toxicity and biodegradation studies indicate non classification of Stearic acid, esters with methyl α-D-glucoside for the aquatic environment (acute and chronic toxicity) according to GHS Regulation EC No 1272/2008 and Directive 67/548 EEC.