Fatty acids, C16-18 and C18-unsatd., reaction products with glycidyl neodecanoate and 7-oxabicyclo[4.1.0]hept-3-ylmethyl 7-oxabicyclo[4.1.0]heptane-3-carboxylate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 July 2016 to 22 September 2016

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

The test substance is listed as ZEF 6099/100. The test substance, a brown liquid, is the reaction product of C16-C18 and C18 unsaturated fatty acids, with (3,4-epoxycyclohexyl) methyl 3,4-epoxycyclohexylcarboxylate and neodecanoic fatty acid, oxiranylmethylester. The test substance was obtained from the sponsor and was stored at room temperature (15.2 – 24.4°C) in a closed vessel dark and dry.

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge from a biologic sewage treatment plant treating mostly domestic sewage was used in the study. The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, in D-67435 NW-Lachen-Speyerdorf on 27 July 2016, 24 August 2016 and 21 September 2016.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Hardness:

The hardness of the drinking water used in the study was 1.03 mmol/L.

Test temperature:

Test temperature was 20.6 to 21.2 °C (first experiment); 21.8 to 22.8 °C (second experiment); 20.0 to 20.8 °C (third experiment).

pH:

The pH during the test measured between 7.7 and 8.1 (first experiment); 7.0 and 7.5 (second experiment); 7.7 to 7.8 (third experiment).

Dissolved oxygen:

No information provided.

Salinity:

No information provided.

Conductivity:

The conductivity of the drinking water used in the test measured 242 µS/cm at 25°C.

Nominal and measured concentrations:

Three valid experiments were performed. In the first experiment, the range finding test, 4 nominal concentrations were used ranging from 1,000 to 1 mg/L ZEF 6099/100. In the second experiment, 5 nominal concentrations were used ranging from 1,000 to 10 mg/L ZEF 6099/100. A third experiment was conducted with 2 nominal concentrations ranging from 3.2 to 1 mg/L ZEF 6099/100 to determine a NOEC.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (CAS-No. 591-35-5) was used as a positive control.

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

For the positive control an EC50 of 8.1 mg/L (95% confidence interval; 5.1 to 11 mg/L) was determined, which lies within the protocol range of 2 to 25 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The three experimental tests performed measured the respiration inhibition rate of the test substance on activated sewage sludge. The 3 h NOEC was 3.2 mg/L and the 3 h EC50 was > 1,000 mg/L ZEF 6099/100.

Description of key information

The key study was a respiration inhibition of activated sludge test conducted in accordance with OECD Guideline 209 and.EU Method C.11. The study determined the 3-h NOEC to be = 3.2 mg/L and the 3-h EC50 to be > 1,000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

3.2 mg/L