Fatty acids, tall-oil, polymers with glycidyl neodecanoate

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:

From November 08, 2016 to April, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

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)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Due to its poor solubility, the test substance was weighed directly into the test vessels.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant in D-67435 NW-Lachen-Speyerdorf.
Upon arrival in the test facility, the sludge was filtrated, washed with tap water 3 times and re-suspended in tap water. The activated sludge was aerated until usage in the test and fed daily with 50 mL synthetic sewage feed /L.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

19.5 – 20.3 °C

pH:

7.3 - 7.7

Nominal and measured concentrations:

Nominal: 0, 1, 10, 100 and 1000 mg/L

Details on test conditions:

Duration                                                        3 hours
Replicates                                                    1 replicate/concentration (positive control, test item lower concentrations), 5 replicates for test item treatment 1000 mg/L
Blank Control                                               2 replicates before and 2 after measuring positive control and test item, respectively
Dilution Water                                              tap water
Aeration                                                        purified air, using Pasteur pipettes,
Feeding                                                         nutrient solution, 16 mL/vessel
Temperature                                                19.5 – 20.3 °C

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

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:

EC10

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.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

The calculated values for the positive control 3,5-dichlorophenol are presented in the following table.

Table 1          3h-EC50 Positive Control

Date of Experiment	3h-EC50	95% Confidence Interval
08. Nov. 2016	8.3 mg/L	5.8 – 11 mg/L

All values lie within the recommended range of 2 – 25 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

Based on nominal values, the 3 h NOEC was ≥ 1000 mg/L, the 3h EC10 was > 1000 mg/L and the 3 h EC50 was > 1000 mg/L

Executive summary:

A study was conducted to determine the toxicity of the test substance to activated sludge according to OECD Guideline 209 and EU Method C.11, in compliance with GLP. The substance was tested using 4 concentrations ranging from 1000 to 1 mg/L (nominal). The duration of the test was 3 h. Non adapted activated sludge was used as inoculum. It was taken from a domestic sewage treatment plant and washed before usage. The dry matter was determined as 2.64 g suspended solids/L, giving a concentration of 1.32 g suspended solids/L in the test. 3,5-dichlorophenol was used as positive control. Four concentrations were tested and an EC50 of 8.3 mg/L (95% confidence interval: 5.8 - 11 mg/L) was determined, which lies within the recommended range of 2 – 25 mg/L for this control substance. Because no significant inhibition was observed, no additional experiment was performed with the test substance. Based on nominal values, the 3 h NOEC was ≥ 1000 mg/L, the 3 h EC10 was > 1000 mg/L and the 3 h EC50 was > 1000 mg/L (Muckle, 2017).

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

A study was conducted to determine the toxicity of the test substance to activated sludge according to OECD Guideline 209 and EU Method C.11, in compliance with GLP. The substance was tested using 4 concentrations ranging from 1000 to 1 mg/L (nominal). The duration of the test was 3 h. Non adapted activated sludge was used as inoculum. It was taken from a domestic sewage treatment plant and washed before usage. The dry matter was determined as 2.64 g suspended solids/L, giving a concentration of 1.32 g suspended solids/L in the test. 3,5-dichlorophenol was used as positive control. Four concentrations were tested and an EC50 of 8.3 mg/L (95% confidence interval: 5.8 - 11 mg/L) was determined, which lies within the recommended range of 2 – 25 mg/L for this control substance. Because no significant inhibition was observed, no additional experiment was performed with the test substance. Based on nominal values, the 3 h NOEC was ≥ 1000 mg/L, the 3 h EC10 was > 1000 mg/L and the 3 h EC50 was > 1000 mg/L (Muckle, 2017).