E17-194T, (P,P-diethyl, monoester with 1,2 propanediol)_

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:

Sep-Oct 2019

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))

Version / remarks:

OECD 209 resp. EU C.11

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

The test item was stored in the test facility in a closed vessel dry at room temperature (20 ± 5 °C).

Analytical monitoring:

not required

Vehicle:

no

Details on test solutions:

A stock solution containing 10.0044 g/L in deionised water was prepared. The stock solution then was used to prepare the treatments.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge from a biologic sewage treatment plant was used. The chosen plant treats mostly domestic sewage.
The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant in D-67435 NW-Lachen-Speyerdorf, Im Altenschemel.
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:

18.9 – 21.3 °C

pH:

7.8-8

Nominal and measured concentrations:

Vessel No. Content Concentration in mg/L
(nominal)
1 Blank Control 0
2 Blank Control 0
3 Positive Control 5
4 Positive Control 10
5 Positive Control 20
6 Positive Control 40
7 Blank Control 0
8 Blank Control 0
9 Test Item 1000
10 Test Item 1000
11 Test Item 1000
12 Test Item 1000
13 Test Item 1000
14 Test Item 100
15 Test Item 10
16 Test Item 1
17 Blank Control 0
18 Blank Control 0

Details on test conditions:

Duration 3 hours
Replicates
Positive Control 1 replicate/concentration
Test item 1 replicate/concentration (lower concentrations) 5 replicates/concentration (highest concentration)
Blank Control 2 replicates before and 2 after measuring positive control and test item, respectively
Water tap water
Aeration purified air, using Pasteur pipettes,
Feeding nutrient solution, 16 mL/vessel
Temperature 18.9 – 21.3 °C

Reference substance (positive control):

yes

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.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

One experiment was performed.
The test item was tested using 4 concentrations ranging from 1000 to 1 mg/L nominal con-centration. For the treatment 1000 mg/L, 5 replicates were used; for the other treatments, 1 replicate each.
Because no significant inhibition was observed, no additional experiment had to be per-formed.
All validity criteria were met. For the estimation of the EC50 of the positive control, the fits showed good statistical correspondence of the data with the dose-response-equation. The positive control gave an EC50 of 9.6 mg/L (95 % confidence interval 5.0 – 14 mg/L) which lie within the recommended range of 2 – 25 mg/L. The coefficient of variation of oxygen uptake rate in control replicates was below 30% at the end of the test. The oxygen uptake rate of the blank controls was above 20 mg O2 per gram activated sludge in 1 hour.
No inconsistencies in the dose-response estimation could be observed. Therefore, no fur-ther experiment was performed in order to discern between inhibition of nitrificators and inhibition of total population.
No observations were made which might cause doubts concerning the validity of the study outcome.
The result of the test can be considered valid

Results with reference substance (positive control):

The calculated values for the positive control 3,5-Dichlorophenol are presented in the fol-lowing table.
Table 8.1-a 3h-EC50 Positive Control
Date of Experiment 3h-EC50 95% Confidence Interval
08. Oct. 2019 9.6 5.0 – 14 mg/L
The value lies within the recommended range of 2 – 25 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

One valid experiment was performed.
The test item was tested using 4 concentrations ranging from 1000 to 1 mg/L nominal con-centration. Duration of the test was 3 hours. 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 3.1 g suspended solids/L, giving a concentration of 1.55 g suspended solids/L in the test.
3,5-Dichlorophenol was used as positive control. Four concentrations were tested; an EC50 of 9.6 mg/L (95% confidence interval: 5.0 – 14 mg/L) was determined, which lies within the recommended range of 2 – 25 mg/L stated in the OECD guideline.
Because no significant inhibition was observed, no additional experiment had to be per-formed
The following results for the test item E17-194T were determined:
3h NOEC = 1000 mg/L
3h EC10 > 1000 mg/L
3h EC50 > 1000 mg/L

Executive summary:

The following results for the test item E17-194T were determined:

3h NOEC = 1000 mg/L

3h EC10 > 1000 mg/L

3h EC50 > 1000 mg/L

Description of key information

The test item was tested using 4 concentrations ranging from 1000 to 1 mg/L nominal con-centration. Duration of the test was 3 hours. 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 3.1 g suspended solids/L, giving a concentration of 1.55 g suspended solids/L in the test.

3,5-Dichlorophenol was used as positive control.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L