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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
Deviations:
yes
Remarks:
Temperature range was 22-23oC
Qualifier:
equivalent or similar to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Test item: 4,4'-(1-phenylethane-1,1-diyl)bis(heptyloxybenzene)
Solubility and stability of the test substance in solvent/vehicle: Sparingly soluble in water
Purity: 99.56%
Purity test date: 01.02.2016
Test item storage: Room temperature
Stability under storage conditions: 21 March 2012 (expiry date)
Analytical monitoring:
not required
Vehicle:
no
Details on test solutions:
Test item mixed with Milli-RO water, synthetic medium and activated sludge to achieve nominal test loading rate of 10, 100 and 1000 mg/L
Test organisms (species):
activated sludge of a predominantly domestic sewage
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Hardness:
No data
Test temperature:
Nominal test temperature 20 +/- 2oC
Measured temp 22-23 oC
This deviation was not considered to adversely affect the study integrity
pH:
7.6-7.7 (start)
7.6-8.1 (end)
Dissolved oxygen:
>60% saturation at start (>5 mg/L)
Salinity:
No data
Conductivity:
No data
Nominal and measured concentrations:
Nominal loading rate 10, 100 and 1000 mg/L as test item
Reference substance (positive control):
yes
Key result
Duration:
3 h
Dose descriptor:
other: ELR50
Remarks:
Effect loading rate
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Key result
Duration:
3 h
Dose descriptor:
other: NOELR
Remarks:
No observed effect loading rate
Effect conc.:
>= 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.

Type of bottle

Nominal loading rate

(mg/L)

pH

Respiration rate

(mg O2/g/h)

% inhibition

(mean value)

Start

End

Control

0

7.6-7.7

7.6-7.8

43.4

-

Reference item

2

7.7

8.1

25.7

41

Reference item

4

7.7

8.1

22.8

48

Reference item

8

7.7

8.0

20.2

54

Reference item

16

7.7

8.0

11.3

74

Test item

10

7.7

7.6

50.3

-16

Test item

100

7.6

7.6

38.8

11

Test item

1000

7.6

7.5-7.6

46.2

-6

Abiotic control

1000

7.6

7.4

0.9

99

Validity criteria fulfilled:
yes
Conclusions:
The test item did not inhibit the respiration rate of activated sludge at a loading rate of 1000 mg/L, under the conditions of the test
Executive summary:

A reliable study to determine the activated sludge respiration inhibition for the test substance was conducted in accordance with OECD test guideline 209 and in compliance with GLP.

Under the conditions of the test, the test item was not toxic to waste water bacteria (activated sludge) after 3 hours incubation at a nominal loading rate of 1000 mg/L. The ELR50 and NOELR were both >1000 mg/L. This value is greater than the limit of solubility of the test substance.

This study is considered acceptable and satisfies the guideline requirements for a toxicity to microorganisms study.

Description of key information

A reliable study (Klimisch 1) to determine the activated sludge respiration inhibition for the test substance was conducted in accordance with OECD test guideline 209 and in compliance with GLP.

Under the conditions of the test, the test item was not toxic to waste water bacteria (activated sludge) after 3 hours incubation at a nominal loading rate of 1000 mg/L. The ELR50 and NOELR were both >1000 mg/L. The toxicity value is greater than the limit of solubility of the test substance.

The test validity criteria were met and there were no significant deviations noted to affect the integrity of the study. This study is considered acceptable and satisfies the guideline requirements for a toxicity to microorganisms study.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information