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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
Version / remarks:
adopted April 4, 1984
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Version / remarks:
May 30, 1988
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Name and location of sewage treatment plant where inoculum was collected: Municipal sewage treatment plant: 'Waterschap de Maaskant','s-Hertogenbosch, the Netherlands, receiving predominantly domestic sewage
- Preparation of inoculum for exposure: The sludge was coarsely sieved, washed and diluted with ISO-medium. A small amount of the sludge was weighed and dried overnight at ca. 105°C to determine the amount of suspended solids (4.6 g/L of sludge). The pH varied between 7.3 and 7.8 on the day of sampling and on the day of testing. The respective batch of sludge was used one day after collection; therefore 50 mL of synthetic sewage feed was added per litre of activated sludge at the end of the collection day. The sludge was kept aerated at test temperature until use.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
19.2 - 19.7'C
pH:
8.2 - 8.3
Dissolved oxygen:
>9 mg/L at test start
Nominal and measured concentrations:
100 mg a.i./L
Details on test conditions:
TEST SYSTEM
- Test vessel: All glass, approximately 300 mL oxygen bottles and 1 Iitre test bottles, 500 mL fill volume
- Aeration: yes
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- Nutrients provided for bacteria: synthetic sewage feed

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: adjusted ISO medium

Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: EC50 = 7.1 mg(L (95% c.i. 2.4 - 20.5 mg/L)

Validity criteria:

1. The mean respiration rate of control 1 and 2 was 53.5 mg O2/L/hr. The difference between the controls was within 15% of each other (5.6%).

2. The mean respiration rate of control 2 and 3 was 50.5 mg O2/L/hr. The difference between the controls was within 15% of each other (5.9%).

3. The EC50 of 3,5-dichlorophenol was in the accepted range of 5-30 mg/L (7.1 mg/L).

Since all criteria for acceptability of the final test were met, this study was considered to be valid.

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of this present test, Amphopropionate C8 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg a.i./L
Executive summary:

In a 3 hour toxicity study conducted according to OECD Guideline 209 (1984) and EU Method C.11 (1988), the cultures of activated sludge of a predominantly domestic sewage treatment plant were exposed to Amphopropionate C8 (50.6% a.i.) at nominal concentrations of 0 (control) and100 mg a.i./L mg/L under static conditions.

The batch of activated sludge was checked for sensitivity by testing the reference substance 3,5-dichlorophenol.

There was no inhibitory effect of the test item at the limit concentration.The duplicate measurement confirmed the result of the first measurement (values of -1 and -7% inhibition were recorded). Therefore, no further testing was needed.

Under the conditions of this present test, Amphopropionate C8 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg a.i./L

 

Results Synopsis

Test Organism: activated sludge from a sewage treatment plant treating predominantly domestic sewage

Test Type: Static 

3 h EC50: >/= 100 mg/L

Endpoint effected: Inhibition of respiration

Description of key information

3 h EC50 > 100 mg a.i./L (OECD TG 209 / EU method C.11; RL1, GLP)

Key value for chemical safety assessment

EC50 for microorganisms:
100 mg/L

Additional information

In a 3 hour toxicity study conducted according to OECD Guideline 209 (1984) and EU Method C.11 (1988), the cultures of activated sludge of a predominantly domestic sewage treatment plant were exposed to Amphopropionate C8 (50.6% a.i.) at nominal concentrations of 0 (control) and100 mg a.i./L mg/L under static conditions.

The batch of activated sludge was checked for sensitivity by testing the reference substance 3,5-dichlorophenol.

There was no inhibitory effect of the test item at the limit concentration.The duplicate measurement confirmed the result of the first measurement (values of -1 and -7% inhibition were recorded). Therefore, no further testing was needed.

Under the conditions of this present test, Amphopropionate C8 was not toxic to waste water (activated sludge) bacteria at a concentration of 100 mg a.i./L