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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
GLP compliance:
yes
Specific details on test material used for the study:
Batch: 12/18
Expiry date: 03/2019
Test organisms (species):
activated sludge
Details on inoculum:
- Name and location of sewage treatment plant where inoculum was collected: A sample of aerobic mud was selected by the mixed treatment plant of urban (about 66%) amd industrial (about 34%) liquid sewage situated in San Rocco near Monza (MB). The plant of treatment is managed by Brianzacque Srl (Monza-Italia)

- Method of cultivation:
- Preparation of inoculum for exposure: Activated sludge was collected and used on day of collection. No coarse particles were presnet so settling was not necessary. Then the mud samples, before their use, were washed and analyzed to prepare the inoculum. The sludge was continuously aerated at the test temperature
- Pretreatment:
- Initial biomass concentration: The suspended solids in the mud solution was 3 g/l to have in the final mixture a concentration of 1.5 g/L
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Nominal and measured concentrations:
1000 mg/L, 100 mg/L and 10 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass bottle
- No. of vessels per concentration (replicates): 3
- No. of vessels per blank control (replicates): 3
- No. of vessels per positive control (replicates) 3
- No. of vessels per abiotic control (replicates): 3


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Deionized water

OTHER TEST CONDITIONS
- Temperature: 20°C ± 2°C
-Aeration: - Vessels were aerated to keep the dissolved oxygen concentration above 60-70% saturation adn to maintain the sludge flocs in suspension

EFFECT PARAMETERS MEASURED: % inhibition of respiration rate

TEST CONCENTRATIONS: 1000 mg/L, 100 mg/L and 10 mg/L

Reference substance (positive control):
yes
Remarks:
3,5 dichlorophenol tested at 50mg/L, 10 mg/L and 1 mg/L
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
Results with reference substance (positive control):
- Results with reference substance valid? Yes
:

Mean percent inhibition total respiration rate of the test item 4 -Aminobenzoyl-b-alanine

Concentration

% of inhibition total respiration rate

Reference substance ‘3-5-Dichlorophenol’

10 mg/L

6.95

100 mg/L

11.40

1000 mg/L

14.94

Mean percent inhibition total respiration rate of the reference susbstance is detailed in the following table:

Concentration

% of inhibition total respiration rate

Reference substance ‘3-5-Dichlorophenol’

1 mg/L

15.73

10 mg/L

70.38

50 mg/L

89.98

Validity criteria fulfilled:
yes
Conclusions:
The obtained results in compliance with assay validity criteria show that the EC50 values of the test item after 3 hours is 1000 mg/L.

Description of key information

The effect of 4-aminobenzoyl-b-alanine on micro-organisms from activated sludge was determined in accordance with OECD Guideline 209. The 3 hour EC50 of 4-aminobenzoyl-b-alanine was found to be >1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information