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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
Study period:
August 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: Bacteria toxicity according to method: Bringmann,G. und Kühn,R. (Lit: Zeitschrift flir Wasser- und Abwasserforschung, 10 (1977) S. 87 - 98)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
Principles of method if other than guideline:
Bacteria toxicity according to method: Bringmann,G. und Kühn,R. (Lit: Zeitschrift flir Wasser- und Abwasserforschung, 10 (1977) S. 87 - 98)
GLP compliance:
yes
Specific details on test material used for the study:
TEST MATERIAL (Hüls/Evonik)
- Chemical name: Benzol-1,2,4,5-tetracarbonsauredianhydrid
- Batch number: 3630/81309 (Silodurchschnittsprobe vom 18.02.91)
- Appearance: not indicated
- Expiry date: not indicated
- Manufacturing date: 17.02.1991
- CAS number: 89-32-7
- Purity: Test item: 100.3%
Analytical monitoring:
yes
Details on sampling:
samples were analyzed at the end of the incubation time of 18 hours
Vehicle:
no
Details on test solutions:
the test item was dissolved in bidistilled water and further diluted 1:2, 1:4 and 1:8 to get the corresponding test solutions

Test organisms (species):
Pseudomonas putida
Details on inoculum:
no data
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
18 h
Post exposure observation period:
none
Hardness:
no data
Test temperature:
incubation at 25°C
pH:
the pH was not correctd during the test and was found to be 3.2-4 (without culture medium) and 3.8-6.6 (with culture medium)
Dissolved oxygen:
not measured
Salinity:
freshwater used
Nominal and measured concentrations:
Solutions with the following nominal test item concentrations were tested:
- 80 mg/l (no dilution)
- 40 mg/l (dilution 1:2)
- 20 mg/l (dilution 1:4)
- 10 mg/l (dilution 1:8)
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 ml Erlenmeyer flasks
- Type: open
- Aeration:
- No. of vessels per concentration (replicates): 3 for each of the four dilutions
- No. of vessels per control (replicates): 5 for growing control and 4 for control
- Nutrients provided for bacteria: culture medium

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dilution 1:2, 1:4 and 1:8

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: no data
- Light intensity: no data
Reference substance (positive control):
no
Key result
Duration:
18 h
Dose descriptor:
EC10
Effect conc.:
23 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Details on results:
test result indicted as mean value of two measurements: 22.5 mg/L and 23.5 mg/L
Results with reference substance (positive control):
no reference substance tested
Validity criteria fulfilled:
yes
Conclusions:
The EC10 of the test item in this bacteria respiration inhibition test was found to be EC10 = 23 mg/L
Executive summary:

The purpose of the 18 -hour test was to evaluate the influence of the test item on the activity of the activated sludge by measuring the respiration rate under defined conditions. The test species was Pseudomonas Putida, test duration (incubation) was 18 hours. Nominal test item concentrations of 80 mg/l (no dilution), 40 mg/l (dilution 1:2), 20 mg/l (dilution 1:4) and 10 mg/l (dilution 1:8) were tested and analyzed after 18 hours incubation time by photometric measurement of opacity (extincion coefficient) at a wave length of 436 nm. The test results were indicted as mean value of two measurements: 22.5 mg/L and 23.5 mg/L. In conclusion, the EC10 of the test item in this bacteria respiration inhibition test was found to be EC10 = 23 mg/L.

respiration rates (total, heterotrophic and nitrification oxygen uptake rates) of samples of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours. This preliminary test was used to estimate the range of concentrations of the test item needed in a possible definite test for determining the inhibition of oxygen consumption. The test item was investigated in this study at the nominal concentrations of 10; 100 and 1000 mg/L. Defined amounts of the test item were added directly into the test vessels. Triplicate vessels were prepared and investigated at the examined test item concentrations. The test was performed without pH adjustment. Based on measured oxygen consumption values and calculated specific respiration rates it can be stated that the 3-hour EC10 and EC50 values of the test item are greater than 1000 mg/L. The NOEC was determined to be 1000 mg/L. In conclusion, this preliminary test demonstrated the absence of inhibition of oxygen consumption by the test substance up to and including the limit concentration of 1000 mg/L, therefore a definite test was considered unnecessary.

Description of key information

The purpose of the 18 -hour test was to evaluate the influence of the test item on the activity of the activated sludge by measuring the respiration rate under defined conditions. The test species was Pseudomonas Putida, test duration (incubation) was 18 hours. The EC10 of the test item in this bacteria respiration inhibition test was found to be EC10 = 23 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
23 mg/L

Additional information

Source: GLP-report