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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data for the target chemical is summarized based on the structurally similar read across chemicals
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
WoE report is based on two toxicity study of microorganism for the test chemical
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
other: 2.Actived sludge 3. Tetrahymena pyriformis
Details on inoculum:
2. Where possible activated sludge should be obtained from a sewage works treating predominantly domestic sewage. If this is not convenient, the activated sludge may be obtained from a sewage works treating predominantly industrial waste water. On the return to the laboratory, the sludge is centrifuged and washed with tap water. This procedure is repeated three times. A small amount of the centrifuged wet sludge is weighed and dried. After drying the ratio R of the weight of the dry solid to that of the wet centrifuged sludge is known. From this ratio R the amount of wet sludge can be calculated which has to be suspended in tap water in order to obtain an activated sludge with a mixed liquor suspended solids level of 4 g dry solids/litre. 50 ml OECD concentrate (2.2) is added to each litre of the activated sludge prepared as described above; this is then aerated overnight in a room at 20°C + 2°C, and kept aerated for use during the day. If the same sludge has to be used on subsequent days (up to a maximum of 4) a further 50 ml/litre of OECD concentrate sewage is added at the end of each working day.

3.Cultures are reared in 50 m L of a sem i -defined medium 250-m L Erlenmeyer flasks.
Test type:
static
Water media type:
freshwater
Total exposure duration:
40 h
Details on test conditions:
2.- Test vessel: ACTIVATED SLUDGE RESPIRATION RATE APPARATUS
- Type (delete if not applicable): open / closed: No data
- Material, size, headspace, fill volume: 500 ml flask
- Aeration: Yes
- Type of flow-through: "Pasteur" pipette
-Renewal rate of test solution (frequency/flow rate): No data
- No. of organisms per vessel: No data
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates):No data
- Biomass loading rate: No data

3.Cultures are reared in 50 m L of a sem i -defined medium 250-m L Erlenmeyer flasks.
Key result
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
40 h
Dose descriptor:
other: ICG50
Effect conc.:
0.18 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Validity criteria fulfilled:
not specified
Conclusions:
Study was conducted to determine effect of test chemical on micro-organism. The test chemical is showed varied value on microorganism in the concentration range of 0.18 -100 mg/l
Executive summary:

Data available for the structurally and functionally similar read across chemicals has been reviewed to determine the toxicity of microorganism of the test chemical .The studies are as mentioned below:

A screening method based on the measurement of the respiration rate of activated sludge for assessing the possible inhibitory effect of dyestuffs on aerobic waste-water bacteria. The test principle involves measuring the respiration rate of an activated sludge and comparing it with the respiration rate of the same activated sludge under identical conditions, but in the presence of the chemical under test. The test was carried out in activated sludge respiration rate apparatus with constant 20 ± 2°C and pH about 7-8. The test concentration used was 100 mg/l. OECD recommended synthetic sewage was used as feed, while activated sludge was obtained from a sewage works treating predominantly domestic sewage or from a sewage works treating predominantly industrial waste water. The respiration rate of an activated sludge and the respiration rate of activated sludge with test chemical were noted down. In order to calculate the inhibitory effect of a particular chemical at 100 mg/l test concentration its respiration rate is expressed as a percentage of the mean of the two control respiration rates. For those chemicals whose respiration rate is at least 80% of the control, the IC50 (concentration for 50% inhibition of respiration rate) is recorded as >100 mg/l.

Thus, IC50 value (concentration for 50% inhibition of respiration rate) for the test chemical on activated sludge (aerobic bacteria) is determined to be >100 mg/1 after 3 hrs of exposure.

The study was conducted to evaluate the toxic effects of the test chemical on the microorganism Tetrahynema pyriformis. The test was conducted for the period of 40-h in static conditions. Five different concentrations were taken to evaluate the ICG 5, median inhibition growth concentration. Test was conducted in the replicates and the growth inhibition was recorded using spectrophotometrically.Based on the results obtained from the experiment the ICG 50 was determined as 0.18 mg/L. The test chemical is showed varied value on microorganism  in the concentration range of  0.18 -100 mg/l

Description of key information

Toxicity to microorganism:

Study was conducted to determine effect of test chemical on micro-organism. The test chemical is showed varied value on microorganism  in the concentration range of  0.18 -100 mg/l

Key value for chemical safety assessment

EC50 for microorganisms:
100 mg/L

Additional information

Toxicity to microorganism:

Data available for the structurally and functionally similar read across chemicals has been reviewed to determine the toxicity of microorganism of the test chemical .The studies are as mentioned below:

A screening method based on the measurement of the respiration rate of activated sludge for assessing the possible inhibitory effect of dyestuffs on aerobic waste-water bacteria. The test principle involves measuring the respiration rate of an activated sludge and comparing it with the respiration rate of the same activated sludge under identical conditions, but in the presence of the chemical under test. The test was carried out in activated sludge respiration rate apparatus with constant 20 ± 2°C and pH about 7-8. The test concentration used was 100 mg/l. OECD recommended synthetic sewage was used as feed, while activated sludge was obtained from a sewage works treating predominantly domestic sewage or from a sewage works treating predominantly industrial waste water. The respiration rate of an activated sludge and the respiration rate of activated sludge with test chemical were noted down. In order to calculate the inhibitory effect of a particular chemical at 100 mg/l test concentration its respiration rate is expressed as a percentage of the mean of the two control respiration rates. For those chemicals whose respiration rate is at least 80% of the control, the IC50 (concentration for 50% inhibition of respiration rate) is recorded as >100 mg/l.

Thus, IC50 value (concentration for 50% inhibition of respiration rate) for the test chemical on activated sludge (aerobic bacteria) is determined to be >100 mg/1 after 3 hrs of exposure.

The study was conducted to evaluate the toxic effects of the test chemical on the microorganism Tetrahynema pyriformis. The test was conducted for the period of 40-h in static conditions. Five different concentrations were taken to evaluate the ICG 5, median inhibition growth concentration. Test was conducted in the replicates and the growth inhibition was recorded using spectrophotometrically.Based on the results obtained from the experiment the ICG 50 was determined as 0.18 mg/L.The test chemical is showed varied value on microorganism  in the concentration range of  0.18 -100 mg/l