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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
Experimental data of test chemical
Justification for type of information:
Experimental data of test chemical is from handbooks and peer reviewed journal
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: Refer below principle
Principles of method if other than guideline:
WoE report is prepared based on toxicity to microorganism studies:
1, 2, 3 and 4th study
GLP compliance:
no
Analytical monitoring:
not specified
Details on sampling:
1st study: - Concentrations: 4 g L−1
- Sampling method: A synthetic feed composed of easily available nutrients was fed to activated sewage sludge together with the test substance or reference substance (3,5 dichlorophenol) and the mixture was aerated for 30 min.
- Sample storage conditions before analysis: No data available
Vehicle:
yes
Details on test solutions:
1. PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Controls: Feed
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Synthetic feed composed of easily available nutrients
Test organisms (species):
other: 2. activated sludge of a predominantly domestic sewage, 3, 4. Unadapted biological waste water treatment plants, 5. Tetrahymena pyriformis
Details on inoculum:
1. - Laboratory culture: No
- Method of cultivation: Municipal sludge was obtained from the aeration tanks of wastewater treatment plants treating mostly household sewage.
- Preparation of inoculum for exposure: Test mixture was transferred to Karlsruhe bottles, an oxygen electrode was inserted to prevent headspace formation over the liquid. The oxygen content was recorded for 10 min.
- Pretreatment: No data available
- Initial biomass concentration: No data available
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
17 h
Post exposure observation period:
2nd study: 10 min
5th study: 60.0 hours
Details on test conditions:
1. TEST SYSTEM
- Test vessel: Karlsruhe bottles
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: An oxygen electrode was inserted to prevent headspace formation over the liquid.
- Aeration: Yes, for 30 min
- Type of flow-through (e.g. peristaltic or proportional diluter): No data available
- Renewal rate of test solution (frequency/flow rate): No data available
- No. of organisms per vessel: No data available
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Municipal sludge was obtained from the aeration tanks of wastewater treatment plants treating mostly household sewage in Delmenhorst (Germany).


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Respiration inhibition were observed
Reference substance (positive control):
yes
Remarks:
1. 3,5-dichlorophenol
Duration:
10 min
Dose descriptor:
LOEC
Effect conc.:
1 000 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks on result:
other: 1st study
Duration:
17 h
Dose descriptor:
EC50
Effect conc.:
7 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 2nd study
Duration:
17 h
Dose descriptor:
EC50
Effect conc.:
3 800 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 3rd study
Key result
Duration:
60 h
Dose descriptor:
IC50
Effect conc.:
387.7 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 5th study
Reported statistics and error estimates:
1. Statistical analysis was performed by using Shapiro–Wilk and Bartlett tests to confirm normality and equal variance, respectively. For those data, which met these criteria, a one way analysis of variance (ANOVA) was performed to identify differences between treatment levels and controls.

1. Obtained LOECs for target compounds towards investigated test systems.

 

LOEC [mg L−1]

 

Activated sludge

respiration

inhibition

Test chemical

>1000

Validity criteria fulfilled:
no
Conclusions:
1. NOECs was considered to be 1000 mg/L when Activated Sludge was treated with test chemical for 10 minutes.
2. Based on the 17 hrs exposure study of bacteria with the test chemical, the EC50 was determine to be 7000 mg/l on the basis of growth rate inhibition.
3. Based on the growth rate inhibition of bacteria by the test chemical for 17 hrs, the EC50 was 3800 mg/l.
4. Inhibition concentration IC50 to 50% of Tetrahymena pyriformis when expeosed to test chemical for 60 h is 387.7 mg/L.
Executive summary:

Various studies available for the test chemical were reviewed to determine the toxic nature of test chemical on the growth and other activity of microorganisms. The studies are as mentioned below:

In a Respiration Inhibition Test, Activated Sludge treated with test chemical in the synthetic feed composed of easily available nutrients for 10 min. no effect were observed on respiration rate of treated Activated Sludge as compared to control. Therefore, NOECs was considered to be 1000 mg/L when Activated Sludge were treated with test chemical.

First study supported by second study. Study was carried out to evaluate the nature of chemical on the bacterial growth. Study was conducted for 17 hrs in which unadapted biological waste water treatment plants were exposed with chemical. Based on the 17 hrs exposure study of bacteria with the test chemical, the EC50 was determine to be 7000 mg/l on the basis of growth rate inhibition.

Aim of this next study was to determine the nature of test chemical on the growth of bacteria. Study was conducted for 17 hrs in which unadapted biological waste water treatment plants were exposed with chemical. Based on the growth rate inhibition of bacteria by the test chemical for 17 hrs, the EC50 was 3800 mg/l. Thus the chemical was not highly toxic to the growth of bacteria.

Similar study was carried out to detrmine the effects of test chemical on micro-orgnaisms test was carried out under static condition for 60 hours. Decreasing trend of Population growth rate was measured during the test. Inhibition concentration IC50 to 50% of Tetrahymena pyriformis when expeosed to test chemical for 60 h was determine to be 387.7 mg/L.

Thus based on the overall data for the test chemical, it was consider that the chemical was not toxic to microorganisms.

Description of key information

1. NOECs was considered to be 1000 mg/L when Activated Sludge was treated with test chemical for 10 minutes.

2. Based on the 17 hrs exposure study of bacteria with the test chemical, the EC50 was determine to be 7000 mg/l on the basis of growth rate inhibition.

3. Based on the growth rate inhibition of bacteria by the test chemical for 17 hrs, the EC50 was 3800 mg/l.

4. Inhibition concentration IC50 to 50% of Tetrahymena pyriformis when expeosed to test chemical for 60 h is 387.7 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
387.7 mg/L

Additional information

Various studies available for the test chemical were reviewed to determine the toxic nature of test chemical on the growth and other activity of microorganisms. The studies are as mentioned below:

In a Respiration Inhibition Test, Activated Sludge treated with test chemical in the synthetic feed composed of easily available nutrients for 10 min. no effect were observed on respiration rate of treated Activated Sludge as compared to control. Therefore, NOECs was considered to be 1000 mg/L when Activated Sludge were treated with test chemical.

First study supported by second study. Study was carried out to evaluate the nature of chemical on the bacterial growth. Study was conducted for 17 hrs in which unadapted biological waste water treatment plants were exposed with chemical. Based on the 17 hrs exposure study of bacteria with the test chemical, the EC50 was determine to be 7000 mg/l on the basis of growth rate inhibition.

Aim of this next study was to determine the nature of test chemical on the growth of bacteria. Study was conducted for 17 hrs in which unadapted biological waste water treatment plants were exposed with chemical. Based on the growth rate inhibition of bacteria by the test chemical for 17 hrs, the EC50 was 3800 mg/l. Thus the chemical was not highly toxic to the growth of bacteria.

Similar study was carried out to detrmine the effects of test chemical on micro-orgnaisms test was carried out under static condition for 60 hours. Decreasing trend ofPopulation growth rate was measured during the test.Inhibition concentration IC50 to 50% of Tetrahymena pyriformis when expeosed to test chemical for 60 h was determine to be 387.7 mg/L.

Thus based on the overall data for the test chemical, it was consider that the chemical was not toxic to microorganisms.