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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
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Type: mixed population of aquatic microorganisms (activated sludge)
- Origin: aeration tank of a domestic sewage treatment plant (Wupper area water authority)
- Date of collection: 2004-09-13
- Pretreatment: aeration of the activated sludge; daily feed with synthetic medium
- pH of the suspension before application: 6.3
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
19.7 - 20.1°C
pH:
6.8 - 7.6
Nominal and measured concentrations:
nominal concentrations [mg/L]: 32, 56, 100, 180, 320
Test item concentration in physico-chemical oxygen consumption control [mg/L]): 10000
Concentration reference substance (3,5-Dichlorophenol) [mg/L] : 2.5, 5, 10, 20, 40
Details on test conditions:
- Type of application: direct weighing
- Test concentration of the activated sludge: 480 mg/L suspended solids
- two controls, one physico-chemical oxygen consumption control
- Test concentrations [mg/L]: 32, 56, 100, 180, 320
- Test temperature: 20 ± 2° C
- Stirring period of test item before start of incubation time: 16 hours
- Incubation time: 3 hours with permanent aeration
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol (Aldrich), purity 97%, bach no. 15809KI-392
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
135 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
The test item and reference substance concentrations are not confirmed by analytical methods; they are based on nominal concentrations.
Results with reference substance (positive control):
Toxicity of the reference substance 3,5-Dichlorophenol to bacteria: EC50 = 6.2 mg/L.
Reported statistics and error estimates:
The EC values are determined by statistical methods (probit analysis).
Validity criteria fulfilled:
yes
Remarks:
respiratory rates of the 2 controls differ less than 15 %, respiratory rate of the controls < 60 mg O2 /L*h, EC50 of the reference substance 3,5-dichlorophenol is in the range 5-30 mg/L
Conclusions:
The 3h-EC50 of 2-chloro-5-chloromethylpyridine towards bacteria is 135 mg/L.
Executive summary:

A study was performed to assess the toxicity of 2 -chloro-5 -chloromethylpyridine to bacteria. The study was conducted in accordance with the Commission Directive 88/302/EEC; Official Journal of the EG LI 33 Part C (1988). This test method is in most parts identical with OECD Guideline 209.

Activated sludge was exposed to 2 -chloro-5 -chloromethylpyridine for 3 h. Two controls without test item are included in the test design, one at the start and the other at the end of the test series. The respiration rate of the activated sludge is measured after a contact time of 3 hours. The respiration rate of the same activated sludge in the presence of various concentrations of the test item ( 32, 56, 100, 180, 320 mg/L), under otherwise identical conditions, is also measured.

The 3h-EC50 of 2-chloro-5-chloromethylpyridine towards bacteria is 135 mg/L.

The EC50 of the reference substance 3,5- Dichlorophenol is 6.2 mg/L.

Description of key information

A study was performed to assess the toxicity of 2 -chloro-5-chloromethylpyridine to bacteria. The study was conducted in accordance with the Commission Directive 88/302/EEC; Official Journal of the EG LI 33 Part C (1988). This test method is in most parts identical with OECD Guideline 209.

Activated sludge was exposed to 2 -chloro-5 -chloromethylpyridine for 3 h. Two controls without test item are included in the test design, one at the start and the other at the end of the test series. The respiration rate of the activated sludge is measured after a contact time of 3 hours. The respiration rate of the same activated sludge in the presence of various concentrations of the test item ( 32, 56, 100, 180, 320 mg/L), under otherwise identical conditions, is also measured.

The 3h-EC50 of 2-chloro-5-chloromethylpyridine towards bacteria is 135 mg/L.

The EC50 of the reference substance 3,5- Dichlorophenol is 6.2 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
135 mg/L

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