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Toxicity to microorganisms

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Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1999-09-14 to 1999-11-30
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
yes
Specific details on test material used for the study:
- Name: 1,2-epoxybutane
- CAS no.: 106-88-7
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: stock solution stirred for about 48 hours in deionized water
- Controls: blank control without test item, procedure control using reference compound
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Activated sludge from laboratory wastewater plants treating municipal sewage
- The inoculum was washed, brought to a concentration of 5 g/L dry substance and aerated for about 24 hours
- 50 mL were added to a total volume of 250 mL to obtain a concentration of 1 g/L dry substance in the test
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
30 min
Test temperature:
20°C
Details on test conditions:
TEST SUBSTANCE
- preparation of the stock solution: test substance was stirred for about 48 hours in deionized water
- the test substance hydrolysed and the hydrolysate was tested
- summary parameters of the test substance:
theoretical organic carbon (ThOC): 667 mg/g
total organic carbon (TOC) before hydrolysis: 600 mg/g; pH = 7.5 (not adjusted)
dissolved organic carbon (DOC) before hydrolysis: 582 mg/g
total organic carbon (TOC) after 48 hours hydrolysis: 591 mg/g; pH < 5 (adjusted to 7.6)
dissolved organic carbon (DOC) after 48 hours hydrolysis: 575 mg/g
remark: the deviation of 10%-14% to the ThOC is probably due to the hydrolysis.

TEST CONDITIONS
- incubation time: 30 min
- test vessels: Erlenmeyer vessels
- test volume: 250 ml
- synthetic medium: 8ml/Vessel 100-fold concentrated OECD medium
- oxygen concentration during aeration: > 2.5 mg/l
- oxygen concentration immediately before measurement: > 6.5 mg/l
- duration of the measurement of oxygen consumption: 8-10 min
Reference substance (positive control):
yes
Duration:
30 min
Dose descriptor:
other: EC20
Effect conc.:
ca. 160 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
30 min
Dose descriptor:
other: EC80
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Key result
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
ca. 900 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
VALIDITY CRITERIA
- deviation of blank controls <15%: yes
- EC50 of 3,5-dichlorophenol in the range of 5-30 mg/L: yes
Results with reference substance (positive control):
The EC50 (30 min) was determined to be ca. 7.0 mg/L.
Validity criteria fulfilled:
yes
Conclusions:
In an activated sludge respiration inhibition test, the EC50 was determined at 900 mg/L, based on nominal concentrations.
Endpoint:
toxicity to microorganisms
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
according to guideline
Guideline:
DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)
GLP compliance:
no
Analytical monitoring:
no
Details on test solutions:
- Concentration of the stock solution: 12500 mg/L
Test organisms (species):
Pseudomonas putida
Details on inoculum:
- Pseudomonas putida
- Strain: DSM 50026
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
17 h
Test temperature:
20°C
Nominal and measured concentrations:
- Nominal test concentrations: 1250, 2500, 5000, 7500 and 10000 mg/L
Key result
Duration:
17 h
Dose descriptor:
EC10
Effect conc.:
2 920 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Key result
Duration:
17 h
Dose descriptor:
EC50
Effect conc.:
4 840 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Duration:
17 h
Dose descriptor:
other: EC90
Effect conc.:
7 350 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Validity criteria fulfilled:
not specified
Conclusions:
In an reproduction test with Pseudomomas putida, the EC50 was determined at 4840 mg/L and the EC10 was determined at 2920 mg/L, based on nominal concentrations.

Description of key information

The inhibition of the degradation activity of activated sludge is not anticipated when 1.2 -epoxybutane introduced in appropriate low concentrations.

Key value for chemical safety assessment

EC50 for microorganisms:
900 mg/L

Additional information

Key information


The toxicity of 1.2 -epoxybutane on microorganisms was tested in an respiration inhibition test with activated domestic sludge, according to OECD guideline 209 [BASF AG, 1999]. The 30-min EC50 for respiration inhibition was determined to be approximately ca. 900 mg/L 1.2 -epoxybutane.


 


Supporting information


Additional information on the toxicity to microorganisms are available from growth inhibition tests with Pseudomonas putida [BASF AG, 1988]. The 17 h EC10 values for the cell growth inhibition of Pseudomonas putida was 2920 mg/L.


 


Conclusion


Based on the most reliable information [BASF AG, 1999] the 30-min EC50 is considered ca. 900 mg/L. This result is supported by even higher effect values (7-hour EC10 = 2920 mg/L).