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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:
1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Version / remarks:
adopted 4 April 1984
Deviations:
yes
Remarks:
other reference substance: 2,4,5-trichlorophenol
Qualifier:
according to guideline
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Version / remarks:
1988
Deviations:
yes
Remarks:
other reference substance: 2,4,5-trichlorophenol
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test substance was absorbed onto silica gel using a stock solution of 10 g/litre in dichloromethane.
- Controls: yes
- Chemical name of vehicle: dichloromethane
- Concentration of vehicle in test medium: 10 g/L in the stock solution
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Laboratory culture: no (Source: RZWI Nieuwgraaf in Duiven)
- Preparation of inoculum for exposure: The activated sludge plant predominantly treats domestic wastewater. Prior to use, the activated sludge was diluted with tap water (1.5 x) and hmogenized for two minutes in a lab blender 400.
- Initial biomass concentration: The activated sludge concentration in the incubation vessels was 0.5 g dry weight/L.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
30 min
Test temperature:
20 °C
pH:
7.5 to 7.9
Dissolved oxygen:
0.36 - 0.37 mg O2/L min
Nominal and measured concentrations:
- nominal concentration: 1000 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: The volume of the vessel was 10 mL.
- Type: closed (by the electrode to measure the oxygen depletion)


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water
- Intervals of water quality measurement: The pH of the reaction mixture was measured before the respiration measurement.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable): The respiration rates of the activated sludge were measured in a Biological Oxygen Monitor YSI5300.
Reference substance (positive control):
yes
Remarks:
2,4,5-trichlorophenol
Key result
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
No inhibition of the respiration rate occured at 1000 mg/L of the test item absorbed onto silica gel. This result shows that the test item, at the obtained distribution, is not toxic for activated sludge.
Results with reference substance (positive control):
The respiration rate of 86 % was occured at 40 mg/L of 2, 4, 5-trichlorophenol.
Validity criteria fulfilled:
yes
Conclusions:
No inhibition of the respiration rate occured at 1000 mg/L of ditetradecyl peroxydicarbonate absorbed onto silica gel. This result shows that the test item, at the obtained distribution, is not toxic for activated sludge.
Executive summary:

Ditetradecyl peroxydicarbonate was tested in an activated sludge respiration inhibition test according EU method C.11 and OECD guideline No. 209. The test substance was not soluble in water and therefore the activated sludge was exposed to

ditetradecyl peroxydicarbonate adsorbed onto silica gel at a concentration of 1g/L. By this exposure no effect was recorded indicating that the obtained distribution of the test substance in the water system did not inhibit the activated sludge.

No inhibition of the respiration rate occured at 1000 mg/L of ditetradecyl peroxydicarbonate absorbed onto silica gel. This result shows that the test item, at the obtained distribution, is not toxic for activated sludge.

Description of key information

No inhibition of the respiration rate occurred at 1000 mg/L of ditetradecyl peroxydicarbonate absorbed onto silica gel. This result shows that the test item, at the obtained distribution, is not toxic for activated sludge.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

Ditetradecyl peroxydicarbonate was tested in an activated sludge respiration inhibition test according EU method C.11 and OECD guideline No. 209. The test substance was not soluble in water and therefore the activated sludge was exposed to ditetradecyl peroxydicarbonate adsorbed onto silica gel at a concentration of 1g/L. By this exposure no effect was recorded indicating that the obtained distribution of the test substance in the water system did not inhibit the activated sludge. No inhibition of the respiration rate occured at 1000 mg/L of ditetradecyl peroxydicarbonate absorbed onto silica gel. This result shows that the test item, at the obtained distribution, is not toxic for activated sludge.