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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:
11 Sep - 22 Oct 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
Qualifier:
according to
Guideline:
other: SEPA, The Guidelines for the Testing of Chemicals, 2004, 209 Activated Sludge, Respiration Inhibition Test.
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The test substance was directly weighted and added into the test vessels.
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Source: a fresh sample of activated sludge for the range-finding was collected from the aeration stage of Longhua Wastewater Treatment Plant in
Shanghai which treated predominantly domestic sewage on 2013-09-11 and for the definitive test on 2013-10-21.
- Preparation of inoculum for exposure: the sludge was washed with an isotonic solution containing 0.85% NaCI (w/v). After centrifuging the supernatant was decanted. This procedure was repeated 3 times (4000rpm, 4 °C, centrifuge 20 minutes). A small amount (0 .1 - 0.5 g) of the washed sludge was weighed and dried at 105 °C for 1h to calculate the dry weight. The dry weight of sludge used in range-finding test count up to 6.64% of the gross weight and in the definitive test count up to 4.94%, respectively.
- Initial biomass concentration: 1.5 g/L
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
none
Nominal and measured concentrations:
Test concentrations: 92.3, 171, 309, 556, 1000 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel: 1000 mL glass vessels
- Aeration: yes, ca. 1 L air/min

EFFECT PARAMETERS MEASURED: dissolved oxygen at the begining and at the end of the experiment

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 10, 100, 1000 mg/L (nominal)
- Results used to determine the conditions for the definitive study: IC50 > 1000 mg/L (nominal)
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: respiration inhibition
Results with reference substance (positive control):
IC50 = 13.53 mg/L

Description of key information

IC50 (3 h) > 1000 mg/L (OECD 209)

Key value for chemical safety assessment

Additional information

One study investigating the toxicity of Reaction mass of 1,1'-(isopropylidene)bis[3,5-dibromo-4-(2,3-dibromo-2-methylpropoxy)benzene] and 1,3-dibromo-2-(2,3-dibromo-2-methylpropoxy)-5-{2-[3,5-dibromo-4-(2,3,3-tribromo-2-methylpropoxy)phenyl]propan-2-yl}benzene to microorganisms is available (Jing, 2014). The study was performed according to the OECD guideline 209 and GLP. A range finding test was conducted. Synthetic sewage was tested for 3 h on 5 different concentrations of 92.3, 171, 309, 556 and 1000 mg/L at 20.9 °C. 3,5-dichlorophenol was used as a reference substance. The rate of respiration was recorded. Results revealed an IC50 (3 h) of > 1000 mg/L.