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Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
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
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The appropriate amount of test substance were added to the test medium. The volume was adjusted to 200 mL with water and aerated for 3 hours.
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Laboratory culture: Activated sludge collected from the sewage treatment plant of 4153 Reinach, Swiss
- Preparation of inoculum for exposure: The preparation was carried out according to the method described in the guideline. The sludge was separated from the aqueous layer by settling instead of centrifugation.
- Initial biomass concentration: 1.7 g/L
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
20 ± 2 °C
Nominal and measured concentrations:
Nominal test concentrations: 0 (control), 1.2, 3.0, 22.0, 42.0 and 106.0 mg/L
Details on test conditions:
- Vessels: 250 mL BOD flasks with gas inlet
- Water: dechlorinated drinking water
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol
Key result
Duration:
180 min
Dose descriptor:
IC50
Effect conc.:
26 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
180 min
Dose descriptor:
other: IC20
Effect conc.:
7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
180 min
Dose descriptor:
other: IC80
Effect conc.:
101 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Results with reference substance (positive control):
IC50 = 12 mg/L

Description of key information

Depending on local conditions and existing concentrations disturbances in the biodegradation process of activated sludge are possible.  

The 3-h EC50 value is 26 mg/L as observed in a respiration inhibition study with domestic activated sludge.

Key value for chemical safety assessment

Additional information

The toxicity of the substance to microorganisms was investigated in an activated sludge respiration inhibition study according to OECD TG 209 (BASF, 1989). In this study, domestic activated sludge was exposed to nominal test substance concentrations of 0 (control), 1.2, 3.0, 22.0, 42.0 and 106.0 mg/L for 3 hours. Test concentrations were not analytically verified. The effects on microorganisms was determined by measuring total respiration rates and comparing these to an unexposed control. The 3-h EC50 and EC20 values were determined at 26 mg/L and 7.0 mg/L, respectively.