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Ecotoxicological information

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:
1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Similar to Guideline but some test condition details missing
Justification for type of information:
Read-across from supporting substance (structural analogue or surrogate)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
GLP compliance:
not specified
Analytical monitoring:
no
Details on sampling:
- Concentrations: 100, 180, 320, 580, 1000 mg/L
Vehicle:
no
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Pretreatment: After 2nd sedimentation, washed with tap dechlorinated water
- Initial biomass concentration: 2 g/L
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
21C
Nominal and measured concentrations:
nominal - 100, 180, 320, 580, 1000 mg/L
Details on test conditions:
no data
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
240 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
580 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Details on results:
3h EC10 ca 240 mg/L
3h EC20 ca 650 mg/L
3h EC30 ca >1000 mg/L
3h EC80 ca >1000 mg/L
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Relevant effect levels: 47% inhibition at 60 mg/L
Reported statistics and error estimates:
Statistical Method - Ausgewahite Methoden der Wasseruntersuchung, part 2, p 379-382, VEB Fisher Verlang
EC determinations made using probability grid

Test Concentration - Control #1, Control #2, Positive Control, and 100, 180, 320, 580, 1000 mg/L

Respiratory Rate (mg O2/L/h) - 29.2, 33.6, 16.8, 28.8, 28.4, 28.4, 27.6, 23.2

Inhibition (%) - 0, 0, 47, 8, 10, 10, 12, 26

Validity criteria fulfilled:
yes
Conclusions:
The 3h EC10 for the test substance was 240 mg/L which is equivalent to 156 mg/L active substance. The NOEC based on growth inhibition was 580 mg/L which is equivalent to 377 mg/L active substance.

Description of key information

There is a single study of microbial toxicity; a 1989 bacteria toxicity test with activated sludge microbes. The 3-hour NOEC for growth inhibition is 580 mg/L.  

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
580 mg/L

Additional information