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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:
24/3-25/3/14
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
GLP compliance:
yes (incl. certificate)
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: direct addition
- Eluate:
- Differential loading:
- Controls:
- Chemical name of vehicle (organic solvent, emulsifier or dispersant):
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)):
- Evidence of undissolved material (e.g. precipitate, surface film, etc.):
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Laboratory culture:
- Name and location of sewage treatment plant where inoculum was collected: WWTP Mannheim, Germany (collection date: 24.03.14)
- Method of cultivation:
- Preparation of inoculum for exposure: sieving (1 mm mesh)
- Pretreatment: pre-aeration overnight, washing once with tap water
- Initial biomass concentration: 3 g/L dw
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Test temperature:
20.9-21.2 °C
pH:
pre incubation: 7.4-7.6
post incubation: 7.9 - 8.1
Nominal and measured concentrations:
1000, 500, 250, 125, 62.5 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel: glass beakers
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: glass, 1 L, 500 mL, 500 mL
- Aeration:
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates):
- No. of vessels per abiotic control (replicates):
- Sludge concentration (weight of dry solids per volume): 1.5 g/L dw
- Weight of dry solids per volume of reaction mixture per unit of time:
- Nutrients provided for bacteria:
- Nitrification inhibitor used (delete if not applicable): none / N-allylthiourea
- Biomass loading rate:
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: local tap water
- Particulate matter:
OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod:
- Light intensity:
- Details on termination of incubation:
EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using fewer concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:
Reference substance (positive control):
yes
Remarks:
3,5-DCP
Key result
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
410 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Duration:
3 h
Dose descriptor:
other: EC20
Effect conc.:
680 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Results with reference substance (positive control):
The EC50 of the reference substance 3,5-dichlorophenol was in the range of 2-25 mg/L in 3 hours.
Reported statistics and error estimates:
The degree of inhibition was evaluated by Probit analysis according to Finney.
Validity criteria fulfilled:
yes
Executive summary:

In conclusion the 3 hours effect concentrations for Azo Initiator VA044 in the Activated Sludge Respiration Inhibition Test are:

The following effect concentrations (mg/L) were obtained:

Toxicity Response Variable

Based on nominal effect concentration [mg/L]

Confidence Limits (95%) lower/upper

EC10

410

302.2/555.7

EC20

680

572.3/810.5

EC50

> 1000

-

EC80

> 1000

-

The value of effect concentrations of EC10 EC20 were given with an accuracy of 2 significant digits. The degree of inhibition was evaluated by Probit analysis according to Finney.

The results in this study are consistent with all validity criteria and the test is valid according to the guidelines used for this study.

No deviations from the test guidelines or other incidents occurred during the course of the reported test which may have influenced the results.

Description of key information

Based on the findings in an OECD 209 study exposing activated sludge with the test substance an EC10 value of 410 mg/L and an EC50 value > 1000 mg/L after an exposure period of 3 hours were determined.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
410 mg/L

Additional information