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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010-04-20 to 2010-04-23
Reliability:
1 (reliable without restriction)
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:thorough mixing
- Eluate:water
- Differential loading:
- Controls:
- Chemical name of vehicle (organic solvent, emulsifier or dispersant):water
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)):5 g/l (stock), 100mg/l (final)
- Evidence of undissolved material (e.g. precipitate, surface film, etc):none
Test organisms (species):
activated sludge of a predominantly domestic sewage
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Hardness:
CaCl2.2H2O 211.5 mg/l
MgSO4.7H2O 88.8 mg/l

Test temperature:
Between 18.0 and 19.0 deg C
pH:
8.3
Dissolved oxygen:
At the start of test 1 - 9.1 mg O2/l
At the start of test 2 - 7.9 mg O2/l
Salinity:
n/a
Details on test conditions:
TEST SYSTEM
- Test vessel:0.3 litre oxygen bottle and 1 litre test bottle
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume:glass
- Aeration:aerated by pipette during contact time
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate): static
- No. of organisms per vessel: not relevant
- No. of vessels per concentration (replicates):2
- No. of vessels per control (replicates):2
- No. of vessels per vehicle control (replicates): not relevant
- Biomass loading rate: not relevant

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:ISO medium
- Total organic carbon:
- Particulate matter:3.9 g/l
- Metals:
- Pesticides:
- Chlorine:
- Alkalinity:
- Ca/mg ratio:
- Conductivity:
- Culture medium different from test medium:
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod:
- Light intensity:

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :oxygen consumption

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
> 100 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values:none
- Effect concentrations exceeding solubility of substance in test medium:none
Results with reference substance (positive control):
- Results with reference substance valid?Yes
- Relevant effect levels:
- Other:reference substance 3,5-dichlorophenol with a final conc. of 0.5 g/l

Table2 presents the results of the test.

 

No significant inhibition of respiration rate of the sludge was recorded at 100 mg

MEAPolyborate 1:3 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore, no further testing was needed.

Hence, the EC50of Polyborate 1:3 exceeded 100 mg/l (based on nominal concentrations).

 

Table2            Controls (C) and Polyborate 1:3 (T): pH, oxygen concentration, oxygen consumption and percentage inhibition of the respiration rate

Flask

Concentration

(mg/l)

Oxygen conc.

at the start

(@mg O2/l)

Oxygen consumption

(mg O2/l/h)

% Inhibition

respiration

rate

pH

Cstart T

0

8.4

38

-

8.3

Cend T

0

8.9

35

-

8.3

 

∆ 9%

 

T 1

100

9.1

34

7

8.3

T 2

100

7.9

40

-10¹

8.2

¹: A negative value indicates stimulation of the respiration rate. This value is considered as not significant.

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of a GLP OECD 209 test, MEA Polyborate 1:1 was not toxic to waste water (activated sludge) bacteria at 100 mg/l. The 3-hour EC50 of MEA Polyborate 1:3 exceeded 100 mg/l (based on nominal concentrations).
Executive summary:

The influence of MEA Polyborate 1:3 on the respiration rate of activated sludge was investigated after a contact time of 3 hours.

 

The study procedures described in this report were based on the OECD guideline No. 209, 1984.In addition, the procedures were designed to meet the test methods of the Commission Regulation (EC) No. 440/2008 of 30 May 2008, Publication No. L142, Part C11 and ISO Standard 8192 (2007).

 

The batch of MEA Polyborate 1:3 tested was a clear colourless liquid. MEA Polyborate 1:3 was tested as delivered by the sponsor.

 

A stock solution of 0.5 g/l was prepared by adding 0.1255 g test substance to 250 ml of

Milli-RO water. Thorough mixing (14 minutes) was used to accelerate dissolution and to ensure homogeneity. The synthetic sewage feed (16 ml), activated sludge (200 ml) and an adequate amount of the clear colourless test substance stock solution were mixed and made up to 500 ml with Milli-RO water in a 1-litre bottle. A concentration of 100 mg/l was tested in duplicate.

Two controls without test substance were tested in each test series.

Optimal contact between the test substance and test medium was ensured applying continuous aeration and stirring during the 3-hour exposure period. Thereafter, oxygen consumption was measured and recorded for approximately 10 minutes.

 

No significant inhibition of respiration rate of the sludge was recorded at 100 mg

MEA Polyborate 1:3 per litre. The duplicate measurement confirmed the result of the first measurement. Therefore, no further testing was needed.

Hence, the EC50of MEA Polyborate 1:3 exceeded 100 mg/l (based on nominal concentrations).

 The batch of activated sludge was checked for sensitivity by testing the reference substance

3,5-dichlorophenol.

 

Since all criteria for acceptability of the test were met, this study was considered to be valid.


Description of key information

Under the conditions of a GLP OECD 209 test, MEA Polyborate 1:1 was not toxic to waste water (activated sludge) bacteria at 100 mg/l. The 3-hour EC50 of MEA Polyborate 1:3 exceeded 100 mg/l (based on nominal concentrations).

Key value for chemical safety assessment

Additional information