Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
13.03.2006 to 29.03.2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study performed according to the guideline.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report Date:
2006

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
Impurities: Manganese dioxide (cca 0.1%). Appearance of Potassium permanganate is dark violet-purple crystalline powder with bronze lustre.
The test substance is soluble in water. The stock solution was prepared by dissolving 1.0g of Potassium permanganate in 500 mL deionised water on the day of testing. The solution prepared in this way has a concentration of 2000 mg/L and the pH value of 7.8.
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Potassium permanganate is being used as a surrogate for sodium permanganate. Read-across from potassium permanganate to sodium permanganate is appropriate from the ecotoxicological point of view as the most toxicologically relevant part of the substances is the same (permanganate). The contribution of the sodium/potassium ions to the toxicity of the respective substances is likely to be minimal. The toxicity of both substances is therefore likely to be very similar and will be dominated by local (site of contact) irritant/corrosive effects and systemic toxicity due to the absorption of manganese ions.

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
Not applicable

Test solutions

Vehicle:
no
Details on test solutions:
Deionised water was used for the preparation of solutions. The stock solution of cultivation medium (synthetic nutrient medium) is composed of: peptone 16g, meat extract 11g, urea (NH2)2CO 3g, NaCl 0.7g, CaCl2.2H2O 0.4g, MgSO4.7H2O 0.2g, K2HPO4 2.8g and water up to 1L. The pH of the solution was between 7.0-8.0 and the cultivation medium was prepared fresh of the day of use.

Test organisms

Test organisms (species):
activated sludge
Details on inoculum:
The activated biological sludge contained a mixture culture of microorganisms obtained from the second step sewage treatment plant in AliaChem Inc. The wastewater processed by the sewage treatment plant is predominantly municipal. The activated sludge was collected two days before the day of esting. After the sample collection the sludge was washed with potable water for 0.5 hour and subsequently decanted for 0.5 hour. This procedure was repeated three times in total. The sludge was further modified by addition of 50 mL of cultivation medium per 1 litre of sludge suspension at permanent aeration till the day of the test. The dry weigh was determined from 10 mL of sludge suspension after 0.5 hour sedimentation. Before the test the sludge was suspended in water up to a concentration of 3800-4000 mg of sludge dry weight per litre and the pH adjustment to approx 6.5 was carried out. In that way modified sludge suspension was aerated until ready for use.

Study design

Test type:
not specified
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
Not relevant.

Test conditions

Hardness:
Not applicable
Test temperature:
20 ± 2oC
pH:
The pH range in the treated vessles was 7.47 - 8.0
Dissolved oxygen:
Measurement of oxygen content was performed in aliquots of the reaction mixtures after a 3-hour incubation period using an oxygen electrode and the decine of oxygen was measured at 10 minute intervals.
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations - 46, 68, 100, 152, 220 and 320 mg/L
Details on test conditions:
20 ± 2oC, 180 min deposition time, daily light, stirring and aeration with filtered pressured air and an airflow rate of 0.8 L/min. The pH value of the reaction mixture during the test was 6-8.
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

Results and discussion

Effect concentrations
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
164 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: 131-220 mg/L
Details on results:
The difference in the respiration rates for the control experiments at the beginning and end of the main test was 2.92 mg/L/h = 7.2% (if value of the lower control 40.40 mg/L/h = 100%).
Results with reference substance (positive control):
The EC50 value of the reference substance 3,5-dichlorophenol was 12.4 mg/L (95% confidence interval of 9.6-19.1 mg/L). The acceptable range for the reference substance is 5 to 30 mg/L.
Reported statistics and error estimates:
EC values of the test and reference substance were calculated using statistical software (Software QC Expert 2.5 (1998-2000) product of TriloByte Ltd., Czech Republic).

Any other information on results incl. tables

Evaluation of inhibition of respiration

Conc. (mg/L)

P1 (mg 02/L)

P2 (mg O2/L)

T1 (min)

T2 (min)

Respiration rate (mg/L/h)

Inhibition %

Control

0

6.29

2.68

0.5

5.5

43.32

0

Reference substance

19

8.24

6.10

0.5

10

13.52

67.7

14

8.52

6.24

0.5

10

14.40

65.6

10

6.58

3.78

3.0

10

24.00

42.7

7.2

6.44

2.71

1.5

7.5

37.30

10.9

5.2

6.33

2.54

2.0

7.5

41.35

1.2

Test substance

46

6.26

2.75

0.5

5.5

42.12

0 (-0.6)

68

6.46

2.47

1.0

7.0

39.90

4.7

100

6.29

2.71

2.0

8.5

33.05

21.0

152

6.37

4.14

4.5

10

24.33

41.9

220

7.92

5.40

0.5

10

15.92

62.0

320

9.10

8.36

0.5

10

4.67

88.8

Control

0

6.48

2.44

2.5

8.5

40.40

0

Abiotic control

320

9.01

8.96

0.5

10

0.32

-

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The respiration rates of the two control experiments should not differ from each other more than 15% and the EC50 value of the reference substance should be in the range of 5-30 mg/L for a contact time of 3 hours.
Conclusions:
A 3 hour microorganism toxicity study was performed to assess the respiration inhibition of potassium permanganate. The study was performed according to GLP and the EU Method C.11 Test Guideline. The 3 hour EC50 was calculated to be 164 mg/L, with 95% confidence limits of 131 to 220 mg/L (based nominal exposure concentrations)
Executive summary:

A 3 hour microorganism toxicity study was performed to assess the respiration inhibition of potassium permanganate. The study was performed according to GLP and the EU Method C.11 Test Guideline. The 3 hour EC50 was calculated to be 164 mg/L, with 95% confidence limits of 131 to 220 mg/L (based nominal exposure concentrations)