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Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2010-02-01
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted on read-across material
Remarks:
Study conducted to GLP and to a current guideline. The read-across from MnSO4 to Mn(NO3)2 is justified on the following basis: both substances are very soluble in water hence bioavailable and both will release Mn2+ ions. Therefore, from an ecotoxicity standpoint, the nitrate or sulphate anions are not considered to have any influence on the effective toxicity of Mn2+ or any toxicity in their own right, so the anions can be disregarded. Therefore any effect will be related to the Mn2+ cation, and the data from MnSO4 ecotoxicity tests is regarded as a suitable surrogate for read-across.
Justification for type of information:
See the read-across report attached in Section 13.
Cross-reference
Reason / purpose:
other: Read-across target
Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted on read-across material
Justification for type of information:
See the read-across report attached in Section 13.
Reason / purpose:
read-across source
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
Remarks:
Respiration rate
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
560 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
Respiration rate

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): MnSO4 (actually manganese sulphate monohydrate based on description in the GLP water solubility report)
- Physical state:solid
- Lot/batch No.: 08729
- Storage condition of test material: room temperature in the dark
- Other: extremely pale pink powder

Sampling and analysis

Analytical monitoring:
no

Test organisms

Test organisms (species):
activated sludge of a predominantly domestic sewage

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
Not applicable i.e. not performed after 3hrs

Test conditions

Hardness:
140 mg/L as CaCO3
Test temperature:
21+/-1°C
pH:
7.2-7.9
Dissolved oxygen:
Initial reading = 4.7-7.0 mg/L
Final reading = 1.5- 3.7 mg/L
Salinity:
Not applicable as freshwater used.
Nominal and measured concentrations:
Nominal concentrations were 10, 32, 100, 320 and 1000 mg MnSO4/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 500mL conical flask
- Type : open
- Aeration: yes
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 3.8g/L in actual activated sewage sludge, of which 16 ml used in tests.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Alvaston water supply
- Total organic carbon: 1.018 mg/L average
- Metals: Aluminium < 15.57 µg/L average, iron < 11.4µg/L, mercury < 0.012µg/L, nickel < 3.04µg/L, lead < 2.3 µg/L, sodium 25µg/L, manganese < 1.5µg/L, Selenium < 0.5µg/L
- Pesticides: no single species was > 0.1 µg/L
- Chlorine: 0.307 mg/L
- Alkalinity: 7.62 average
- Conductivity: 386.192 µS/cm at 20°C


OTHER TEST CONDITIONS
- Light intensity: normal lighting

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : 0 hrs and after 30 min, and 3 hrs: Observation of test preparation. 3 hr: oxygen consumption rate

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Test concentrations: 10, 32, 100, 320, 1000 mg MnSO4/L
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol

Results and discussion

Effect concentrationsopen allclose all
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
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
560 mg/L
Nominal / measured:
nominal
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: no precipitation
- Effect concentrations exceeding solubility of substance in test medium: no
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- Relevant effect levels: Variation in respiration rates of controls 1 and 2 after 3 hours contact time was ± 3%.
Reported statistics and error estimates:
Not reported

Any other information on results incl. tables

Table 1 Oxygen Consumption Rates and Percentage Inhibition Values after 3 Hours Contact Time

Nominal

Concentration

(mg/l)

Initial O2

(mg O2/l)

Measurement Period

(minutes)

Final O2Reading

(mg O2/l)

O2Consumption Rates

(mg O2/l/min)

% Inhibition

Control

R1

6.0

7

2.5

0.50

-

 

R2

4.8

4

2.7

0.53

-

Test item

10

4.7

6

1.5

0.53

[3]

 

32

4.8

5

2.0

0.56

[9]

 

100

5.2

5

2.5

0.54

[5]

 

320

5.3

6

2.2

0.52

[1]

 

1000

7.0

10

3.7

0.33

36

3,5-dichlorophenol

3.2

5.9

10

1.6

0.43

17

 

10

7.3

10

5.2

0.21

59

 

32

8.0

10

7.2

0.08

84


[Increase in respiration rate as compared to controls]

R1– R2= Replicates 1 to 2

Table 2 pH Values of the Test Preparations at the Start and End of the Exposure Period

Nominal

Concentration

(mg/l)

pH

0 Hours

3 Hours

Control

R1

7.5

7.9

 

R2

7.7

7.9

Test item

10

7.6

7.8

 

32

7.5

7.8

 

100

7.5

7.7

 

320

7.3

7.7

 

1000

7.2

7.9

3,5-dichlorophenol

3.2

7.5

8.0

 

10

7.5

8.1

 

32

7.6

8.3


R1– R2= Replicates 1 to 2

Table 3 Observations on the Test Preparations Throughout the Test Period

Nominal

Concentration

(mg/l)

Observations on Test Preparations

0 Hours

30 Minutes

Contact Ti

3 Hours

Contact Ti

Control

R1

Dark brown dispersion

Dark brown dispersion

Dark brown dispersion

 

R2

Dark brown dispersion

Dark brown dispersion

Dark brown dispersion

Test item

10

Clear colourless solution[1]

Dark brown dispersion, no undissolved test item visible

Dark brown dispersion, no undissolved test item visible

 

32

Clear colourless solution*

Dark brown dispersion, no undissolved test item visible

Dark brown dispersion, no undissolved test item visible

 

100

Clear colourless solution*

Dark brown dispersion, no undissolved test item visible

Dark brown dispersion, no undissolved test item visible

 

320

Clear colourless solution*

Dark brown dispersion, no undissolved test item visible

Dark brown dispersion, no undissolved test item visible

 

1000

Clear colourless solution*

Dark brown dispersion, no undissolved test item visible

Dark brown dispersion, no undissolved test item visible

3,5-dichlorophenol

3.2

Dark brown dispersion, no undissolved reference item visible

Dark brown dispersion, no undissolved reference item visible

Dark brown dispersion, no undissolved reference item visible

 

10

Dark brown dispersion, no undissolved reference item visible

Dark brown dispersion, no undissolved reference item visible

Dark brown dispersion, no undissolved reference item visible

 

32

Dark brown dispersion, no undissolved reference item visible

Dark brown dispersion, no undissolved reference item visible

Dark brown dispersion, no undissolved reference item visible


R1– R2= Replicates 1 to 2

[1]Observations made prior to the addition of synthetic sewage and activated sewage sludge.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
MnSO4 is not considered toxic to micro-organisms in the STP with an EC50 > 1000 mg/L and NOEC = 560 mg/L. The read-across from MnSO4 to Mn(NO3)2 is justified on the following basis: both substances are very soluble in water hence bioavailable and both will release Mn2+ ions. Therefore, from an ecotoxicity standpoint, the nitrate or sulphate anions are not considered to have any influence on the effective toxicity of Mn2+ or any toxicity in their own right, so the anions can be disregarded. Therefore any effect will be related to the Mn2+ cation, and the data from MnSO4 ecotoxicity tests is regarded as a suitable surrogate for read-across