Manganese sulphate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-02-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and to a current guideline.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Manganese sulphate

EC Number:

232-089-9

EC Name:

Manganese sulphate

Cas Number:

7785-87-7

Molecular formula:

H2O4S.Mn

IUPAC Name:

manganese(2+) sulfate

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: roomtemperature 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 concentrations

Effect concentrations 1

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

Effect concentrations 2

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)	Measurent 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.