Manganese dinitrate

Toxicity to soil macroorganisms except arthropods

Administrative data

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted on read-across material

Remarks:

Conducted to a guideline with plenty of detail.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 for cross-reference:

other: Read-across target

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

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 for cross-reference:

read-across source

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

267 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

other: Mn

Basis for effect:

reproduction

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

157 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

other: Mn

Basis for effect:

reproduction

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

ISO 11268-2 (Effects of Pollutants on Earthworms. 2. Determination of Effects on Reproduction)

Deviations:

yes

Remarks:

Natural soil was used instead of an artificial substrate

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Manganese sulphate monohydrate

IUPAC Name:

Manganese sulphate monohydrate

Details on test material:

- Name of test material (as cited in study report): Manganese sulphate monohydrate
- Lot/batch No.: Stock# 33341 Lot#I18129

Sampling and analysis

Analytical monitoring:

yes

Test substrate

Details on preparation and application of test substrate:

The soil was a natural soil containing 1.2% organic matter.

Test organisms

Test organisms (species):

Enchytraeus sp.

Animal group:

annelids

Study design

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

28 d

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

267 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

other: Mn

Basis for effect:

reproduction

Effect concentrations 2

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

157 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

other: Mn

Basis for effect:

reproduction

Any other information on results incl. tables

The natural background manganese concentration determined in the negative control treatment was 94 mg/kg. Total extractable manganese concentrations (in excess of background) in the experimental treatments ranged from 50 to 117% and averaged 94% of nominal. Exchangeable Mn fraction expressed as percent of total concentration increased with increasing soil Mn loads.

Table 1: Nominal and measured concentrations

Nominal (mg/kg)	Measured (mg/kg)	Corrected recovery (%)
0	94	-
10	99	50
18	110	89
31	119	80
54	157	117
94	191	103
164	267	105
287	386	102
503	644	109

Range finding test:

Range finding test for manganese was conducted using MnSO4·H20. Adult survival decreased by 10% at 500 mg/kg and by 95% at 1,000 mg/kg. Juvenile production decreased by 33% at 100 mg/kg. There were no surviving adults above 1,000 mg/kg or juveniles above the 100 mg/kg treatment concentrations.

Definitive test:

Test results complied with the validity criteria defined in the test guideline. Mean adult survival in negative controls ranged from 97.5 to 100%. The mean juvenile production in negative controls ranged from 735 to 1104 juveniles, and the coefficient of variation ranged from 6 to 18%.

Manganese did not affect (P = 0.721) adult E. crypticus survival up to 191 mg/kg concentration. Adult survival was reduced by 5% (P = 0.48) at 267 mg/kg. Juvenile numbers were significantly (P < 0.0001) higher in the 99 mg/kg treatment compared to negative control suggesting the hormetic effect of Mn on reproduction at this exposure level. The bounded No Observed Adverse Effect Concentration (NOAEC) for juvenile production was 157 mg/kg (P = 0.52). The bounded Lowest Observed Adverse Effect Concentration (LOAEC) for juvenile production was 191 mg/kg (P < 0.0001). No juveniles were produced in 644 mg/kg treatment. The hormetic effect at the 99 mg/kg concentration level suggested the use of the hormetic model to estimate ECp parameters for Mn data.

Applicant's summary and conclusion

Conclusions:

The NOEC was 157 mg Mn/kg. 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