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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
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:
Meets generally accepted scientific standards, well documented and acceptable for assessment. The read-across from MnCl2 to MnSO4 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 chloride 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 MnCl2 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:
short-term toxicity to aquatic invertebrates
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:
96 h
Dose descriptor:
LC50
Effect conc.:
3 other: mg Mn/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
other: Dissolved
Basis for effect:
other: Survival
Remarks on result:
other: Soft water
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
8.6 other: mg Mn/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
other: Dissolved
Basis for effect:
other: Survival
Remarks on result:
other: Moderately hard water
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
13.7 other: mg Mn/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
other: Dissolved
Basis for effect:
other: Survival
Remarks on result:
other: Hard water

Data source

Reference
Reference Type:
publication
Title:
Toxicity of Manganese to Ceriodapnia dubia and Hyalella azteca
Author:
Lasier PJ, Winger PV & Bogenrieder KJ
Year:
2000
Bibliographic source:
Arch.Environ.Contam.Toxicol.38:298-304

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Sensitivity of H.azteca to Mn was determined with 7-day-old animals in acute 96-h tests. Tests were run at three levels of water hardness (soft, moderately hard and hard).
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material : Manganese chloride tetrahydrate
- Molecular formula : MnCl2.4H2O

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: Concentration of Mn and major cation and ions (Na, K, Ca, Mg, Cl, SO4) were measured for each test solution. Concentration was determined at test termination.
- Sampling method:Test solutions with the highest and lowest Mn concentrations for each type of water was also sampled and preserved after 96-h to assess changes in concentrations that occurred during the tests.
- Sample storage conditions before analysis: Preserved by adding 1% (v:v) ultrapure NHO3.

Test organisms

Test organisms (species):
other aquatic crustacea: H.azteca
Details on test organisms:
TEST ORGANISM
- Common name: Scud
- Source: Known-age H.azteca were obtained for testing from in-house cultures using methods similar to those of Tomasovic et al. (1995).
- Age at study initiation : < 24-h old animals
- Method of breeding: Mixed caged animals from the cultures were placed on 1-mm mesh transferred to 355-µm mesh sieves in 8-L plastic containers with 6L of MH5 water. Approximately 500 adults animals placed on each sieve produced around 600 young in 24h. T
- Feeding during test: Not fed during the test.



ACCLIMATION
- Acclimation period: The young H.azteca were held for 6 days with water exchanged (60%) every other day, at which time additional food was added.
- Type and amount of food: A small amount of Tetrafin was added to the sieves for food. After 24h, the sieves were again agitated and transferred to a container with 6L of freshwater to which 45mL of S. capricornutum algae and 25 ml of YCT had been added as food for the young.

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
96 h
Post exposure observation period:
Not reported

Test conditions

Hardness:
SW = soft water = 26 mg/L
MH4= four-salt moderately hard water = 92 mg/L
H4= four-salt hard water = 184 mg/L
Test temperature:
25°c
pH:
8.0-8.4
Dissolved oxygen:
Not reported
Salinity:
Not reported
Nominal and measured concentrations:
2.5, 5, 10, 20, 40, 80 mg Mn/L - Nominal Concentration
Details on test conditions:
Test System
Test vessel: plastic cup. The plastic cup consisted of a 1.5-cm2 piece of Nitex netting.
- Type :closed
- fill volume: 30 ml
- Aeration: yes
- No. of organisms per vessel:10
- No. of vessels per concentration (replicates):5
- No. of vessels per control (replicates):5


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: See table 1. Sodium bromide (1 mg/L) was added to the MH5, H5 and SW waters to bolster survival of H. azteca . Each water was used to prepare the most concentrated Mn solution and was also used as the dilulent and control in their respective test.
- Intervals of water quality measurement: Alkalinity and pH of all test solutions were measured at test initiation (titration with H2SO4 for alkalinity, pH electrode and meter for pH).

OTHER TEST CONDITIONS
- Photoperiod: 16 h light: 8 h dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Survival was the endpoint in test with tH.azteca

TEST CONCENTRATIONS
Manganese solution for the test were prepared 24 h prior to test initiation by adding MnCl2.4H2O to the waters with a targeted nominal concentration of 89 mg Mn/L. This solution was then serially diluted (0.5 x) to produce six Mn concentrations (80, 40, 20, 10, 5 , 2.5 Mn/L.

Results and discussion

Effect concentrationsopen allclose all
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
3 other: mg Mn/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Basis for effect:
other: Survival
Remarks on result:
other: Soft water (see table 1)
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
8.6 other: mg Mn/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Basis for effect:
other: Survival
Remarks on result:
other: Moderately hard (see table 1)
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
13.7 other: mg Mn/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
dissolved
Basis for effect:
other: Survival
Remarks on result:
other: Hard water (see table 1)
Details on results:
Survival of H.azteca in control waters ranged between 90 and 100%.

Manganese was toxic to H.azteca and increased water hardness significantly reduced toxicity.Manganese was more toxic to H.azteca in soft water (SW), followed by moderately hard (MH5) and hard (H5) waters, and lethal concentrations (lC50s) were significantly different from one another. In the current. the LC50 values for H.azteca were 3.0 and 8.6 mg Mn/L for waters with hardness of 26 and 80, respectively. These values bracket the LC50 of 4.2 Mn/L reported by Stubblefield et al (1997).
Reported statistics and error estimates:
Calculations of LC50 values were performed with the trimmed Spearman Karber method (Hamilton et al. 1977).

Applicant's summary and conclusion

Conclusions:
LC50s determined for H.azteca progressively increased from 3.0 to 8.6 to 13.7 mg Mn/L in soft, moderately hard, and hard waters, respectively. The read-across from MnCl2 to MnSO4 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 chloride 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 MnCl2 ecotoxicity tests is regarded as a suitable surrogate for read-across.