Samarium

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
In accordance with Section 2 of REACH Annex XI, this study does not need to be conducted as testing is not technically possible. It is not possible to produce a powdered form of the substance suitable for testing as the powdered form is flammable.
Furthermore, samarium metal is highly insoluble in water - testing the bulk form of the material (as supplied) would not generate test solutions with a sufficient amount of dissolved metal ions. Testing with the registered substance was therefore omitted.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Qualifier:

no guideline followed

Principles of method if other than guideline:

The toxicity of an atomic absorption standard of Sm was measured in one-week exposures using the freshwater amphipod Hyalella azteca in both Lake Ontario, Canada, and soft water (10 % Lake Ontario). Lethal concentrations resulting in 50 % mortality (LC50s) were obtained. The basic experimental design was modified from the classical toxicity test.

GLP compliance:

not specified

Specific details on test material used for the study:

The samarium metal standard (containing 1 g metal/L) was preserved in 2% HCl

Analytical monitoring:

yes

Test organisms (species):

other: Hyalella azteca

Details on test organisms:

TEST ORGANISM
Hyalella used for toxicity tests originated from Valens Conservation Area (ON, Canada), in 1985 and were cultured as described in Borgmann et al. (Borgmann U, Ralph KM, Norwood WP. 1989. Toxicity test procedures for Hyalella azteca, and chronic toxicity of cadmium and pentachlorophenol to H. azteca, Gammarus fasciatus, and Daphnia magna. Arch Environ Contam Toxicol 18:756–764.)
Culture water was dechlorinated Burlington City tap (Lake Ontario, Canada) water (hardness 124 mg/L, carbonate alkalinity 84 mg/L, Ca 35 mg/L, Mg 8.7 mg/L, Na 13 mg/L, K 1.6 mg/L, SO4 32 mg/L, Cl 25 mg/L, and dissolved organic carbon [DOC] 1.1 mg/L from January 2001 to October 2003, n=69, coefficient of variation 3-12 %, except DOC, which was 74 %). Culturing and toxicity tests were conducted in an incubator at 24 to 25 °C under a 16:8-h light:dark photoperiod. Culture water was renewed and young separated from adults weekly on Mondays. Toxicity tests were set up Tuesday to Friday, making the initial age of the test animals 1 to 11 d at the start of the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

1 wk

Test temperature:

24 - 25 °C

Nominal and measured concentrations:

A large number of substances were tested simultaneously at one concentration only (either the maximum concentration of interest, or a concentration close to the predicted toxic threshold) in the first experiment. The concentration of each substance was then either increased or decreased in the next experiment, depending on whether mortality was observed. This procedure was repeated until the toxic range was covered for each substance, or until the substance was demonstrated to cause less than 50 % mortality at the highest concentration of interest. Repeat tests were then conducted on either side of the LC50. If estimates of survival from replicate test containers for each concentration near the LC50 differed by more than 25 %, tests were repeated giving a total of up to 2 to 5 replicates per test concentration. The number of concentrations tested was reduced from the usual 10, 18, 32, 56, 100 logarithmic series to 10, 32, 100.

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 mL polyethylene cups (snap-top specimen containers)
- Fill volume: 400 mL
- Aeration: Yes (overnight to allow equilibration of pH and CO2, and any rapid changes in metal speciation that might occur). Test containers were not aerated during the test.
- No. of organisms per vessel: 15
- Feeding during test: 2.5-mg Tetra-Mint (Ulrich Baensch, Melle, Germany) fish food flakes were added at study initiation. An additional 2.5 mg of food was provided midweek.
- No. of vessels per concentration (replicates): 2 (one in tap (Lake Ontario) water, and another in soft water consisting of 10 % tap water and 90 % Milli-Qt deionised water)
- No. of vessels per control (replicates): Each experiment consisted of three controls, three acid controls, if needed.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
> Dechlorinated tap (Lake Ontario) water (hardness 124 mg/L, carbonate alkalinity 84 mg/L, Ca 35 mg/L, Mg 8.7 mg/L, Na 13 mg/L, K 1.6 mg/L, SO4 32 mg/L, Cl 25 mg/L, and dissolved organic carbon [DOC] 1.1 mg/L from January 2001 to October 2003, n = 69, coefficient of variation 3-12 %, except DOC, which was 74 %).
> Soft water consisting of 10 % tap water and 90 % Milli-Qt deionised water (soft water measured hardness 18 mg/L, carbonate alkalinity 14 mg/L, Ca 5.6 mg/L, Mg 0.90 mg/L, Na 1.4 mg/L, K 0.15 mg/L, SO4 3.4 mg/L, Cl 2.5 mg/ L, and DOC 0.28 mg/L, n 5 17, coefficient of variation 5-11 %, except for Ca 45 %, alkalinity 51 % and DOC 69 %).
- Intervals of water quality measurement: After 7 d, the pH, conductivity, and ammonia and oxygen concentrations were measured

OTHER TEST CONDITIONS
- Adjustment of pH: A solution of 19 parts 1 M NaHCO3 plus 1 part 1 M KOH (similar to the Na:K ratio of the test water) was used to neutralise excess acid in the metal standards and control pH. Sufficient buffer to control pH, if required, was added first, followed by addition of the metal standard. This resulted in better survival of acid controls than adding the metal solution first. Neutralisation was required primarily for tests conducted in soft water.
Acid-controls consisted of acid and neutralising solution additions equal to the amount added in the tests with acidified metal standards.

EFFECT PARAMETERS MEASURED: Mortality

Reference substance (positive control):

not specified

Key result

Duration:

1 wk

Dose descriptor:

LC50

Remarks:

(soft water)

Effect conc.:

296 µg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Sm

Basis for effect:

mortality

Remarks on result:

other: 95 % CL 231 - 378 µg/L

Key result

Duration:

1 wk

Dose descriptor:

LC50

Remarks:

(soft water)

Effect conc.:

74 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Remarks:

Sm

Basis for effect:

mortality

Remarks on result:

other: 95 % CL 57 - 95 µg/L

Key result

Duration:

1 wk

Dose descriptor:

LC50

Remarks:

(tap water)

Effect conc.:

846 µg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Sm

Basis for effect:

mortality

Remarks on result:

other: 95 % CL 603 - 1188 µg/L

Details on results:

WATER QUALITY
Addition of AA standards and neutralizing buffer contributed to conductivity somewhat. The effect was proportionately greater in soft water.
Final oxygen values ranged from 7 to 10 mg/L and temperature from 24 to 25 °C.

Reported statistics and error estimates:

The concentration resulting in 50 % mortality (LC50) and 95 % confidence limits were computed using the Trimmed Spearman-Karber method.

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of the study the 1-week LC50 of samarium, to the crustacean Hyalella azteca was determined to be 296 µg/L (96 % CL: 231-378 µg/L) - nominal; 74 µg/L (95 % CL: 57-95 µg/L) - mesaured, in soft water and 846 µg/L (95 % CL: 603-1188 µg/L) - nominal, in tap water.

Executive summary:

The toxicity of an atomic absorption standard of Sm was measured in one-week exposures using the freshwater amphipod Hyalella azteca in both Lake Ontario, Canada, and soft water (10 % Lake Ontario). Lethal concentrations resulting in 50 % mortality (LC50s) were obtained. The basic experimental design was modified from the classical toxicity test.

Under the conditions of the study the 1-week LC50 of samarium, to the crustacean Hyalella azteca was determined to be 296 µg/L (96 % CL: 231-378 µg/L) - nominal; 74 µg/L (95 % CL: 57-95 µg/L) - measured, in soft water and 846 µg/L (95 % CL: 603-1188 µg/L) - nominal, in tap water.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

3 May 2013 to 8 May 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The surface of samarium metal oxidises on contact with air to form an outer layer of samarium oxide. It is therefore considered appropriate to read across information from samarium oxide to the metal where testing on the metal is not technically possible. It is not possible to produce a powdered form of the substance suitable for testing as the powdered form is flammable. Furthermore, samarium metal is highly insoluble in water - testing the bulk form of the material (as supplied) would not generate test solutions with a sufficient amount of dissolved metal ions.

Reason / purpose for cross-reference:

other: read-across target

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

As soloubility of the test material is < 100 mg/L, a saturated solution was prepared by weighing 99.6 mg/L test material and adding it to a corresponding amount of dilution water. The solution was shaken vigorously for 24 hours and the resulting solution filtered through 0.45 µm filters.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain/clone: Berlin
- Source: Umweltbundesamt Berlin

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

Resulting hardness in mmol/L: 2.502
Resulting hardness in mg CaCO3/L: 250

Test temperature:

21.4 - 22.5°C

pH:

7.7 - 7.9

Dissolved oxygen:

8.6 - 8.9 mg O2/L

Nominal and measured concentrations:

100 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL glass beakers
- Fill volume: 20 ± 5 mL
- Aeration: No
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: water was enriched with 293.3 mg/L CaCl2.2H2O, 123.3 mg/L MgSO4.7H2O, 64.8 mg/L NaHCO3, 5.8 mg/L KCl. After preparation the dilution water was aerated and then the pH adjusted to 7.8 ± 0.2.
- Intervals of water quality measurement: the pH, dissolved oxygen concentration and content of Sm in the test vessels was measured at the beginning and at the end of the test.

OTHER TEST CONDITIONS
- Lighting: None

EFFECT PARAMETERS MEASURED
Immobilised daphnia were counted at 24 and 48 hours

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.15 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mobility

Remarks on result:

other: no effect at limit of solubility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

MORTALITY AND MOBILITY OBSERVATIONS
In the control, two of the daphnia died. In the treatment replicates, none of the animals died or showed any signs of abnormal behaviour.

ANALYTICAL DETERMINATIONS
At the start and at the end of the test, the content of the test material in the test solutions was determined by determination of samarium content using ICP-OES.
Stability in test medium without animals was tested before the start of the test. The test material showed sufficient stability in test medium (97 % recovery after 48 hours). In the Daphnia study, in presence of the animals, the recovery after 48 hours was 67.45 % of the start concentration. The poor recovery was probably caused by ingestion by the animals or adsorption on their excrements. The correlation of the measured concentrations with the nominal concentrations was poor, due to the low solubility of the test material in the test medium. Nevertheless, the obtained measured concentrations show that the test material was present in the solution and sufficient dissolution was achieved. Therefore, the determination of the results was based on the geometric mean of the measured concentrations which should be regarded as the limit of solubility.

Results with reference substance (positive control):

Potassium dichromate K2Cr2O7 (CAS N0. 7778-50-9) was used as positive control in a current reference study (201301 R201). The value was determined as 1.2 mg/L, lying within the demanded range of 0.6 - 1.7 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study no effects were observed at the limit of solubility. The 48-hour EC50 to the freshwater invertebrate, Daphnia magna, was concluded to be in excess of 0.15 mg/L.

Executive summary:

The toxicity of the test material to the freshwater invertebrate, Daphnia magna, was assessed in a study which was conducted in accordance with the standardised guidelines OECD 202 and EU Method C.2, under GLP conditions.

Twenty daphnia were exposed to the test material for 48 hours in a static test system. After 24 and 48 hours, the immobilised daphnia were counted. The concentration (limit of solubility) showed no toxicity. Two of the animals were immobilised in the control which can be stated as not significant.

At the start and at the end of the test, the content of the test material in the test solutions was determined by measurement of the Samarium content using ICP-OES.

Stability in test medium without animals was tested partly under non-GLP conditions before the start of the test. The test material showed sufficient stability in test medium (97 % recovery after 48 hours). In the Daphnia study, the recovery after 48 hours was 67.45 % of the start concentration. The poor recovery was probably caused by ingestion by the animals or adsorption on their excrements. The correlation of the measured concentrations with the nominal concentrations was poor, due to the low solubility of the test material in the test medium. Nevertheless, the obtained measured concentrations show that the test material was present in the solution and sufficient dissolution was achieved. Therefore, the determination of the results was based on the geometric mean of the measured concentrations which should be regarded as limit of solubility.

Under the conditions of the study no effects were observed at the limit of solubility. The 48-hour EC50 to the freshwater invertebrate, Daphnia magna, was concluded to be in excess of 0.15 mg/L.

Reference 4

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

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:

The surface of samarium metal oxidises on contact with air to form an outer layer of samarium oxide. It is therefore considered appropriate to read across information from samarium oxide to the metal where testing on the metal is not technically possible. It is not possible to produce a powdered form of the substance suitable for testing as the powdered form is flammable. Furthermore, samarium metal is highly insoluble in water - testing the bulk form of the material (as supplied) would not generate test solutions with a sufficient amount of dissolved metal ions.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.15 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Remarks on result:

other: no effects at the limit of solubility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Description of key information

In accordance with Section 2 of REACH Annex XI, this study does not need to be conducted as testing is not technically possible. It is not possible to produce a powdered form of the substance suitable for testing as the powdered form is flammable.

Furthermore, samarium metal is highly insoluble in water - testing the bulk form of the material (as supplied) would not generate test solutions with a sufficient amount of dissolved metal ions. Testing with the registered substance was therefore omitted.

- Supporting information on an atomic absorption standard of Sm

Under the conditions of the study the 1-week LC50 of samarium, to the crustacean Hyalella azteca was determined to be 296 µg/L (96% CL: 231-378 µg/L) - nominal; 74 µg/L (95% CL: 57-95 µg/L) - mesaured, in soft water and 846 µg/L (95% CL: 603-1188 µg/L) - nominal, in tap water.

- Supporting information on the read-across substance, samarium oxide

Under the conditions of the study no effects were observed at the limit of solubility. The 48-hour EC50 to the freshwater invertebrate, Daphnia magna, was concluded to be in excess of 0.15 mg/L.

Since the surface of samarium metal oxidises on contact with air to form an outer layer of samarium oxide, it is considered appropriate to read across information from samarium oxide to the metal where testing on the metal is not technically possible.

Additional information

In accordance with Section 2 of REACH Annex XI, this study does not need to be conducted as testing is not technically possible. It is not possible to produce a powdered form of the substance suitable for testing as the powdered form is flammable.

Furthermore, samarium metal is highly insoluble in water - testing the bulk form of the material (as supplied) would not generate test solutions with a sufficient amount of dissolved metal ions. Testing with the registered substance was therefore omitted.

Supporting information is available in the form of a publication which reports on findings from a study conducted with an atomic absorption standard of Sm. Supporting information from a GLP guideline study on samarium oxide is also available.

The literature reference reports on the toxicity of an atomic absorption standard of Sm. In the study, toxicity of the atomic absorption standard of Sm was measured in one-week exposures using the freshwater amphipod Hyalella azteca in both Lake Ontario, Canada, and soft water (10% Lake Ontario). Lethal concentrations resulting in 50% mortality (LC50s) were obtained. The basic experimental design was modified from the classical toxicity test.

Under the conditions of the study the 1-week LC50 of samarium, to the crustacean Hyalella azteca was determined to be 296 µg/L (96% CL: 231-378 µg/L) - nominal; 74 µg/L (95% CL: 57-95 µg/L) - mesaured, in soft water and 846 µg/L (95% CL: 603-1188 µg/L) - nominal, in tap water.

- Supporting information on the read-across substance, samarium oxide

The toxicity of the test material to the freshwater invertebrate, Daphnia magna, was assessed in a study which was conducted in accordance with the standardised guidelines OECD 202 and EU Method C.2, under GLP conditions.

Twenty daphnia were exposed to the test material for 48 hours in a static test system. After 24 and 48 hours, the immobilised daphnia were counted. The concentration (limit of solubility) showed no toxicity. Two of the animals were immobilised in the controwhich can be stated as not significant.

At the start and at the end of the test, the content of the test material in the test solutions was determined by measurement of the Samarium content using ICP-OES.

Stability in test medium without animals was tested partly under non-GLP conditions before the start of the test. The test material showed sufficient stability in test medium (97 % recovery after 48 hours). In the Daphnia study, the recovery after 48 hours was 67.45 % of the start concentration. The poor recovery was probably caused by ingestion by the animals or adsorption on their excrements. The correlation of the measured concentrations with the nominal concentrations was poor, due to the low solubility of the test material in the test medium. Nevertheless, the obtained measured concentrations show that the test material was present in the solution and sufficient dissolution was achieved. Therefore, the determination of the results was based on the geometric mean of the measured concentrations which should be regarded as limit of solubility.

Under the conditions of the study no effects were observed at the limit of solubility. The 48-hour EC50 to the freshwater invertebrate, Daphnia magna, was concluded to be in excess of 0.15 mg/L.

Since the surface of samarium metal oxidises on contact with air to form an outer layer of samarium oxide, it is considered appropriate to read across information from samarium oxide to the metal where testing on the metal is not technically possible.

In consideration of the information that is available, it is assumed that samarium metal would have no toxic effect on aquatic invertebrates at the limit of its solubility.