Samarium

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

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, information requirement section 7.8, 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 that would be suitable for testing as the powdered form of the substance is flammable.
OECD 29 necessitates testing on powders or testing on spheres of substance with 1 mm diameter (to represent the massive form). It is not possible to produce samarium metal in the form required for testing.

Reference 2

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

6 May 2013 to 24 June 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 samarium metal that would be suitable for testing, as the powdered form of the substance is flammable.

Reason / purpose for cross-reference:

other: read across target

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

other: flask method with ICP-OES analysis

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

963 µg/L

Element analysed:

Sm

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

20 °C; pH 5.5

Remarks on result:

other: Result relevant to day 14

Details on results:

- Preliminary Test
The highest concentration of samarium was measured at pH 5.5 (15.3 mg/L Sm). The main study was therefore conducted at pH 5.5.

- Main Test
ln the period 2 h - 14 days, the samarium concentration lay in the range 262 - 828 µg/L.
The measured concentrations of samarium on days 21 and 28 were nearly identical: 674 and 671 µg/L (mean values), respectively.
The lower concentration of samarium on days 21 and 28 in comparison to day 14 is a result of the addition of 150 mL fresh medium after sampling on day 14 (replenishing as demanded in guideline). As the test material was almost completely dissolved on day 14, the test solution was diluted with the medium. The same
concentration of samarium in the flasks 3 - 5 on days 21 and 28 suggests that no undissolved test material was available in the test solution after dilution on day 14.
Therefore, the concentration of samarium was stated as 828 µg/L (mean value of flasks 3 - 5 on day 14, nominal concentration of the test material 1000 µg/L). This corresponds to a test material concentration of 963 µg/L. Almost complete dissolution of the test material was already observed on day 14.

Conclusions:

Under the conditions of the study the test material was almost completely dissolved following a 14-day dissolution period. The water solubility of samarium oxide was therefore concluded to be 963 µg/L at 20 °C, pH 5.5.

Executive summary:

The transformation/dissolution of the test material was investigated in a study which was conducted in accordance with the standardised guideline OECD 29 and under GLP conditions.

Following a preliminary study conducted at different environmentally relevant pH levels, it was concluded that the highest release occurred at pH 5.5. The main test was therefore conducted at pH 5.5.

ln the period 2 h - 14 days, the samarium concentration lay in the range 262 - 828 µg/L.

The measured concentrations of samarium on days 21 and 28 were nearly identical: 674 and 671 µg/L (mean values), respectively.

The lower concentration of samarium on days 21 and 28 in comparison to day 14 is a result of the addition of 150 mL fresh medium after sampling on day 14 (replenishing as required in the guideline). As the test material was almost completely dissolved on day 14, the test solution was diluted with the medium. The same concentration of samarium in the flasks 3 - 5 on days 21 and 28 suggests that no undissolved test material was available in the test solution after dilution on day 14.

Therefore, the concentration of samarium was stated as 828 µg/L (mean value of flasks 3 - 5 on day 14, nominal concentration of the test material 1000 µg/L). This corresponds to a test material concentration of 963 µg/L. Almost complete dissolution of the test material was already observed on day 14.

Reference 3

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

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 samarium metal that would be suitable for testing, as the powdered form of the substance is flammable.

Reason / purpose for cross-reference:

read-across source

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

963 µg/L

Element analysed:

Sm

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

20 °C; pH 5.5

Remarks on result:

other: result relevant to day 14

Description of key information

In accordance with Section 2 of REACH Annex XI, information requirement section 7.8, 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 that would be suitable for testing as the powdered form of the substance is flammable.

OECD 29 necessitates testing on powders or testing on spheres of substance with 1 mm diameter (to represent the massive form). It is not possible to produce samarium metal in the form required for testing.

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

Findings from a transformation/ dissolution protocol study indicate that the water solubility of samarium oxide is 963 µg/L at 20 °C, pH 5.5.

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, information requirement section 7.8, 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 that would be suitable for testing as the powdered form of the substance is flammable.

OECD 29 necessitates testing on powders or testing on spheres of substance with 1 mm diameter (to represent the massive form). It is not possible to produce samarium metal in the form required for testing.

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

The transformation/dissolution of the read across substance, samarium oxide, was investigated in a study which was conducted in accordance with the standardised guideline OECD 29 and under GLP conditions.

Following a prelminary study conducted at different environmentally relevant pH levels, it was concluded that the highest release occurred at pH 5.5. The main test was therefore conducted at pH 5.5.

ln the period 2 h - 14 days, the samarium concentration lay in the range 262 - 828 µg/L.

The measured concentrations of samarium on days 21 and 28 were nearly identical: 674 and 671 µg/L (mean values), respectively.

The lower concentration of samarium on days 21 and 28 in comparison to day 14 is a result of the addition of 150 mL fresh medium after sampling on day 14 (replenishing as demanded in guideline). As the test material was almost completely dissolved on day 14, the test solution was diluted with the medium. The same concentration of samarium in the flasks 3 - 5 on days 21 and 28 suggests that no undissolved test material was available in the test solution after dilution on day 14.

Therefore, the concentration of samarium was stated as 828 µg/L (mean value of flasks 3 - 5 on day 14, nominal concentration of the test material 1000 µg/L). This corresponds to a test material concentration of 963 µg/L. Almost complete dissolution of the test material was already observed on day 14.

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.