Caesium carbonate

Endpoint summary

Description of key information

No skin sensitising properties were extrapolated for cesium carbonate from a local lymphnode assay performed with the structural analogue cesium nitrate.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

HYPOTHESIS FOR THE ANALOGUE APPROACH
Cesium carbonate completely dissociates in water forming cesium cation and the corresponding carbonate anion. Thus, cesium salts with different anion moieties were found to be suitable candidates for read-across. (Eco)toxicological properties were extrapolated to different endpoints by using the lowest effect concentration.
For further information, please refer to the read-across justification in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

SI

Value:

0.91

Test group / Remarks:

25 % CsNO3 in 1 % Pluronic

Remarks on result:

other: As cesium nitrate was not a sensitizing substance, it was extrapolated that cesium carbonate is not sensitizing substance either.

Parameter:

SI

Value:

1.05

Test group / Remarks:

2.5 % CsNO3 in 1 % Pluronic

Parameter:

SI

Value:

0.97

Test group / Remarks:

5 % CsNO3 in 1 % Pluronic

Parameter:

SI

Value:

0.72

Test group / Remarks:

10 % CsNO3 in 1 % Pluronic

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No study data is available for cesium carbonate and read across was performed to cesium nitrate as a structural similar substance. As carbonate does not contribute to the overall toxicity of the metal salt (please refer to the counterion file attached to the read across statement) the study data with cesium nitrate will be suitable to cover this endpoint.

The aim of this study was to determine the skin sensitisation potential of cesium nitrate in the Local Lymph Node Assay (LLNA) according to the OECD Guideline 429 and EU Method B.42. The individual approach was used in this test whereby the lymph nodes of each animal were evaluated individually (in comparison to a pooled test group approach). The maximum attainable test item concentration, resulting in a homogenous formulation in an appropriate vehicle, was examined.

A preliminary solubility test was performed to select a suitable vehicle. The maximum attainable test concentration based on solubility was 25 % (w/v) in aqueous 1 % Pluronic. No higher test concentration was available in this test.

Based on results of a preliminary irritation/toxicity test 25 % was selected as the highest test concentration in the main test.

In the main test, 35 female CBA/Ca mice were allocated to seven groups of five animals each:

-four groups received cesium nitrate at 25 %, 10 %, 5 % or 2.5 %,

-the negative control group received the vehicle (1 % Pluronic) only,

-the positive control group received 25 % alpha-Hexylcinnamaldehyde

-the negative control group for the positive control group received Acetone: Olive oil 4:1 mixture (v/v/) (AOO) only.

 

Each substance was applied on the external surface of each ear (25 µL/ear) of the animals for three consecutive days (Day 1, 2 and 3).

There was no treatment on Days 4, 5 and 6. On Day 6, the cell proliferation in the local lymph nodes was measured by determining incorporation of tritiated methyl thymidine (3HTdR) and the obtained values were used to calculate stimulation indices (SI). No mortality was observed during the test. No local effects at the application sites (ears) were observed in any treatment group. Larger lymph nodes than the control were observed in the positive control group only. No statistically significant lymphoproliferation was observed in any group treated with the test item. The obtained SI values for the test item were 0.91, 0.72, 0.97 and 1.05 at concentrations of 25 %, 10 %, 5 % and 2.5 %, respectively. No dose-related response was observed. The positive control item induced the appropriate stimulation (SI = 11.82), thus confirming the validity of the assay. Since the mean SI value was below 3 at the maximum attainable test concentration of 25 % and at concentrations of 10 %, 5 % and 2.5 % and no dose-related response was observed, the test item was considered to be a non-sensitiser in the LLNA.

Based on the above data it is assumed that the target substance cesium carbonate is not skin sensitising.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available experimental data, the test item is considered not to be classified as skin sensitising under Regulation (EC) No 1272/2008.