Caesium hydroxide

Endpoint summary

Description of key information

The test substance is considered to have skin corrosive properties based on its strong basic character.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation / corrosion

Data waiving:

other justification

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation

Data waiving:

other justification

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin:

In accordance with column 2 of REACH Regulation EC No. 1907/2006, Annex VII, the test on skin irritation/corrosion (required in section 8.1) does not need to be conducted as the available information for cesium hydroxide monohydrate and cesium hydroxide anhydrous indicate that the criteria for classification as corrosive to the skin are met. Cesium hydroxide compounds are corrosive to the skin, due to its strong basic character (chiefly based on the OH- content of the salt) and is thus classified as skin corrosive (H314). This classification is in accordance to other alkali metal hydroxides. In conclusion, no further testing is required in accordance with animal welfare reasons.

A public available study with 5% Cesium hydroxide was given for completeness sake and to show the lack of skin irritation in diluted solutions. In this primary dermal irritation study, albino rabbits (6 animals) were dermally exposed to 0.1 mL of cesium hydroxide (5%) in water. Animals were observed for 48 hours. Irritation was scored by the method of Draize. Cesium hydroxide (5%) was considered to be non irritating to the intact skin (overall irritation score = 0). When applied to the abraded skin CsOH was considered to be a mild irritant (overall irritation score = 1.58), but has not to be classified according to 67/548/EC (DSD) and Regulation (EC) No 1272/2008.

Eye:

In accordance with column 2 of REACH Regulation No. 1907/2006, Annex VII, the test on eye irritation (required in section 8.2) does not need to be conducted as the available information indicates that the criteria are met for classification as corrosive to the skin. Cesium hydroxide monohydrate and cesium hydroxide anhydrous are corrosive to the skin and in consequence as severely damaging to the eye, due to its strong basic character (chiefly based on the OH- content of the salt) and is thus classified as severely eye damaging (H318). This classification is in accordance to other alkali metal hydroxides. In conclusion, no further testing is required in accordance with animal welfare reasons.

A public available study with diluted cesium hydroxide was given for completeness sake, to support the waiving of the study and to show the lack of eye irritation in diluted solutions. In this primary eye irritation study, 0.1 mL of cesium hydroxide (0.1, 0.5 and 5.0 %) in water was instilled into the conjunctival sac of the eye of albino rabbits (in total eight animals) for 5 min or 24 hours. Eyes were washed with water after the exposure period. Animals then were observed for 21 days. Irritation was scored by the method of Draize. CsOH (5%) is considered extremely irritating and corrosive to the rabbits eye. Based on the marked response, an attempt was made to determine the concentration that produced no ocular reaction. 0.5 % CsOH produced no ocular reaction in the eye of rabbits.

Justification for selection of skin irritation / corrosion endpoint:
Available information for cesium hydroxide monohydrate and cesium hydroxide anhydrous indicate that the criteria for classification as corrosive to the skin are met. Therefore, the evaluation of skin irritation is not appropriate.

Justification for selection of eye irritation endpoint:
Available information for cesium hydroxide monohydrate and cesium hydroxide anhydrous indicate that the criteria for classification as corrosive to the skin are met. Therefore, the evaluation of eye irritation is not appropriate.

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: corrosive

Justification for classification or non-classification

Based on the strong basic character due to the OH- ions of the salt, cesium hydroxide monohydrate and cesium hydroxide anhydrous are classified as skin corrosive cat. 1A (H314) according to Regulation (EC) No 1272/2008.

Based on the strong basic character due to the OH- ions of the salt and the classification as skin corrosive, cesium hydroxide monohydrate and cesium hydroxide anhydrous are classified as severely eye damaging cat. 1 (H318) according to Regulation (EC) No 1272/2008.