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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Description of key information

Calcium magnesium oxide is considered to be irritating to skin and the respiratory system and to entail a risk of serious damage to the eye.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Eye irritation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Additional information

The results of an available in vivo skin irritation study (rabbit) with Ca(OH)2 indicate that calcium magnesium oxide may be irritating to skin (pH effect) by read-across.

In the available eye irritation studies (in vivo, rabbit), CaO caused irreversible lesions in the eye. By read across the results are also applicable for calcium magnesium oxide.

From human data it is concluded that calcium magnesium oxide is irritating to the respiratory tract.


Effects on skin irritation/corrosion: irritating

Effects on eye irritation: highly irritating

Effects on respiratory irritation: irritating

Justification for classification or non-classification

Based on experimental results on a similar substance utilised by read-across, calcium magnesium oxide requires classification as irritating to skin [R38, irritating to skin; Skin Irrit 2 (H315 – Causes skin irritation)].

Based on experimental results on a similar substance utilised by read-across, calcium magnesium oxide requires classification as severely irritating to the eye [R41, Risk of serious damage to eye; Eye Damage 1 (H318 - Causes serious eye damage)].

Based on human data as summarised and evaluated in the SCOEL recommendation

(Anonymous, 2008: Recommendation from the Scientific Committee on Occupational Exposure Limits for Calcium oxide (CaO) and calcium hydroxide (Ca(OH)2), European Commission, DG Employment, Social Affairs and Equal Opportunities, SCOEL/SUM/137 February 2008, see section 7.2.2 of the technical dossier)

, it is proposed by read-across from the similar substances CaO and Ca(OH)2 to classify calcium magnesium oxide as irritating to the respiratory system [R37, Irritating to respiratory system; STOT SE 3 (H335 - May cause respiratory irritation)].