Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

For this REACH registration dossier of the ‘reaction mass of calcium carbonate, calcium hydroxide and calcium peroxide’, several ecotoxicity endpoints were assessed based on test data that are available for hydrogen peroxide and calcium hydroxide, the two primary degradation products resulting from the hydrolysis of calcium peroxide.

 

As described in the section on environmental fate and pathways, hydrogen peroxide is a degradation product that is formed upon hydrolysis of calcium peroxide. In ECHA’s Guidance document on information requirements and chemical safety assessment it is mentioned that testing on the hydrolysis product can be justified if the DT50 (50% disappearance time) is very short, i.e. less than 3 days.

 

CaO2 + 2 H2O            -->      Ca2 ++ 2 (OH)- + H2O2

H2O2 + H2O               -->       2 H2O + O2

Ca(OH)2                    -->       Ca2++ 2 OH-

CaCO3                       -->       Ca2++ CO32 -

 

The DT50value of calcium peroxide can be estimated from the water solubility study:

As 100 mg of the ‘reaction mass of calcium carbonate, calcium hydroxide and calcium peroxide’ contains 77.5 mg of calcium peroxide, the test show that the hydrolysis of 77.5 mg/L calcium peroxide in water occurs within 24 hours under the conditions of the test (double distilled water, 20°C). As a consequence, the DT50 for the disappearance of calcium peroxide in an aqueous environment will be well below 24 hours.

Therefore, the use of test results obtained for its hydrolysis product hydrogen peroxide for the assessment of ecotoxicological endpoints of the REACH registration dossier is considered acceptable and justified. It is to be noted that the hydrogen peroxide that is formed upon hydrolysis of calcium peroxide itself undergoes further degradation.

 

According to the applicable chemical reaction (see above), the amount of hydrogen peroxide formed is equimolar to the amount of calcium peroxide present in the reaction mass. As the concentration of calcium peroxide in the reaction mass is ca. 75%, 100 mg of the reaction mass contains 75 mg of calcium peroxide, which corresponds to 1.04 mmol of calcium peroxide. Therefore, 1.04 mmol (= 35.36 mg) of hydrogen peroxide is formed upon dissolution of 100 mg of the reaction mass.

 

For example, a 96h-LC50 of 16.4 mg/L for hydrogen peroxide can be extrapolated to result in the following 96h-LC50 for the reaction mass of calcium carbonate and calcium dihydroxide and calcium peroxide:

           100 mg/L reaction mass                   yields             35.36 mg/L hydrogen peroxide

           46.4 mg/L reaction mass                  yields             16.4 mg hydrogen peroxide

The extrapolated 96h-LC50 for the multi-constituent substance is: 46.4 mg/L.