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Long-term toxicity to aquatic invertebrates

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Description of key information

No experimental data are available that assess the long-term toxicity of the reaction mass of magnesium carbonate and magnesium hydroxide and magnesium oxide and magnesium peroxide to aquatic invertebrates. Nevertheless, a 21d-NOEC value can be derived from reliable information that is available for hydrogen peroxide.
The 21d-NOEC for the reaction mass is 2.82 mg/L.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
2.82 mg/L

Additional information

No experimental data are available that assess the long-term toxicity of the reaction mass of magnesium carbonate and magnesium hydroxide and magnesium oxide and magnesium peroxide to aquatic invertebrates. Nevertheless, for this endpoint reliable informationis available for hydrogen peroxide, one of the primary hydrolytic degradation products of the reaction mass of magnesium carbonate and magnesium hydroxide and magnesium oxide and magnesium peroxide.

The long-term toxicity of hydrogen peroxide to invertebrates was tested in a 21d experiment with Daphnia pulex (Meinertz et al, 2008). The test was performed in 2008 according to an ASTM guideline. The 21d-NOEC value determined from this study was 0.63 mg/L.

 

From this 21d-NOEC value a corresponding 21d-NOEC value can be calculated for the reaction mass, by taking into account the applicable chemical reaction (i.e. the amount of hydrogen peroxide formed is equimolar to the amount of magnesium peroxide present in the reaction mass) and the composition of the reaction mass (i.e. the reaction mass contains ca. 37% magnesium peroxide).

Thus: 100 mg of the reaction mass contains 37 mg of magnesium peroxide, which corresponds to 0.66 mmol of magnesium peroxide. Therefore, 0.66 mmol (= 22.35 mg) of hydrogen peroxide is formed upon dissolution of 100 mg of the reaction mass.

As a consequence, the 21d-NOEC for the reaction mass of magnesium carbonate and magnesium hydroxide and magnesium oxide and magnesium peroxide can be calculated from the 21d-NOEC for hydrogen peroxide (0.63 mg/L):

100 mg/L reaction mass         yields              22.35 mg/L hydrogen peroxide

2.82 mg/L reaction mass        yields              0.63 mg/L hydrogen peroxide

==> the 21d-NOEC (reaction mass) = 2.82 mg/L