Magnesium dipropan-2-olate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Magnesium isopropanolate rapidly hydrolyzes in aqueous environments. Toxicity is mediated by its degradation products isopropanol and Mg(OH)2 and assessed for these products.

Isopropanol

In a non-GLP bacterial reverse mutation assay (equivalent to OECD guideline 471), isopropanol was tested at doses of 0; 100; 333; 1,000; 3,333 or 10,000 µg/plate in Salmonella typhimuriumstrains TA 97, TA 98, TA 100, TA 1535, and TA 1537, both in the presence and absence of exogenous metabolic activation (Aroclor 1254-induced rat and hamster liver S9) (Zeigeret al.,1992).  The incubations were conducted in triplicate and an independent repeated experiment was performed. Distilled water was used as the vehicle and positive controls were included in all incubations. No cytotoxicity was observed and no increase in the reverse mutation rate was observed at any isopropanol concentration, either in the presence or absence of metabolic activation. Incubation with positive control substances in the presence or absence of metabolic activation did not always result in anticipated increases inreverse mutation rates. As a result this study is considered reliable with restrictions.

Mg(OH)2

Magnesium hydroxide was tested in theSalmonella typhimurium reverse mutation assay with four histidine-requiring strains of Salmonella typhimurium(TA1535, TA1537, TA98 and TA100) and in the Escherichia coli reverse mutation assay with a tryptophan-requiring strain o fEscherichia coli(WP₂uvrA). The test was performed as two independent experiments in the presence and absence of S9-mix (rat liver S9-mix induced by a combination of Phenobarbital and β-naphthoflavone).

The study procedures described in the report were based on the most recent OECD and EC guidelines.

Based on the results of a dose range finding test, magnesium hydroxide was tested in the first mutation assay at a concentration range of 100 to 5000 µg/plate in the absence and presence of 5% (v/v) S9-mix in tester strains TA1535, TA1537 and TA98. In an independent repeat of the assay with additional parameters, magnesium hydroxide was tested at the same concentration range as the first assay in the absence and presence of 10% (v/v) S9-mix in tester strains TA1535, TA1537, TA98, TA100 and WP₂uvrA. The bacterial background lawn was not reduced at any of the concentrations tested and no biologically relevant decrease in the number of revertants was observed.

 

Magnesium hydroxide did not induce a significant dose-related increase in the number of revertant colonies in any of the tester strains, both in the absence and presence of S9-metabolic activation. The results were confirmed in an independently repeated experiment.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Justification for classification or non-classification

Magnesium isopropanolate

Magnesium isopropanolate rapidly hydrolyzes in aqueous environments. Toxicity is mediated by its degradation products isopropanol and Mg(OH)2 and assessed for these products.

Both hydrolysis products should not be classified for genetic toxicity. Based on the available information, magnesium isopropanolate thus does not have to be classified and has no obligatory labelling requirement for genetic toxicity.

Isopropanol

A non-GL P bacterial reverse mutation assay (equivalent to OECD guideline 471) produced negative results. There is no need for classification.

Mg(OH)2

A bacterial reverse mutation assay was carried out on magnesium hydroxide according to current guidelines and under GLP. Its result was negative and there is no need for classification.