Sodium 2-methylpropan-2-olate

Endpoint summary

Additional information

No genotoxicity studies are available for sodium tert-butanolate. Sodium tert-butanolate is the salt of tert-butyl alcohol ion and the sodium metal cation. In the presence of water it reacts under formation of tert-butyl alcohol and sodium hydroxide (NaOH). For that reason, read-across to tert-butyl alcohol was performed. For tert-butyl alcohol, 6 in vitro and 1 in vivo genotoxicity studies are available.

A sister chromatid exchange test was performed equivalent to OECD 479 (NTP, 1995). Here, CHO cells were treated with tert-butyl alcohol with and without S9-mix and concentrations up to 5000 ug/mL were tested. A negative test result was obtained.

Three bacterial reverse mutation assays are available.

An Ames test equivant to OECD 471 (Zeiger et al., 1987) was done using concentrations from 100 to 10000 ug/plate. The test was negative for the Salmonella typhimurium strains TA 1535, TA 1537, TA 98 and TA 100. This test was done with and without metabolic activation.

Another Ames test was published by Chemische Werke Huels AG (Huels AG, 1979). Salmonella typhimurium strains TA 1535, TA 1537, TA 1538, TA 98 and TA 100 were used to test tert-butyl alcohol with concentrations ranging from 10 to 1000 ug/plate. Negative test results were obtained with and without metabolic activation. An additional Ames test was performed by McGregor et al., 2005. Doses ranging from 5 to 5000 ug/plate were tested in Salmonella typhimurium TA 102 with and without S9-mix and showed a negative result.

A mammalian cell gene mutation assay is available for tert-butyl alcohol performed equivalent to OECD 476 (MCGregor et al., 1988). Mouse lymphoma L5178Y cells were treated with increasing doses of tert-butyl alcohol ranging from 625 to 5000 ug/mL with and without S9 -mix. A small increase in mutant colonies was observed in a single trial at the highest dose in the absence of S9-mix which could not be reproduced. So, the conducted test results were considered as negative.

NTP reported an in vitro mammalian chromosome aberration test which was performed equivalent to OECD 473 (NTP, 1995). CHO cells were used in this experiment. The chosen test concentrations of tert-butyl alcohol were between 160 and 5000 ug/mL. The experiment was performed with and without metabolic activtion. In one out of 4 experiments results were considered to be "equivocal" since in the 5000 ug/mL dose group, the number of cells with chromosome aberration was significantly increased (p<=0.05). This result was not reproducible in the second experiment, the experiments without S9-mix were also negative, so the test substance was considered to be negative.

In vivo:

A micronucleus assay is available for tert-butyl alcohol. Here, peripheral blood samples were collected from male and female B6C3Fl mice at the end of the 13-week drinking-water toxicity study. Applied doses were: 0, 2.5, 5, 10, 20 or 40 mg/mL. Smears were prepared, fixed, and stained. The frequency of micronuclei in 10,000 normochromatic erythrocytes (NCB) was analyzed. No effects could be detected.

Short description of key information:
In vitro:
Sister Chromatid Exchange test (NTP, 1995) = negative
Ames test (Huels AG, 1979; Zeiger et al., 1987; McGregor, 2005) = negative
MLT (McGregor et al., 1988) = negative
Chromosome aberration (NTP, 1995) = negative

In vivo:
MNT in mice and rats (NTP, 1995) = negative

Endpoint Conclusion:

Justification for classification or non-classification

Based on the available data received from tert-butyl alcohol, no classification is proposed according to EU directive 67/548/EEC and EU regulation (EC) NO. 1272/2008 (CLP).