2-methylpropan-2-ol

Endpoint summary

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Skin Irritation

The potential for tertiary butyl alcohol to cause skin corrosion/irritation is well understood. In a dermal irritation study in which tertiary butyl alcohol was applied to intact and abraded skin sites in male and female rabbits for 24 hours, no edema was noted in any of the animals, the mean erythema score was 0.7 at 24 hours, and irritation was fully reversible by the 72 hour observation period. In addition, when a dermal toxicity study utilizing albino rabbits was performed on abraded skin in 5 rabbits/sex up to the limit dose level of 2000 mg/kg bw, dermal observations at 14 days post-exposure were limited to slight edema (1/10) and erythema described as absent (5/10), very slight (1/10) or slight (4/10). Based on the available data, prolonged exposure to tertiary butyl alcohol would be expected to cause, at most, slight transient skin irritation.

  

Eye Irritation

  

The potential for tertiary butyl alcohol to cause eye burns/irritation has been evaluated based on the physical properties of the substance, an absence of corrosivity or irritation following 24-hour contact with intact or abraded skin, and the results of an eye irritation study in which a mixture containing at least 91% tertiary butyl alcohol was instilled into the eye of rabbits. In an eye irritation study, a mixture containing at least 91% tertiary butyl alcohol was instilled into the conjunctival sac of the right eye of 9 albino rabbits, followed by immediate flushing of the eyes of 3 rabbits with water. By Day 16, all unwashed eyes were normal. All animals in this group exhibited corneal opacity≥1 at the 24, 48 and 72-hour observation periods. All washed eyes were normal by Day 22. However, minor corneal effects, described as vascularization, were observed in two of three animals in the washed-eye group from Day 25 until termination on Day 34. There was insufficient information in the test report to explain the effects observed in washed eyes following a period of normalcy. Current regulatory guidelines for the conduct of an eye irritation study do not require washing, and if washing is done, it is performed at least 24 hours following instillation of the test substance. Mean scores following grading at 24, 48 and 72 hours after instillation of the test material were less than 3 and 1.5 for corneal opacity and iritis, respectively, in both treatment groups. Based on all available data, tertiary butyl alcohol is not expected to be corrosive but based on the results of a single in vivo eye irritation study, tertiary butyl alcohol has the potential to cause eye irritation.

  

Respiratory Irritation

  

The potential for tertiary butyl alcohol to cause respiratory tract irritation is well understood. In an acute inhalation study conducted by a method similar to the current EPA OPPTS guideline 870.1300 in which groups of male and female rats were exposed to 10000 ppm tertiary butyl alcohol for 4 hours, no clinical signs suggestive of respiratory tract irritation were observed; however gross pathological examination revealed focal areas of redness on the lungs of 4 of 10 animals. In repeat exposure studies conducted according to NTP guidelines in which groups of rats and mice of each sex were exposed for 6 hr/day, 5 days/week to 7000 ppm tertiary butyl alcohol for 18 days or 2100 ppm for 13 weeks, no clinical signs of respiratory irritation were reported during gross and microscopic examination of the entire respiratory tract. In a developmental toxicity/teratogenicity study (Nelson et al., 1989) conducted by a method equivalent to OECD Guideline 414, female rats were exposed to up to 5000 ppm tertiary butyl alcohol for 7 hr/day, 7 days/week throughout gestation with no reported clinical signs of respiratory distress. These results suggest that exposure to high airborne concentrations of tertiary butyl alcohol may cause respiratory tract irritation.

Effects on eye irritation: irritating

Effects on respiratory irritation: irritating

Justification for classification or non-classification

The test conditions used in both the skin irritation and dermal toxicity studies used to evaluate the potential for tertiary butyl alcohol to cause skin corrosion/irritation were significantly more severe, i. e. 24-hr exposure to abraded skin, than current OECD guideline specifications. Tertiary butyl alcohol does not belong to a chemical class known to cause corrosivity. Low molecular weight undiluted alcohols commonly cause localized defatting and drying of the skin but not corrosion or significant irritation. Based on a weight-of-the evidence assessment, tertiary butyl alcohol is not classified for skin irritation/corrosion according to the classification criteria of the Directive 67/548/EEC, EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 or UN GHS.

 

There were no clinical signs indicative of respiratory tract irritation in rats and mice following acute or repeat exposure to high airborne concentrations of tertiary butyl alcohol. In addition, no gross or microscopic effects were observed in the respiratory tract of rats and mice exposed to 7000 ppm tertiary butyl alcohol for 6 hr/day, 5 days/week for 18 days or to 2100 ppm for 13 weeks. However, focal areas of redness observed on the lungs of 4 of 10 animals following acute exposure to 10000 ppm suggest that tertiary butyl alcohol has the potential to cause respiratory tract irritation. Tertiary butyl alcohol does not belong to a chemical class known to cause corrosivity. Tertiary butyl alcohol is not classified as a skin irritant according to the Directive 67/548/EEC or EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008. Tertiary butyl alcohol will be classified under Regulation (EC) No. 790/2009 (1st ATP of CLP – effective 1.12.2010) as irritating to the respiratory system (STOT-SE; H335).

   

A mixture containing approximately 91% tertiary butyl alcohol did cause irritation in the unwashed eyes of 6/6 rabbits at the 96-hr observation period. All animals in this group were normal by Day 16. Tertiary butyl alcohol does not belong to a chemical class known to cause corrosivity, i. e., materials with pH <2 or > 11.5 nor is it classified under the Directive 67/548/EEC, EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 or UN-GHS for either skin corrosivity or irritation following 24-hr contact with intact or abraded rabbit skin. Based on a weight-of-the-evidence assessment, tertiary butyl alcohol will be classified under Regulation (EC) No. 790/2009 (1st ATP of CLP – effective 1.12.2010) as irritating to the eyes (H319).