tert-butyl hydroperoxide

Endpoint summary

Description of key information

A total of four studies have been identified as having assessed the skin and eye irritation potential of TBHP in the rabbit (one key study and one supporting study per endpoint). The two key studies have been conducted according to a recognised guideline and performed under GLP. 

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Skin irritation

In the key study evidence of necrosis and long-term skin damage (not repaired 14 days post-treatment) were concluded to indicate corrosive action. While the supporting study found only low-level irritation, this may be explained by the method of test substance application (onto gauze pads, applied under plaster): in the key study direct application onto the skin was followed by an occlusive cover. Such direct application to the skin and occlusion was also employed in the key study of rat dermal toxicity cited elsewhere in this dossier: here (following application to abraded skin) areas of necrosis surrounded by an inflammatory ring and then skin blanching were recorded. Taken together, all of this information leads to a conservative conclusion that TBHP should be classified as corrosive.

Eye irritation

The key study showed that TBHP causes severe and irreversible damage to rabbit eyes (including iritis and corneal opacity persisting 21 days post-treatment).

The supporting study gives similar evidence of severe and persistent eye damage.

Respiratory irritation

A recent acute inhalation study has provided evidence of respiratory irritation in laboratory animals.

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: highly irritating

Respiratory irritation: Irritating

Justification for classification or non-classification

Skin irritation

Based on the results of the key study and the discussion noted previously, it is concluded that TBHP should be classified as corrosive. Although experimental evidence of full-depth skin destruction after 4h of skin contact is absent, the severity of the early reactions and the persistence of skin damage recorded in the key study (performed with aqueous 70% TBHP) are considered to warrant classification of TBHP as:

- Skin Corrosion Category 1C (causes severe skin burns and eye damage) under Regulation 1272/2008 (EU CLP)

Eye irritation

Based on the results of the key study and supporting studies, TBHP should be classified as:

- Corrosive Category 1 (causes serious eye damage) under Regulation 1272/2008 (EU CLP)

Respiratory irritation

A 70% (in water) solution of tert-butyl hydroperoxide (TBHP) has been evaluated for target organ toxicity following single exposures with no confounders identified.  Toxicokinetic data demonstrate rapid conversion of tertiary-butyl hydroperoxide to tertiary-butyl alcohol in vivo limiting the potential for systemic exposure. Morbidity seen in experimental studies around or even below the LD/LC50 is presumed to occur secondary to site of contact corrosion, the predominant effect of TBHP. Data from a new acute toxicity study indicates rapid onset of respiratory irritation at all doses, hence classification as a respiratory irritant is warranted. As such the substance is classified as STOT SE 3 (respiratory irritation) under Regulation EC No. 1272/2008, as adapted.