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Toxicological information

Carcinogenicity

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Description of key information

While no carcinogenicity study per se is available, a number of investigations have been conducted over the years to determine the initiation/promotion activity of di-tert-butyl peroxide (DTBP). Taken together, DTBP was inactive as an initiator or promotor. See Specific Investigations section 7.9.3 of IUCLID.   In addition, DTBP is not mutagenic in vitro. While DTBP was weakly positive in an in vivo IP micronucleus study (not a relevant route of exposure) and equivocal in an in vivo oral micronucleus study, it was negative in an in vivo micronucleus assay by inhalation, which is the most likely route of exposure and negative in a spermatogonal assay.  Therefore, DTBP is not expected to be carcinogenic based on a weight of evidence.  We are trying to work with the NL or BE Competent Authorities to remove the mutagenicity classification of 110-05-4 and 75-91-2 based on new in vivo studies, however, they wish to await the carcinogenicity study results of 75-91-2 (which was unfortunately required via testing decision prior to new definitive negative in vivo mutagenicity results) before assessing possible new CLH dossiers to remove mutagenicity.  Furthermore, there is a draft decision (SEV-D-2114360151-63-01/D) for carcinogenicity study testing on 110-05-4 which has been challenged and awaiting further feedback from the authorities.

Key value for chemical safety assessment

Carcinogenicity: via oral route

Link to relevant study records
Reference
Endpoint:
carcinogenicity: inhalation
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint conclusion
Endpoint conclusion:
no study available

Carcinogenicity: via inhalation route

Link to relevant study records
Reference
Endpoint:
carcinogenicity: inhalation
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint conclusion
Endpoint conclusion:
no study available

Carcinogenicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Justification for classification or non-classification

No carcinogenicity study is available. However, based on a weight of evidence, the registered substance is not expected to be carcinogenic.