Registration Dossier

Administrative data

Key value for chemical safety assessment

Additional information

Formally, the REACH Annex XI standard testing regime adaptation options of 1.5 – Grouping of substances and read-across approach and 2. – Testing technically not possible, apply to trimethyl borate: As the borate will not exist in an organism for longer than one second, it is technically not possible to test its effects. Additionally, REACH Annex XI lists substances with ‘common precursors and/or the likelihood of common breakdown products via physical and biological processes, which result in structurally similar chemicals’, as qualifying for read-across.

Based on the instant hydrolysis of trimethyl borate to release boric acid (see IUCLID section 5.1.2 and analogue approach rationale in section 13), genetic toxicity information from boric acid is taken forward for hazard characterisation.


Short description of key information:
Due to the immediate hydrolysis of trimethyl borate under physiological conditions, data on the hydrolysis product boric acid are applied in the hazard assessment for genotoxicity.
In vitro gene mutation studies in bacteria (Stewart, 1991) in vitro gene mutation studies in mammalian cells (Rudd, 1991) and in vitro cytogenicity studies (NTP, 1987) concluded that boric acid is not genotoxic under the conditions of the studies. In addition the results of an in vivo bone marrow cytogenetic assay (chromosome aberration assay, O’Loughlin 1991) also showed boric acid to be non genotoxic.
Cytotoxicity observed at 5 mg/mL in the in vitro gene mutation studies in mammalian cells (Rudd, 1991).

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

No classification is required for trimethyl borate as the hydrolysis product boric acid did not show any potential for genotoxicity in multiple studies.