Hydrogen bromide

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Additional information

Though there is minimal animal repeat dose data available for hydrogen bromide (HBr)(supporting study provided in Section 8.6.1: 20-day repeat inhalation dose study in the rat), there is sufficient data available on the analogue substance hydrogen chloride (HCl) (Section 8.6.1 and 8.6.2; inhalation exposure) to indicate an appropriate level for hazard identification for the main route of exposure (i.e., inhalation). Further human data from accidental exposure (Section 8.6.4) indicates that primary toxic effects from exposure will occur at levels below which secondary effects on development and reproductive effects could occur. Because of the identified effects of HBr risk mitigation measures are in place to prevent exposure. The available data on the analogue HCl has been used for indication of an EU Indicative Occupational Exposure Level value (IOELV) for HBr given in Directive 2000/39/EC (15 minute IOELV limit = 6.7 mg/m³or 2 ppm). ECHA Guidance states that an EU IOELV can be used in place of a derived DNEL.  Additional routes of exposure (i.e., oral or dermal) are not considered as appropriate routes for determination of repeat dose toxicity. HBr is a substance that rapidly undergoes changes in contact with moisture – either in the air or in contact with respiratory or oral tissues (See Annex VIII Section 9.2.2.1 Hydrolysis). HBr is generally unmeasurable in the body as it changes directly to hydrobromic acid in water forming hydrogen and bromide ions. In air it may form bromine but the reaction pathway ultimately ends with the formation of bromide ions (Annex VIII Section 8.8.1 Toxicokinetics assessment). It is generally accepted that bromide is the chemical moiety of concern for long-term assessment of systemic HBr toxicity.

Short description of key information:
Though there is minimal animal repeat dose data available for hydrogen bromide (HBr)(supporting study provided in Section 8.6.1: 20-day repeat inhalation dose study in the rat), there is sufficient data available on the analogue substance hydrogen chloride (HCl) (Section 8.6.1 and 8.6.2; inhalation exposure) to indicate an appropriate level for hazard identification for the main route of exposure (i.e., inhalation). Further human data from accidental exposure (Section 8.6.4) indicates that primary toxic effects from exposure will occur at levels below which secondary effects on development and reproductive effects could occur. Because of the identified effects of HBr risk mitigation measures are in place to prevent exposure. The available data on the analogue HCl has been used for indication of an EU Indicative Occupational Exposure Level value (IOELV) for HBr given in Directive 2000/39/EC (15 minute IOELV limit = 6.7 mg/m3 or 2 ppm). ECHA Guidance states that an EU IOELV can be used in place of a derived DNEL.
Additional routes of exposure (i.e., oral or dermal) are not considered as appropriate routes for determination of repeat dose toxicity. HBr is a substance that rapidly undergoes changes in contact with moisture – either in the air or in contact with respiratory or oral tissues (See Annex VIII Section 9.2.2.1 Hydrolysis). HBr is generally unmeasurable in the body as it changes directly to hydrobromic acid in water forming hydrogen and bromide ions. In air it may form bromine but the reaction pathway ultimately ends with the formation of bromide ions (Annex VIII Section 8.8.1 Toxicokinetics assessment). It is generally accepted that bromide is the chemical moiety of concern for long-term assessment of systemic HBr toxicity.