Bromine

Endpoint summary

Description of key information

Bromine is a highly reactive substance which is well known to cause burns to skin and eyes. and is classified/labelled with symbol "C" (R35, causes severe burns) and "T+" (R26, very toxic by inhalation). Acute inhalation studies in animals have been submitted (Annex VIII Section 8.5.2) in support of the existing classification. Therefore in accordance with the conditions outlined under the column 2 adaptation for this endpoint, it is not necessary to conduct the acute oral or dermal toxicity tests.
In an acute inhalation exposure study in male albino mice, mortalities and time to death were measured for bromine as well as for chlorine, formaldehyde and sulfur dioxide. For bromine at a constant concentration, time of death depended markedly on exposure duration. The LT50 value for 750 ppm was 9 minutes, and for 240 ppm was 100 minutes. Median time of death at the LT50 value was 11 and 6 days, respectively.
The study by Bitron and Aharonson (1978) was considered by Oak Ridge National Laboratory to provide sufficient data for the derivation of the relationship between concentrations that resulted in lethality (LC50 values) and exposure duration that could be expressed as: C2.2x t = k. Based on the data, and using the relationship expressed, Oak Ridge National Laboratory calculated an overall LC50 value for this study to be 424 ppm for a 30 minute exposure.
Schlagbauer and Henschler (1967) found inhalation of bromine by groups of female NMRI mice led to severe irritation and corrosion of the respiratory tract. Death occurred through lung edema and bronchospasm secondary to the irritation. A 30 min LC50 of 174 ppm was derived. No mortality occurred after 3 hours of exposure to 22 ppm of bromine, while 7/10 animals died after exposure to 22 ppm of bromine for 6 hours. 40 ppm of bromine inhaled for 3 hours led to mortality of 3/10 animals, while 9/10 animals died after exposure to the same concentration for 6 hours. 

Key value for chemical safety assessment

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

discriminating conc.

Value:

0.7 mg/m³ air

Additional information

Bromine is a highly reactive substance which is well known to cause burns to skin and eyes and is classified/labelled with symbol “C” (R35, causes severe burns) and “T+” (R26, very toxic by inhalation). Acute inhalation studies in animals have been submitted (Annex VIII Section 8.5.2) in support of the existing classification. Therefore, in accordance with the conditions outlined under the column 2 adaptation for this endpoint, it is not necessary to conduct the acute oral or dermal toxicity tests.

In an acute inhalation exposure study in male albino mice, mortalities and time to death were measured for bromine as well as for chlorine, formaldehyde and sulfur dioxide. For bromine at a constant concentration, time of death depended markedly on exposure duration. The LT50 value for 750 ppm was 9 minutes, and for 240 ppm was 100 minutes. Median time of death at the LT50 value were 11 and 6 days, respectively.

The study by Bitron and Aharonson (1978) was considered by Oak Ridge National Laboratory to provide sufficient data for the derivation of the relationship between concentrations that resulted in lethality (LC₅₀values) and exposure duration that could be expressed as: C^2.2x t = k. Based on the data, and using the relationship expressed, Oak Ridge National Laboratory calculated an overall LC₅₀value for this study to be 424 ppm for a 30 minute exposure. 

Schlagbauer and Henschle (1967) found inhalation of bromine by groups of female NMRI mice led to severe irritation and corrosion of the respiratory tract. Death occurred through lung edema and bronchospasm secondary to the irritation. A 30 min LC₅₀of 174 ppm was derived. No mortality occurred after 3 hours of exposure to 22 ppm of bromine, while 7/10 animals died after exposure to 22 ppm of bromine for 6 hours. 40 ppm of bromine inhaled for 3 hours led to mortality of 3/10 animals, while 9/10 animals died after exposure to the same concentration for 6 hours.

The existing key studies show that acute toxicity of bromine is related initially to the corrosive effects of the substance. Data in both animals and humans indicate that there is an additional delay factor which affects the concentration at which acute toxic effects are observed. Based on the available animal data the LC50 (4 hr) is below 40 ppm. Clinical observations of humans after acute bromine exposure indicate that the toxic level could be lower than that observed in animals but there are no measured air borne concentrations in these cases.

An Indicative Occupational Exposure Level value (IOELV) given in Directive 2006/15/EC (8 hr IOELV = 0.7 mg/m³or 0.1 ppm) has been set for bromine. In view of the irritant effects on mucous membranes at comparable exposure concentrations the IOELV is also applicable for the potential for acute toxicity/irritation in humans.

Justification for classification or non-classification

Bromine is a highly reactive substance which is well known to cause burns to skin and eyes and is classified/labelled with symbol "C" (R35, causes severe burns) and "T+" (R26, very toxic by inhalation). Acute inhalation studies in animals have been submitted (Annex VIII Section 8.5.2) in support of the existing classification.