Potassium bromide

Endpoint summary

Description of key information

Oral: The LD50 was determined to be > 2000 mg/kg bw
Dermal: The acute dermal LD50 was determined to be > 2000 mg/kg bw. 
Inhalation: The substance is not volatile and extremely hydroscopic. It will not become airborne.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Additional information

Potassium bromide is an inorganic salt that dissociates to its composite ions in aqueous solutions at environmental pH and temperature. Comparison of the available data on the various bromide salts have shown that the bromide ion is the relevant ion for determination of the toxicological profile with simple cations such as potassium, sodium or ammonium, that are ubiquitous in nature, having little or no influence on the bromide ion properties. It is therefore justified to read-across data from other inorganic bromide salts to potassium bromide.

Oral

In a key acute oral toxicity study performed according to EPA OPP 81 -1 guideline and in compliance with GLP, groups (5/sex//dose) of CD strain of Sprague Dawley rats were given a single oral dose of Potassium bromide at 4000 and 5000 mg/kg bw. Animals were then observed for mortality, clinical signs and bodyweights for 14 days and were all sacrificed on Day 15 for macroscopic examination. Before the main study, a preliminary range-finding study was conducted with the dose-levels of 20, 200, 2000 and 5000 mg/kg bw.

Four animals (two males and two females) and one female were died at 5000 and 4000 mg/kg bw, respectively and deaths occurred 6-9 days after dosing. Clinical signs observed were prone posture, decreased motor activity, ataxia, hunched posture, eyelids partially closed, piloerection, bradypnoea, pigmented orbital secretion, thinness, urogenital staining and failure to groom. Treatment related signs had resolved 10 days after dosing. Several survivors had lost weight when weighed a week after dosing, but normal body weight gains were achieved at the second week following administration of test material. No abnormality related to treatment was observed in animals sacrificed at termination. In animals dying during the observation period changes considered related to treatment with Potassium bromide included: externally, emaciation, muzzle, urogenital and periorbital staining. Internally, in the stomach, duodenum, jejunum, ileum, caecum, colon and rectum, haemorrhagic contents were noted. On the gastric glandular mucosa, congestion, haemorrhage, dark foci and ulcerations were noted; on the non-glandular mucosa dark foci and wall thickening were observed. Other lesions included meningeal vascular congestion, darkening of the kidneys, mucosal congestion of the urinary bladder and blood stained or haemorrhagic contents. In this study, the combined oral LD50 of Potassium bromide was considered to be higher than 5000 mg/kg bw in rats.

In a second key acute oral toxicity study (limit test) performed according to OECD Guideline 401 and in compliance with GLP, group (5/sex/dose) of Ico : OFA.SD. (IOPS Caw) rats were given a single oral (gavage) dose of potassium bromide at 2000 mg/kg bw. Animals were then observed for mortality, clinical signs and bodyweights for 14 days and were all sacrificed for macroscopic examination.

No mortality was observed. All animals showed subdued behaviour from 15 minutes after administration of the test article to Day 2 as well as infrequent stools on Day 2. All animals were normal from Day 3 onwards. Body weight was not affected by treatment. No macroscopic abnormalities were observed at study termination on Day 15. In this study, the combined oral LD50 of Bromure de Potassium was considered to be higher than 2000 mg/kg bw in rats.

In a supporting study performed to OECD 401 5 rats/sex/dose group were each given a single dose of sodium bromide by gavage in 20 mL of 1 % aqueous methylcellulose. Clinical observations were made over the following 14 days including weekly bodyweight measurements. At death during the study period, or sacrifice at study termination, the animals were subjected to a macroscopic post mortem examination. An LD50 was determined from the observation data. Females: 3900 mg/kg bw, males: 4500 mg/kg bw (equivalent to females: 3028 mg (Br-)/kg bw, males: 3492 mg (Br-)/kg bw) Males + females combined: 4200 mg/kg bw (equivalent to: 3260 mg (Br-)/kg bw)

 

Inhalation

The bromide ion is not a volatile species [sodium bromide, vapour pressure value of 1.8 x 10-6 Pa, potassium bromide melting temperature > 300°C], it remains in the water phase. Furthermore, Potassium bromide is a hygroscopic inorganic solid. The substance has to maintained at elevated temperatures in a dry environment to maintain the powdered form. Introduction to atmospheric moisture causes clumping and hydration of the substance. The hygroscopic nature of the substance means it is unlikely to form dusts or inhalable aerosols. Therefore, exposure to significant quantities of bromide ions by direct inhalation is not likely to occur.

 

Dermal

5 Rabbits/sex were each given a single application of 2000 mg/kg bw the test substance moistened with 1 mL/kg water. Clinical observations were made over the following 14 days including weekly bodyweight measurements. At death during the study period, or sacrifice at study termination, the animals were subjected to a macroscopic post mortem examination. An LD50 was determined from the observation data.

LD50: >2000 mg/kg bw (both sexes)

(equivalent to: >1552 mg (Br-)/kg bw (both sexes))

Justification for classification or non-classification

Based on the experimental results, potassium bromide is not classified for acute toxicity by the oral, inhalation or dermal routes.