Potassium bromide

Toxicity to soil macroorganisms except arthropods

Description of key information

The toxic effects of Sodium Bromide (NaBr) on survival, growth, and reproduction of the earthworm Eisenia fetida were assessed during a test period of eight weeks based on the OECD Guideline 222. Taking into account the survival, growth and reproduction rates of the exposed adult test organisms, the highest concentration of Sodium Bromide (NaBr) without toxic effects was determined to be 32 mg/kg dry soil. The lowest concentration with toxic effects (LOEC) was 100 mg/kg dry soil due to a high mortality, statistically significant change in mean body weight, reduced food consumption and reduced reproduction rate of the worms at this test concentration.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

1 000 mg/kg soil dw

Long-term EC10, LC10 or NOEC for soil macroorganisms:

32 mg/kg soil dw

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.

Acute

A study to OECD 207 was performed to assess the acute toxicity of sodium bromide to the earthworm (Eisenia foetida) in an artificial soil. Earthworms were exposed to a range of concentrations of 10, 32, 100, 320 and 1000 mg bromide/kg of soil for a period of 14 days. The number of mortalities were determined after 7 and 14 days exposure. The No Observed Effect Concentration (NOEC) was 10 mg bromide/kg on the basis that no mortalities were observed after 14 days exposure and additionally no sub-lethal effects on weight or behaviour were observed at 10 mg bromide/kg.

Long term

The toxic effects of Sodium Bromide (NaBr) on survival, growth, and reproduction of the earthworm Eisenia fetida were assessed during a test period of eight weeks based on the OECD Guideline 222.

Sodium Bromide (NaBr) was homogeneously mixed into an artificial soil at the following test concentrations: 1.0, 3.2, 10, 32 and 100 mg per kg dry soil. Adult earthworms were exposed in treated soils for a period of four weeks. After this period, the adults were removed from the test vessels and the survival and growth rate were determined. The cocoons and juvenile earthworms remained in the vessels for additional four weeks. The reproduction rate was determined by counting the number of offspring hatched from the cocoons after this additional test period of four weeks.

Taking into account the survival, growth and reproduction rates of the exposed adult test organisms, the highest concentration of Sodium Bromide (NaBr) without toxic effects was determined to be 32 mg/kg dry soil. The lowest concentration with toxic effects (LOEC) was 100 mg/kg dry soil due to a high mortality, statistically significant change in mean body weight, reduced food consumption and reduced reproduction rate of the worms at this test concentration.