2,4,6-tribromophenol

Biodegradation in water: screening tests

Description of key information

As there was no stand alone key study which could fulfil the requirements of the endpoint available, a weight of evidence approach was taken to determine the biodegradation potential of the test substance in water using the collective conclusions of the  available data.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Reference: Herbert, M. (1975)

Reliability: 2

Results: The report concludes that Ann Arbor waste water bacteria are capable of biodegrading Na+TBP in the proper media. This media being Ann Arbor raw sewage which contains basically 99.5% water and domestic waste. In an enriched culture media, where other nutrients have been added, Na+TBP is not biodegraded significantly. It is postulated that bacteria will degrade Na+TBP significantly only when there is a scarcity of other nutrients present.

As the report text does not specify the % removal of the test material in the 4 cultures tested, and the data plot for the second culture (described above in detail; 53 ppm test material in 500 ml of non-diluted raw sewage) is missing from the end of the report, it cannot be determined from this study alone whether the degradation of the test material observed was due to inherent or ready biodegradation.

 

Reference: Herbert, M. (1976)

Reliability: 3

Results: Although the conclusions drawn from the summary are "under test conditions no biodegradation observed”, this lack of biodegradation was attributed to the other materials in the waste water which the bacteria preferentially employ as a food source.

 

Reference: Steward, C.C. et al. (1995)

Reliability: 2

Results: Under research-specific conditions the substance is readily biodegradable. Rapid (36 hours degradation of 2,4,6-tribromophenol (via a reductive debromination process with transformation to 4-bromophenol) was observed in enriched cultures of bacteria isolated from a marine sediment. Although this degradation rate may only be applicable to these specific conditions, and may not be representative of environmental systems it is important to note that the aim of the study was to isolate bacteria from marine sediment capable of degrading the test material, which was successfully achieved.

 

Reference: Abrahammson, K. and Klick, S. (1991)

Reliability: 2

Results: Rapid debromination of 2,4,6-tribromophenol, was observed at 6, 20, and 30 °C in two of the sediments used in the test (degraded within "a few days"). In the third sediment, the degradation was slow (however the rate was not specified). 2,6-dibromophenol was observed as a degradation product, which subsequently disappeared similarly. Although there is variation between in the ability of the different sediments in biodegrading the test substance, degradation was noted in all three of the cultures employed in this test.

 

Although, no one defining study was available to assess the potential for ready biodegradation of the test substance, it can be reasonably concluded that the test material is readily biodegradable in both freshwater and marine conditions.