Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Three ready biodegradation studies are available for Distilled tall oil, maleated. The ready biodegradation criteria were not met in any of these studies, however all the studies were extended beyond 28 days. In two OECD 301D studies > 60% biodegradation was observed in less than 60 days. In an OECD 301B study  the maximum level of biodegradation achieved  was  52%. 
Distilled tall oil maleated does not meet the criteria for readily biodegradability but does show a potential to degrade in the environment.

Key value for chemical safety assessment

Additional information

Three reliable ready biodegradation studies have been conducted for Distilled tall oil, maleated. Sowders (2014a and b) reports two extended OECD 301D screening studies. The two studies differ only in the concentration of innoculum used for the test (0.08 or 0.16 ml per litre). In both studies the ready biodegradation criteria were not achieved within 28 days (i.e. >60% oxygen consumption). Both studies did, however, show the potential for Distilled tall oil, maleated to achieve the ready biodegradation criteria within 60 days (with 63 and 67% oxygen consumption at high and low inoculum levels respectively after 60 days). Distilled tall oil, maleated is therefore not expected to persist in the environment.

Roulstone (2014) conducted a GLP study following OECD 301B and showed approximatly 50% biodegradation after 42 days. Distilled tall oil, maleated was not considered to be 'readily biodegradable' as it did not meet the strict terms of OECD Guideline No. 301B (i.e. >60% CO2 evolution after 28 days and within a 10 day window), however, there is evidence from this study that the test substance has the potential to degrade. The three extended 'ready biodegradation' studies show that while Distilled tall oil, maleated can not be considered 'readily biodegradable' it is not expected to persist in the environment.