2,6,10-Trimethyldodecane (Farnesane)

Biodegradation in soil

Description of key information

This study showed that the majority of [14C]Farnesane dissipated over time in all four soils (loam sand (Soil I), silt loam (Soil II and II), or silty clay loam (Soil IV)) at 12°C; the majority of the applied radioactivity was captured in the volatile traps.

Between 14.5% to 20.3% of applied radioactivity remained in the soils on Day 120 as bound radioactivity after all extractions had been carried out.  On day 120 the ‘harsh’ extractions removed 0.4, 0.5, 1.3 and 0.7% of the applied radioactivity for soil I, II, III, and IV respectively.  Therefore, these residues are not considered to be bioavailable and binding to soils was considered a pathway for disappearance.

Radio-TLC analysis of solvent extractions 1 and 2 showed the applied radioactivity was present as [14C]Farnesane, and no degradation products were detected.

On day 120 mineralisation accounted for 45.6, 38.8, 37.6 and 12.7% of the applied radioactivity in Soil I, II, III, and IV vessels, respectively, therefore Farnesane showed the potential to degrade.

For dissipation kinetic analysis the decline in [14C]Farnesane concentration was deemed to have occurred by degradation or transfer processes and was calculated using soil extracts only; bound residues were not considered to be bioavailable and were considered a method of disappearance.  The DT50 was calculated as 5.11, 5.01, 2.82 and 9.39 days for Soil I, II III, and IV vessels, respectively.

For degradation kinetic analysis the decline in [14C]Farnesane concentration was deemed to have occurred by degradation only, bound residues were considered to be 100% parent and not a mechanism for disappearance.  The DegT50 was calculated as 7.38, 7.68, 7.05 and 25.8 days for Soil I, II, III, and IV vessels, respectively.

Key value for chemical safety assessment

Half-life in soil:

9.39 d

at the temperature of:

12 °C