[3R-(3α,3aβ,7β,8aα)]-1-(2,3,4,7,8,8a-hexahydro-3,6,8,8-tetramethyl-1H-3a,7-methanoazulen-5-yl)ethan-1-one

Biodegradation in water and sediment: simulation tests

Description of key information

Natural surface water was treated with [14C]-methyl cedryl ketone at nominal application rates of 10 μg/L and 100 μg/L. Treated surface water samples were kept in test vessels sealed with 2-way taps and incubated with continuous stirring to maintain aerobic conditions at 12 ± 2℃ in darkness for periods of up to 61 days.

DT50 and DT90 values for the decline of methyl cedryl ketone from the surface water are shown below.

Compartment                                            Nominal 10 μg/L                                      Nominal 100 μg/L

                                                           DT50 (days)      DT90 (days)                 DT50 (days)      DT90 (days)

Water                                                    34.4                    233                               39.3                    130

Methyl cedryl ketone in surface water treated at 10 μg/L and 100 μg/L degraded to two major unknown degradation products; unknown B with retention time of 19.7 minutes (up to 15.4% AR; tentatively identified as a di-oxygenated and hydrated form of methyl cedryl ketone with a molecular formula of C17H28O3) and unknown C with retention time of 21.3 minutes (up to 12.9% AR; tentatively identified as a di-oxygenated form of methyl cedryl ketone with a molecular formula of C17H26O3).

Low levels of mineralization were observed, accounting for a maximum of 0.7% AR as carbon dioxide. Volatile radioactivity, confirmed as methyl cedryl ketone, adhered to the test vessel adapter heads and to the plastic tubing of the trap lines between the test vessel and the first trapping vessel.

Key value for chemical safety assessment

Half-life in freshwater:

34.4 d

at the temperature of:

12 °C