2,2,5-trimethyl-5-pentylcyclopentan-1-one

Bioaccumulation: aquatic / sediment

Description of key information

Weight of evidence approach with two experimental studies and two QSAR results:
BCF = 43-883.
In conclusion, the registered substance is considered to be bioaccumulative according to CLP criteria (>500) but not considered to be bioaccumulative according to PBT criteria (< 2000). 

Key value for chemical safety assessment

BCF (aquatic species):

883 dimensionless

Additional information

To assess the bioaccumulation potential of the registered substance, a weight of evidence approach was used using two experimental studies and two QSAR results.

The first experimental study (Huntingdon, 1984; Klimisch score 2) was performed on the registered substance, according to OECD Guideline 305C (with some deviations) but without GLP statement. The carp Cyprinus carpio were exposed to two nominal exposure levels (level 1: 0.1 ppm; level 2: 0.01 ppm) during the exposure period of 8 weeks, in order to calculate the Bioconcentration factor (BCF). This study was performed at 25 ± 2 °C and the dissolved oxygen concentration was 7 mg/L. Test water and fish analysis were performed on Weeks 2, 3, 4, 6 and 8 using Gas Chromatography (GC). No mortalities or other signs of intoxication were observed in either test or control fish during the study. BCF values of test substance were in the ranges of 156-883 at level 1 and 43-508 at level 2. Therefore, the BCF is comprised between 43 and 883.

The second experimental study (Kyushu, 1986) was performed on the registered substance, according to OECD Guideline 305C (with some deviations) but without GLP statement. The carp Cyprinus carpio were exposed to two nominal exposure levels (level 1: 0.1 mg/L; level 2: 0.01 mg/L; each of means exposure concentrations were about 60 -70% of nominal value) during the exposure period of 8 weeks, in order to calculate the Bioconcentration factor (BCF). This study was performed at 25 ± 2 °C and the dissolved oxygen concentration was comprised between 5.3 and 6.5 mg/L at level 1, and 5.0 to 5.9 mg/L at level 2. Test water analysis was performed twice a week (n = 1) and test fish analysis was performed every two weeks [(2, 4, 6 and 8th week); n = 2 (except for fish analysis at 4th week in level 2)] using Gas Chromatography (GC). No abnormality in behaviour and appearance was observed. BCF values of test substance were in the ranges of 180-402 at level 1 and 71 -341 at level 2. Therefore, the BCF is comprised between 71 and 402. This result should be considered with caution because based on data lacking on temperature variation, all validity criteria cannot be assess.

In addition to experimental studies, QSAR predictions were performed on the registered substance using the BCFBAF model v3.01 from EPI Suite v4.1, which fulfilled all OECD principles. This model estimates BCF using two separate estimation methodologies: using the compound's log octanol-water partition coefficient (Kow) and the Arnot-Gobas method. The BCF value using the log Kow value was estimated at 586.2 L/Kg. The BCF value using Arnot-Gobas method was estimated between 335 and 459 L/kg, including biotransformation rate estimate.

In conclusion, according to this weight of evidence approach, the BCF of the registered substance is comprised between 43 and 883. In order to consider a worst case approach, the greater BCF value at 883 is retained for chemical safety assessment.