1,3,4,6,7,8a-hexahydro-1,1,5,5-tetramethyl-2H-2,4a-methanonaphthalen-8(5H)-one

Bioaccumulation: aquatic / sediment

Description of key information

Study Title:PICONIA : A Flow-Through Bioconcentration Screening Test with Rainbow Trout (Oncorhynchus mykiss). OECD 305. Project number:558A-116 (RIFM , 2011).

Additional data on Piconia (previous trade name for Isolongifolanone) - a Fish Bioaccumulation study supports the result of 'Not Readily Biodegradable' from biodegradability study.

Rainbow trout (O. mykiss) were exposed to a single test concentration of PICONIA (CAS No. 23787-90-8) of 44.5 µg a.i./L.  A Kinetic Bioconcentration Factor (BCFk) of 381 L/kg wet wt was determined.

Additional information

Key Value for Chemical Safety Assessment -  BCFk  381 L/kg wet wt.

Rainbow trout (O. mykiss) were exposed to a single test concentration of PICONIA (CAS No. 23787-90-8).  The nominal concentration of 50 µg a.i./L was selected in consultation with the Sponsor and is approximately 1% of the estimated LC50 concentration.  Fish were exposed in a single tank.  No Control groups were used in this test.  The test was divided in to two phases.  Uptake and Depuration.  During the Uptake phase, the fish were exposed under flow-through conditions to a sub-lethal concentration of the test substance at 12 ± 1°C.  The duration of the Uptake phase was 28 Days and the Depuration phase was 15 Days.  During both phases of the test, test organisms and water samples were collected and analysed for test substance content to determine the Uptake Rate Constant (k₁), the Depuration Rate Constant (k₂), and, subsequently< the kinetic bioconcentration factor (BCFk) for whole-body tissues.  On each sampling day, six fish were collected and composited to make one sample, with four composite samples being collected at each sampling day for each treatment group.

Physical and Chemical Measurements of Water – Water temperature ranged between 12.0 and 12.6°C.  Dissolved oxygen concentrations remained ≥ 8.0 mg/L (74% saturation) throughout the test.  Water pH ranged from 8.0 to 8.3.  Total Organic Carbon in the test chambers was < 1 mg C/L throughout the test.

Observations of Mortality and Clinical Signs of Toxicity – All fish in the treatment group appeared normal throughout the test with no treatment-related mortalities or signs of toxicity.

Concentrations of PICONIA in Water – The nominal test concentration was 50 µg a.i./L.  The measured concentrations of PICONIA in the exposure water ranged from 83.9 to 92.4% of nominal, with a mean of 89% (44.5 µg a.i./L) throughout the study.

Concentrations of PICONIA in Fish Tissues – The mean measured tissue concentration of PICONIA in whole fish at Day 28 of the Uptake phase was 16.95 µg a.i./g.

The Kinetic BCF (BCFk) value for PICONIA in Rainbow Trout (O. mykiss) was calculated for the 44.5 µg a.i./L treatment group (mean measured concentration) using a reduced sampling guideline study.  The BCFk value for PICONIA in whole fish tissue was determined to be 381 L/kg wet wt.  The estimated time to reach 90% of steady state during the Uptake phase was 9.14 days.  The Day 14 Depuration tissue concentration was approximately 3% of the Day 28 Uptake mean tissue concentration.  The estimated time to reach 50% clearance for whole fish tissue concentrations was established to be 2.75 Days.

CONCLUSIONS

The Kinetic BCF (BCFk) value for PICONIA in Rainbow Trout (O. mykiss) was calculated for the 44.5 µg a.i./L treatment group (mean measured concentration) using a reduced sampling guideline study. The BCFk value for PICONIA in whole fish tissue was determined to be 381 L/kg wet wt. The estimated time to reach 90% of steady state during the Uptake phase was 9.14 days. The Day 14 Depuration tissue concentration was approximately 3% of the Day 28 Uptake mean tissue concentration. The estimated time to reach 50% clearance for whole fish tissue concentrations was established to be 2.75 Days.