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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

The effect values for the bioaccumulation in aquatic species (fish) endpoint for the target substance Technical Grade have been generated by interpolation from the experimental test data on the source substances Distilled and Distillation Residue Grades. In this context interpolation is considered to be the ‘estimation of a value for a member of the group using measured values from other members on both sides of that member within the defined group spectrum’ (ECHA 2008: Guidance on information requirements and chemical safety assessment. Chapter R.6: QSARs and grouping of chemicals).


 


The interpretation of the data for the bioaccumulation in aquatic species endpoint has been complicated by the fact that the OECD TG305 study on Distilled Grade used an aqueous exposure route and generated Bioconcentration Factors (BCFs) for the different forms of cardanol (i.e. monoene, diene, triene and saturated side chain) measured. In contrast, the dietary route had to be used in the corresponding study on Distillation Residue Grade due to technical problems in conducting the test via an aqueous exposure route. However, it was possible to generate estimated BCFs values from the data from the dietary exposure study.


 


For Distilled Grade the Bioconcentration Factors (BCFs) for the four different forms of cardanol (monoene, diene, triene and saturated side chain) in the UVCB showed that accumulation in fish was always below 900 L/kg at each sampling point (Days 1, 3, 7, 14, 21 and 28). Due to the low levels of accumulation during uptake no depuration phase was conducted. Since the individual BCF values obtained, both before and after lipid normalisation, were below the threshold value of 2000 L/kg in all cases Distilled Grade is not considered to be bioaccumulative.


 


For Distillation Residue Grade dietary Biomagnification Factors (BMFs) and overall depuration rate (k2) constants were derived for the three forms of cardanol measured. Bioconcentration Factors (BCFs) were also derived using the data generated in the study. The tentative BCF values (L/kg) derived from the study (based on the methods of Brooke and Crookes, 2012 and Inoue et al 2012) were 837-893, 414-478 and 280-362 for the monoene, diene and triene forms of cardanol respectively. These values are significantly below the 2000 L/Kg threshold for a substance to be considered to be bioaccumulative. The estimated BCF values (L/kg) for the different forms of cardanol based on the k2 values (and the Brooke and Crookes, 2012 method) are 672, 333 and 245 for the monoene, diene and triene forms of cardanol respectively. These results also indicate that the different forms of cardanol (monoene, diene and triene) did not markedly bioaccumulate and were significantly below the 2000 L/Kg threshold. As a result the test substance Distillation Residue Grade is not considered to be bioaccumulative. The estimated BCF values for the different forms of cardanol in the dietary study are consistent with those from the Distilled Grade study carried out via the aqueous exposure route.


 


On the basis of the data generated in the studies on Distilled and Distillation Residue Grade for the different forms of cardanol the test substance Technical Grade is not considered to be bioaccumulative.

Key value for chemical safety assessment

BCF (aquatic species):
900 L/kg ww
BMF in fish (dimensionless):
0.039

Additional information

It was planned to use the aqueous exposure route in both studies for ease of comparison of the resulting data.  Therefore, conduct of the test on Distillation Residue Grade via the aqueous exposure route has been attempted at two different test laboratories. In the first study it did not prove possible to obtain a sufficiently sensitive and reliable analytical method to quantify the different key forms of cardanol (monoene, diene and triene) present in Distillation Residue Grade. In the second study at another laboratory a suitable analytical method was developed and validated. However, water sample analysis showed that it was not possible to maintain stable exposure concentrations of the different forms of cardanol in the Distillation Residue Grade test. Therefore, the study was carried out using the Dietary Exposure Bioaccumulation in Fish Test Method in OECD TG305 primarily resulting in the generation of Biomagnification Factors (BMFs) for the different forms of cardanol measured. However, it was possible to generate estimated BCFs values from the data from the dietary exposure study.


 


 


In a valid (reliable without restrictions, Klimisch Code 1) OECD TG305 Bioaccumulation in Fish study on Distilled Grade Bioconcentration Factors (BCFs) were generated for the four forms of cardanol, the triene (m/z 297), diene (m/z 299), monoene (m/z 301) and saturated side chain (m/z 303) measured. The study design involved exposing groups of juvenile carp (Carpio carpio) to concentrations of 0.3 and 3.0 µg/l over a 28 day uptake phase in a flow-through system. A depuration phase was included in the study if there was significant accumulation of the different forms of cardanol during the uptake phase. Stock solutions of Distilled Grade were prepared in dimethylformamide (DMF) and dosed via a computer-controlled system consisting of micro-dispensers into a mixing flask separately from the dilution medium supply (ISO medium). Medium was supplied via a flow meter at a rate of 16 L/h. In the mixing flask, the dosed stock solution volume and the dilution medium were mixed at a ratio of 1:10,000 with continuous stirring. At the start of the exposure period, 44 fish were exposed to each test concentration and 23 fish were exposed to a DMF control. Samples were taken from the test medium and from the fish on days 1, 3, 7, 14, 21 and 28 during the exposure period. Individual fish length and weight and body lipid content were measured throughout the study to determine potential effects of these factors on measured body concentrations of the different forms of cardanol.


 


The measured concentrations in most fish samples were below the limit of detection (LOD) of the analytical method (i.e. <30 µg/kg). Where the concentrations in fish were below the LOD, the BCF was indicated to be <100 L/kg. All other, calculated, BCFs are indicative because the measured concentrations in fish were determined by extrapolation.


 


A reliable without restrictions (Klimisch Code 1) definitive dietary study has been carried out according to the OECD TG305 method using a total of 50 juvenile rainbow trout (Oncorhynchus mykiss) in each of the control and treatment tanks. The dietary exposure study incorporated a 14 day uptake phase where test animals were exposed to diet spiked with 1000 mg/kg Distillation Residue Grade followed by a 21 day depuration phase where animals were fed unspiked diet. Fish in the control tank were fed unspiked diet throughout the study. Fish were sampled on day 14 of the uptake phase and on days 1, 4, 7, 14 and 21 of the depuration phase. The concentrations of the three key forms of cardanol present in the test substance (monoene, diene and triene) were measured in the spiked diet and fish tissues.


 


During the uptake phase levels of the three forms of cardanol increased in the animals receiving the spiked diet. The mean concentrations on day 14 (the measured time zero concentrations) were 7.46 µg/g for the monoene form, 3.91 µg/g for the diene form and 2.80 µg/g for the triene form. These constituents of the test substances were not detectable in fish from the control tank which received unspiked diet. During the depuration phase elimination of the accumulated forms of cardanol was rapid and 95% loss had been measured for both the diene and triene forms by day 7 and by day 14 for the monone form (where elimination after 7 days was 84%). All forms of cardanol were below the limit of quantification (<0.10 µg/g) by either depuration day 14 (diene and triene forms) or day 21 (monoene form). The time to reach 50% clearance of the monoene, diene and triene forms of cardanol was 1.653, 0.929 and 0.676 days respectively.

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