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Environmental fate & pathways

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Description of key information

Bioaccumulation : aquatic/sediments:

The growth-corrected BCFvalue for test chemical was determined to be 10395 L/kg and non-growth corrected BCF determined 6695 l/kg in a dietary bioaccumulation study with rainbow trout (Oncorhynchus mykiss). By considering the above mentioned BCF value test chemical is considered to be very bioaccumulative in nature.

Additional information

Bioaccumulation : aquatic/sediments:

Experimental study for target chemical and supporting predicted studies have been reviewed for bioaccumulation of test chemical endpoint and their results are summarized below.

To determine BCF value of test chemical a dietary bioaccumulation study was performed with rainbow trout (Oncorhynchus mykiss) was carried out with styrenated phenol. The substance tested was a mixture of distyrenated phenol (40 per cent by weight) and tristyrenated phenol (60 per cent by weight). The study consisted of a 10-day uptake period, during which the fish were fed a diet spiked with the test substance, followed by a 42-day depuration period where the fish were fed uncontaminated diet. Hexachlorobenzene was used as positive control. The spiked food was prepared by using solvent and fish oil. The test system used was a flow-through system.

One replicate was carried out per test group with each replicate consisting of 125 fish in either 140 litres of water (test substance exposure) or 110 litres of water (control and positive control group). The initial loading rates were therefore 0.57 g fish/litre/day for the group exposed to the mixture of di/tristyrenated phenol and 0.059 g fish/litre/day for the control and positive control group. A daily feeding rate of three per cent of the body weight was used during the study.The fish were observed daily for mortality, behaviour and other effects. The levels of distyrenated phenol and tristyrenated phenol in the exposed fish were determined analytically on days 0, 1, 5 and 10 of the uptake phase and days 1, 2, 4, 7, 14, 28 and 42 of the depuration phase (ten fish were analysed at each sampling point).

The uptake and depuration pattern for tristyrenated phenol shows increasing concentrations with time over the entire exposure period followed by decreasing concentrations during the depuration period thw growth-corrected depuration half-life in the fish was around 18.4 days. The growth-corrected BCFvalue for test chemical was determined to be 10395 L/kg and non-growth corrected BCF determined 6695 l/kg in a dietary bioaccumulation study with rainbow trout (Oncorhynchus mykiss). By considering the above mentioned BCF value test chemical is considered to be very bioaccumulative in nature.

Further, to corroborate the above study prediction was done by using BCFBAF Program (v3.00) model of EPI suite (2018) in this prediction the bio concentration factor (BCF) for test chemical distyrenated phenol was estimated to be 11440 L/kg wet-wt at 25 deg. c tristyrenated phenol. Therefore it is concluded that test chemical is very bioaccumulative in food chain.

In addition to it one prediction was done by using BCFBAF Program (v3.00) model of EPI suite (2018) the estimated bio concentration factor (BCF) for test chemical tristyrenated phenol is 3246  L/kg wet-wt at 25 deg. c which  exceeds the bioconcentration threshold of 2000. Therefore it is concluded that test chemical bioaccumulative in food chain.

By considering results of all the studies mentioned above it is concluded that BCF value of test chemical is in range of 3246- 11440 L/kg. This range BCF value exceeds the bioconcentration threshold of 2000 which indicates that test chemical is very bioaccumulative in aquatic organisms.