Reaction mass of 2-(1,1-dimethylpropyl)anthraquinone and 2-(1,2-dimethylpropyl)anthraquinone

Bioaccumulation: aquatic / sediment

Description of key information

Two studies on bioaccumulation and biomagnification in fish were available. The study on biomagnification in fish is considered to be not reliable, but the study on bioaccumulation in fish was performed comparable to the OECD305 test guideline. At a concentration of 0.05 mg/L, hence below the water solubility (0.15 mg/l) the BCF of the two components has a mean value of 1215 L/kg ww, which was used for risk assessment purposes.

Key value for chemical safety assessment

BCF (aquatic species):

1 215 L/kg ww

Additional information

Two studies describing bioaccumulation and biomagnification of the substance in fish are available.

The first study was performed comparable to OECD305 test guideline. Fish, carp, were exposed to the test substance for 8 weeks in a flow-through system, followed by 8 days of depuration in clean water. Nominal concentrations of 0.05 and 0.5 mg/L were tested. Water samples were removed from treated aquaria after 2, 4, 6 and 8 weeks of uptake. Two-three fish were sampled from treated aquaria after 2, 4, 6 and 8 weeks of uptake and after 3 and 8 days of depuration. Whole fish and water samples were analysed for residues of the test substance. In addition, after 8 weeks of uptake two fish were dissected into head area, skin, internal organs and edible areas, and the different portions were analysed for residues of the test substance. It was reported that during external observations the test fish appeared normal. The concentrations of 2-(1,1-dimethyl propyl)anthraquinone (Peak A) and 2 -(1,2 -dimethyl propyl)anthraquinone (Peak B) in the aquarium water were measured and the concentration rate (BCF) calculated. The measured concentrations of peak A and peak B in the test water were fairly stable during exposure, and represented 77-92% of the target concentration at a nominal concentration of 0.5 mg/L, and 69-83% of the target concentration at a nominal concentration o 0.05 mg/L. The residues in fish of both peak A and peak B appeared to have reached a plateau concentration after 6 weeks of exposure at a nominal concentration of 0.5 mg/L, and after 4 weeks of exposure at a nominal concentration of 0.05 mg/L. The average BCF during the plateau was 2919 and 1185 L/kg at 0.5 and 0.05 mg/L, respectively, for peak A and 2192 and 1245 L/kg at 0.5 and 0.05 mg/L, respectively, for peak B. At a concentration of 0.05 mg/l, hence below the water solubility (0.15 mg/l) the BCF of the two components has a mean value of 1215 L/kg ww.

At 0.5 mg/L, after 3 and 8 days of depuration in clean water, respectively, the residues of peak A and peak B represented 57-58% and 61-62% of those at the end of the uptake phase. The duration of the depuration phase is too short to evaluate the depuration behaviour of peak A and peak B. The CT50 and CT90 of peak A and B are >8 days.

At 0.05 mg/L, after 3 and 8 days of depuration in clean water, respectively, the residues of peak A and peak B represented 56-58% and 8.6-10.0% of those at the end of the uptake phase. Hence the CT50 of peak A and B is about 3 days, and the CT90 about 8 days.

The second study, provides data on residue levels of 2-amylanthraquinone in carp following feeding of the test fish with feed contaminated with the test material at 3000 mg/kg at rate 0.5% of fish body weight per day. This data could, potentially, be useful for PBT assessment (i.e., to assess whether the Bio-Magnification Factor (BMF) is <1). The study indicates a BMF of 0.00073 or 0.0012 kg food/kg fish, depending on the method of administration. However, there are several comments on the study conduct. Firstly, the study employed yearling carps (weighing about 25 g), rather than juvenile carps (weighing a few grams). The feed intake of juveniles per kg body weight is much higher than that of yearlings. A study using juvenile carp fed at the maximum possible rate may give a much higher BMF, provided that there are no uptake rate limiting factors. Secondly, the study was conducted using a concentration of 3000 mg/kg food. This concentration is likely to be very high compared to concentrations which occur in the environment. Only test material which is in the dissolved state in the intestinal tract of the fish may be available for uptake. As the solubility in water of the test substance (0.15 mg/L at 20°C) is very low, it may be rate limiting for uptake. An indication that concentration in feed is indeed rate limiting was obtained from a pre-test described in the same paper, with single feeding of treated feed (3000 mg/kg) at rate 0.25%, 0.5% and 1.0% of fish body weight, in which 16 hours after feeding concentrations in fish were measured of 0.87, 1.36 and 1.82 mg/kg, respectively, with corresponding BMF values of 3.5, 2.7 and 1.8 kg food/kg fish, respectively. Hence, where the total amount of test material administered with feed increased by a factor of 4, the BMF decreased by a factor of 2. Therefore, the study does not provide a reliable estimate of the BMF in fish, and the study was disregarded.