Aniline

Bioaccumulation: aquatic / sediment

Description of key information

Does not accumulate in aquatic/sediment organisms

Additional information

"There is only one reliable study available concerning the bioaccumulation of aniline in fish (Zok et al., 1991). Brachydanio rerio was exposed to 14C-labelled aniline at a concentration of 0.2 μg/L under static conditions. The amount of radioactivity in the medium was kept constant by adding stock solution if required. After reaching a steady state of uptake and elimination, the remaining fish were transferred to a flow-through system containing clean water. A BCF of 2.6 ± 0.06 was determined. This result is in accordance with the measured log Kow of 0.9. The result shows no indication of a bioaccumulation potential due to the exposure of the organisms via water.

The bioavailability of the reaction product of aniline with humic acids in sediment was examined in a test with the benthic oligochaete Lumbriculus variegatus that was performed in parallel to a sediment toxicity test (Egeler and Nésa, 2002). The sediment used in the test was an artificial sediment consisting of 5% peat, 20% kaolinite clay and 75% quartz sand. The sediment had a mean organic matter content of 2± 0.5% . As food source for the test organisms urtica powder in a concentration of 0.5% of sediment dry weight was added. The test substance was added to the sediment as an aqueous solution. The test system was allowed to equilibrate for 48 hours before the worms were introduced. The oligochaetes were exposed to a nominal aniline concentration of 31.25 mg/kg dw for 28 days at 20 ± 2°C using a static system. Four replicate chambers, each containing 1-2 g wet weight of worms, were maintained. The worms were not fed throughout the test. Gentle aeration was used throughout the test, with the vessels being covered. During the study most of the worms in the replicates were observed lying on the sediment surface for one day. As possible reason the authors mention the relatively high stocking density in these replicates. Deviating from the study plan, the overlying water was renewed with uncontaminated water in order to improve water quality. The addition of uncontaminated water may lead to a further diffusion of test item from the sediment to the overlying water, as the formation of covalent bound to humic substances may not have been completed. A decrease of worm biomass was also observed in the replicates designated to determine body residues of aniline in the worms. The biomass in each single replicate was not sufficient for separate analysis per replicate. Therefore, the worms from the 4 replicates were pooled.

 

Analytical monitoring of the aniline concentration in the sediment shows a recovery of 22.27% after 28 days for this concentration level. The difference between nominal and measured aniline concentrations can be both attributed to biodegradation and formation of non-hydrolyzable binding to sediment components that is inaccessible for analytical determination. To consider the decrease of the aniline concentration by biodegradation, as a rough approach the revovery of 22.27% is used to correct the nominal aniline concentrations. As this recovery also covers formation of non-hydrolyzable binding of aniline to the sediment it represents a worst-case approach. The concentration of aniline in the pooled worm sample was 0.97 mg/kg worm tissue ww. The measured value was corrected for average recovery found in fortified worm tissue samples (73.3%). So a body residue of 1.32 mg/kg worm tissue ww was calculated. Body residue was normalised for the estimated dry weight and for the measured lipid content. The following table shows the obtained accumulation factors normalised for wet weight (AFww), dry weight (AFdw) and lipid/TOC (AFlipid) based on nominal and measured concentration.

In all cases the concentrations found in the worms were below the concentration in the sediment. However, the values for the accumulation factor were not statistically evaluated and they have not been evaluated for steady state conditions. Although the study shows some limitations and can therefore not be used unrestrictedly for a quantitative assessment of the bioaccumulation of aniline for sediment organisms, the result from this study can at least give an indication that no bioaccumulation of aniline in the test organisms from sediment occurs. Therefore, further tests on the bioaccumulation of aniline in sediment organisms are not of high priority for the risk assessment."

Reference:

ECB (2004). European Union Risk Assessment Report, Aniline, CAS No: 62 -53 - 3, EINECS No: 200 -539 -3, 1st Priority List, Volume 50.