Fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol

Sediment toxicity

Description of key information

Taking all available information into account, fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol is unlikely to pose a risk for sediment organisms and testing is thus omitted.

Additional information

No experimental data evaluating the toxicity of the target substance fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol to sediment organisms are available. However, the substance is characterized by poor water solubility (< 0.518 mg/L, 20 °C, OECD 105) and a log Koc indicating a high adsorption potential to soil and sediment particles (log Koc > 5). Thus, the potential of sediment toxicity was assessed and considered to be negligible.

Intrinsic properties and fate

Based on the results of an experimental study according to OECD 301F the substance is considered as not readily biodegradable (3 % after 28 d). Nevertheless, an extensive elimination of the substance in sewage treatment plants is expected by adsorption to suspended solids. According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2017) once poorly soluble chemicals enter a standard STP, they will be extensively removed in the primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms. Due to the high adsorption potential of the substance (log Koc > 5, EU Method C.19) a removal from the water column to a significant degree by adsorption to sewage sludge can be expected (Guidance on information requirements and chemical safety assessment, Chapter R.7b, (ECHA, 2017). Therefore, the concentration of the substance in conventional STP effluents is presumably negligible. Release to surface waters and subsequent exposure of sediment is therefore highly unlikely. Furthermore, as the substance has a high molecular weight of 1370.31 – 1426.42 g/mol, it is unlikely that it is readily absorbed, due to the steric hindrance of crossing biological membranes.

Aquatic ecotoxicity

According to the available short-term toxicity data for fish, aquatic invertebrates and aquatic algae, as well as the long-term toxicity data for aquatic invertebrates and algae, fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol is not expected to cause acute and/or chronic toxicity to aquatic organisms up to its limit of water solubility (< 0.518 mg/L). Moreover, due to the low water solubility, it is highly unlikely that relevant, bioavailable concentrations of the test item will ever occur in the water phase, i.e. that concentrations high enough to induce any measurable acute or chronic effects in aquatic organisms are ever attained. Furthermore, no toxic effects on activated sludge microorganisms occurred up to the limit of water solubility. Significant deviations from this overall ecotoxicological profile are not expected and it is thus concluded that fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol is unlikely to cause toxic effects to sediment organisms.

Metabolism/Bioaccumulation

In the unlikely case of absorption by aquatic organisms, fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol is expected to be enzymatically hydrolyzed by carboxylesterases into the corresponding free fatty acid and alcohol components. The metabolism of the hydrolysis products is well established and not of concern in terms of bioaccumulation (Heymann, 1980; Lech & Bend, 1980; Lech & Melancon, 1980; Murphy & Lutenske, 1990; Sand et al., 1973).

Fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol is characterized by a low water solubility ((< 0.518 mg/L at 20 °C), high log Kow (> 10) and high molecular weight (1370.31 – 1426.42 g/mol). Based on the physico/chemical properties such as low water solubility and high potential for adsorption a reduced availability in water is expected. The high molecular weight of the substance significantly reduces the absorption due to steric hindrance to cross biological membranes. In addition, no toxicologically relevant effects for mammals were observed in a 90-day oral feeding toxicity study with an analogue substance. BCF/BAF values estimated by QSAR (BCFBAF v3.01) also support this assumption (BCF values all well below 2000 L/kg). In consideration of all the available information, it is concluded that the potential for bioaccumulation is low.

Conclusion

Due to the low water solubility and high adsorption, only negligible concentrations of the target substance are expected to be discharged into water bodies. Furthermore, the high molecular weight of the substance significantly reduces the absorption due to steric hindrance to cross biological membranes. If uptake should occur, extensive and fast biotransformation of the substance and its metabolites is expected by the action of carboxylesterases. In addition, the available aquatic toxicity data suggest that no toxic effects occur up to the limit of water solubility and no toxicologically relevant effects for mammals were observed in a 90-day oral feeding toxicity study with an analogue substance. Therefore, it is concluded that fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol does not pose a risk to sediment organisms.

REFERENCES

Heymann, E. (1980): Carboxylesterases and amidases. In: Jakoby, W.B., Bend, J.R. & Caldwell, J., eds., Enzymatic Basis of Detoxication, 2nd Ed., New York: Academic Press, pp. 291-323.

Lech, J., Melancon, M. (1980): Uptake, metabolism, and deposition of xenobiotic chemicals in fish. EPA-600 3-80-082. U.S. Environmental Protection Agency, Duluth, MN, USA.

Lech, J.J. & Bend, J.R. (1980): Relationship between biotransformation and the toxicity and fate of xenobiotic chemicals in fish. Environ. Health Perspec. 34, 115-131.

Murphy, P.G., Lutenske, N.E. (1990): Bioconcentration of haloxyfop-methyl in bluegill (Lepomis macrochirus Rafinesque). Environ. Intern. 16, 219-230.

Sand, D.M., Rahn, C.H., Schlenk, H. (1973): Wax esters in fish: Absorption and metabolism of oleyl alcohol in the gourami (Trichogaster cosby). J Nutr 103: 600-607.