Fatty acids, montan-wax, stearyl esters

Sediment toxicity

Description of key information

Based on all the available information, toxicity to sediment organisms is not expected to be of concern.

Additional information

No experimental data is available for the toxicity of Fatty acids, montan-wax, stearyl esters (CAS 68308-30-5) to sediment organisms.

The substance is characterized by poor water solubility (< 0.539 mg/L, 20 °C, OECD 105). If released into the aquatic environment, only low concentrations of the substance are expected to dissolve in the water phase. Rather, the substance is expected to sorb to organic matter, leading to an effective reduction of its bioavailability in the water column. Thus, sediment and soil are expected to be its main compartments of environmental distribution and sediment organisms are potentially exposed via feed and contact with suspended organic particles. However, based on the physico-chemical properties, the bioavailability of the substance is expected to be low due to its strong binding behavior. Furthermore, the substance is not toxic to aquatic organisms up to the limit of water solubility. Based on all the available information, toxicity to sediment organisms is therefore not expected to be of concern.

Intrinsic properties and fate

Fatty acids, montan-wax, stearyl esters (CAS 68308-30-5) is poorly water soluble (< 0.539 mg/L, 20 °C, OECD 105) and has a high, estimated log Kow (> 10.0, (Q)SARs). Therefore, only low concentrations of this substance are expected to be released into the aquatic environment, if at all.

The Guidance on information requirements and chemical safety assessment, Chapter R.7b (ECHA, 2017) states that once insoluble 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. Thus, discharge into the aqueous/sediment compartment is likely to be negligible and chronic exposure of sediment organisms is improbable.

If released into the aquatic environment, only low concentrations of the substance are expected to dissolve in the water phase. Rather, the substance is expected to sorb to organic matter, leading to an effective reduction of its bioavailability in the water column. Therefore, sediment and soil are expected to be its main compartments of environmental distribution.

 

Aquatic ecotoxicity

According to the available short-term toxicity data for fish and aquatic algae, as well as the long-term toxicity data for aquatic algae, Fatty acids, montan-wax, stearyl esters (CAS 68308-30-5) is not expected to cause acute or chronic toxicity to aquatic organisms up to its limit of water solubility (< 0.539 mg/L). Moreover, due to its 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 were recorded

Significant deviations from this overall ecotoxicological profile are not expected and it is thus concluded that Fatty acids, montan-wax, stearyl esters (CAS 68308-30-5) is unlikely to cause toxic effects to sediment organisms.

Metabolism/Bioaccumulation

If absorption by aquatic organisms should occur, Fatty acids, montan-wax, stearyl esters (CAS 68308-30-5) is expected to be enzymatically hydrolyzed by ubiquitous carboxylesterases into its 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). The available BCF values consistently predicted very low BCF values of maximally 28.18 L/kg, which are clearly below the threshold values of 2000 L/kg and 5000 L/kg for bioaccumulative and very bioaccumulative substances according to Regulation (EC) 1907/2006 (Annex XIII, section 1), thus providing additional evidence for a low potential for bioaccumulation in aquatic organisms.

In consideration of all the available information described above, it is concluded that the potential for aquatic bioaccumulation is low.

Conclusion

Due to the high adsorption, only negligible concentrations of the target substance are expected to be discharged into the aquatic environment, if at all. Whatever fraction is released is expected to adsorb to particles of sediment and soil where sediment organisms are potentially exposed via feed and contact with suspended organic particles. However, based on the physico-chemical properties of the substance (i.e. strong binding behaviour), bioavailability is expected to be low. If uptake should occur, extensive and fast biotransformation of the substance and its metabolites is expected by the action of ubiquitous carboxylesterases.

Furthermore, the available aquatic toxicity data suggest that no toxic effects occur up to the limit of water solubility. Moreover, due to the extremely low water solubility of the substance, relevant concentrations of the substance are not expected to ever be attained in water. Predicted BCF values suggest that the potential for bioaccumulation in aquatic organisms is low. Therefore, it is concluded that Fatty acids, montan-wax, stearyl esters (CAS 68308-30-5) 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.