Fatty acids, tall-oil, reaction products with ethanolamine, ethoxylated

Bioaccumulation: aquatic / sediment

Description of key information

Based on QSAR simulation in 2 QSAR models , the bioaccumulation potential is expected to be 28- 156 L/kg. Therefore, unacceptable risks due to possible bioaccumulation are not expected.

Key value for chemical safety assessment

BCF (aquatic species):

156 L/kg ww

Additional information

Bioaccumulation of Fatty acids, tall-oil, reaction products with ethanolamine, ethoxylated (1.5EO)

No experimental data evaluating the bioaccumulation potential are available for the UVCB Fatty acids, tall-oil, reaction products with ethanolamine, ethoxylated (1.5EO). However, an experimental determined value of Log Pow > 5 at 20°C and calculated Log Pow values (Log Pow 5.4 - 5.9) for the main components of the test substance based on the experimentally derived water solubility of 30 mg/L indicate a potential for bioaccumulation. Estimations of the BCF were performed by means of QSAR models. The results are evaluated in a weight-of-evidence approach.

Structure                                                                                   

The main components of the test substance are reaction products of a linear fatty acid backbone - C18 or C18 unsat., ethanolamine and 1-2 ethylenoxide molecules.

Main components of the test item:

·        Fatty acid C-Chain C18 sat.+1MEA +1EO                   (Log Pow: 5.9)

·        Fatty acid C-Chain C18 unsat. +1MEA +1EO               (Log Pow: 5.6)

·        Fatty acid C-Chain C18 sat. +1MEA +2EO                  (Log Pow: 5.6)

·        Fatty acid C-Chain C18 unsat. +1MEA +2EO               (Log Pow: 5.4)

Intrinsic properties

Fatty acids, tall-oil, reaction products with ethanolamine, ethoxylated (1.5EO) are readily biodegradable. It can be expected that substances like the test item undergo a rapid and ultimate degradation in the environment and in sewage treatment plants. Therefore, after the passage of a sewage treatment plant only very low concentrations are likely to enter the environment.

Entering the environment a further decrease of the substance concentration in the water phase is to be assumed due to adsorption processes to organic matter (Log Koc > 3). Thus the actual dissolved fraction to organisms like fish via the water phase is further reduced.

Biotransformation and metabolism

Biotransformation plays a key role in the bioaccumulation of organic chemicals in aquatic organisms, (Katagi, 2010). Ethoxylated molecules have been shown to be easily degradated in organisms (fish) by biotransformation (Tolls et al., 2000) or metabolism to body inherent molecules. Amid and fatty acid structures are furthermore known to be body inherent molecules undergoing diverse metabolism steps (Farrell et. al.,2012).

QSAR modelling

BCF calculations using the CATALOGIC v.5.11.6 TB BCF base-line model for the main components of this UVCB are available The BCF model calculates the BCF implicating the estimated log Kow value of 5.4 - 5.9 and the measured water solubility of 30mg/L. Furthermore, the influence of mitigating factors like ionization of the molecule, water solubility, size and metabolism are also considered by the model. Taking into account these mitigating factors, e.g. the BCF is reduced from 20063 L/kg (log BCF = 4.30) to BCF 95 L/kg (log BCF = 1.97 for Fatty acid C-Chain C18 sat.+1MEA +1EO being the worst case).

Besides metabolism also the relatively low water solubility and the molecular size reduce the log BCF as estimated by the model. Both parameters are discussed within the literature whether certain threshold values are suitable as cut-off criteria for indication of limited bioaccumulation. Regarding molecular size, the PBT working group on hazardous substances discussed a maximum diameter of > 17.4 Å (Comber et al., 2006). The average diameter of the main components of the test item are determined to be 19.98 – 21.39 Å (DiamMax-Average), depending on its conformation. When used as single mitigating factors (no combination with other factors), metabolism and size reduce the overall bioaccumulation. All in all, based on the predicted log BCF of 1.15 – 1.97, a significant bioaccumulation is not expected in animal tissues. The structure of the main components of the test item is covered by 100 % by the applicability domain.

- EPISuite v4.1/BCFBAFv3.01: BCF values for the main components of the test item (UVCB) in the range of 74 – 156 were estimated on the basis of the log Kow of 5.4 - 5.9. Using the Arnot-Gobas method including biotransformation rates, the BCF for the upper trophic level was estimated to be in a range of 68- 122 L/kg.

CONCLUSIONS ,

Following the calculated log Kow values of 5.4 – 5.9 and an experimentally derived Log Pow value of >5, bioaccumulation in organisms may not be excluded. The bioaccumulation potential is therefore estimated on the basis of a worst-case log Kow in the range of 5.4 - 5.9.

The two QSAR models (CATALOGIC v5.11.2, BCFBAF v3.01) calculate a maximum BCF value of 20063 L/kg. However, considering mitigating factors like biotransformation, water solubility and molecular size, the BCF is reduced to values between 14 and 156 L/kg indicating a low potential for bioaccumulation. In addition, due to the readily biodegradability, the adsorption (log Koc > 3) and the limited water solubility (30 mg/L) exposure of aquatic organisms to significant amounts is unlikely. Therefore, unacceptable risks due to possible bioaccumulation are not expected.