Propanol, iminobis-, N-(C16-18 and C18-unsatd. alkyl) derivs.

Bioaccumulation: aquatic / sediment

Description of key information

The calculated BAF is 59.6 L/kg.

Key value for chemical safety assessment

BCF (aquatic species):

59.6 L/kg ww

Additional information

The log Kow observed for di (2-hydroxypropyl)tallow amine using the slow-stirring method according to OECD 123, is 6.2 at pH 7 and 3.7 at a pH between 3 and 4.. For this product also a water solubility of 0.2 mg/L was observed. The measured log Kow value of 6.2 at pH 7 indicates that this substance may have a bioaccumulation potential if it would have been a narcotic substance and if the metabolic rate of the substance is not taken into consideration. For polar narcotics surface active substances like the primary fatty amine propoxylates however there is only limited information on the relationship between log Kow and BCF.

Di-(2-hydroxypropyl)tallow amine is readily biodegradable and like the primary alkyl amine ethoxylates expected to be quickly metabolized by fish liver S9 it is therefore unlikely that they will accumulate in the food chain.  The bioaccumulation potential of primary fatty amine propoxylates should based on this be considered as low.

 

 

No measured BCF for fish is available for di (2-hydroxypropyl)tallow amine.

 

Standard OECD 305 tests are technically not feasible with these sorbing and biodegradable substances. In addition, the route of exposure in a standard OECD 305 test is unrealistic for these substances because the substance will either be sorbed or biodegraded. The bioaccumulation potential of primary fatty amine propoxylates was therefore assessed based on a measured log Kow of its consituents. As indicated before, primary fatty amine propoxylates are biodegradable and it is therefore unlikely that they will accumulate in the food chain. Since there is a measured log Kow value available this value can be used to evaluate the bioaccumulation potential.

 

Primary fatty amines propoxylates	Measured log Kow (pH 7)	Measured log Kow (pH 3 - 4)	Calculated log Kow (KOWWIN)
C16 amine, 2PO	5.7	3.3	6.7
C18:1 amine, 2PO	6.1	3.6	7.5
C18 amine, 2PO	6.9	4.4	7.7

 

The log Kow observed for the di (2-hydroxypropyl) tallow amine is 6.2 at pH 7 and 3.7 at a pH between 3 and 4. For this product also a water solubility of 0.2 mg/L was observed. The measured log Kow value of 6.2 at pH 7 indicates that this substance may have a bioaccumulation potential if it would have been a narcotic substance and if the metabolic rate of the substance is not taken into consideration. For polar narcotics like the primary fatty amine propoxylates however there is only limited information on the relationship between log Kow and the bioconcentration factor (BCF).

As indicated before, the substance is biodegradable and it is therefore unlikely that it will accumulate in the food chain. Even if the log Kow value of 6.2 at pH 7 for the target substance may indicate that the substance may have a bioaccumulation potential, this would only be applicable if the substance would have been a narcotic substance and if the metabolic rate of the substance is not taken into consideration. For surfactants like the primary fatty amine propoxylates and the primary fatty amine ethoxylates however there is only limited information on the relationship between log Kow and the bioaccumulation factor. Many organic substances are partially or completely ionized under environmentally relevant conditions and due to their charge, ionic organic substances differ in their environmental behaviour from neutral substances (Franco et al 2010; Rendal et al 2011). According to the REACH PBT guidance R.11, evidence of high biotransformation/metabolization rate in fish may be used to support for arguing for a limited bioaccumulation potential but quantitative thresholds have not been established. The in vitro biotransformation of different primary fatty amine ethoxylates with an alkyl chain length ranging from C12 to C18 by rainbow trout hepatic S9 subcellular fraction was tested according to a slightly adapted Cellzdirect/Invitrogen Hepatic Rainbow Trout S9 Incubation Protocol (Geurts 2013). A rapid biotransformation of the C12 to C18 alkyldiethanol amines was observed and estimated BCF with biotransformation were all below 500 L/kg. Hereby, the highest log Kow of 4.4 was measured for C16 diethanolamine resulting in an estimated BCF with biotransformation of 465 L/kg. The BCF values are calculated using a standardized extrapolation method according to Nichols (2013). The use of QSAR- and mechanistically based bioaccumulation models is also considered valuable in the overall bioaccumulation assessment process. The BCFBAF model (v3.0) as included in EPIsuite (v4.0) allows the inclusion of metabolism into the BCF calculation but the results of this model should be considered with care as the training set holds only a limited number of substances which can reliably be used to predict the fate of cationic surfactants. Also, in the biotransformation study of Geurts (2013) a good correlation was found between the BCFBAF model results and the measured log Kow values according to OECD 123 for the different primary fatty amine ethoxylates. With a measured log Kow of 6.2 for target substance 1 the BCFBAF model predicts a BCF of 9,669 L/kg without metabolism and a BAF of 59.6 L/kg wwt with metabolism. The bioaccumulation potential of primary fatty amine propoxylate based on this assumption is considered as low by including the biotransformation rate estimates. In a research project from the German Federal Environment Agency the bioaccumulation potential of fully ionized compounds (ionic organic chemicals) was experimentally determined in feeding studies according to OECD TG 305 (German Fereradl Environmental Agency 2021). More than twenty screening parameters were assessed for six different ionic organic chemicals (two cations and four anions). None of the twenty screening parameters showed particularly high correlations to the test results nor to the BMF values collected from literature and it can be concluded that ionization lowers the tendency of a chemical to bioaccumulate, compared to non-ionized chemicals. The hydroxy groups of the target substance are mainly protonated at environmental pH 7 and therefore ionized. Also, the amine is partly protonated at different tissues in the human body with lower pH. Consequently, based on the results of this study it can be assumed that bioaccumulation and biomagnification potential of charged compounds like it is the case for the target and source substances is lowered compared to uncharged chemicals.

 

References: 

Federal Ministry of the Environment, Nature Conservation and Nuclear Safety (2021) Bioaccumulation of ionic compounds – Deriving of alternative screening criteria from experimental studies, project no. (FKZ) 63818 67 402 0, report no. (UBA-FB) FB000468/ENG.

Franco, A, Ferranti, A., Davidsen, C.; Trapp, S. (2010) An unexpected challenge: ionizable compounds in the REACH chemical space. International Journal Life Cycle Assessment 15(4):321-325

Geurts, M (2013). The in vitro biotransformation of C_12-18 (evennumbered alkyl diethanol amines by rainbow trout (Oncorhynchus mykiss) hepatic S9 subcellular fraction, Akzo Nobel Ecotoxicology & Environmental Testing, Report NG13029 BTA

Nichols, J. W.; Huggett, D.,B.; Arnot, J. A., Fitzsimmons, P. N. & Cowan-Ellsberry, C. E. (2013) Toward improved models for predicting bioconcentration of well-metabolized compounds by rainbow trout using measured rates of in vitro intrinsic clearance. Environmental toxicology and chemistry, 32(7), 1611-1622

Rendal, C., Kusk K. O., Trapp, S. (2011) The effect of pH on the uptake and toxicity of the bivalent weak base chloroquine tested on Salix viminalis and Daphnia magna. Environmental Toxicology & Chemistry 30(2):354-359

 

The BCFBAF QSAR is used to assess this parameter. The result obtained indicates that the estimated Bioaccumulation Factor (BAF) of the substance is 59.6 L/kg, calculated from its major constituents. The low calculated BCF is realistic as primary fatty amine propoxylates are inherently biodegradable and the structural similar primary fatty amine ethoxylates have been found to be metabolized quickly in fish liver S9 fraction as described above.