Glycine, N-methyl-, N-coco acyl derivs., sodium salts

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Additional information

Glycine, N-methyl-, N-coco acyl derivatives, sodium salts (CAS 61791-59-1) is a UVCB salt characterized by a high water solubility of 42.19 g/L (20 °C, OECD 105), a log Kow of -1.3 (OECD 117) and a log D of 0.61 to 2.40 at pH 7 and of -0.30 to 1.53 at pH 9 (SPARC v4.6). Since there is only limited experimental data available for the environmental fate of the substance, QSAR calculations were performed to estimate the dissociation constants (pKa) and the log Koc values of the three representative main constituents of the substance, i.e. Sodium palmitoyl sarcosinate (CAS 4028-10-8), Sodium myristoyl sarcosinate (CAS 30364-51-3) and Sodium lauroyl sarcosinate (CAS 137-16-6).

The calculated pKa value for all three molecules is 3.96 (SPARC v4.6), indicating that the ionized, charged ionic forms will predominate at environmentally relevant pH values in the range of 4 to 9. The SPARC model predicts that the acid form constitutes 47.4% at pH 4, 0.1% at pH 7 and 0.0% at pH 9, at which point the molecules completely dissociate into the corresponding anionic forms. The estimated log Koc (ChemProp v6.5, Franco, Fu & Trapp model for ionisable substances) is 0.87 at pH 4, and 1.40 at pH 7 and 9, indicating a low potential for adsorption to particles present in soil and sediment. Thus, the substance is expected to preferentially distribute into the water compartment where it is expected to be mobile at environmentally relevant pH ranges.

Glycine, N-methyl-, N-coco acyl derivatives, sodium salts (CAS 61791-59-1) has a log D (used for ionisable substances instead of log Kow) of 0.61 to 2.40 at pH 7, and -0.30 to 1.53 at pH 9 (SPARC v4.6), indicating low lipophilicity at the environmentally relevant pH of 7 and 9. Thus, according to REACh regulation (EC) No 1907/2006 the substance has a low potential for bioaccumulation at the environmentally relevant pH of 7 and 9 (log D is ≤ 3). Furthermore, the estimated BCF values provide further evidence that the potential for bioaccumulation is low. The estimated BCF values range from 3.0 to 74.0 L/kg wet-wt and are thus well below the threshold value of 2000 L/kg for bioaccumulative substances, as laid down by the REACH regulation (EC) No 1907/2006, section 1 of Annex XIII.

Moreover, the substance is readily biodegradable based on standard biodegradation studies with two structurally and chemically closely related source substances (85.2% in 28 d, OECD 301 B, activated sludge). Consequently, abiotic degradation via hydrolysis is not a relevant degradation pathway. According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b, readily biodegradable substances can be expected to undergo rapid and ultimate degradation in most environments, including biological sewage treatment plants (ECHA, 2016). Therefore, the substance will not persist in the environment. Thus, release into the environment is expected to be low due to ready biodegradability. Moreover, the substance will not persist in surface waters and bioavailability to aquatic organisms can therefore be expected to be low.