Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

The registration substance was under the test condition of an standard OECD 301 B CO2 EvolutionTest not readily biodegradable. Under the test conditions of an OECD 302B Zahn-Wellens Test the registration substance was not inherently biodegradable.

In an enhanced OECD301B study the registration substance (17 mg/L; 10.8 mg C/L) reached the required level of 60% degradation to be ultimately biodegradable within 43 days using a non-adapted municipal activated sludge. Continuous degradation could be observed starting at day 6 reaching a maximum of 91% degradation on day 60. The only enhancement was the prolongation to 60 days.

 

No studies on degradation in soil or sediment of the registration substance are available.

The substance is a cyclo-alkyl amine ethoxylate and the only structural difference to the readily biodegradable linear fatty amine ethoxylates is the ring structure of the alkyl moiety, which, due to steric hinderance is most likely responsible for the prolonged degradation time.

 

Primary fatty linear alkyl amines and primary fatty linear alkyl amine ethoxylates are readily biodegradable and share the same, well investigated, degradation pathway [1] . The biodegradation is initiated by the cleavage of the C-N-bond. The resulting fatty aldehyde is oxidized to the corresponding fatty acid, which is degraded through the β-oxidation cycle. Diethanolamine is stoichiometrically produced and is readily biodegradable2, [2] . A consortium of microorganisms degrading the alkyl chain of alkylbis(2-hydroxyethyl) amines and diethanolamine [3]  are therefore capable of complete (ultimate) degradation of alkylbis(2-hydroxyethyl) amines.

 

As shown by the EAWAG predictions (s. IUCLID Ch 5.2.4) it can be assumed that the degradation pathway is similar to the linear substances. The only difference is the way the alkyl chain degrades. The linear chain degrades by β-oxidation and the ring-structure follows the cyclohexane pathway. Both ways lead to complete mineralization. Different degradation rates might occur, but the enhanced ready test shows the constant biodegradability of the registration substance, which therefore, considering the steric hinderance again, will behave similar to primary alkyl amines.

For 14C hexadecylamine a half-life in three soils was measured according to an OECD 307 test [4] . Although this C16 amine is strongly sorbing to soil (median Kp soil of 3875 L/kg at lowest measured concentration), half-life’s of 8.14 to 8.98 days were observed at 20 °C. These values can be recalculated (EUSES) to 12 °C a maximum half-life in soil of 16.9 days. Following ECHA Guidance R.16.3.2.2 this value can be used for aerobic sediment, too. For bulk sediment the value is set to 169 days.

With this result, considering the similar behavior, it can be stated that degradation of the registration substance in soil and sediment is likely. Even if assuming a difference in degradation rates the values for the registration substance will be well below the trigger values for P assessment.

   

[1]  Ginkel CG and Kroon AGM (1993). Metabolic pathways for the biodegradation of octadecylbis(2-Hydroxyethyl) amine. Biodegradation 3 435-443.

[2]  Davis JW and Carpenter CL (1997). Environmental assessment of alkanolamines. Rev Environ Contam Toxicol 149: 87-137.

[3]  Williams GR and Callely AG (1982). The biodegradation of diethanolamine and triethanolamine in a yellow Gram-negative rod. J Gen Microbiol 128 1203-1209.

[4]  https://echa.europa.eu/registration-dossier/-/registered-dossier/14853/5/3/4/?documentUUID=90778244-0c8c-402e-b491-f1166808a8f8

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