Reaction mass of ethoxylated N-oleyl-1,3-propanediamine, hydrofluorides of and ethoxylated N-palmityl-1,3-propanediamine, hydrofluorides of and ethoxylated N-stearyl-1,3-propanediamine, hydrofluorides of and olaflur

Biodegradation in water: screening tests

Description of key information

The study on ready biodegradability was performed with the free amine base of the fluoride salt (= Olaflur), the alkoxylated amine Ethanol, 2,2´-[[3-[(2-hydroxyethyl)amino]propyl]imino] bis-, N-tallow alkyl derivs. (CAS no. 90367-27-4). Under environmental conditions, biodegradation of alkylamines or its salts is predominantly determined by the solubility of the amine component and potential bacteriotoxicity. Solubility is dependent on the pH value of the medium. Therefore, results for amines allow also a conclusion for the respective salts (Olaflur represents the fluoride salt of the amine) (see also APAG "INFLUENCE OF COUNTER IONS ON THE BIODEGRADABILITY OF SALTS OF FATTY AMINE DERIVATIVES AND QUATERNARY AMMONIUM SALTS").

A CO₂-Evolution-Test was performed according to OECD guideline 301B. Ethanol, 2,2´-[[3-[(2-hydroxyethyl)amino]propyl]imino] bis-, N-tallow alkyl derivs. was tested at a concentration of nominally 15.7 mg test item/L, the test was left running for 28 days. Based on the results obtained, the free amine base of the fluoride salt (= Olaflur), can be considered as readily biodegradable although the 10-day-window-criteria were not 100% fulfilled. The 10-day-window-criteria are not applicable for substances like Olaflur or its amine component, as it represents a mixture of substances with potentially different bacteriotoxic profiles, resulting in different lag-phases. This approach has been accepted by authorities e.g. in the field of surface active substances (see also APAG "10-DAY TIME WINDOW; AN UNSUITABLE PASS/FAIL CRITERION FOR FATTY AMINE DERIVATIVES"). In summary, the amine base and consequently Olaflur can also be considered as ready biodegradable.

 

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The study on ready biodegradability was performed with the free amine base of the fluoride salt (= Olaflur), the alkoxylated amine Ethanol, 2,2´-[[3-[(2-hydroxyethyl)amino]propyl]imino] bis-, N-tallow alkyl derivs. (CAS no. 90367-27-4).

Due to the difficulties in testing and interpreting test results for substances, such as Olaflur or its amine component, representing a mixture of substances with potentially different bacteriotoxic profiles, an APAG team of industry experts and specialists was set up to review available data utilising both internal company studies and external literature. The paper “INFLUENCE OF COUNTER IONS ON THE BIODEGRADABILITY OF SALTS OF FATTY AMINE DERIVATES AND QUATERNARY AMMONIUM SALTS” presents an overview of the biodegradation properties of a family group of amine products:

“Water-soluble quaternary ammonium salts and a number of fatty amine derivatives consist of two parts i.e. a cationic ammonium ion and an anionic counter ion. In water, quaternary ammonium salts dissolve to form both ions. In aqueous environments salts of fatty amine derivatives exist as ammonium species or as amines depending on the pH. Dissolution and dissociation of the salts lead to an equilibrium of the ions and amines in the (test) medium, so the fatty amine derivative will reach essentially the same state regardless of counter ion in the product (present or absent). It is, therefore, expected that counter ions do not influence the biodegradation. Indeed, the biodegradation of quaternary ammonium salts is not influenced by the counter ion as demonstrated with hexadecyltrimethylammonium salts and dodecylbenzyldimethylammonium salts (Ruiz Cruz and Dobarganes Garcia, 1979; Baleux and Caumette, 1977). This expectation was also confirmed by the results obtained with a primary amine. The primary biodegradation of dodecylammonium with chloride and acetate as counter ions added to river water was comparable (Ruiz Cruz and Dobarganes Garcia, 1979). Finally, Closed Bottle test results demonstrate that the biodegradability is not influenced by the presence of the acetic acid because a biodegradation percentage in excess of 60% was achieved with tallow-1,3-diaminepropane and its acetate salt (Akzo Nobel, 1990a, b). Chloride is already fully mineralised anion. Acetate used as reference compound is degraded within 14 days in ready biodegradability tests. Salts of a fatty amine derivative with acetic acid are therefore readily biodegradable when the fatty amine derivative has been classified as readily biodegradable (References: Akzo Nobel (1990a) Internal Report CRL F90045 GLP; Akzo Nobel (1990b) Internal Report CRL F90046 GLP; Baleux B and Caumette P (1977) Biodegradation of some cationic surfactants. Water Res. 11 833-841; Ginkel CG van (1995) Biodegradation of cationic surfactants In; Biodegradation of surfactants. Eds MR Porter and R Karsa, Blackie Academic & Professional, pp 183-203; Ruiz Cruz J and Dobarganes Garcia MC (1979) Pollution of natural waters by synthetic detergents XV Relation between structure and biodegradation of cationic surfactants in river water. Grasa y Aceites 30 67—74) ".

The test material attained 61% degradation after 28 days but did not meet the 10-day window validation criterion. Therefore, based on the study results as such, in general the substance Ethanol, 2,2´-[[3-[(2-hydroxyethyl)amino]propyl]imino] bis-, N-tallow alkyl derivs. would not be considered as readily biodegradable under the strict terms and conditions of the OECD Guidelines. However, the complex chemistry leads to difficulties in testing and interpreting of test results for such kind of materials leading to a critical discussion and evaluation by an APAG team of industry experts and specialists set up to review available data utilising both internal company studies and external literature. The paper “10-DAY TIME WINDOW; AN UNSUITABLE PASS/FAIL CRITERION FOR FATTY AMINE DERIVATIVES” published by APAG clearly explains and justifies the unsuitability of the 10-day effect for fatty amine derivatives. The 10-day window concept in ready biodegradability tests has been introduced as a simple alternative to quantify the rate of biodegradation. However, a reasonable estimation of growth rates from biodegradation curves obtained is only possible and valid when a single water-soluble chemical substance is studied.

In general, the solubility of fatty amine derivatives decreases with increasing alkyl chains. In addition to that many fatty amine derivates have the tendency to adsorb to surfaces (e.g. sludge particles). Both, adsorption as well as poor water solubility is expected to affect biodegradation kinetics and thus, an important reason for not applying the 10-day time window. Chemicals in which a hydrophilic group is linked to a hydrophobic moiety require the concerted action of at least two microorganisms as a single organism usually lacks the full complement of enzymatic capabilities with regard to biodegradation (van Ginkel, 1996). In ready biodegradability tests, the two moieties of fatty amine derivatives are degraded sequentially. The biodegradation of the two moieties may be fully in line with the 10-day window criterion when judged as separate chemicals. Biodegradation curves of fatty amine derivatives should therefore not be used to assess a 10-day effect. Fatty amine derivates are often consisting of homologue mixtures, the biodegradation an addition of different biodegradation curves. Thus individual compounds might meet the 10-day time window criterion whereas the biodegradability curve of the mixture of homologues suggests that the surfactant is not readily biodegradable. The 10-day time window is therefore an inappropriate pass/fail criterion for mixtures of chemicals (Richterich and Steber, 2001).

Conclusion

These scientific arguments demonstrate that the 10-day window is not a valid method to quantify biodegradation rates of fatty amine derivatives. The fact that fatty amine derivatives are degraded by at least two microorganisms is already recognised by the Scientific Committee on Toxicity, Ecotoxicity and the Environment (CSTEE) of the EU (1999) as an argument for not using the 10-day window. Moreover, the 10-day window criterion also does not need to be applied for surfactants in eco-labelled laundry detergents (Madson and Stranddorf, 2003). Finally, the 10-day time window is considered as unimportant for the assessment of persistence (EU, 1996). It is reasonable therefore to conclude that the 10-day window should be rejected as a criterion for the classification and labelling of fatty amine derivatives.

Based on this argumentation, the interpretation of the results obtained in this study can be considered as misleading, the 10-day window approach not suitable for fatty amine derivatives with regard to the evaluation of the biodegradation properties.

As mentioned above, Ethanol, 2,2´-[[3-[(2-hydroxyethyl)amino]propyl]imino] bis-, N-tallow alkyl attained 61% degradation after 28 days, which conforms with the validity criteria requested by the OECD guideline to be classified as readily biodegradable besides of the 10-day-window. So, even though not meeting the 10-day window validation criterion, Ethanol, 2,2´-[[3-[(2-hydroxyethyl)amino]propyl]imino] bis-, N-tallow alkyl can be considered as readily biodegradable.

Based on this, the results regarding the biodegradation properties obtained for Ethanol, 2,2´-[[3-[(2-hydroxyethyl)amino]propyl]imino] bis-, N-tallow alkyl derivs. are also assignable to Olaflur, being the dihydrofluoride salt of this fatty amine derivate and can thus be considered as ready biodegradable, too.