Amines, N-(3-aminopropyl)-N'-(C16-18 and C18-unsatd. alkyl)trimethylenedi-

Endpoint summary

Additional information

Long-term test results for three trophic levels are available for N-(3-aminopropyl)-N'-C16-18 (evennumbered), C18 unsaturated alkyl -propane-1,3-diamine (Triamine T; CAS 1219458-14-6)   with the following results.

Tests performed	Nominal		TWA
	EC(L)50/L(L)C50	EC(L)10/NOEC(L)	EC50	EC10/NOEC
	(µg/L)	(µg/L)	(µg/L)	(µg/L)
Algae test (2023)	63.8	39.0	1.42	0.967
Long-term daphnia test (2023)	24.3	0.808	6.96	0.179
Long-term fish (2023)	10.4	4.73	5.67	3.03

 

Triamine T is a multicomponent mixture (UVCB) of cationic surface-active constituents with different water solubilities. The fate of cationic surfactants in general deviates from standard chemicals. These substances are therefore considered as difficult substances for which the results of standard guideline studies are very difficult to interpret when considering them in a standard way. The reasons are the intrinsic properties like the relatively low water solubility and strong sorption to equipment and organisms. Classical ecotoxicity testing with these substances using reconstituted water often leads to test results which are poorly reproducible and are associated with high uncertainty. In addition, because of the complex sorption mechanisms (van der Waals and Ionic mechanisms) the actual dissolved exposure concentration cannot reliably be quantified.

To determine the intrinsic toxicity of Triamine T (for C&L purposes) an algae and long-term daphnia test (OECD TG 211) were performed according to the Water Accommodated Fraction (WAF) approach as described in “OECD guidance document on aqueous-phase aquatic toxicity testing of difficult test chemicals” (No. 23 Feb. 2019) with a daily refreshment of the test solutions. The term “loading rate” is advocated to express exposure to a WAF and is considered analogous to the nominal concentration.

 

In addition a long-term fish test was performed with Triamine T using a flow-through setup using as a worst-case a solvent to maintain stable exposure concentrations.

 

For the preparation of the test solutions according to the WAF approach, all reasonable efforts were taken to produce a solution of all soluble components of the test item in test media. The test solutions for the long-term daphnia test were prepared daily, by gentle mixing the test item with test medium for a prolonged period sufficient to ensure equilibration between the test item and the water phase. At the completion of mixing and following a settlement period, the WAF was separated by siphoning. This procedure was followed for each renewal of the test solutions.

No undissolved or emulsified material was observed in the WAF solutions based on the Tyndall effect check. Adsorptive losses to the glass test vessels were kept as low as possible by pre-conditioning the test vessels already with appropriate test solution for at least 12 hours under test conditions. Before the start of the exposure and each renewal, the test containers were emptied and refilled with freshly prepared test solutions. 

It should be noted that the test substance sorbs strongly to the food algae (van Wijk, 2009) which leads to an apparent reduction of the freely dissolve concentration (when algae are separated prior to analysis) but are still providing a secondary exposure route via ingestion.

The results in the table above are presented based on nominal test loadings and on time weighted average (TWA) measured concentrations. The TWA results are given in this summary despite the fact that per definition of the WAF, all terms related to concentration level should be given as loading rates (mass-to-volume ratio of the substance to the medium) because partly dissolved compounds and mixtures cannot be related to concentrations. Analytical verifications of selected components can be helpful and deliver supporting information, but they do not represent the whole test substance and therefore, toxicity results will be evaluated based on WAF loading rate (Wheeler, Lyon et al. 2020). Several guidance documents suggest to use the WAF loading rate for the environmental hazard classification of chemical substances e.g. the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (OECD 2002, OECD 2019) as well as OECD guidance documents on the classification of chemicals which are Hazardous for the Aquatic Environment. The test item concentrations of Triamine T were analytically verified via LC-MS/MS daily in the algae test and 3 times during the long-term daphnia test in the fresh media at the start of an exposure-renewal interval (0 hours; on test days 0, 7 and 14) as well as in the old media at the end of an exposure-renewal interval (24 hours; on test days 1, 8 and 15) in all WAFs and in the control.
 

• OECD (2002). Guidance Document on the Use of the Harmonised System for the Classification of Chemicals which are Hazardous for the Aquatic Environment.


• Wheeler, J. R., D. Lyon, C. Di Paolo, A. Grosso and M. Crane (2020). "Challenges in the regulatory use of water-accommodated fractions for assessing complex substances." Environmental Sciences Europe 32(1): 1-10.


• OECD (2019): Guidance document on aqueous-phase aquatic toxicity testing of difficult test chemicals. OECD series on testing and assessment no. 23 (second edition), ENV/JM/MONO(2000)6/REV1