N-{3-[C12-14-(even numbered)-alkyloxy]propyl}propane-1,3-diamine

Short-term toxicity to fish

Description of key information

A nominal loading of 25.0 µg/L (99.8% active) was tested as a threshold concentration in a limit test. The selection of the test loading was based on the derivation of a threshold loading (TL) from the data of the test item of results of a daphnia test and of an alga toxicity test. The 96 h threshold loading of the test item at the nominal loading of 25 µg/L was found to have neither lethal nor non-lethal effects on zebrafish. 

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Remarks:

WAF approach was used, endpoint based on loading level (LL50)

Effect concentration:

> 25 µg/L

Additional information

One short-term fish study for etherdiamine C12-14 is available. The study was performed semi-statically (daily water renewal) according to OECD TG 203 with specific chemical analysis (LC-MS/MS) under GLP conditions.

 

Etherdiamine C12-14 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 intrinsic properties like the relatively low water solubility and strong sorption to equipment and organisms. Classical ecotoxicity testing with this type of substance using reconstituted water often leads to test results which are poorly reproducible and are associated with high uncertainty. Because of the complex sorption mechanisms (van der Waals and ionic mechanisms) the actual dissolved exposure concentration cannot reliably be estimated.

 

Short-term fish test was 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.

 

The test solutions for the WAF approach were prepared by gentle mixing the test item with test medium for a prolonged period (24 hours) sufficient to ensure equilibration between the test item and the water phase. At the completion of mixing and following a settlement period (1 hour), the WAF was separated by siphoning. This procedure was followed for each renewal of the test solution (daily water renewal). One WAF was prepared and tested at nominal loading rate of 25 µg/L (threshold loading) corresponding to the time weighted mean measured test item concentration 7.28 µg/L. No undissolved or emulsified material was observed in the WAF solutions based on the Tyndall effect check. Adsorptive losses to glass vessels was 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.

The results are presented based on nominal test loading and on time weighted average (TWA) measured concentrations. The threshold concentration of the test item at the nominal loading of 25.0 µg/L respectively 7.28 µg/L (TWA) was found to have neither lethal nor sub-lethal effects on zebrafish. The TWA results are given 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

References:

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

 

OECD (2019). Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures.

 

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.