Amines, C16-18-alkyl

Endpoint summary

Additional information

1. AQUATIC BIOACCUMULATION

Weight of Evidence Approach (WoE)

None of the approaches described in the chapter 5.3.1 used to derive the BCFof Primary alkyl amines can give a reliable results which addresses the full ADME process especially for fish. Therefore a Weight of Evidence Approach has to be applied.

1) The test design for an OECD 305 test for the measuring of theBCFis not suitable. The result from this preliminary test has an uncertainty which cannot be judged.

2) The ADME model of Arnot & Gobas (2003) can address the ADME process but only for the unprotonated amine. Due to the relatively high metabolic rate from an in vitro measurement lowBCFare predicted based on uptake of the unprotonated C16 amine which is considered as a worst case assumption.

3) ClassicalBCFestimation methods based on Log K_ow,predict higher BCFvalues for the unprotonated than for the protonated C16 amine

4) The model of Fu et al (2009) is the only model which can address the coexisting protonated and unprotonated C16 amine as function of pH. Unfortunately it does address only the Adsorption of the ADME process and in addition it is not known if it is valid for cationic surfactants.

The most suitable approach to derive aBCFfor Primary alkyl amines is the ADME Model of Arnot and Gobas (2003) for the unprotonated C16 amine. Most likely this is conservative when the values are compared with the pH dependend results from Fu et al (2009).

Overall conclusion: 

C16 amine is a model compound for the Primary alkyl amines. Therefore it is proposed to use for the Primary alkyl amines aBCFof 173 L/kgas estimated by the ADME Model of Arnot & Gobas (2003) on basis of a Weight of Evidence.

2. TERRESTRIAL BIOACCUMULATION

It is known from the literature that worms e.g. earthworm Eisenia fetida can metabolize xenobiotics like di-(2-ethylhexyl) phthalate enzymatically and with help of intestinal microorganisms (Albro et al, 1993).

Unfortunately for 1-Hexadecanamine (C16 amine) and other primary alkylamines no measured rates for metabolic degradation in worms are available. In addition a measured BCF_wormdoes not exist as well.

Only recently models for the estimation of bioaccumulation in terrestrial food-chain became available (e.g. Armitage & Gobas, 2007). But these models require Log K_owas well as a metabolic rate constant and therefore BCF_wormfor primary alkylamines cannot be estimated reliably. But it may be assumed that the BCF_wormis similarly low as the BCF_fishas the amines will most likely also be rapidly biodegraded by the worms as well as by the microorganism being present in the worm gut. In addition C12 to C18 amines are rapidly biodegraded in soils with a median half-life of 8.9 d at 20 degree C which lowers considerably the exposure in soil.