Potassium 2-ethylhexanoate

Endpoint summary

Additional information

Read-across approach

In the assessment of the environmental fate and ecotoxicity of potassium 2-ethylhexanoate, a read-across approach from data for 2-ethylhexanoic acid (CAS 149-57-5; EC 205-743-6) is followed. This read-across strategy is based upon the assumptions that i) upon release to the environment, potassium 2-ethylhexanoate will completely dissociate and only be available in its dissociated form, i.e. as potassium cation and the 2-ethylhexanoate anion and ii) toxicity is only caused by the 2-ethylhexanoate anion.

Upon dissolution in water, it is indeed predicted that metal carboxylates dissociate completely into the metal cation and the organic anion at environmentally relevant conditions. No information is available on the stability constants of potassium 2-ethylhexanoate, but predictions of stability of another potassium carboxylate (K isovalerate) in a standard ISO 6341 medium (2 mMCaCl₂, 0.5 mM MgSO₄, 0.77 mM NaHCO₃ and 0.077 mM KCl, pH 6 and 8) clearly show that carboxylic acids have no potential for complexing potassium ions in solution (Visual minteq. Version 3.0, update of 18 October 2012. http://www2.lwr.kth.se/English/OurSoftware/vminteq/index.html).

Potassium is abundantly present in natural environments (Table 1), and emissions of potassium 2-ethylhexanoate are not expected to significantly increase the exposure concentration for potassium in water, sediment and soil. Moreover, potassium is a major essential element for living organisms and therefore it is not considered as critical for the environmental effects assessment of potassium 2-ethylhexanoate.

Table 1. Typical baseline background concentrations for potassium in water, sediment and soil (data for freshwater, sediment and soil from FOREGS*, data for marine water from Culkin and Cox, 1966)

Compartment	Unit	Typical (P50) baseline level	P90 of baseline concentrations
Aquatic (freshwater)	mg K/L	1.60	6.83
Aquatic (marine)	mg K/L	399
Sediment (freshwater)	mg K/kg dw	11,050	17,650
Topsoil	mg K/kg dw	10,560	17,870

* The FOREGS geochemical baselines mapping program represents the end twentieth century state of the surficial environment in Europe. The main aim of the FOREGS (Forum of European Geological Surveys) Geochemical Baseline Mapping Program was to provide high quality, multi-purpose environmental geochemical background data for stream water, stream sediment, floodplain sediment, soil, and humus across Europe. A baseline background concentration was defined as the concentration of an element in the present or past corresponding to very low anthropogenic pressure (i.e., close to the natural background). The FOREGS-data set was published in September 2007 (http://www.gsf.fi/publ/foregsatlas/ForegsData.php) and is considered to be of high quality. A detailed description of sampling methodology, sampling preparation and analysis is given by Salminen et al. (2005).

References: Culkin, F. and R.A. Cox. 1966. Sodium, potassium, magnesium, calcium and strontium in sea water. Deep-Sea Res., 13: 789-804. Salminen, R. (Chief-editor), Batista, M.J., Bidovec, M. Demetriades, A., De Vivo. B., De Vos, W., Duris, M., Gilucis, A., Gregorauskiene, V., Halamic, J., Heitzmann, P., Lima, A., Jordan, G., Klaver, G., Klein, P., Lis, J., Locutura, J., Marsina, K., Mazreku, A., O'Connor, P.J., Olsson, S.Å., Ottesen, R.-T., Petersell, V., Plant, J.A., Reeder, S., Salpeteur, I., Sandström, H., Siewers, U., Steenfelt, A., Tarvainen, T., 2005. Geochemical Atlas of Europe. Part 1 – Background Information, Methodology and Maps. Geological Survey of Finland, Espoo, Finland, 526 pp. ISBN 951-690-921-3 [also available at: http://www.gtk.fi/publ/foregsatlas/].