Fatty acids, C9-13-neo-, calcium salts

Endpoint summary

Additional information

Read-across approach

In the assessment of the environmental fate and ecotoxicity of fatty acids, C9-13, neo, calcium salts, a read-across approach from data for C9-C13-neo fatty acids (CAS 68938-07-8; EC 273-114-3) is proposed, because i) upon release to the environment and dissolution in aqueous media, fatty acids, C9-13, neo, calcium salts will dissociate and only be available in their dissociated form, i.e. as calcium cation and the C9-C13-neo carboxylate anion and ii) toxicity is caused by the C9-C13-neo carboxylate 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 fatty acids, C9-13, neo, calcium salts, but predictions of stability of other calcium carboxylates (Ca valerate, Ca isovalerate and Ca propionate) in a standard ISO 6341 medium (2 mM CaCl₂, 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 calcium ions in solution (Visual minteq. Version 3.0, update of 18 October 2012. http://www2.lwr.kth.se/English/OurSoftware/vminteq/index.html).

Calcium is abundantly present in natural environments (Table 1), and emissions of fatty acids, C9-13, neo, calcium salts are not expected to significantly increase the exposure concentration for calcium in water, sediment and soil. Moreover, calcium is a major essential element for living organisms and therefore it is not considered as critical for the environmental effects assessment of fatty acids, C9-13, neo, calcium salts.

Only few data on environmental fate are available for fatty acids, C9-13-neo or its salts. Based on the similarities in structure, physical-chemical properties, environmental fate and toxicity between fatty acids C9-13-neo and neodecanoic acid (C10-neo acid; CAS 26896-20-8), data for neodecanoic acid were therefore selected for the read-across approach. This is consistent with the grouping approach followed by the US EPA HPV programme for even a wider range of neo acids (C5 -C28; http://www.epa.gov/hpvis/rbp/Category_Neoacids%20C5-28_Web_April%202009.pdf).

Table 1. Background concentrations for calcium 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 Ca/L	40.2	119
Aquatic, marine water	mg Ca/L	418
Sediment, freshwater	mg Ca/kg dw	16,650	119,360
Topsoil	mg Ca/kg dw	6,590	75,760

* 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/].