Sorbitan monolaurate, ethoxylated

Toxicity to terrestrial plants

Description of key information

The chemical safety assessment according to Annex I of Regulation (EC) No. 1907/2006 does not indicate the need to investigate further the toxicity to terrestrial plants.

Additional information

In accordance with Regulation (EC) No. 1907/2006, Annex X, Column 2, 9.4 further studies on the effects on terrestrial organisms do not have to be conducted since the chemical safety assessment indicates that there is no need. No experimental data on toxicity to terrestrial plants are available for the Sorbitan monolaurate, ethoxylated. The substance is expected to show high adsorption potential due to its surface active structural properties. Therefore, tests with soil-dwelling organisms that feed on soil particles are most relevant for these substances. Exposure of plants to this substance is expected to be very limited, since it is not expected to be found in the pore water in significant quantities, due to poor water solubility and high adsorption potential.

In absence of a clear indication of selective toxicity towards a specific group of organisms, terrestrial toxicity of Sorbitan esters was tested on the earthworm Eisenia fetida, as recommended by the “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance” (ECHA, 2012). The study was conducted with the analogue substances Sorbitan, octanoate (2:3) (CAS No. 91844-53-0) and Anhydro-D-glucitol trioleate (CAS No. 26266-58-0). Both studies were performed as limit test according to OECD Guideline 207, with a test concentration of 1000 mg/kg, and no mortality occurred in any of the studies during the 14 day exposure period.

According to the “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance” (ECHA, 2012) R.7.11.5.3 a single short-term soil test on a suitable species would be enough to meet the requirements of Annex IX, where there is no toxicity (LC50) in the standard acute toxicity tests > 10 mg/L or no effects in chronic toxicity at the limit of water solubility (ECHA, 2012).As testing on the toxicity on earthworm evaluates the exposure to the test substance via soil pore water, surface contact as well as by ingestion of soil particles, it can be assumed that earthworms would be highly exposed to toxicants in soil. Therefore, earthworms are sensitive to the potential adverse effects of the substance (ECHA, 2012).

Additionally, Sorbitan esters are expected to enter the common metabolic pathways of plant cells. As stated in the “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance“ (ECHA, 2012) Section R.7.10.3.4, readily biodegradable substances are likely to be rapidly metabolised in organisms. Esterase activity in plants has been shown by several studies, e.g. Schwarz et al., 1964 and James and Smith, 1974. Sorbitan monolaurate, ethoxylated is thus expected to hydrolyse to ethoxylated D-glucitol and the respective fatty acids. The resulting C12- C18 fatty acids are either metabolised via the β-oxidation pathway in order to generate energy for the cells or reconstituted into triglycerides and stored as oil is plant seeds (Berg, 2002; Vance and Vance, 2002). D-glucitol is naturally found inapples, pears, peaches and prunesand several berries as well as in seaweed and algae (FDA, 1972;Griffin and Lynch 1968, Informatics Inc. 1972) and is thus not expected to be of concern for plants. The ethoxylation is not expected to significantly increase the toxicity of D-glucitol to plants. Using the OECD toolbox Vs. 2.3, the liver metabolism simulator provided 42 potential metabolites indicating that the ethoxylated part of the substance remains intact. Studies on genotoxicity (Ames test, chromosomal aberration and gene mutation in mammalian cells) were negative, indicating no reactivity of the test substance or its metabolites under the test conditions. Studies with Sorbitan monolaurate, ethoxylated, available for aquatic algae, also show low toxicity (ErL10 = 19.05 mg/L and ErL50 = 58.8 mg/L) (Wenzel, 2012).

Based on the above information, toxicity to terrestrial plants is expected to be low. Moreover, the substance is not expected to remain in the terrestrial environment, due to ready biodegradation. Bioaccumulation is not likely due to rapid metabolism. In accordance with Regulation (EC) No. 1907/2006, Annex IX, Column 2, 9.4 further studies on the effects on terrestrial organisms do not have to be conducted since the chemical safety assessment indicates that toxicity to terrestrial plants is not expected to be of concern.

 

References:

Berg, J.M., Tymoczko, J.L. and Stryer, L., 2002, Biochemistry, 5th edition, W.H. Freeman and Company

ECHA (2012) Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance, European Chemicals Agency, Helsinki

FDA (1972): Study of the mutagenic effects of Sorbitol. Report No PB 221816, U.S. Food and Drug Administration, Washington, USA

Griffin, W.C. and Lynch, M.J. 1968. Polyhydric alcohols. Pages 447-460 in T.E. Furia, ed. Handbook of food additives. The Chemical Rubber Co., Cleveland, Ohio.

D. J. James, A. R. W. Smith (1974) A biochemical study of non-specific esterases from plant cells, employing the histochemical substrate, naphthol AS-D acetate, The Histochemical Journal, 6 (1), 7-23

Helen M. Schwartz, Sieglinde I. Biedron, Mavis M. von Holdt, S. Rehm (1964) A study of some plant esterases, Phytochemistry, 3 (2), 189–200

Informatics, Inc. 1972. Monograph on sorbitol. Submitted under DHEW contract no. FDA 72-104. Rockville, Md.

Vance, D.E., Vance, J.E. (2002) Biochemistry of Lipids, Lipoproteins and Membranes, 4^thEdition, Elsevier Science B.V.