Reaction products resulting from the esterification of Sorbitol with C8 – 18 (even) and C18 unsaturated fatty acids in the ratio of 1:1

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 esters. Based on calculated estimation, larger Sorbitan esters (all triesters, diesters from fatty acid chain length C12 and monoesters with C18 fatty acids) show high adsorption potential (log Koc 3.3 - >10). Smaller Sorbitan mono- and diesters (fatty acid chain length <C18 and <C12, respectively) have lower calculated adsorption potential (log Koc 1.0 - 2.8). However, all Sorbitan esters have surface active properties, which is not taken into account by the model calculation, and further increases the adsorption potential of the substances. Therefore, tests with soil-dwelling organisms that feed on soil particles are most relevant for these substances.

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, 2008). The study was conducted with the category members Sorbitan, octanoate (2:3) (CAS No. 91844-53-0) and Anhydro-D-glucitol trioleate (CAS No. 26266-58-0), which represent the two ends of the Sorbitan esters category in term of size, water solubility and Koc and can thus be used to cover the category. 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 ECHAs guidance 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, as stated in the “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance“ (ECHA, 2012), readily biodegradable substances are likely to be rapidly metabolised in organisms. Sorbitan esters are expected to enter the common metabolic pathways of plant cells. Esterase activity in plants has been shown by several studies, e.g. Schwarz et al., 1964 and James and Smith, 1974. Sorbitan esters are thus expected to hydrolyse to D-glucitol and the respective fatty acids. 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 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). Studies available for aquatic algae also show low toxicity (NOELR = 560 mg/L and EL50 > 1000 mg/L).

Based on the above information, toxicity to terrestrial plants is expected to be low. Moreover, the substances are 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.

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within CSR.