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Toxicity to soil macroorganisms except arthropods

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Description of key information

NOEC (56 d) 500 mg/kg soil dw based on reproduction (OECD 222)
NOEC (56 d) ≥ 1000 mg/kg soil dw based on reproduction (OECD 222)

Key value for chemical safety assessment

Additional information

Since no studies investigating the toxicity to soil macroorganisms oftetradecyl stearateare available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to the structurally related source substances 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) and Fatty acids, C8-10, C12-18-alkyl esters (CAS 95912-86-0) was conducted. 2-octyldodecyl isooctadecanoate is characterized by a C18iso fatty acid (isooctanoate) and a C20iso alcohol (2-octyldodecanol). This substance covers the upper end of C-chain distribution of the target substance. The second source substance is characterized by a C8-C10 fatty acid and a C12-C14 alcohol covering the lower end of C-chain distribution of the target substance. Using both substances for the prediction of terrestrial toxicity of the target substance is reliable since the endpoint is covered by interpolation. This read-across is justified in detail in the overall summary (IUCLID Section 6.1) and within the analogue justification in IUCLID Section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment.

The study with the source substance 2-octyldodecyl isooctadecanoate (CAS 93803-87-3) was performed according to OECD 222 (GLP) with the earthworm Eisenia fetida. Five nominal concentrations were mixed into artificial soil and mortality/growth (after 4 weeks) and reproduction (after 8 weeks) were measured. No significant effects on mortality/growth and reproduction were found resulting in a NOEC (56 d) ≥ 1000 mg/kg soil dw.

The second study with the source substance Fatty acids, C8-10, C12-18-alkyl esters (CAS 95912-86-0) was performed according to OECD 222 (GLP) for 56 d with artificial soil. Test concentrations up to nominal 1000 mg/kg dw were tested for impacts on mortality, biomass and reproduction. Mortality and biomass were investigated after 28 d whereas the number of juveniles was measured after 56 d. No mortality and no effects on biomass were recorded after 28 d. However, effects on reproduction expressed in the number of juveniles was observed at the highest test concentration of 1000 mg/kg soil dw. Thus, a NOEC (56 d) of 500 mg/kg soil dw was derived. Analyzing the results in detail shows that the number of juveniles was very variable within the replicates at the highest concentration. In two replicates out of four the number of juveniles were 186 and 189, respectively whereas in the other two replicates 303 and 371 juveniles were recorded which is in the range of the solvent control. Nevertheless, since no indications are given in the report why the replicates show such a high variability at the highest test concentration the reported NOEC of 500 mg/kg soil dw has to be used for the assessment as a worst case assumption. 

Based on the result from two structurally related source substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which are characterized by a similar ecotoxicological profile and comparable structure, no effects on earthworms are expected for tetradecyl stearate.