Fatty acids, tall-oil, Bu esters

Short-term toxicity to aquatic invertebrates

Description of key information

No effects up the limit of water solubility 

Additional information

No studies are available for the short-term toxicity of Fatty acids, tall-oil, Bu esters (CAS 67762-63-4) to aquatic invertebrates. The assessment was therefore based on studies conducted with the structurally most similar category members, for which data is available, Fatty acids, C16-C18 and C18 unsatd., branched and linear, Bu esters (CAS 163961-32-8), Isopropyl myristate (CAS 110-27-0) and Isopropyl oleate (CAS 112-11-8), as part of a read across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Grouping of substance and read across approach. Further justification is given within the endpoint summary 6.1 and within the category justification section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was entered into IUCLID. Nevertheless, as can be seen in the data matrix of the category justification in Section 13, all reliable data in the category support the hazard assessment for this endpoint, by showing a consistent pattern of results.

In the selected key study, the acute toxicity of Fatty acids, C16-C18 and C18 unsatd., branched and linear, Bu esters (CAS 163961-32-8) to Daphnia magna was tested under semi-static conditions according to OECD 202 as limit test under GLP conditions (Wetton and Hill 2004). The tested concentration of 0.2 mg/L (nominal) was applied in a solvent-spike method (with acetone). The time weighted mean measured test concentrations of the centrifuged test media in order to give the a "worst case" analysis of data, resulted in a value of 0.044 mg/L. There was no toxic effect on invertebrates after an incubation period of 48 hours at the limit of the water solubility observed, so an EL50(48h) > 0.044 mg/L was stated.

In the second selected key study with Isopropyl myristate (CAS 110-27-0) three different treatments of test material were applied for the test performance according to EU Method C.2 and to GLP (Küch 1995). Method 1: limit test 100 mg/L test substance and 5 min ultrasonic treatment; Method 2: limit test 100 mg/L, 24 h stirring and removal of undissolved test substance via filtration through glass fibre filter; Method 3: 3-5 times saturation, 24 h stirring. In all tests animals were swimming at the water surface. Furthermore, using method 1, an oily film was present. Method 1 (limit test without substance separation) resulted in an EC50 < 100 mg/L (nominal), whereas in method 2 and 3 (both tests with substance separation) the EC50 was established as greater than the water solubility. In conclusion: the results indicate that physical effects may occur in the prescence of undissolved test material.

In a further study with Isopropyl oleate (CAS 112-11-8), the acute toxicity to the marine species Crangon crangon was tested under constant stirring (Clitherow 1991). Part of the test sample was observed to remain on the liquid surface, even with continuous stirring. The agitation was sufficient to maintain a distribution within the body of the liquid, but at higher concentrations the thickness of the floating layer increased. No mortalities occured up to the highest tested concentration of 8500 mg/L.

Thus, based on the above mentioned result, and due to the structural and profile similarities of the substances, as are explained with in the overall endpoint summary 6.1 it can be concluded that no toxicological effects on aquatic invertebrates are expected up to the limit of water solubility for Fatty acids, tall-oil, Bu esters (CAS 67762 -63 -4).