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Toxicity to aquatic algae and cyanobacteria

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Description of key information

No toxic effects to aquatic algae up to the limit of water solubility.

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Additional information

Since no studies investigating the toxicity to aquatic algae and cyanobacteria of fatty acids, C14-18 and C16-18-unsatd., esters with propylene glycol (CAS 84988-75-0) are available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to two structurally related category members butylene glycol dicaprylate / dicaprate (CAS 853947-59-8) and decanoic acid, mixed diesters with octanoic acid and propylene glycol (CAS 68583-51-7) was conducted. This read-across is justified in detail in the overall summary (IUCLID chapter 6.1) and within the category 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. Nevertheless, as it can be seen in the data matrix of the category justification in section 13 and the overall summary, all reliable data in the category support the hazard assessment of each category member by showing a consistent pattern of results. The first study with butylene glycol dicaprylate / dicaprate was performed as a limit test according to EU Method C.3 using the freshwater algae Scenedesmus subspicatus (Scholz, 1997). A test substance concentration of 1000 mg/L (nominal) and 3 mg/L (measured, based on TOC content) respectively, did not result in any effects on the growth rate and biomass after 72 h resulting in an EL10/50 > 3 mg/L (measured, initial). The recovery rate in the stability test was > 80% and the concentration after 48 and 72 h did not differ more than 20%. Therefore, the test substance was bioavailable throughout the test. The second study with the read-across substance decanoic acid, mixed diesters with octanoic acid and propylene was performed according to the EU Method C.3 under GLP conditions (Scholz, 1995). The green algae Scenedesmus subspicatus was exposed to a Water Accommodated Fraction (WAF) of nominal 5.3 mg/L and subsequent dilutions for 72 h. No effects on the growth rate of S. subspicatus up to the limit of water solubility were observed resulting in an ELr50 > 5.3 mg/L and a NOELR of ≥ 5.3 mg/L. Based on the results from structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which are characterized by a similar ecotoxicological profile, it can be concluded that fatty acids, C14-18 and C16-18-unsatd., esters with propylene glycol will not exhibit toxic effects to aquatic algae up to the limit of water solubility.