Diesters of alcohols, C7-9-iso-, C8-rich, 2-ethylhexyl and nonanedioic acid

Endpoint summary

Description of key information

In a test in L. idus melatonus, no effects of C9-11 branched alcohols, C10 rich diesters with nonanedioic acid in the range of water solubility were observed testing a saturated test solution which was subsequently filtered. Thus, an LC50 (96h) greater than the highest tested concentration of 10 g/L is determined (Hansonis 1993)

In a test on bis(2-ethylhexyl) azelate, where carp were exposed to this substance during 96 hours, no mortality was observed at loading rates up to 10000 mg/L. Effects on swimming behaviour became apparent at concentrations of 100 mg/L and above. The LD50 based on loading rate is > 10000 mg/L (Bogers 1998).

In a 48 hours test daphnia were exposed to bis(2-ethylhexyl) azelate at a nominal concentration of 0.1 mg/L (measured 0.093 mg/L). At this concentration, which is above the maximum water solubility of bis(2-ethylhexyl) azelate no effects on mobility were observed. Therefore it can be concluded that the EC50 is > 0.1 mg/L (MOE 2004).

In a daphnia reproduction study 21 days exposure to C9-11 branched alcohols, C10 rich diesters with nonanedioic acid did not affect reproduction of Daphnia magna at a WAF prepared at a loading rate of 4.0 mg/L after 21 days of exposure (NOELR). At 4 mg/L there were some slight statistically significant effects on growth (decrease by 2.4%), which were considered not to be of toxicological relevance. Based on the complex nature of the substance analytical determination of the actual test concentrations was not possible (Migchielsen, 2016).

In a daphnia reproduction study with bis(2-ethylhexyl) azelate no effects on mortality, reproduction and growth were seen at a loading rate of 0.1 mg/L (0.0637 mg/L TWA measured concentration). The tested concentration is well above the water solubility of bis(2-ethylhexyl) azelate. Therefore it is concluded that the NOEC is above the water solubility (MOE 2004).

In a test on algae exposure to 0.1 mg/L bis(2-ethylhexyl) azelate (measured initial concentration 0.0084 mg/L) did not lead to decreased growth rates or inhibition of biomass. The EC50 for growth rate is > 0.0084 mg/L and the NOEC is 0.0084 mg/L. As this concentration is above the reported water solubility of bis(2-ethylhexyl) azelate, no toxicity of this substance is expected up to maximum solubility (MOE 2004).

Pseudomonas putida were exposed to C9-11 branched alcohols, C10 rich diesters with nonanedioic acid during 16 hours at 10 g/L (a saturated test solution which was subsequently filtered). It can be concluded that no effects of the test substance in the range of water solubility were observed (growth measured by examination with a spectrophotometer) Thus the EC50 (16h) is greater than the water solubility (Hansonis 1993).

In another study bis(2-ethylhexyl) azelate (concentrations up to 10 g/L (siphoned)) was shown not to influence the growth rate of Pseudomonas putida at any of the concentrations tested. The NOEC in this study is 10 g/L (Bertens 1993)

Additional information

The results of the tests are indicative for no mortality and very low toxicity at the water solubility level of both analogues of diesters of alcohols, C7-9-iso-, C8-rich, 2-ethylhexyl and nonanedioic acid. Therefore in view of the structural similarities and the similarities of the starting materials and degradation products, the starting point for the risk assessment will be taken from the long-term daphnia toxicity study with bis(2-ethylhexyl) azelate, which has a NOELR of 0.1 mg/L. This value is considered representative for the maximum solubility of alcohols, C7-9-iso-, C8-rich, 2-ethylhexyl and nonanedioic acid and is similar to the NOELR as found in the algae study with bis(2-ethylhexyl) azelate.

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