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Long-term toxicity to aquatic invertebrates

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For the test item Reaction product of adipic acid and sebacic acid and isotridecan-1 -ol is no study available. However, it is likely that the studies conducted on the component diisotridecyl adipate and the read-across substance bis(2 -ethylhexyl) adipate are valid for Reaction product of adipic acid and sebacic acid and isotridecan-1 -ol (please see justification for read-across). 
In a 21 day Daphnia magna reproduction test with the analogue substance bis-(2-ethylhexyl) adipate as test substance, a NOEC of >= 0.77 mg/L was determined (highest dose tested). Toxic effects on reproduction and mortality of adult daphnids are above the water solubility of the test substance (Huels AG, 1996a). This result is confirmed by another valid study of Robillard et al., 2008. Therefore it is likely that the less water soluble substance diisotridecyl adipate is also not toxic to aquatic invertebrates in the range of its water solubility.

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Additional information

For the test item Reaction product of adipic acid and sebacic acid and isotridecan-1 -ol is no study available. However, it is likely that the studies conducted on the read-across substance bis(2 -ethylhexyl) adipate are valid for Reaction product of adipic acid and sebacic acid and isotridecan-1 -ol (please see justification for read-across).

In a valid 21 day reproduction test according to OECD test guideline 202 (1984, part 2), the water flea Daphnia magna was exposed to three different concentrations of di-2-ethylhexyl adipate (nominal concentrations 0.5, 1.0, and 2.0 mg/L, measured concentrations 0.19, 0.39, and 0.77 mg/L). To solubilise the test substance, a vehicle was used (1g/L MARLOWET R 40).

During the test, no effects were observed. Based on reproduction, a NOEC of>= 0.77 mg/L was determined. Toxic effects on reproduction and mortality of adult daphnids are above the water solubility of the test substance (Huels AG, 1996a).

This is considered a valid proof of the absence of long-term aquatic toxicity to invertebrates in the range of water solubility of bis(2-ethylhexyl) adipate. This result is confirmed in a study performed by Robillard et al. (2008). A chronic Daphnia magna limit test was conducted at an average exposure of 4.4 μg/L (measured water solubility = 5.5 µg/L) in laboratory diluent water to avoid insoluble test material and avoid physical entrapment. One hundred percent of the DEHA-treated organisms survived compared to 90% survival in both the controls and solvent controls. Mean neonate reproduction was 152, 137, and 148 and mean dry weight per surviving female was 0.804, 0.779, and 0.742 mg in the treatment, control and solvent control, respectively. No adverse effects were observed. Felder et al. (1986) observed in a study, which was not conducted according to a current guideline and GLP, a significantly reduced yield of young per adult per day at mean measured exposure levels of 0.087 and 0.18 mg/L. A MATC (maximum acceptable toxicant concentration) for long-term toxicity to Daphnia magna was calculated to be between 0.024 and 0.052 mg/L based on statistical analyses of adult mean length, survival and young per adult per reproduction day. The geometric mean of the LOEC and NOEC was 0.035 mg/L, which is approximately ten-fold above the solubility limit of bis(2-ethylhexyl) adipate. Since the solubility in the test medium is not expected to be ten-fold higher than in water it assumed that a solvent was used; however, it cannot be deduced from the study which solvent was used to establish the test concentrations. Hence, it is not clear whether the observations made are due to the solved fraction of the test substance or if any undissolved matter caused the effects. Furthermore, information provided in the results section of the publication is rather scarce. Neither raw data nor details about the extent of impairment daphnids had to face at a given concentration are given. Furthermore, no information about a dose-response relationship is included. In conclusion, there is some uncertainty remaining with regard to the meaning of the obtained results. Structure activity relationship (SAR) does not provide any useful information on the issue. According to ECOSAR v1.0, reasonable values on chronic toxicity can only be estimated for substances with a maximum log KOW of 8. Hence, for bis(2-ethylhexyl) adipate (log KOW = 8.94), the calculation of a chronic toxicity value is not appropriate. Taking the available information into account it is concluded, that bis(2-ethylhexyl) adipate does not show long-term toxicity to aquatic invertebrates in the range of its water solubility.