Diisotridecyl adipate

Endpoint summary

Description of key information

All acute and chronic toxicity information available for DITA resulted in no toxic effects up to the limit of water solubility.

 

In the acute Daphnia study, toxic effects were seen, but only above the limit of water solubility of DITA. In this study, after exposure to the 100 mg/L and 1000 mg/L Water Accommodated Fraction (WAF), 10 % and 17.5 % immobile Daphnia, respectively, were counted after 48. These effects are considered to be related to physical effects rather than to systemic toxicity. The 48h-EL50 is determined to be > 1000 mg/L based on the loading rates (tested as WAF).

 

From an algal inhibition test with diisotridecyl adipate as test substance it can be concluded that the ErL50 (24 -72 h) based on the growth rate is > 1000 mg/l nominal loading rate and the NOErL based on the growth rate is≥100 mg/l nominal loading rate. 

 

The available long-term toxicity study towards aquatic invertebrates for DITA (Simon, 2016) was conducted by using the column elution method for test medium preparation. Daphnids were exposed to a steady state column eluate in form of the 100% eluate and 10 % eluate for a period of 21 days in a semi-static test design. No significant differences between the control group and the test groups were found for the following endpoints: Mobility, age at first reproduction, length and intrinsic rate. In the undiluted eluate, a ~27% reduction of mean cumulative offspring per surviving daphnids after 21 days were seen, whereas the exposure to the 10%-dilution of the eluate resulted in no significant effects for this endpoint, as well. The concentrations measured in both, the undiluted eluate and the 10%- eluate tests solution, are far above the reported and experimentally determined (e.g. Kotthoff, 2016) water solubility for DITA of ~0.7 µg/L. Hence, micelle formation or other processes causing the inhibition cannot be excluded. Consequently, this study is considered to be invalid (see study and testing proposal) and a testing proposal for a new study using a more appropriate test solution preparation technique (developed in an extensive research project) is entered in the dossier.

Although the the study is invalid the obtained NOEC of 1.64 µg/L and the total tonnage of all registrants is used for an environmental exposure assessment for safety reasons until the toxicity to aquatic invertebrates is clarified. Available data for read-across substances (details below) and the valid water solubility figure for DITA (0.7 µg/l) supports the assumption that there is no toxicity in the range of water solubility. This is also supported by QSAR calculations for chronic toxicity to fish.

Additional information

Short-term-toxicity to fish

The acute lethal toxicity of diisotridecyl adipate to Poecilia reticulata (Guppy) was investigated under static exposure conditions over a period of 96 h. The absence of mortality provides that the LL50 at 96 h is therefore > 100 mg/l (nominal concentration) (Häner/Panolin AG, 1998). The 96h-LC50 in sheepshead minnow (saltwater) was determined to be > 5000 mg/L for the test substance diisotridecyl adipate (BenKinney/Mobil, 1986).

 

Long-term toxicity to fish

Long-term aquatic toxicity was estimated using the ECOSAR model (applicability explained in the attached reports). No toxic effects are expected to occur in saturated solutions even with long-term exposures.  

 

Short-term toxicity to aquatic invertebrates

 

Based on the results of the key study it can be concluded that the 24 h and 48 h EL50 values for Daphnia magna of diisotridecyl adipate are >1000 mg/l based on loading rates (Häner/Panolin, 1998).

 

Long-term toxicity to aquatic invertebrates

 

Chronic aquatic toxicity data (Daphnia magna) are available for DITA itself and the respective read across substances. The available long-term toxicity study towards Daphnia magna for DITA (Simon, 2016) is considered invalid due to significant methodological deficiencies. A testing proposal is entered in the respective chapter.

  

Toxicity to aquatic algae and cyanobacteria

 

From an algal inhibition test with diisotridecyl adipate as test substance can be concluded that the ErL50 (24 -72 h) based on growth rate is > 1000 mg/l nominal loading rate and the NOErL based on growth rate is ≥ 100 mg/l nominal loading rate.

 

Toxicity to microorganisms

Data for diisotridecyl adipate could not be located. But an activated sludge respiratory inhibition test was conducted with the supporting substance bis-(2-ethylhexyl) adipate. A NOEC of 350 mg/L was determined (EC50 >350 mg/L) (Huels AG, 1996b).

 

All effect levels determined are far above the water solubility of the test substances. It can be concluded that diisotridecyl adipate does not exhibit toxic effects in aquatic organisms up to its limit of water solubility ( ~ 0.0007 mg/L). Long-term toxicity to aquatic invertebrates need to be verified using a suitable test solution preparation technique.