Diisononyl adipate

Endpoint summary

Additional information

Since no study assessing the toxicity of DINA to soil macroarthropods is available, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of substances, a read-across to the structurally very similar Bis(2-ethylhexyl) adipate (CAS 103-23-1, DEHA) was conducted. The read across is justified due to the similarity of structure and functional groups and accordingly similar physico-chemical properties which result in similar environmental behavior and fate (see table below).

Substance	Diisononyl adipate	Bis(2-ethylhexyl) adipate
CAS number	33703-08-1	103-23-1
Structure	see attachment	see attachment
Molecular formula	C24H46O4	C22H42O4
Molecular weight	398.63 g/mole	370.58 g/mole
PC parameter
Water solubility	RA to 103-23-1	0.0032 mg/L (EU A.6)
Partition coefficient	9.54 (OECD 117)	8.94 (OECD 117)
Vapour pressure	0.00000002 hPa at 20 °C (calculation)	0.0000003 hPa at 20 °C (calculation)
Environmental fate
Biodegradability	> 90% in 28 days (OECD 301F)	>90% in 28 days (OECD 301F)
Adsorption [log KOC]	5.15 (calculation)	4.56 (calculation)
Hydrolysis	not relevant
Ecotoxicology
Short-term toxicity to fish [96h-LC50]	No toxicity within the limit of water solubility	No toxicity within the limit of water solubility
Long-term toxicity to aquatic invertebrates [NOEC]	-	-
Short-term toxicity to aquatic invertebrates [48h-EC50]	No toxicity within the limit of water solubility	No toxicity within the limit of water solubility
Long-term toxicity to aquatic invertebrates [21d-NOEC]	RA from 103 -23 -1	No toxicity within the limit of water solubility
Short-term toxicity to algae [72h-EC50]	No toxicity within the limit of water solubility	No toxicity within the limit of water solubility
Long-term toxicity to algae [72h-NOEC/EC10]	No toxicity within the limit of water solubility	No toxicity within the limit of water solubility
Toxicity to microorganisms [NOEC]	The inhibition of the degradation activity of activated sludge is not anticipated when DINA is introduced in appropriate low concentrations.	The inhibition of the degradation activity of activated sludge is not anticipated when DEHA is introduced in appropriate low concentrations.

The short-term toxicity test with DEHA was performed according to EU method C.8 using Eisenia foetida as test organisms (Huels 1996). Different nominal concentrations between 100 and 1000 mg/kg d.w. were tested. Mortality was recorded after 7 and 14 days exposure time. Whereas no earthworm died in the control and test concentrations up to 500 mg/kg, 17 animals (out of 40) died in the 1000 mg/kg treatment. Thus, the 14d-LC50 is determined to be 865 mg/kg d.w. based on nominal concentrations.

Based on the mentioned structural similarities between the source and the target substance resulting in a similar efate and ecotoxicological profile this effect value can also considered to be true for Diisononyl adipate (CAS 33703-08-1).

In accordance with Regulation (EC) No. 1907/2006, Annex X, Column 2, 9.4 further studies on the effects on terrestrial organisms does not have to be conducted since the chemical safety assessment indicates that there is no need. The test substance is readily biodegradable and will therefore not persist in soil for an extended period of time. Furthermore, the substance is not toxic to aquatic organisms up to the limit of water solubility and available data indicate that DINA is not bioaccumulative. Due to its high adsorption potential DINA is considered to be immobile in soil and uptake by roots via pore-water is not expected. Studies with aquatic microorganisms showed that DINA is rapidly degraded and show no inhibitory effect. Hence, the risk the substance poses to terrestrial plants and microorganisms is considered to be low and a study is not considered to be necessary.