2,6-dimethyloct-7-en-2-yl acetate

Endpoint summary

Description of key information

Abiotic degradation:

Air: No experimental data on the phototransformation of the substance in air are available. Based on estimation with the QSAR model AopWin (v1.92), in air the substance undergoes rapid degradation after reaction with hydroxyl radicals with a DT50 -value of 3 .8 hours. Degradation after reaction with ozone radicals is also rapid with a DT50 -value of 23 hours. This indicates that the substance is not a long-range transported chemical in air according to the UNECE criteria (http://www.unece.org/fileadmin/DAM/env/documents/2000/ece/eb/ece%20eb%20air.60.e.pdf). These half-lives will not be used for the CSA because these are calculated and not experimental values. Furthermore, the substance does not have an ozone depletion potential because it does not contain halogens and does not have the potential to reach the stratosphere (EU CLP (ECno 1272/2008 and its updates).

Water: The hydrolysis endpoint is waived as the substance is qualified as readily biodegradable. Some hydrolysis can be expected based on the substance’s ester functionality. To be conservative a hydrolysis half-life of 1 year is used.

Biotic degradation:

The biodegradation potential of Dihydromyrcenyl Acetate was examined in a study according to OECD TG 301B and in compliance with GLP criteria. The test substance achieved 87.7% biodegradation in 28 days and passed 10-d window criterion (11.9% day 4, 67.2% day 14). Thus it can be concluded that theDdihydromyrcenyl acetate is readily biodegradable according to this test (modified OECD guideline 301B using sealed vessels).

Bioaccumulation:

Aquatic bioaccumulation in fish: The BCF is 156 L/kg based on read across from Verdox, which is tested in an OECD TG 305.

Terrestrial bioaccumulation:The BCF for terrestrial organisms was calculated using the QSAR of Jager (1998), incorporated in the EUSES model, and yielded a value of 954 L/kg ww.

Transport and distribution:

The adsorption potential of Dihydromyrcenyl acetate is 2468 L/kg based on read-across from Dihydromyrcenol (CAS# 18479 -58 -8). For Dihydromyrcenol, data is available from a HPLC screening study according to OECD TG 121 and in compliance with GLP criteria. From this study a log Koc of 2.25 was determined. The respective Koc value is ca. 178 L/kg. The log Koc is corrected: log Koc Dihydromyrcenyl acetate = log Koc Dihydromyrcenol * (log Kow Dihydromyrcenyl acetate/log Kow Dihydromyrcenol) = 2.25 * (4.9/3.25) = 3.39. The respective Koc value for Dihydromyrcenyl acetate is 2468 L/kg.

The Henry's law constant is calculated using the equation from EUSES. Using a molecular weight of 198.3 g/mol, and the experimentally determined vapour pressure of 14.4 Pa (at 24 °C) and water solubility of 6.1 mg/L (at 24 °C) the Henry's Law constant at environmental temperature (12 °C) is calculated to be 236 Pa·m³/mol.

Based on Level III environmental distribution modelling using EPISUITE (assuming equal and continuous releases to air, water and soil) using the CAS number 53767 -93 -4 and the measured physico-chemical parameters (water solubility = 6.1 mg/L, vapour pressure = 0.108 mm Hg and log Kow = 4.9) as input, it is estimated that the majority of the substance released to the environment will partition mainly into soil (62.2%) and water (33.7%) with minor amounts to air (3.29%) and sediment (0.785%).

The SimpleTreat model, which is incorporated in EUSES, simulates the distribution of the substance in a Sewage Treatment Plant (STP). Model calculations show that 49.6% of the substance will be degraded and that 26.9%, 17.1% and 6.39% will partition to air, sewage sludge and water, respectively.