Reaction mass of 3-O-acetyl-1,5-anhydro-4-butyl-2,4-dideoxy-2-methyl-D-xylitol and (2R,3S)-2-methyloctane-1,3-diyl diacetate

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 DT50 values in the range of < 1 day for both type of constituents using Cas no 38285 -49 -3 and 67634 -09 -7, respectively. 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). No ozone reaction estimations are available for any of the constituents. 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 biodegradability is assessed based on read-across from the close structural analogue Jasmal (Generic CAS# 18871-14-2). For Jasmal a ready biodegradation study is available according to OECD TG 301F (Manometric Respirometry Test under GLP, Rel. 1). In this study, Jasmal was biodegraded by 71% at day 28 and considered to be readily biodegradable.

Bioaccumulation:

The bioaccumulation of Jessemal in fish is based on the experimental BCF of the analogue Verdox (CAS# 20298 -69 -5), which was tested in an OECD TG 305, Rel. 1. Steady-state concentrations of 14C-labelled Verdox were achieved in fish tissues after 33 days and based on 5% lipid content the BCF was 156 L/Kg.

Terrestrial: The BCF for terrestrial organisms was calculated using the QSAR of Jager (1998), incorporated in the EUSES model, and yielded a value of 65.3 L/kg ww.

Transport and distribution:

Adsorption / Desorption potential: For Jessemal the Koc of 760 is derived based on read-across from the close structural analogue Jasmal (CAS# 18871-14-2). For Jasmal, the Koc was tested in an HPLC estimation method according to OECD TG 121 (Rel. 1). The log Koc values of the major components range from 2.42 - 2.88 (Koc: 260 - 760). The log Koc values of the minor components range from 2.37 - 2.51 (Koc ranges from 240 to 320). The Koc of 760 (log Koc 2.88) is reported as key value for chemical safety assessment covering also the higher values.

The Henry's law constant is calculated using the equation from EUSES using a weighted average molecular weight of 226 g/mole, and the experimentally determined (averaged) vapour pressure of 0.38 Pa (at 24 °C) and water solubility of 714.1 mg/L (at 24 °C). The Henry's Law constant at environmental temperature (12 °C) is calculated to be 0.061 Pa·m³/mol. The substance is not expected to volatilise from water to a significant extent.

Based on Level III environmental distribution modelling using EPISUITE for all constituents (assuming equal and continuous releases to air, water and soil), using the EPISuite default physico-chemical parameters for each constituent as input, it is estimated that the majority of the constituents released to the environment will partition mainly into soil (72%) and water (27%) with minor amounts to air (≤2%) and sediment (<1%) using average values of the two main Cas no. 38285-49 -3and 67634-09 -7, respectively.

The SimpleTreat model, which is incorporated in EUSES, simulates the distribution of the substance in a Sewage Treatment Plant (STP). Based on the weighted average molecular weight of 226 g/mole, a Koc value of 760 L/kg, a vapour pressure of 0.38 Pa (at 24 °C) and a water solubility of 714.1 mg/L (at 24 °C), and the qualification as readily biodegradable, the model predicts that 81.5% of the substance will be degraded and that 11.9, 6.5%, and 0.024% will partition to water, sewage sludge and air, respectively.