Reaction mass of 3,7-dimethyl-1-octyl acetate and citronellyl 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 DT50 values in the range of 0.1 - 1.2 days. Degradation after reaction with ozone radicals is also rapid with DT50 values in the range of 0.01 -0.96 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 according to EU CLP (EC 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 substance is readily biodegradability based on read-across from its main constituent Citronellyl Acetate mono (CAS# 150 -84 -5), which showed ready biodegradability (82%) in an OECD TG 301B.

Bioaccumulation:

Bioaccumulation in aquatic and terrestrial species is based on the available information (log Kow 4.6 and calculated BCF values). The BCFs for aquatic and terrestrial organisms were calculated using QSARs of Veith et al. (1979) and Jager (1998), both incorporated in the EUSES model, and yielded values of 1620 and 479 L/kg ww, respectively. This value is conservative because the acete ester will be cleaved by carboxyl esterases in fish and bioaccumulation of the ester will be low.

Transport and distribution:

The adsorption coefficient (Koc) of the substance was determined using the HPLC estimation method based on soil-adsorption reference data. The study was performed in accordance with EC C.19 and OECD 121 and in compliance with GLP. The log Koc at neutral pH and ca. 20°C for the constituent with peak area of 65% was determined to be 3.85 (Koc = 7.1E3). The log Koc for the constituent with peak area of 35% was determined to be 3.52 (Koc = 3.3E3). The Koc value of 7100 L/kg is used for assessment.

The Henry's law constant is calculated using the equation from EUSES using a molecular weight of 198 g/mole, and the experimentally determined vapour pressure of 2.58 Pa (at 24 °C) and water solubility of 12.1 mg/L (at 24 °C). The Henry's Law constant at environmental temperature (12 °C) is calculated to be 21.3 Pa·m³/mol. The substance may show some volatilisation from water.

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 (ca. 64 -79%) and water (ca. 20 -27%) with minor amounts to air (ca. 0.04 -8.2%) and sediment (all <1%).

The SimpleTreat model, which is incorporated in EUSES, simulates the distribution of the substance in a Sewage Treatment Plant (STP). Based on the molecular weight of 198 g/mole, a Koc value of 7100 L/kg, a vapour pressure of 2.58 Pa (at 24 °C) and a water solubility of 12.1 mg/L (at 24 °C), and the qualification as readily biodegradable, the model predicts that 53.9% of the substance will be degraded and that 8.0%, 34.5%, and 3.6% will partition to water, sewage sludge and air, respectively.