α,α,6,6-tetramethylbicyclo[3.1.1]hept-2-ene-2-propionaldehyde

Endpoint summary

Description of key information

Abiotic degradation

Air: Based on estimation with the QSAR model Aopwin the substance undergoes in air rapid degradation after reaction with hydroxyl radicals and ozone. The DT50 value after reaction with hydroxyl radicals is 1.11 hours and for ozone it was estimated 38.4 minutes. Based on these half-lives, the substance will not reach the stratosphere and is therefore not considered to be a long-range transported chemical in air. 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, EC no 1272/2008 and its amendments).

Water: The substance is hydrolytically stable in an OECD TG 111 study at pH 4, 7 and 9 at 25°C (DT50> 1 year).

Biotic degradation

In the key GLP Closed Bottle test (OECD TG 301D) secondary activated sludge was exposed to 2 mg/l substance for 28 days. In this test 3% biodegradation was observed at day 28. Therefore the substance is not readily biodegradable. In the follow up enhanced test (Closed Bottle, non-GLP) with river water as inoculum at 1 mg/L, 73% biodegradation was found after 56 days showing that the substance is not persistent in accordance with ECHA guidance (R.11 -3, 2017). In a MITI test (OECDTG 301C) the substance is not biodegraded but full primary degradation occurred the key metabolites being the Pinyl Isobutyr-acid and Pinyl Isobutyr-alcohol, the oxidation and reduction product of Pinyl Isobutyraldehyde, respectively.

Bioaccumulation

The bioaccumulation potential for aquatic species was concluded based on an experimental BCF for fish performed according to a Japanese guideline and under GLP, equivalent to OECD TG 305. The BCF was concluded < 27 L/kg ww, indicating no potential for bioaccumulation.

Bioaccumulation result for terrestrial species is based on log Kow and calculated BCF value using QSAR of Jager (1998), incorporated in the EUSES model yielded a value of 3020 L/kg ww. This value is considered conservative because the substance likely oxidises into the acid under environmental circumstances and the absence of a bioaccumulation potential in fish.

Transport and distribution

The adsorption potential of the substance was determined in a study according to OECD TG 121 (HPLC method). Under the conditions of the test, the log Koc of the substance was determined at 4.07 (equivalent Koc = 12000 L/kg). Based on this value the substance has potential for adsorption to solid surfaces and soil.

A Henry's law constant of 36.6 Pa·m³/mol (at 12 °C) was calculated in EUSES (Vap pressure 3.4 Pa (22°C) , 206.29 molecular weight and 10.8 mg/l water solubility (22°C). Based on this value the substance has potential to partition from water to air.

Based on Level III environmental distribution modelling using EPISUITE (assuming equal and continuous releases to air, water and soil) using the CAS number 33885-52-8 and the measured physico-chemical parameters (water solubility and log Kow) as input , it is estimated that the majority of the substance released to the environment will partition mainly into soil (83.8%) and water (15.8%) with small amounts to air (0.1%) and sediment (0.3%).

The SimpleTreat model simulates the distribution of the substance in a Sewage Treatment Plant. Model calculations (default assumptions, local) show that 0% of the substance will be degraded and that 30.5%, 53.2%, and 16.3% will partition to water, sludge and air, respectively.