A mixture of: 4-(2,2,3-trimethylcyclopent-3-en-1-yl)-1-methyl-2-oxabicyclo[2.2.2]octane; 1-(2,2,3-trimethylcyclopent-3-en-1-yl)-5-methyl-6-oxabicyclo[3.2.1]octane; spiro[cyclohex-3-en-1-yl-[(4,5,6,6a-tetrahydro-3,6',6',6'a-tetramethyl)-1,3'(3'aH)-[2H]cyclopenta[b]furan]; spiro[cyclohex-3-en-1-yl-[4,5,6,6a-tetrahydro-4,6',6',6'a-tetramethyl)-1,3'(3'aH)-[2H]cyclopenta[b]]furan]

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 1.2 hours. Ozone reaction estimate is 3.3 hours. 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 has a half-life of 22 days at pH 7 and 25°C.

Biotic degradation

In a biodegradation screening study (OECD TG 301D) activated sewage sludge from an STP treating predominantly domestic sewage was exposed to the substance for 28 days. In this test 3% biodegradation was observed at day 28. Therefore, the substance is not readily biodegradable.

In the water simulation test according to OECD TG 309 ca 40% of Cassiffix volatilised. In the surface water Cassiffix dissipated/degraded and showed T1/2 ranged from 2.9 - 13 days and 10 - 18 days for 20 µg/L and 100 µg/L, respectively. There was one key metabolite, called Cassiffix-Lactone and exceeding the 10% level (present at ca. 14%), which had a log Kow between 2.5 and 3. Based on these results Cassiffix is not persistent.

Bioaccumulation

Bioaccumulation in aquatic species is based on an experimental BCF test according to OECD TG 305 with aqueous exposure and result in a BCFssl of 670 l/kg using the highest BCF of one of the four constituent and the higher BCFssl compared to BCFkl. 

BCF terrestrial species is based on the available information (log Kow and calculated BCF value). The BCFs for terrestrial organisms were calculated using the QSAR of Jager (1998), incorporated in the EUSES model, and yielded a values of 631 L/kg ww, respectively, using a log Kow of 4.72.

Bioaccumulation for air-breathing organisms is based on available information of Log Koa, persistency information, identification of the key degradation product and anticipated metabolism. The Koa for Cassiffix exceeds the cut off criterion of 5. The substance is considered persistent. In this biodegradation study Cassiffix-Lactone has been the key metabolite including a reduction into a double bond in the same ring as the lactone. This metabolite is also anticipated to be the key metabolite in organisms being a simple oxidation and reduction, respectively. This metabolite may be excreted as such via the kidneys based on its log Kow of 3. It is more likely that this lactone will be reduced into an alcohol or de-esterified resulting in an acid and an alcohol and subsequently conjugation in the Phase 2 metabolic pathway. Via this pathway the kidneys will be the key excretion route as is seen in the repeated dose toxicity studies. Air is therefore not the key excretion route (e.g in contrast to fish) and therefore there is no concern for air-breathing organisms. This is explained in more detail by Gobas et al. (2020). They present that Oxygen containing chemicals are unlikely a concern for air-breathing organisms, because of their metabolism and kidneys being the key excretion pathways (see Toxico-kinetic section for more details).

The log Koc of Cassiffix was determined using the HPLC method according to OECD TG 121. Cassiffix consists of four main constituents and of each the log Koc was determined: 4.02, 4.12, 4.19. 4.25. The weighted average value of all 4 constituents (5, 55, 20 and 20%, respectively) were used to derive the log Koc for Cassiffix of 4.2.

The Henry's law constant is calculated using the equation from EUSES. Using a molecular weight of 234.2 g/mole, and the experimentally determined vapour pressure of 1.5 Pa (at 25 °C) and water solubility of 11.1 mg/L (at 20 °C), the Henry's Law constant at 25°C and at environmental temperature (12°C) is calculated to be 29.5 and 14.1 Pa·m³/mol, respectively. The substance is expected to volatilise from water to some extent (in the OECD TG 309 ca 40% was volatilised). 

Based on Level III environmental distribution modelling using EPISUITE (assuming equal and continuous releases to air, water and soil) using the SMILES code (CC3=CCC(C12CCC(C)(CC1)OC2)C3(C)C) and the measured physico-chemical parameters (water solubility (11.9 mg/l at 25 °C) and log Kow 4.72) as input, it is estimated that the majority of the substance released to the environment will partition mainly into soil (89.1%), less to water (7.2%) and sediment (3.7%) and minimally to air (<0.1%).

The SimpleTreat model, which is incorporated in EUSES, simulates the distribution of the substance in a Sewage Treatment Plant based on vapour pressure, water solubility, log Koc and ready biodegradability. Model calculations show that 0% of the substance will be degraded, and that 61%, 32.2%, and 6.6% will partition to sludge, water and air, respectively.