cis-2-tert-butylcyclohexyl acetate

Endpoint summary

Description of key information

Long-term term earthworm reproduction according to OECD TG 222, EC10: 45.1 mg/kg soil dw

Long-term plant test, seedling emergence and growth according to OECD TG 208, EC10: 44 mg/kg soil dw

Long-term micro-organisms, nitrogen transformation according to OECD TG 216, NOEC: 100 mgkg soil dw

Additional information

Long-term toxicity to earthworms

The long-term toxicity of the substance for earthworm Eisenia foetida was tested in OECD TG 222. The test material was dissolved in equal amounts of acetone, mixed with the quartz sand and allowed to slowly evaporate and mixed with the standard soil containing 10% Sphagnum peat, 20% kaolinite clay, approximately 70% fine quartz-sand (grain size 0.05 -0.2 mm) and 0.4% calcium carbonate to adjust to pH 6.0±0.5. Adult worms were exposed to nominal concentrations in soil of 5, 15.8, 50, 158.1 and 500 mg/kg dw soil. Weights of the adult worms ranged between 322 and 596 mg. The worms were fed weekly with finely ground cattle manure. Adult worms were removed after 4 weeks of exposure, counted and weighed. The remaining offspring remained in the test containers for another four weeks. Nominal concentrations are used to present the effects. No worms survived at 500 mg/kg soil dw. The NOEC for mortality and growth was 158.1 mg/kg dw. The EC10 for reproduction was 45.1 mg/kg dw soil (95% confidence interval is 21-65 mg/kg soil dw).

Long-term toxicity to plants:

In a terrestrial plant test according to OECD TG 208 under GLP, 6 plant species were tested for seedling emergence, growth and phytotoxic effects (chlorosis, necrosis and abnormal growth). The soil is a sandy loam and was sterilised before use. All particles were < 0.2cm. The organic matter content is 0.67 +/-0.03% and the pH was 5.9 +/-0.6. The substance was mixed with quarts sand and thereafter mixed into the soil. The following dicotyles were used: Brassica napus, Glycine max, Solanum lycopersicum and Cucumis sativus. The following monocotyles were use: Avena sativa and Allium cepa. Doses were selected based on a dose range finding study and were 12.3, 37, 111, 333 and 1000 mg/kg soil dw for most species. Two additional concentrations were used for Brassica napus and Glycine max: 1.37 and 4.12 mg/kg dw soil. One additional concentration was used for Solanum lycopersicum: 4.12 mg/kg dw soil. The concentration in the stock solution was verified but actual measures in the soil were not performed. Untreated seeds were sewn in pots and plants were grown for 14 days, except Allium cepa which was grown for 21 days. Fresh weight of the leaves of plants was the more sensitive endpoint compared to germination, phytotoxicity and mortality. The EC10 of all six plant species was averaged as the number of species =>5. The overall EC10 on leaf fresh weight being the most sensitive parameter resulted in 44 mg/kg soil dw based on nominal values and being the average of 6 plant species based on nominal values.

Long-term toxicity to micro-organisms

The toxicity of Verdox for soil microflora was tested according to OECD TG 216 using nitrogen transformation in soil. The concentrations tested were 0, 10, 32, 100, 320 and 1000 mg/kg dw soil. The reference substance was sodium chloride. The soil used was abiologically active agricultural soil: Silty sand. The effect parameter was NO3-nitrogen production after 28 days exposure (soil nitrogen transformation). Nominal concentrations were used. No statistical significant effects of the test item on nitrate content in soil were observed at day 28 up to a concentration of 100 mg Verdox/kg soil dw by Williams Multiple t-test Procedure. For concentrations of 320 mg and 1000 mg Verdox/kg soil dw, the deviations to control were significant (Williams Multiple t-test Procedure). At day 28 differences in nitrogen production to the control were -30.25%, 36.26%, 35.90% for 10-100 mg/kg soil, not significantly and not concentration related. At 320 and 1000 mg/kg dw the reduction was -99.64% and -73.94% for 320 mg and 1000 mg Verdox /kg soil dw significantly though no clear dose relation. The NOEC was determined to be 100 mg/kg soil dw based on nominal values but an EC10 could not be calculated.

 

Discussion on the experimental terrestrial toxicity testing

It was expected that the high Henry coefficient of Verdox would confound the results. The clear dose responses especially in the earthworm and plant test show that this has not been the case. The adsorption to sludge and release into the pore water seem to have balanced the volatility.