4-propylcyclohexanone

Endpoint summary

Description of key information

Hydrolysis:

The hydrolysis of the test substance was determined according to OECD 111. Under the given conditions the DT50 is more than one year (reference 5.1.2-1).

Biodegradation:

The degradation rate of the test material was 1.2% after 28 days and did not reach 60 % within the 10-day window and after 28 days of incubation. Therefore the test substance cannot be described as ready biodegradable under the test conditions (reference 5.2.1-1).

Additional information

Hydrolysis:

The hydrolysis of the test substance was determined according to OECD TG 111. The test substance (400 mg/L) and 50 mL of the buffer solution (pH 4, 7 and 9) were put in brown iodine determination flasks. The three replicates were analysed with GC after 2.4 h and 5 days. Additionally the hydrolysis of the reference substance acetylsalicylic acid was determined the same way and analysed with HPLC. Mean values and standard deviation were calculated with a programmed pocket calculator (TI SR-51-11). The hydrolysis of the test substance was below 50% independent of the pH. The reference substance acetylsalicylic acid is totally hydrolysed after 5 days at pH 7 and 9. After 5 days at pH 4 0.1% of the start concentration was measured. After 2.4h at pH 4 72.73 % of the start concentration were measured, at pH 7 50.93% and at pH 9 45.60%. The test substance is an arylketone, theoretical no hydrolisation is possible. The test results after 2.4 h exposure in aqueous medium in a decrease in concentration of approx. 10-20%. Since the values are again higher after 5 days it can be assumed that this decline is not due to degradation, but an artifact of the method could be responsible. As the water solubility of the substance is not good, the determination of the concentration is only possible with a relatively large error. The results lead to a DT50 of the test substance in the environment of more than one year (reference 5.1.2-1).

Biodegradation:

The test item was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days according to OECD TG 301D. The biodegradation was followed by the oxygen depletion of the microorganisms during exposure. As a reference substance sodium-n-dodecylsulfate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The oxygen depletion was measured after 5, 15, and 28 days by means of an oxygen electrode. Control- and blank-series without the test substance were run simultaneously and the effectiveness of the inoculum was confirmed (in a third series with sodium-n-dodecylsulfate as reference substance) and found to be 72.8 % after 28 days under the conditions of the test. The value of chemical oxygen demand (TOD) of the test substance was calculated to be 2.86 mg 02/mg active substance. For the test substance, a biodegradability of about 1.2 % (after 28 days) was found. Therefore the test substance cannot be described as ready biodegradable under the test conditions. Moreover it should be tested, whether the test substance exerts an inhibiting effect on biological degradation processes. As a result it was established that the test substance has no inhibiting effect on the biological degradation of the reference substance (reference 5 .2.1-1).