Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Hydrolysis

OS1600 has been demonstrated to hydrolyse very quickly with the following half-life times at room temperature:

pH 4: t1/2 < 4 minutes

pH 7: t1/2 < 4 minutes

pH 9: t1/2 < 4 minutes

According to the relevant guideline, the test substance is considered hydrolytically unstable.

 

A hydrolysis test was also performed on MPKO, the hydrolytic product of OS1600. In all tests performed, a decrease in concentration was observed. At the end of the main tests, concentrations became stable at 50 -60% of the initial concentration. This indicates that equilibrium is formed and that this is not hydrolysis. MPKO is therefore considered hydrolytically stable (i.e. half-life time of > 1 year at 25°C) at pH 4, pH 7 and pH 9.

 

Biodegradation

A ready biodegradation test was performed with OS1600 according to OECD guideline 301 B (CO2 Evolution Test). The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant. Both a positive control (sodium acetate) and toxicity control were included in the test design. All validity criteria were fulfilled.The ThCO2 of OS 1600 was calculated to be 2.05 mg CO2/mg. The ThC02 of Sodium Acetate was calculated to be 1.07 mg CO2/mg. The relative degradation values calculated from the measurements performed during the test period revealed no significant degradation of OS 1600. In the toxicity control more than 25% degradation occurred within 14 days (32% based on ThCO2). Therefore, the test substance was assumed not to inhibit microbial activity. Since OS 1600 attained 1% biodegradation within 28 days it is considered not readily biodegradable.

The same study was performed with the hydrolysis product MPKO. The relative degradation values based on CO2 consumption calculated from the measurements performed during the test period revealed 4 and 12% degradation within 28 days. In the toxicity control, the test substance was found not to inhibit microbial activity. In conclusion, MPKO was also designated as not readily biodegradable.

Adsorption

OS1600 shows quick hydrolysis in aqueous solutions. Therefore the adsorption coefficient cannot be determined. However, the log Koc was determined for MPKO, the hydrolysis product of OS1600. It was determined to be < 1.32.

Additional information