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Environmental fate & pathways

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If the substance is released to the environment it will be transported and distributed depending on its substance specific properties (e.g. physico-chemical properties, log Koc).
Based on the vapour pressure of 3.2 x 10E-6 Pa at 20 °C it can be concluded that volatilization of the substance in the environment is not expected. Thus, the substance is expected to partition mainly to the water phase (water solubility: approx. 1 mg/L) with potential for adsorption to sediment particles based on its log Koc of 2.33. In soil the mobility for adsorption and desorption is considered to be low.
In the environment the substance will undergo several abiotic and biotic transformation/degradation processes. Hydrolysis as well as photodegradation and biotic degradation contribute to the overall environmental fate of the substance. Bioaccumulation in biota and biomagnification within the food chain is not expected. An experimental BCF of < 2 indicated that the substance has a low potential for bioaccumulation.
For hydrolysis the experimental data could be well described by a single first order (SFO) kinetic model. The hydrolytic degradation of the substance was observed to be pH dependent. At 20 °C the experimental half-lives were 265, 58.0 and 1.27 d for pH 4, 7 and 9, respectively. One major metabolite was found during the process of hydrolysis. Therefore, hydrolysis is an important route of dissipation for the substance in water.
Photolytic degradation in sterile buffer and in natural water was studied. From experimental results, in sterile buffer the predicted environmental DT50 values are calculated to be e.g. 10.5 solar summer days at Phoenix, Arizona, USA. The calculated DT50 value for the substance under dark conditions was 188.5 d. Degradation of the substance in irradiated samples was accompanied by the formation of one major degradation product. 
The photolytic route and rate of degradation of the substance was also measured in sterile natural water (pH 8.0 to 8.5) with 14C-marked test item at 25 °C. Up to four degradation products and carbon dioxide (max. formation 38.9%AR) were identified in irradiated samples. The half-life of the substance in irradiated samples was 0.7 d and 0.77 d. The predicted environmental DT50 values were calculated to be e.g. 4.7 and 4.9 solar summer days at Tokyo, Japan. Under dark conditions the substance degraded to one major metabolite and had an experimental DT50 value of between 0.3 and 0.75 d. Formation of carbon dioxide in dark samples was insignificant at ≤ 0.1%AR. Therefore, photodegradation was found to contribute to the overall degradation of the substance under aqueous conditions in natural water. 
In a biodegradation screening study according to OECD 301 F the substance was found to be not readily biodegradable under the test conditions at the end of the 28-day exposure period. Simulation studies investigating the degradation in aerobic and anaerobic water sediment systems were conducted in order to assess further the degradation in the environment.

Aerobic aquatic metabolism of the substance was studied in two water sediment systems with 14C-marked test substance. Carbon dioxide was formed at a maximum of 0.2%AR at study end (DAT-101), and non-extractable residues were formed at a maximum of 12.1%AR at DAT-29. Two degradation products were identified at a maximum of 84.8%AR at DAT-59 and 9.2%AR at DAT-101. The rate of degradation ranged from a DT50 of 5.3 to 6.3 d in water to a DT50 of 11.1 to 122 d in the entire system. 
Anaerobic aquatic metabolism of the substance was studied in two water sediment systems with 14C-marked test substance. Carbon dioxide and volatile organic compounds were formed at a maximum of 0.4%AR at DAT-12, and non-extractable residues were formed at a maximum of 10.4%AR at DAT-82. One degradation products was identified, at a maximum of 40.4%AR at DAT-104. The rate of degradation ranged from a DT50 of 16.0 to 24.1 d in water to a DT50 of 103.5 to 217.9 d in the entire system. 
In both aerobic and anaerobic metabolism studies, degradation rates were higher in systems where the pH was more alkaline, illustrating the importance of abiotic hydrolysis in the degradation pathway. In conclusion the substance is not considered to be rapidly degraded in the environment.