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EC number: 691-719-4 | CAS number: 1072957-71-1
Biodegradation in water and sediment: simulation tests
Administrative data
Link to relevant study record(s)
Description of key information
Studies demonstrated that, although SYN545192 is not significantly labile under normal aerobic or anaerobic study conditions, under more realistic conditions where light is provided and phototrophic organisms such as algae and aquatic macrophytes can grow, degradation of SYN545192 was significantly faster.
Key value for chemical safety assessment
Additional information
Study Conducted Using Pyrazole Label
In standard water-sediment systems incubated in the dark, the dissipation rate (DT50) of 14C SYN545192 from the water column was 25 and 21 days for Swiss Lake samples under aerobic and anaerobic incubations, respectively. The corresponding values for Calwich Abbey were 14 and 16 days, respectively. Levels of SYN545192 declined slowly in the total systems (sum of surface water and sediment extract), with >82% of the applied radioactivity remaining as the parent molecule at the end of the study, and no significant degradation products were formed. Degradation rates (DegT50) of 749 and 934 days were obtained for Swiss Lake samples incubated under aerobic and anaerobic conditions, respectively. Corresponding values for Calwich Abbey were 502 and 436 days, respectively.
The dissipation from the water column and total system degradation rates in the modified incubations systems containing algae and macrophytes were significantly faster than the corresponding dark aerobic incubations. The dissipation rate (DT50) of SYN545192 from Swiss Lake water in algal and macrophyte incubations was 7 and 5 days, respectively. The corresponding values for Calwich Abbey were 4 and 3 days, respectively. The total system DegT50 for the Swiss Lake incubation group containing algae was 85 days and in systems containing macrophytes was 39 days. The DegT50 for the Calwich Abbey incubation group containing algae was 70 days and in systems containing macrophytes was 19 days.
Study Conducted Using Phenyl Label
In standard water-sediment systems incubated in the dark, the dissipation rate (DT50) of 14C-SYN545192 from the water column was 19 and 20 days for Swiss Lake samples under aerobic and anaerobic incubations, respectively. The corresponding values for Calwich Abbey were 18 and 11 days, respectively. Levels of SYN545192 declined slowly in the total systems (sum of surface water and sediment extract), with >85% of the applied radioactivity remaining as the parent molecule at the end of the study, and no significant degradation products were formed. The total system degradation rates (DegT50) of 616 and 767 days were obtained for Swiss Lake samples incubated under aerobic and anaerobic conditions, respectively. Corresponding values for Calwich Abbey were 427 and 620 days, respectively.
The dissipation from the water column and total system degradation rates in the modified incubations systems containing algae and macrophytes were significantly faster than the corresponding dark aerobic incubations. The dissipation rate (DT50) of SYN545192 from Swiss Lake water in algal and macrophyte incubations was 9 and 8 days, respectively. The corresponding values for Calwich Abbey were 4 and 3 days, respectively. The total system DegT50 for the Swiss Lake incubation group containing algae was 81 days and in systems containing macrophytes was 46 days. The DegT50 for the Calwich Abbey incubation group containing algae was 52 days and in systems containing macrophytes was 28 days.
Summary/Conclusions
In the modified systems, biotransformation proceeded by hydroxylation of the alicyclic ring to yield the metabolites SYN546039 and SYN546040. N-demethylation of the pyrazole ring occurred to form SYN546206 with subsequent hydroxylation of the alicyclic ring to give the metabolite SYN546041. Cleavage of the bond between the pyrazole and phenyl rings occurred to give the pyrazole carboxylic acid NOA449410. In Swiss Lake sediment only, the metabolite SYN546648 was formed through further oxidation of the alicyclic hydroxy metabolite SYN546039 and SYN546040.
This study demonstrated that SYN545192 is not significantly labile under standard aerobic or anaerobic study conditions. However, under more realistic conditions, where light is provided and phototrophic organisms such as algae and aquatic macrophytes can grow,degradation of SYN545192 was significantly faster.
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