Pyrasulfotole

Endpoint summary

Additional information

In a study following OECD 308 the test substance dissipated only moderately from the water in two water/sediment systems under aerobic conditions. The calculated DT50 values for the dissipation of the parent substance from the water phase were 38 and 327 days for the water-sandy loam and water-silty clay loam sediment systems, respectively (126.5 and 1088.8 days, recalculated to 12 °C). In the total test system, the calculated DT50 values were 69 and 578 days for the water-sandy loam and water-silty clay loam sediment systems, respectively (229.7 and 1924.5 days, recalculated to 12 °C). No major transformation products were detected in the water or sediment phases. The sole minor transformation product was 2-methylsulfonyl-4-(trifluorormethyl)benzoic acid which did not exceed 3% in the total system of either water-sediment system.

In the water-sandy loam sediment system,, <1% of the applied radioactivity was present as either CO2 or organic volatile compounds at the end of the study. In the water-silty clay loam sediment system, <0.1% of the applied radioactivity was present as either CO2 or organic volatile compounds at the end of the study.

 The anaerobic biodegradation of test substance radiolabelled as [Pyrazole-3-14C] (M-250846-01-1) or [Phenyl-UL-14C]- (M-250839-01-2) (5-Hydroxy-1,3-dimethyl-1H-pyrazol-4-yl)[2-(methylsulfonyl)-4-(trifluoromethyl)phenyl]-methanone was studied in identical pond water/sediment systems for 365 days in the dark at 20 ± 1 °C. For the [Pyrazole-3 -14C] labelled test substance the half-lives using first-order nonlinear degradation kinetics in anaerobic water and in the entire system were 75 days (k = 0.0093 day-1; r² = 0.56) and 227 days (k = 0.0031 day-1; r² = 0.46), respectively (159.2 and 481.9 days, recalculated to 12 °C). For the [Phenyl-UL-14C] labelled test substance, the half-lives using first-order nonlinear degradation kinetics in anaerobic water and in the entire system equalled 84 days (k= 0.0083 day-1; r² = 0.63) and 273 days (k = 0.0025 day-1; r² = 0.40), respectively (178.3 and 579.6 days, recalculated to 12 °C). No major transformation products were detected in the water or sediment phases of either test system. There was no degradation of test substance in either anaerobic test system, but test substance partitioned to the sediment and formed bound residues. At the end of the study, 1.8 and 2.8% of the applied radioactivity was present as CO2, respectively.

In soil, the biodegradation of radiolabelled test substance in a silty clay loam at 20 °C under aerobic conditions (M-765810-01-1), conducted according to OECD Guideline 307 (2002) and GLP, was faster. After an incubation period of 119 days 22.6% of the applied radioactivity were mineralized to 14CO2. The degradation half-life of the parent substance was calculated using a first order multi compartment model (FOMC) and accounted for 3.06 days (6.5 days, recalculated to 12 °C).

Investigations on the aerobic/anaerobic biotransformation of radiolabelled test substance, according to OECD 307, revealed degradation half-lives of >120 days for the parent substance.

At the end of the aerobic phase 1.3% and 1.4% of the applied radioactivity was present as CO2