1-(3-chloropyridin-2-yl)-N-[4-cyano-2-methyl-6-(methylcarbamoyl)phenyl]-3-{[5-(trifluoromethyl)-2H-tetrazol-2-yl]methyl}-1H-pyrazole-5-carboxamide

Phototransformation in water

Description of key information

DT50 = 3.4 days (M-484185-01-1, pH 4, water, OECD 316)

DT50 = about 0.4 to 1.2 days (M-467310-01-2, water, pH 4, OECD 316,101)

DT50 = 0.7 days (M-489424-01-1, natural water, pH 8, OECD 316)

DT50 = 0.77 days (M-568022-01-1, natural water, pH 8.5, OECD 316)

Key value for chemical safety assessment

Half-life in water:

0.7 d

Additional information

Four studies were performed to investigate the photolytic degradation of the test item in water and natural water, respectively according to OECD 316 and GLP (M-484185-01-1, M-467310-01-2, M-489424-01-1, M-568022-01-1). For the two water studies, sterile aqueous buffer solution at pH 4 was tested under exposure to simulated sunlight with 0.96 mg/L and 0.48 mg/L test item and at a temperature of 25 ± 2 °C. The unsterile natural water studies (at pH 8 and 8.5) from the river Rhine were performed under simulated sunlight coditions for 10 and 11 days at 25 ± 2 °C, respectively. For the natural water studies 0.45 mg/L and 0.5 mg/L test item was applied as application rate for 10 and 11 days at 25 ± 2 °C, respectively.

The experimental data were described by a single first order (SFO) kinetic model. The half-life (DT50) for the test item in the irradiated samples was 0.4 -3.4 days in buffer solution and 0.7 - 0.77 days in sterile natural water. Based on the experimental DT50 value of 0.4 - 3.4 days, the environmental DT50 value is calculated to be e.g. 10.4 solar summer days at Phoenix, Arizona, USA. In natural water the DT50 was considerably shorter with calculated environmental DT50 values of 4.7 - 4.9 solar summer days at Tokyo, Japan. The results show that photodegradation contributes to the degradation of the test item in the aquatic environment.

Reference:

Heinemann, O.; Kasel, D, 2014; “[test item]” Phototransformation in water, unpublished report, Report No.: EnSa-13-0320; Study No.: M- 48185-01-1; Endpoints: DT50=3.4 days and 10.5 days based on solar summer days at Phoenix, Arizona, USA

Heinemann, O.; 2013: [test item]: Determination of the quantum yield and assessment of the environmental half-life of the direct photo-degradation in water, unpublished report, Report No.: M-467310-01-2; Study No.: M-467310-01-2; Endpoints: DT50 = 0.4 - 1.2 days for a direct phototransformation of the test item during periods of main use in spring to summer.

Heinemann, O.; Junge, T.; 2014: [test item]: Phototransformation in natural water, unpublished report, Report No.: EnSa-13-0321; Study No.: M-489424-01-1; Endpoints: DT50= 0.7 days and 4.7 solar summer days at Tokyo, Japan.

Heinemann, O.; Kasel, D.; 2016: [test item]: Phototransformation in natural water, unpublished report, Report No.: EnSa-16-0158; Study No.: M-568022-01-1; Endpoints: DT50= 0.77 days and 4.9 solar summer days at Tokyo, Japan.