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Environmental fate & pathways

Adsorption / desorption

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Description of key information

US EPA Guideline N 163-1, GLP, key study, validity 1:
The mean value of the adsorption coefficients based on organic carbon is 153 L/kg. Therefore THPS has a medium to high mobility in various soil and sediment matrices.

(For more details please read CSR available in section 13).

Key value for chemical safety assessment

Koc at 20 °C:
153

Additional information

One study of reliability 1 is available to assess the soil/sediment adsorption/desorption of the active substance THPS. This study was performed on the THPS in solution and have been defined as key study.

In this study (Heim, 1998), the adsorption and desorption coefficients on five soil/sediment types (i.e. agricultural sand, silt loam, pond sediment, sandy loam and marine sediment) were determined according to US EPA Pesticide Assessment Guidelines, Subdivision N 163-1. The test substance was not stable in the test matrix of soil/sediment and water to accurately determine the purity at initiation, and degradation of the test substance occurred during the 2 hour equilibration period. Since the potential for adsorption of the test substance to the soil/sediment matrix is low, and this degradation will occur in the environment, the adsorption/desorption values determined represent an environmentally relevant estimate for mobility of the test substance in the environment. The mean value of the adsorption coefficients based on organic carbon is 153 +/- 69.2 L/kg. Therefore, THPS has a medium to high mobility in various soil and sediment matrices. The major degradable product observed was THPO (Tris(hydroxymethyl) phosphine oxide, CAS No 1067-12-5).