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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to solid soil phase is not expected. 

Key value for chemical safety assessment

Additional information

The Koc of bronopol is estimated as 5, using a water solubility of 2.0E+5 mg/L and a regression-derived equation [HSDB 2009]. This estimated Koc value suggests that bronopol is expected to have very high mobility in soil.

Additionally, the adsorption of 14C-Bronopol onto and desorption from four different soil types was investigated according to US EPA Pesticide Assessment Guidelines, Subdivision N, Paragraph OPP 163 -1 [The Boots Company 1992].

The results indicated that highest adsorption was observed in loam (< 26 %). Lower adsorption was observed in clay loam (< 25 %), loamy sand (< 13 %) and sand (< 8 %). Moreover, the test material was instable under test conditions and the observed degradation varied in the four soil types.

Adsorption of Bronopol and/or its degradation products was correlated to the soil pH. Higher adsorption was observed in alkaline soil (loam) than in acidic soil (clay loam) due to differences in the degradation pathway of Bronopol.

In fact, in the more alkaline loam soil, relatively non-polar degradation products (such as 2 -bromo-2 -nitroethanol) were observed which might be potentially more adsorptive than the relatively polar product (such as tris-(hydroxyl-ethyl)-nitromethane) formed in the more acidic clay loam soil.

Conclusively, adsorption to soil differs among the various soil types, however, the adsorption potential of Bronopol is generally low, indicating no obvious risk to the soil compartment.