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Environmental fate & pathways

Phototransformation in water

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Description of key information

Key value for chemical safety assessment

Half-life in water:
41 min

Additional information

The photodegradation of Triclosan in water was investigated following EPA Guideline Subdivision N 161-2. Radiolabelled substance was mixed with water and exposed to light for 240 minutes at 24.6 °C - 25.8 °C. A half life of 41 minutes was detected (Ciba-Geigy 1993). Direct photolysis in surface waters was tested in a series of field and laboratory studies using artificial light and sunlight. The dependence of phototransformation on pH and dissolved organic matter was considered. Direct phototransformation of the anionic form with a quantum yield of 0.31 (laboratory conditions at 313 nm) was identified as the dominant photochemical degradation pathway of Triclosan (Tixier et al. 2002).