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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Half life period of clioquinol in water is observed to be 38 days (912 hrs.) while in sediment it is 340 days (8160 hrs).Based on these half life values ofclioquinol, it is concluded that the chemical is readily biodegradable in water where as it is non biodegradable in sediment. However, since there is slight diffusion of the substance in the sediment as evident from the reported data (3% in sediment) and hence persistence in the sediment compartment is not likely to be critical.

Key value for chemical safety assessment

Half-life in freshwater:
38 d
at the temperature of:
25 °C
Half-life in freshwater sediment:
340 d
at the temperature of:
25 °C

Additional information

Based on the Level III Fugacity Model, the half life period of theclioquinolwas estimated. The half period ofclioquinolin water is 38 days (912 hrs) therefore it is considered that the substance will qualify as not persistent as the half life does not exceed the threshold of 60 days. So, it can be confirmed that the substance is readily biodegradable in water medium where as in sediment the half life is 340 days (8160 hrs).

Based on this value, it can be inferred that the substance is persistent in sediment medium and is not readily biodegradable probably due to the anaerobic conditions existing in most sediments. However, it can be observed that clioquinol have very slightdiffusion in the sediment medium since it's percentage in the sediment medium is reported to be 3% and hence persistence in the sediment compartment is not likely to be critical.

Media

Half-Life 
(days)

Percent in
Each Medium

Water

38

  11%

Sediment

340

  3 %

 

Media

Half life

(hrs)

Percent in Medium

Emission

(kg/hr)

 

Water

900

10.8

1000

Sediment

8100

3.38

0