Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Biodegradation in water

The half life period ofclioquinolin water is 38 days and based on this value it can be concluded that the chemical is not persistent in water medium since the half life is less than the threshold of 60 days (to qualify the chemical as persistent). Also the diffusion percentage ofclioquinolin water medium is 11%. This coupled with the dilution of water shall result in ready biodegradabililty of the chemical.

The supporting study also shows the half life of clioquinol to be 900 hrs (37.5 days) indicating thet it is readily biodegradable

Media

Half-Life 
(days)

Percent in
Medium

Water

38

  11%

 

Media

Half life

(hrs)

Percent in Medium

Emission

(kg/hr)

 

Water

900

10.8

1000


 

Biodegradation in water and sediment

Based on the Level III Fugacity Model, the half life period of the clioquinol was 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 EPA criteria 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

Biodegradation in soil

The PBT Profiler & EPI Suite has estimated thatclioquinolis expected to be found predominantly in soil and its persistence estimate is based on its transformation in this medium. Its half-life in soil, 75 days (1800 hrs). This exceeds the threshold of >= 2 months (and <= 6 months). Therefore,clioquinolis estimated to be persistent in the soil environment.

PBT profiler estimate

Media

Half-Life 
(days)

Percent in
Medium

Soil

75

 86%

Fugacity Model by EPI Suite estimation database

 

Mass Amount

(percent)

Half-Life

(hr)

Emissions

(kg/hr)

soil

85.9

1.8e+003

1000