Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

The environmental fate and behaviour of Hexachlorocyclopentadiene was determined using available data on the substance. A weight-of-evidence approach was used when no key studies could be used or were available.


The octanol/water partition coefficient of the substance was calculated and a Log Kow of 5.04 was determined. This value suggests that the substance has the potential to bioaccumulate. However, the bioaccumulation of Hexachlorocyclopentadiene in fish was determined using a method similar to the OECD Testing Guideline 305 (non GLP) and Bioaccumulation Factors below 11 were obtained, indicating that the substance is not bioaccumulative.


The adsorption/desorption coefficient of Hexachlorocyclopentadiene was calculated using available information on this substance. A Log Koc at 20°C of 4.06 was obtained, indicating that the substance has the tendency to strongly adsorb to particles such as soil or sediments.


An assessment of the biodegradation of the substance in water was performed. It was concluded that the registered substance is expected to be inherently biodegradable. A study investigated the photolysis of the substance in water, which allowed to determine that the half-life of Hexachlorocyclopentadiene was less than 1.03 minutes under the conditions of the test. The hydrolysis was assessed using available information on the substance, which concluded that Hexachlorocyclopentadiene would have a half-life of 2.5 days in water at 22°C. Therefore, despite Hexachlorocyclopentadiene is not expected to be readily biodegradable, the substance has shown to have a short half-life in the aquatic environment due to the process of hydrolysis and photolysis.

Additional information