Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

The Koc of 2 -methylbutane has been read across within the category from n-pentane as the substance have similar structures and so are predicted to have similar behavious in the environment. The calculated Koc is based on the method detailed in the TGD. Calculation of the log Koc to determine the potential for adsorption/desorption of chemicals is acceptable provided that a recognised and scientifically robust method is used. The TGD includes a method for calculating a log Koc using the log Kow. The Koc of 2 -methylbutane and n-pentane was calculated from Log Kow 3.45 using TGD calculation of Koc = 0.81 x Log Kow + 0.1. The Koc for 2 –methylbutane and n-pentane is 794.3 (log Koc = 2.9). The calculated Koc of 794.3 was used in the EU RAR for n-pentane and so is considered suitable as key study for this endpoint. These values indicate that although the adsorption of n-pentane and 2 -methylbutane to soil will be moderate, they still have good mobility in the environment.