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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Weight of Evidence approach, geometric mean of QSAR results:
Koc = 759.7 L/Kg
log Koc = 2.88

Key value for chemical safety assessment

Koc at 20 °C:
759.7

Additional information

Three QSARs models, which are recommended by the ECHA guidance document on information requirements, were used in a weight of evidence approach to determine the adsorption coefficient of the registered substance.

The first and second models are KOCWIN v2.00, available from the US EPA (MCI and log Kow methodologies).

The adsorption coefficient (Koc) of the registered substance was estimated to be 712.1 L/kg and 1003 L/kg, calculated from the MCI and log Kow methodologies respectively, using an experimental log Kow value at 3.40.

The third model is TGD (2003). Based on the chemical class of Nonhydrophobics, the estimated adsorption coefficient of the registered substance was 613.8 L/kg (with an experimental log Kow at 3.40).

The summary of the estimated adsorption coefficients is presented in the table below:

 

(2E)-1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-2-buten-1-one

CAS N° 23726-93-4

Experimental Log Kow = 3.40

KOCWIN v2.00 – MCI approach

Koc = 712.1 L/kg

KOCWIN v2.00 – Kow approach

Koc = 1003 L/kg

TGD, 2003

Koc = 613.8 L/kg

Geometric mean

Koc = 759.7 L/kg

Log Koc = 2.88

Based on these predictions, the Koc of the registered substance is estimated to be 759.7 L/kg, corresponding to a log Koc at 2.88 (geometric mean of QSAR results). This result indicates that the substance is low mobile in soils (according to P.J. McCall et al., 19811).

1 McCall P.J., Laskowski D.A., Swann R.L., and Dishburger H.J., (1981), “Measurement of sorption coefficients of organic chemicals and their use, in environmental fate analysis”, in Test Protocols for Environmental Fate and Movement of Toxicants. Proceedings of AOAC Symposium, AOAC,

Washington DC.

Mobility classification scheme:

Range of Koc

Mobility class

0 - 50

Very high

50 - 150

High

150 - 500

Medium

500 - 2000

Low

2000 - 5000

Slightly

> 5000

Immobile

[LogKoc: 2.88]