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Environmental fate & pathways

Adsorption / desorption

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Description of key information

log Koc between 2.5 and 3.9

Key value for chemical safety assessment

Koc at 20 °C:
316

Additional information

Since no reliable adsorption tests are available for C12 -18AS Na (CAS 68955 -19 -1), in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across to another structurally related category members was conducted. Read-across data available for the pure AS homologues: C12AS Na (CAS 151-21-3), C14AS Na (CAS 1191-50-0), C16AS Na (CAS 1120-01-0) and C18AS Na (CAS 1120-04-3) were used. In the publication by Marchesi et al. (1991), the experimental sediment sorption data for several alkyl sulfates with different carbon chain lengths are presented. The Koc values for the longer homologues: C16AS Na (CAS 1120-01-0) and C18AS Na (CAS 1120-04-3) were extrapolated from the available data on C8-14 alkyl sulfates.

The determined Koc values are:

- for C12AS Na (CAS 151-21-3) between 316 and 446 which corresponds to log Koc values in the range of 2.5 and 2.65.

- for C14AS Na (CAS 1191-50-0) between 1337 and 1567 which corresponds to log Koc values in the range of 3.13 and 3.19.

- for C16AS Na (CAS 1120-01-0) the extrapolated value of Koc equals 3273 which corresponds to log Koc 3.515.

- for C18AS Na (CAS 1120-04-3) the extrapolated value of Koc equals 8166 which corresponds to log Koc 3.912.

Due to structural and property similarities with the tested category members these results apply also to C12 -18AS Na (CAS 68955 -19 -1). The Koc range is between 316 and 8166 corresponding to the log Koc range between 2.5 and 3.9. Adsorption of the substance to soil or sediment is therefore assumed to be low to moderate. For the PNEC sediment and soil derivation according to the equilibrium partitioning method (EPM), the lower boundary of the range (Koc = 316) was taken into account, since this value represents the worst case scenario for the chemical safety assessment.

[LogKoc: 2.5]