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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The adsorption potential is considered to be high, based on log Pow values of relevant constituents in the substance 'Naphtha (petroleum), steam-cracked, C8-10 aromatic hydrocarbon fraction, alkylated and oligomerised' (NAF-AO) [EC no. 710-299-7] (see Chap. 1) ranging from about 6.5 to above 10. A log Koc value of 6.085 (Koc 1,216,000) has been calculated with a log Pow value of 6.5 using the relation of Seth 1999 (see below).

Key value for chemical safety assessment

Koc at 20 °C:
1 216 000

Additional information

Measured values of (log) Koc are not available for NAF-AO. As first approximation, a (log) Koc value will be estimated based on a (Q)SAR between log Pow and log Koc. The correlation derived by Seth et al. (1999, Environ Sci Technol 33: 2390-2394) will be used. The relation is based on a large number (n = 117) of substances representing a wide variety of compounds, and the correlation coefficient r² is high (0.95). The equation for the relationship between log Pow and log Koc is: log Koc = 1.03 log Pow - 0.61.

The log Pow values of NAF-AO constituents extent over large range due to constituents groups with different degrees of oligomerisation. For the chemical safety assessment, the group of constituents with the highest water solubility is selected. A representative log Pow of these NAF-AO constituents is 6.5. The (log) Koc is estimated with the equation of Seth using this log Pow value.

log Koc = 1.03 x 6.5 - 0.61

log Koc = 6.085

Koc = 1,216,186