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Environmental fate & pathways

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In accordance with section 9.3.1 of Column 2 of Annex VIII, the study does not need to be conducted if based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g., the substance has a low octanol water partition coefficient). 2.6-Xylenol has a log Kow of 2.3, indicating a low potential for adsorption. It is therefore considered to be justified to omit this study.

For the environmental assessment the EUSES calculated value (Koc = 164 L/kg; non-hydrophobics (default QSAR)) was used.

Supporting information is available in the form of a published study. Although not conducted to a standardised guideline, the study was well-documented study and performed according to scientific methods. It was therefore awarded reliability score of 2 in accordance with the criteria for assessing data quality set forth by Klimisch et al. (1997).

The adsorption to soil was investigated using the batch equilibrium method. Solutions of 2,6-xylenol were added to samples of five types of soil and shaken at room temperature for up to five days. Data fitted to Freundlich equation.

Phenol adsorption by soils is very much time-dependent, with up to 5 days for the adsorption reactions to reach equilibrium in water-saturated soils. Freundlich isotherm constants were derived.

Henry's Law Constant

Three key pieces of data to address this endpoint are provided; two are experimental values and the third is an estimation by calculation. All were awarded a reliability score of 2 in accordance with the criteria for assessing data quality set forth by Klimisch et al. (1997).


A Quantitative Structure Activity Relationship (QSAR) calculation (EPI Suite vs 4.0) was carried out to determine the Henry’s law constant of 2,6-xylenol. By definition, the Henry's law constant is the ratio of vapour pressure to solubility and is determined by calculation. EPISUITE determined the constant to be 0.000004669 atm m³/mol.


The first experimental value was published in Phys. Chem. Chem. Phys. in a well-documented publication. The Henry’s Law constant was directly measured using a dynamic equilibrium system based on the water/air equilibrium at the interface within the length of a microporous tube. The measurements were conducted over the range 278 to 293 K in both deionized water and 35 g/ L solution of NaCl.

The Henry's Law Constant (HLC) for 2,6-xylenol was determined to be 250 M/atm at 20 °C (back calculated to 0.41 Pa m³/mol via: H (Pa m³/mol) = 101.325 / HLC (M/atm)).


The second experimental value was published in Environ. Sci. Technol. In a well-documented study performed according to scientific principles.

The determination of Henry's Law Constants for organic species found to be emitted from shale oil waste waters were determined by the use of a gas-stripping vessel redesigned with a 12 mm i.d. tube but had approximately the same height, so that a much smaller volume of sample water could be used for Henry Law constant determinations. Air was introduced through a glass frit and allowed to bubble through the column of liquid. Henry's Law constants for individual species were calculated from the slope of a plot of the logarithm of the integrated area counts of a chromatographic peak vs. the volume of air which had been bubbled through the water column.

The Henry's Law Constant for 2,6-xylenol measured for a single component dissolved in water was 0.67 atm m³/mol.10E5 (0.68 Pa m³/mol) at 25 °C and for a single mixture in water was 0.76 atm m³/mol.10E5 (0.77 Pa m³/mol) at 25 °C.