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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption, other
Remarks:
Natural plant extract, UVCB - modelling via EPISuite
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Justification for type of information:
Hop extract is a natural plant extract. It is well known as an ingredient for brewing beer. The substance is of type UVCB. The principal components are well known - see boundary composition. The log Koc values of the principal components were estimated using EPISuite. Full details are given in the attached study report.
Qualifier:
no guideline followed
Version / remarks:
Modelling of hop extract by calculating log Koc of the principal components using EPISuite
Principles of method if other than guideline:
Modelling of hop extract by calculating log Koc of the principal components using EPISuite.

Note: Hop extract is a natural plant extract. The substance is of type UVCB. The principal components are well known - see boundary composition. The log Koc values of the principal components were estimated using EPISuite. Full details are given in the attached study report.
GLP compliance:
no
Type of method:
other: Estimation and modelling
Computational methods:
EPISuite used to estimate log Koc for the principal components
Key result
Type:
log Koc
Value:
> 1.7 - < 4.5 dimensionless
Validity criteria fulfilled:
not applicable
Remarks:
Modelling via EPISuite
Conclusions:
Hop extract is a natural extract of hop cones, a UVCB substance, obtained using either liquid or supercritical CO2, or ethanol, as extraction solvents. The principal components are listed in Table 1 of the attached report. The results (Table 2 of the attached report) show that the principal homologues of the α-acids have log KOC values of 1.5 – 2.4, indicating “low sorption to soil/sediment, moderate migration to ground water” and the more hydrophobic β-acids have log KOC values of 2.5 – 3.4, indicating “moderate sorption to soil/sediment, slow migration to ground water”. * The principal components of the hop essential oil, viz. myrcene, humulene and caryophyllene, have log KOC values of 2.5 – 4.4, indicating either “moderate sorption to soil/sediment, slow migration to ground water” or “strong sorption to soil/sediment, negligible to slow migration to ground water”. *

The bulk of hop extract, viz. the bitter acids, accounting for ca. 70% of a typical hop extract, will adsorb to the soil in a low to moderate fashion. The essential oil, accounting for ca. 14% of a typical hop extract, will adsorb in a slightly stronger fashion. The other components of hop extract are mostly other resins (including oxidised bitter acids, which are estimated to behave in a similar fashion to the bitter acids), and hop fats and waxes, which due to their hydrophobicity and large molecular structure, will adsorb more strongly to soil.


* interpreting the values as discussed in Section 5.4.1 of https://www.epa.gov/sites/production/files/2015-05/documents/05.pdf

Description of key information

Key value for chemical safety assessment

Koc at 20 °C:
25 119

Additional information

Hop extract is a natural extract of hop cones, a UVCB substance, obtained using either liquid or supercritical CO2, or ethanol, as extraction solvents. The principal components are listed in Table 1 of the attached report. The results (Table 2 of the attached report) show that the principal homologues of the α-acids have log KOC values of 1.5 – 2.4, indicating “low sorption to soil/sediment, moderate migration to ground water” and the more hydrophobic β-acids have log KOC values of 2.5 – 3.4, indicating “moderate sorption to soil/sediment, slow migration to ground water”. * The principal components of the hop essential oil, viz. myrcene, humulene and caryophyllene, have log KOC values of 2.5 – 4.4, indicating either “moderate sorption to soil/sediment, slow migration to ground water” or “strong sorption to soil/sediment, negligible to slow migration to ground water”. *

The bulk of hop extract, viz. the bitter acids, accounting for ca. 70% of a typical hop extract, will adsorb to the soil in a low to moderate fashion. The essential oil, accounting for ca. 14% of a typical hop extract, will adsorb in a slightly stronger fashion. The other components of hop extract are mostly other resins (including oxidised bitter acids, which are estimated to behave in a similar fashion to the bitter acids), and hop fats and waxes, which due to their hydrophobicity and large molecular structure, will adsorb more strongly to soil.

* interpreting the values as discussed in Section 5.4.1 of https://www.epa.gov/sites/production/files/2015-05/documents/05.pdf

[LogKoc: 4.4]

[LogKoc: 4.4]

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