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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 days
Reliability:
1 (reliable without restriction)
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Hop extract - CO2 extract of Humulus lupulus variety 'Cascade'. Batch number 160025. Principal components: alpha acids: 35.06% w/w; beta acids: 38.47% w/w; essential oils: 8.92% v/w
Oxygen conditions:
aerobic
Inoculum or test system:
other: secondary effluent from a predominantly domestic sewage treatment works.
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 26
Sampling time:
28 d
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The study performed on hop extract is relevant for other key isomers and extracts present in teh raw extract. The rate of biodegradation is very likely related to solublity in water and with these extracts, the pH is critical in determining water solubility with sodium and potassium salts very soluble and acid forms are less soluble.


This result suggests a water soluble / biologically active component rapidly contributing to 20% of the degradation (ie about 30% of the material in view of the low results for the control) and a residual 70% or so of the material that is so insoluble it is not biologically available.

As a natural product, there will be ultimate biodegradation.

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable but failing 10-day window

Additional information

This result suggests a water soluble / biologically active component rapidly contributing to 20% of the degradation (ie about 30% of the material in view of the low results for the control) and a residual 70% or so of the material that is so insoluble it is not biologically available. As a natural product, there will be ultimate biodegradation.

[Type of water: freshwater]

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