Registration Dossier

Diss Factsheets

Environmental fate & pathways

Biodegradation in soil

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
biodegradation in soil: simulation testing
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 307 (Aerobic and Anaerobic Transformation in Soil)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Test type:
laboratory
Radiolabelling:
yes
Soil No.:
#1
DT50:
2.7 h
Type:
(pseudo-)first order (= half-life)
Transformation products:
yes

Degradation of ortho-phenylphenol in soil starts with rapid binding to the soil matrix within hours, with no pronounced formation of soluble intermediates. Humic substances fractionation indicated the non-extractable residues to be predominantly associated with the soil humin and humic acid fractions. Although not extractable, the immobilized residues are moderately mineralized, indicating their participation in soil carbon turnover and breakdown of the radiolabel-containing phenylphenol core structure. The observed behaviour is in-line with literature information on rapid and irreversible soil binding of similar phenolic type compounds. Such effect has been attributed to oxidative coupling reactions, which may be both biologically mediated, or abiotic surface-catalyzed processes.

OPP is not expected to persist in a viable soil environment (t1/2 = 2.7 hours). Due to rapid and irreversible binding to soil matrix, no significant mobility of parent compound or transformation products is indicated.

Description of key information

Persistence in the soil compartment is not expected

Key value for chemical safety assessment

Additional information

According to the REACH regulation Annex IX column 2, studies on the biodegradation in soil do not need to be conducted if the test item is readily biodegradable.

However, additional data obtained from a test according to OECD guideline 307 conducted by Fliege (2005) to investigate the route and rate of OPP degradation are available. In this test the biotransformation of radiolabelled OPP was monitored over 127 days in soil under aerobic conditions. The simple first order DT50 value of OPP in the test soil was 2.7 h.

In conclusion, OPP is not expected to persist in the soil compartment.