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Environmental fate & pathways

Biodegradation in soil

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Reference
Endpoint:
biodegradation in soil: simulation testing
Type of information:
calculation (if not (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:
Data is from computational model developed by USEPA
Qualifier:
according to
Guideline:
other: Modeling database
Principles of method if other than guideline:
Fugacity Model level III by EPI Suite v 4.1 estimation database
GLP compliance:
no
Radiolabelling:
not specified
Oxygen conditions:
other: estimated
Soil classification:
not specified
Parameter followed for biodegradation estimation:
test mat. analysis
Details on experimental conditions:
Level III Fugacity modelEPI Suite contains a Level III fugacity model. In general, fugacity models predict the partitioning of an organic compound in an evaluative environment. A Level III model assumes steady-state but not equilibrium conditions. The Level III model in EPI Suite predicts partitioning between air, soil, sediment and water using a combination of default parameters and various input parameters that may be user defined or estimated by other programs within EPI Suite. The model environment consists of 4 main compartments: air, water sediment and soil. There are also sub-compartments such as an aerosol phase, suspended solids, and biota phase, within specific main compartments. A fixed temperature of 25ᵒC is assumed. Mass transport between the compartments via volatilization, diffusion, deposition and runoff are modeled. level III models is a steady state, non-equilibrium model. Steady state conditions mean that the change in concentration of a chemical in each compartment (i) with respect to time eventually approaches zero. The model does not assume that a common equilibrium (fugacity) exists between the phases, so if a chemical is emitted into one compartment it can partition to the other compartments. Loss of chemical occurs through two processes: reaction and advection. Reaction is the biotic or abiotic degradation of the chemical that is calculated using the user specified or model calculated half-lives of the chemical in each of the 4 main compartments. Advection processes are considered for the air, water and sediment compartments. Advection is the removal of chemical from a compartment through losses other than degradation (reaction). The rate of advection in a given compartment is determined by a flow rate (m3/hour), calculated by dividing the volume of the compartment by an advection time.
Soil No.:
#1
% Recovery:
74.5
Remarks on result:
other: Other details not known
Key result
Soil No.:
#1
% Degr.:
50
Parameter:
other: Half-life
Sampling time:
30 d
Remarks on result:
other: Other details not known
Key result
Soil No.:
#1
DT50:
30 d
Type:
other: estimated data
Temp.:
25 °C
Remarks on result:
other: Other details not known
Transformation products:
not specified
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified

Mass Amount (Percent)

Half-life (hr)

Emission (kg/hr)

Soil

74.5

720

1000

 

Fugacity(atm)

Reaction (kg/hr)

Advection (kg/hr)

Reaction (percent)

Advection (percent)

Soil

1.71e-010

981

0

32.7

0

Conclusions:
Biodegradation half-life of test chemical in soil was estimated to be 30 days (720 hrs).
Executive summary:

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 74.5% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical , it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Description of key information

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2018). If released into the environment, 74.5% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical , it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Key value for chemical safety assessment

Half-life in soil:
30 d
at the temperature of:
25 °C

Additional information

Various predicted data for the test chemical were reviewed for the biodegradation in soil end point which are summarized as below:

 

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 74.5% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical , it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

In a supporting study from secondary source (Robust Summaries & Test Plans: Cinnamyl Derivatives: Revised Summaries, 2005),

half-life of the test chemical in soil by using Mackay EQC Fugacity Level III. The following values has been used in the Mackay EQC Fugacity Level III for the estimating the half-life value. They are water solubility: 8.5 mg/l, vapour pressure: 0.0012 mm Hg, log Kow: 4.7 and melting point: 80°C, repsecitvely. If released into the environment, 57.3% of the chemical will partition into soil according to the Mackay EQC Fugacity Level III. The half-life period of test chemical in soil is estimated to be 15 days (360 hrs). Based on this half-life value of test chemical, it is concluded that the test chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

On the basis of above results for test chemical (from EPI suite, 2017 and secondary source), it can be concluded that the test substance is not persistent in the soil environment and therefore the exposure risk to soil dwelling animals is moderate to low.