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Administrative data

Endpoint:
biodegradation in soil
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
From February 21 to October 1989
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented publication/study report which meets basic scientific principles

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report date:
1989

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: “Fate Screening Test in Soil” Ecova Protocol P87/803206.D28:1t/5 Dated and accepted February 8, 1989
Deviations:
yes
Remarks:
The final time point was taken at 32 weeks rather than at the originally planned 30-weeks. It is not believed that this affected the quality of data as the final time point was to provide data on an extended time frame
GLP compliance:
yes (incl. QA statement)
Test type:
laboratory

Test material

Constituent 1
Reference substance name:
Terphenyl
EC Number:
247-477-3
EC Name:
Terphenyl
Cas Number:
26140-60-3
Molecular formula:
C18H14
IUPAC Name:
1,1':4',1''-terphenyl
Details on test material:
- Physical state: yellowish-white crystalline powder received in a 125 ml screw top glass jar
.: Label Terphenyls, Monsanto notebook page 4068001-1, Dated 8/18/88 (Paul Lin), Log #351277-B.
Radiolabelling:
no

Study design

Oxygen conditions:
aerobic
Soil classification:
other: Soil #1 Missouri Bottoms and Soil #2 Florida Muck
Soil propertiesopen allclose all
Soil no.:
#1
Soil type:
sand
% Org. C:
ca. 0.5
Soil no.:
#2
Soil type:
loam
% Org. C:
ca. 32.9
Details on soil characteristics:
SOIL #1:
- Geographic location: Missouri Bottoms (Amount received = 2015 g); a light brown sandy material
- Moisture at 1/3 atm (%): 11.41% at 1/3 bar

SOIL #2:
- Geographic location: Florida Muck (Amount received = 2127 g); a rich black loamy material
- Moisture at 1/3 atm (%): 81.97% at 1/3 bar

Duration of test (contact time)open allclose all
Soil No.:
#1
Duration:
ca. 32 wk
Soil No.:
#2
Duration:
ca. 32 wk
Initial test substance concentrationopen allclose all
Soil No.:
#1
Initial conc.:
ca. 50 ppm
Based on:
test mat.
Soil No.:
#1
Initial conc.:
ca. 0.5 ppm
Based on:
test mat.
Soil No.:
#2
Initial conc.:
ca. 50 ppm
Based on:
test mat.
Soil No.:
#2
Initial conc.:
ca. 0.5 ppm
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Experimental conditionsopen allclose all
Soil No.:
#1
Temp.:
25°C
Humidity:
80%
Soil No.:
#2
Temp.:
25°C
Humidity:
80%
Details on experimental conditions:
- carrier solvent: methylene chloride
- Sampling intervals: 0 weeks, 0.5 week, 1 week,2 weeks, 4 weeks, 6 weeks, 8 weeks, 12 weeks, 15 weeks and 32 weeks
- Soil (g/replicate): 25 g /replicate, 3 replicates of each active system (soil type/test concentration)
- Application method: soil and test substance are shaken vigorously

Results and discussion

% Degradationopen allclose all
Soil No.:
#1
% Degr.:
ca. 81
Parameter:
test mat. analysis
Sampling time:
32 wk
Soil No.:
#2
% Degr.:
ca. 70
Parameter:
test mat. analysis
Sampling time:
32 wk
Half-life / dissipation time of parent compoundopen allclose all
Soil No.:
#1
DT50:
ca. 8.1 wk
Type:
(pseudo-)first order (= half-life)
Soil No.:
#2
DT50:
ca. 12.1 wk
Type:
(pseudo-)first order (= half-life)
Transformation products:
not measured
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Results with reference substance:
no reference substance

Any other information on results incl. tables

Test results for terphenyl after 32 weeks in soil are shown in Table 1.

 

Table 1: Percent reduction in concentration at week 32 relative to initial concentration (T=0) and to sterile soil

Terphenyl

Relative to nominal

Relative to control

t ½ (weeks)

Soil #1/50 ppm

94

81

8.1

Soil #1/500 ppb

75

-

16.0

Soil #2/50 ppm

84

70

12.1

Soil #2/500 ppb

0

-

(1)

(1)   No change in concentration from T = 0 to T = 32

Applicant's summary and conclusion

Conclusions:
The aim of the test was to measure the change in concentration of terphenyls, quaterphenyls and polyphenyls relative to initial concentration and/or sterile controls. The test concentrations wer 50 and 0.5 mg/kg. The degradation was measured in two soil types.
Losses of the test materials followed expected trends, given the structures of the three test compounds. The lightest, simplest compound (terphenyl) showed the greatest loss, followed by quatraphenyl and then polyphenyl. When compared to the sterile controls, terphenyl appears to have been reduced substantially (81% in soil #1 and 70% in soil #2). The corresponding half-life values are 8.1 and 12.1 weeks
The methods and results are well described and documented, with enough detail to evaluate the test quality.
Executive summary:

The study was performed to assess any potential biodegradation during a 32-week study. The test compound was a mixture of terphenyls, quaterphenyls and polyphenyls. The criteria for assessment of effect was change in the concentration of the test materials with time. The test concentrations were 50 and 0.5 mg per kilogram, for each of the three substances. Dichloromethane was used as carrier solvent. Abiotic controls were maintained for soil #1 and soil #2 at the highest test concentration by amending the soil with 0.5% mercuric chloride. Spike recovery tests were run to validate the analytical method.

Terphenyl appears to more readily biodegradable than the quatraphenyls and polyphenyls tested. Concentration of terphenyl in the test containers began dropping immediately after test initiation with no evident lag period. The 50 ppm test dropped to 3 ppm in soil #1 (94% reduction) and 6 ppm in soil #2 (84% reduction). The 0.5 ppm test dropped to 0.1 ppm (75% reduction) in soil #1 but remained at 0.3 ppm (0% reduction) in soil #2.

The loss of terphenyl in the sterile controls, down to 16 ppm in soil #1 (60% reduction) and 20 ppm in soil #2 (54% reduction), indicates that at least some of the losses seen in the non-sterile test systems were due to abiotic causes.

The primary route of removal appears to be biological. The removal rate in the active systems is more than double that in the sterile system (t ½ = 8.1 and 23.9 weeks respectively in soil #1)