Terphenyl

Biodegradation in soil

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

Test material information

Constituent 1

Reference substance name:

Terphenyl

EC Number:

247-477-3

EC Name:

Terphenyl

Cas Number:

26140-60-3

Molecular formula:

C18H14

IUPAC Name:

2-phenyl-1,1'-biphenyl; 3-phenyl-1,1'-biphenyl; 4-phenyl-1,1'-biphenyl

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 properties

Soil properties 1

Soil no.:

#1

Soil type:

sand

% Org. C:

ca. 0.5

Soil properties 2

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)

Duration of test (contact time) 1

Soil No.:

#1

Duration:

ca. 32 wk

Duration of test (contact time) 2

Soil No.:

#2

Duration:

ca. 32 wk

Initial test substance concentration

Initial test substance concentration 1

Soil No.:

#1

Initial conc.:

ca. 50 ppm

Based on:

test mat.

Initial test substance concentration 2

Soil No.:

#1

Initial conc.:

ca. 0.5 ppm

Based on:

test mat.

Initial test substance concentration 3

Soil No.:

#2

Initial conc.:

ca. 50 ppm

Based on:

test mat.

Initial test substance concentration 4

Soil No.:

#2

Initial conc.:

ca. 0.5 ppm

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Experimental conditions

Experimental conditions 1

Soil No.:

#1

Temp.:

25°C

Humidity:

80%

Experimental conditions 2

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

% Degradation

% Degradation 1

Soil No.:

#1

% Degr.:

ca. 81

Parameter:

test mat. analysis

Sampling time:

32 wk

% Degradation 2

Soil No.:

#2

% Degr.:

ca. 70

Parameter:

test mat. analysis

Sampling time:

32 wk

Half-life / dissipation time of parent compound

Half-life / dissipation time of parent compound 1

Soil No.:

#1

DT50:

ca. 8.1 wk

Type:

(pseudo-)first order (= half-life)

Half-life / dissipation time of parent compound 2

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)