Nitrapyrin

Biodegradation in soil

Administrative data

Endpoint:

biodegradation in soil

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: peer reviewed publication, no guideline followed.

Data source

Reference

Reference Type:

publication

Title:

The persistence of 2-chloro-6-(trichloromethyl)-pyridine in soil

Author:

Herlih and Quirke, 19975

Year:

1975

Bibliographic source:

Soil Science and Plant Analysis, 6(5), 513 -520

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

No data about the method was available.

GLP compliance:

not specified

Test type:

laboratory

Test material

Test material information

Constituent 1

Reference substance name:

Nitrapyrin

EC Number:

217-682-2

EC Name:

Nitrapyrin

Cas Number:

1929-82-4

Molecular formula:

C6H3Cl4N

IUPAC Name:

2-chloro-6-(trichloromethyl)pyridine

Radiolabelling:

no

Study design

Soil properties

Soil properties 1

Soil no.:

#3

Soil type:

loam

% Clay:

26

% Silt:

36

% Org. C:

2.3

pH:

6.9

CEC:

21 meq/100 g soil d.w.

Soil properties 2

Soil no.:

#2

Soil type:

other: Coarse sandy loam

% Clay:

15

% Silt:

22

% Org. C:

1.8

pH:

7.5

CEC:

18 meq/100 g soil d.w.

Soil properties 3

Soil no.:

#1

Soil type:

loamy sand

% Clay:

6

% Silt:

9

% Org. C:

1.4

pH:

7.1

CEC:

12 meq/100 g soil d.w.

Duration of test (contact time)

Duration of test (contact time) 1

Soil No.:

#3

Duration:

40 d

Duration of test (contact time) 2

Soil No.:

#2

Duration:

40 d

Duration of test (contact time) 3

Soil No.:

#1

Duration:

40 d

Initial test substance concentration

Initial test substance concentration 1

Soil No.:

#1

Initial conc.:

20 other: µg/g soil sample

Based on:

test mat.

Initial test substance concentration 2

Soil No.:

#2

Initial conc.:

20 other: µg/g soil sample

Based on:

test mat.

Initial test substance concentration 3

Soil No.:

#3

Initial conc.:

20 other: µg/g soil sample

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Experimental conditions

Experimental conditions 1

Soil No.:

#1

Temp.:

10

Experimental conditions 2

Soil No.:

#1

Temp.:

20

Experimental conditions 3

Soil No.:

#2

Temp.:

10

Experimental conditions 4

Soil No.:

#2

Temp.:

20

Experimental conditions 5

Soil No.:

#3

Temp.:

10

Experimental conditions 6

Soil No.:

#3

Temp.:

20

Details on experimental conditions:

EXPERIMENTAL DESIGN
- Soil condition: fresh
- Soil: 10 g/sample
- Control conditions: Soil solvent blanks
- No. of replication controls: 2
- No. of replication treatments: 2
- Test apparatus: 20 mm diameter test tubes
- Identity and concentration of co-solvent: Methanol, stock solutions, 2000 µg test item per mL of solvent

Test material application
- Volume of test solution used/treatment: 0.1 mL
- Application method: applied to soil at five discrete spots
- Is the co-solvent evaporated: no

Any indication of the test material adsorbing to the walls of the test apparatus: no

Experimental condition
- Moisture maintenance method: Test tubes placed in tshallow layer of water to limit evaporation
- Continuous darkness: no data

Other details, if any:

OXYGEN CONDITIONS
- Methods used to create the an aerobic conditions: caps were removed periodically from test tubes

Results and discussion

Half-life / dissipation time of parent compound

Half-life / dissipation time of parent compound 1

Soil No.:

#1

DT50:

77 d

Type:

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

Remarks on result:

other: at 10°C

Half-life / dissipation time of parent compound 2

Soil No.:

#1

DT50:

15 d

Type:

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

Remarks on result:

other: at 20°C

Half-life / dissipation time of parent compound 3

Soil No.:

#2

DT50:

43 d

Type:

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

Remarks on result:

other: at 10°C

Half-life / dissipation time of parent compound 4

Soil No.:

#2

DT50:

9 d

Type:

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

Remarks on result:

other: at 20°C

Half-life / dissipation time of parent compound 5

Soil No.:

#3

DT50:

43 d

Type:

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

Remarks on result:

other: at 10°C

Half-life / dissipation time of parent compound 6

Soil No.:

#3

DT50:

16 d

Type:

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

Remarks on result:

other: at 20°C

Transformation products:

not measured

Details on transformation products:

Previous work indicated that loss of the test item occurred also by hydrolysis to 6-chloropicolinic acid.

Applicant's summary and conclusion

Conclusions:

The half-life of test item in three soils varied from 43 to 77 days at 10°C and from 9 to 16 days at 20°C.

Executive summary:

This study by Herlih at al. (1975) evaluated the persistence of test item in different soils (loamy sand, coarse sandy loam and loam) at two different temperatures (10 and 20°C). The study was not conducted according to current guidelines. The test item was dissolved in methanol and a final test item concentration of 20 µg/g soil was used in the test. Soil solvent blanks were used as controls. Test samples and solvent blanks were prepared in duplicate. Following an aerobic incubation at 10°C and 20°C, the residual amount of test item was determined via distillation followed by absorbance measurements. The degradation varied for each soil type and depended on the incubation temperature. Conclusively, it was stated that the degradation is driven by both biotic and abiotic (volatilisation and hydrolysis) processes. The following half-life values were determined:

Half-life in loamy sand: 77 days at 10°C and 15 days at 20°C

Half-life in coarse sandy loam: 43 days at 10°C and 9 days at 20°C

Half-life loam: 43 days at 10°C and 16 days at 20°C