3-iodo-2-propynyl butylcarbamate

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil: simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1989-08-08 to 1992-05-05

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: U. S. EPA Pesticide Assessment Guidelines Subdivision N, Section 162-1

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Agriculture Canada Trade Memorandum T-1-255

Deviations:

no

GLP compliance:

yes

Test type:

laboratory

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: N.J. L7-93; N.J. AS-2; 30-142-A

SOURCE OF TEST MATERIAL RADIOLABELLED
- Source and lot/batch No.of test material: NSN/1/77/1
- Radiochemical purity: 99.4 %

Radiolabelling:

yes

Oxygen conditions:

aerobic

Soil classification:

not specified

Year:

1991

Soil type:

loam

% Clay:

14

% Silt:

40

% Sand:

46

% Org. C:

1.57

pH:

6.1

CEC:

10.1 meq/100 g soil d.w.

Details on soil characteristics:

SOIL COLLECTION AND STORAGE
- Geographic location: Missouri, U. S. A.
- Pesticide use history at the collection site: No pesticides were applied to this soil during the four year period prior to sampling
- Soil preparation: 2 mm sieved, connected to a moist air saturator prior to use

PROPERTIES OF THE SOILS
#1 and #2 refers to the nonsterile soil; #3 refers to sterile soil

Soil No.:

#1

Duration:

245 d

Soil No.:

#2

Duration:

14 d

Soil No.:

#3

Duration:

28 d

Initial conc.:

> 0.87 - < 1.03 ppm

Based on:

other: Fortification level ranges

Parameter followed for biodegradation estimation:

CO2 evolution

radiochem. meas.

Soil No.:

#1

Temp.:

22 °C

Soil No.:

#2

Temp.:

5 °C

Soil No.:

#3

Temp.:

22 °C

Details on experimental conditions:

1. EXPERIMENTAL DESIGN
- Soil preincubation condition: non-sterile samples were allowed to acclimate to the test conditions for at least 5 days prioir treatment
- Soil condition: fresh
- Soil amount 250 g/replicate
- Control conditions: sterile/non-sterile
- Test apparatus: sidearm filter flasks were placed in an environmental chamber with polyurethane foam plug placed on top

Test material application
- Volume of test solution used/treatment: 2 mL of fortifications solution were added to each sample
- Application method: incorporated with a spatula

Any indication of the test material adsorbing to the walls of the test apparatus: none

Experimental conditions
- Moisture maintenance method: soil moisture was adjusted to 75 % of field capacity at monthly intervals
- Continuous darkness: No

2. SAMPLING DETAILS
- Sampling intervals:
Duplicate samples were taken at each specified interval:
Test A (Nonsterile, 22°C):
0, 3, 6, and 12 hours, 1, 2, 4, 7, 11, 21 and 245 days post-treatment.
Test B (Nonsterile, 5°C):
0, 3, 6, and 12 hours, 1, 2, 3, 4, 7 and 14 days post-treatment.
Test C (Sterile, 22°C):
0, 1, 4 and 28 days post-treatment.

Soil No.:

#1

Remarks on result:

other: 89 to 105.2 %

Soil No.:

#2

Remarks on result:

other: 91.6 to 108.0 %

Soil No.:

#3

Remarks on result:

other: 100.0 to 104.4 %

Key result

Soil No.:

#1

DT50:

2.13 h

Type:

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

Temp.:

22 °C

Key result

Soil No.:

#2

DT50:

8.6 h

Type:

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

Temp.:

5 °C

Key result

Soil No.:

#3

DT50:

4.3 d

Type:

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

Temp.:

22 °C

Remarks on result:

other: sterile soil

Transformation products:

yes

No.:

#1

Evaporation of parent compound:

no

Volatile metabolites:

no

Conclusions:

The test item was rapidly degraded under nonsterile aerobic soil conditions with half-life values of 2.13 and 8.60 hours at 22 and 5 °C, respectively. Propargyl butyl carbamate was the primary soil metabolite formed. Propargyl butyl carbamate (resulting from the test item application) was readily mineralized in nonsterile samples maintained at 22 °C. Mineralization rates were significantly lower at 5 °C. Test item degradation in soil was primarily microbially mediated but nonbiological mechanisms may contribute to the degradative process.

Executive summary:

A laboratory study was performed to investigate the aerobic soil metabolism of the test item in a Blackoar loam soil at temperatures of 22 ± 2 °C and 5 ± 3 °C. The test item was rapidly degraded in soil at 22 °C with a half-life of 2.13 hours. The primary soil metabolite was propargyl butyl carbamate. Propargyl butyl carbamate also was readily degraded in soil at 22 °C with a half-life of 4.30 days. Test item degradation was slowed at 5 °C resulting in a soil half-life of 8.60 hours. The rate of propargyl butyl carbamate degradation decreased to a greater extent than that of the test item itself as temperature decreased from 22 to 5 °C. Fourteen days after treatment, greater than 60% of the applied 14C had been mineralized to 14CO2 at 22 °C whereas less than 5% had been mineralized at 5 °C. The test item and propargyl butyl carbamate degradation in soil is primarily microbially mediated but nonbiological processes may be involved.

Description of key information

The test item was rapidly degraded under nonsterile aerobic soil conditions with half-life values of 2.13 and 8.60 hours at 22 and 5 °C, respectively. Propargyl butyl carbamate was the primary soil metabolite formed. Propargyl butyl carbamate (resulting from the test item application) was readily mineralized in nonsterile samples maintained at 22 °C. Mineralization rates were significantly lower at 5 °C. Test item degradation in soil was primarily microbially mediated but nonbiological mechanisms may contribute to the degradative process.

Key value for chemical safety assessment

Half-life in soil:

2.1 h

at the temperature of:

22 °C

Additional information

A laboratory study was performed to investigate the aerobic soil metabolism of the test item in a Blackoar loam soil at temperatures of 22 ± 2 °C and 5 ± 3 °C. The test item was rapidly degraded in soil at 22 °C with a half-life of 2.13 hours. The primary soil metabolite was propargyl butyl carbamate. Propargyl butyl carbamate also was readily degraded in soil at 22 °C with a half-life of 4.30 days. Test item degradation was slowed at 5 °C resulting in a soil half-life of 8.60 hours. The rate of propargyl butyl carbamate degradation decreased to a greater extent than that of the test item itself as temperature decreased from 22 to 5 °C. Fourteen days after treatment, greater than 60% of the applied 14C had been mineralized to 14CO2 at 22 °C whereas less than 5% had been mineralized at 5 °C. The test item and propargyl butyl carbamate degradation in soil is primarily microbially mediated but nonbiological processes may be involved.