Page 2 of 35

1.0 Introduction

This document serves as an addendum to the April 30, 2009 (Post-Phase 6) risk assessment that 

was completed for metam sodium (Smith; D357118). Since the completion of that risk 

assessment, the Agency has received a number of new flux studies from a variety of 

stakeholders. These studies include:

MRID 47770001 - Estimating Methyl Isothiocyanate Emission Rates Following Soil 

Incorporated Shank and Modified Center Pivot Chemigation Metam Sodium Applications 

(Sponsored by Washington State University) 

MRID 47820001 - Monitoring Chloropicrin, Dimethyldisulfide, and Methyl Isothiocyanate 

Emissions from Shank Applications at Three Sites near Tifton, Georgia (Sponsored by USDA, 

ARS Area-Wide Pest Management Program for Methyl Bromide Alternatives and Florida 

Specialty Crop Foundation) 

MRID 47813901 - Monitoring 1,3-Dichloropropene, Chloropicrin, and Methyl Isothiocyanate 

Emissions from Shank Applications at Three Sites Near Duette, Florida (Sponsored by USDA, 

ARS Area-Wide Pest Management Program for Methyl Bromide Alternatives and Florida 

Specialty Crop Foundation)

MRID 48011601 - Monitoring of Metam Sodium Airborne Flux for Shank Injection for Cultural 

Practice Applicable to Wisconsin (Sponsored by the Wisconsin Potato & Vegetable Growers 

Association, Inc)

MRID 48005901 - Monitoring of Metam Sodium Airborne Flux from Shank 

Injection/Compaction Based on Cultural Practice Applicable to Michigan (Sponsored by the 

Michigan Potato Industry Commission) 

MRID 48115101 - WA Potato Growers Study - Monitoring of Metam Sodium Airborne Flux 

from Shank Injection/Compaction Based on Cultural Practice Applicable to Washington State

(Sponsored by the Washington State Potato Commission)

MRID 47956901 - A Trial to Evaluate Concentrations and Emission Rates from the Application 

of Metam Sodium by Shank Injection/Compaction on a Daytime and Nighttime Basis 

(Sponsored by Amvac Chemical Corporation, Taminco, Inc., and Tessenderlo Kerley, 

Incorporated)

MRID 47956701 - Flux Evaluation of a Metam Potassium Application (KAPAM-HL) Applied 

by the Drench Method (Study SEC- 2008D) (Sponsored by Amvac Chemical Corporation)

Specifically, this document provides information that should be considered in addition to the 

discussions, data, and results previously presented related to MITC (from metam sodium/metam 

potassium applications) flux estimates and PERFUM modeling. Appendix A includes a 
Page 3 of 35

summary of the parameters under which all of the submitted metam sodium/metam potassium

emission studies were performed.

2.0 Study Summary and Flux Calculations

MRID 47770001 Study- Estimating Methyl Isothiocyanate Emission Rates Following Soil 

Incorporated Shank and Modified Center Pivot Chemigation Metam Sodium Applications

In MRID 47770001, the study authors monitored for methyl isothiocyanate at near-field receptor 

location after a drizzle boom modified center pivot chemigation and soil-incorporated shank 

injection application of Sectagon 42®(42% metam sodium). The test site for this study was 

located near Eltopia, Franklin County, WA in October 2008. This study was developed to 

specifically assess emission rates and total cumulative field loss of metam sodium’s gaseous byproduct, methyl isothiocyanate (MITC) during and four days post-application under conditions 

typical for Pacific Northwest (PNW) potato pre-plant fumigation. Metam sodium was applied to 

two treatment plots (1.7 acres for drizzle boom and 1.8 acres for shank injection) within a 122 

acre field circle to assess near-field MITC air emissions before, during, and through 4-days post 

application (from October 8th through the 13th, 2008). The fumigant was applied at a rate of 71 

gal/acre for drizzle boom and 52 gal/acre for shank injection concurrently on October 9, 2008. 

This rate of application is higher than the rate of 35-40 gal/acre used in Washington State for 

control of soil-borne pathogens in/on potatoes, but lower than the allowable maximum label rate 

of 75 gal/acre.

The drizzle boom modified center pivot application was conducted through use of an eight tower 

center pivot. Center pivot towers 1-3 and 8 were capped off and a horizontal boom constructed 

of PVC piping was attached to existing sprinkler heads to allow for application 2-3 feet from the 

soil surface. The drizzle boom application was applied with 1 inch of water to set the product 

within the soil. The soil-incorporated application was conducted through shank injection at a 

depth of about 9 inches followed by soil compaction. The plot area was “double disk plowed” 

before application. 

Eight receptors were positioned about 15 meters from the treated edge and equidistant from each 

other. Four additional ambient air receptors were positioned between the two treatment plots, one 

near the center of the center pivot circle, one near the southwest circle field corner and two near 

equidistant between the drizzle boom and shank injection plot. MITC was monitored preapplication, during fumigation and at either 4 or 8 hour periods through 4 days post-application. 

MITC samples were collected through activated charcoal. 

Wind speed and direction, air and soil temperature, soil moisture, and rainfall data were collected 

throughout the pre-application, fumigation, and air sampling time period with an Onset HOBO 

Weather Station data logger®. Wind speed and direction were recorded at 2 meters height and 

soil temperature and moisture levels were recorded at 6” depth. Average air temperature over 

the sampling interval was approximately 7.7°C (45.9 °F) with a high of 18.9°C (66 °F) and a low 

below freezing (-1.5°C or 29.3°F ). Average 6” depth soil temperature during the trial was 10.2 

°C (50.4 °F), with a high of 16.2 °C (61.2°F) and a low of 6.2 °C (43.2°F ). The measured soil 

moisture level (at 6” depth) dropped from 1.41 m3/m3 at the beginning to 0.094 m3/m3 by the 
Page 4 of 35

end of the sampling period. No measurable rainfall was recorded. Field fortification samples 

were analyzed to ensure proper analysis of air concentration field samples in the study. Field 

recovery analysis was conducted and subsequent adjustments were made to the air concentration 

analysis as appropriate. 

Flux rates were calculated via on-field flux data except during the fumigant application where 

the primary method to compute flux rates was the back-calculation method. The flux profiles 

were calculated based on the field conditions including the application rates used to make the 

applications in the study. For the purposes of completing the PERFUM analyses, these flux 

profiles were subsequently adjusted to the maximum application rate for metam sodium of 320 lb 

metam sodium per treated acre (see Tables 1 and 2).

Table 1. Flux Calculations for Field 1 (Broadcast Shank Injection and 

Compaction) at Franklin County, WA (MRID 47770001)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study Reported 

Flux

(ug/m2-s) (ug/m2-s)

1 10/9/2008 12:00 - 13:00 1 6.560 7.730

2 10/9/2008 13:00 - 14:00 1 12.480 13.310

3 10/9/2008 14:00 - 18:00 4 9.080 9.090

4 10/9/2008 18:00 - 22:00 4 12.210 12.240

5 10/9/2008 22:00 - 02:00 4 11.160 11.490

6 10/10/2008 03:00 - 07:00 4 16.220 21.320

7 10/10/2008 07:00 - 10:00 3 5.070 5.080

8 10/10/2008 10:00 - 14:00 4 6.170 6.790

9 10/10/2008 14:00 - 18:00 4 5.430 5.680

10 10/10/2008 18:00 - 22:00 4 3.880 4.000

11 10/10/2008 22:00 - 02:00 4 3.420 3.680

12 10/11/2008 02:00 - 07:00 5 2.400 2.410

13 10/11/2008 07:00 - 11:00 4 3.490 3.520

14 10/11/2008 11:00 - 15:00 4 3.680 3.940

15 10/11/2008 15:00 - 22:00 7 5.840 5.860

16 10/11/2008 22:00 - 07:00 9 2.780 2.790

17 10/12/2008 07:00 - 14:00 7 0.190 0.200

19 10/12/2008 14:00 - 22:00 8 2.140 2.150

19 10/12/2008 22:00 - 07:00 9 1.390 1.410

20 10/13/2008 07:00 - 11:00 4 2.170 2.160
Page 5 of 35

Table 2. Flux Calculations for Field 2 (Center Pivot Irrigation Using 

Drizzle Boom) at Franklin County, WA (MRID 47770001)

Period No. Sample Interval Times

Duration 

(Hrs.)

Study Reported 

Flux

(ug/m2-s)

1 10/9/2008 12:00 - 13:00 1 172.08

2 10/9/2008 13:00 - 15:00 2 171.80

3 10/9/2008 15:00 – 19:00 4 67.00

4 10/9/2008 19:00 – 23:00 4 40.10

5 10/9/2008 23:00 – 03:00 4 35.32

6 10/10/2008 03:00 - 07:00 4 32.20

7 10/10/2008 07:00 - 12:00 5 26.71

8 10/10/2008 12:00 - 16:00 4 57.15

9 10/10/2008 16:00 – 20:00 4 37.92

10 10/10/2008 20:00 - 24:00 4 26.83

11 10/10/2008 24:00 – 03:00 3 22.60

12 10/11/2008 03:00 - 07:00 4 15.29

13 10/11/2008 07:00 - 11:00 4 15.54

14 10/11/2008 11:00 – 15:00 4 31.90

15 10/11/2008 15:00 – 23:00 8 16.03

16 10/11/2008 23:00 - 07:00 8 9.73

17 10/12/2008 07:00 - 16:00 9 4.40

19 10/12/2008 16:00 - 23:00 7 6.92

19 10/12/2008 23:00 - 07:00 8 3.14

20 10/13/2008 07:00 - 15:00 8 3.28

Note: The Agency did not verify the flux estimates presented in Table 2 at this time. The 

presented flux estimates are presented directly as reported in the study. The Agency did not 

verify the center pivot flux rates at this time because there is currently no fumigant air model that 

will accurately model circular fields (i.e., center pivot applications) to the Agency’s 

specifications. A Beta version of PERFUM is currently in development that will allow the 

Agency to model circular fields. When this PERFUM version is complete the Agency will 

revisit the center pivot portion of this study.

MRID 47820001 Study - Monitoring Chloropicrin, Dimethyldisulfide, and Methyl 

Isothiocyanate Emissions from Shank Applications at Three Sites near Tifton, Georgia

In MRID 47820001, the study authors monitored for chloropicrin, dimethyldisulfide, and methyl 

isothiocyanate during three separate bedded shank injection applications. The test site for this 

study was located in Tifton, Georgia and the field work was conducted in November of 2009. 

Chloropicrin and DMDS (pre-mixed together in a 79% dimethyldisulfide:21% chloropicrin ratio) 

were applied as a pre-bed application using 3 swept back shanks spaced 12 inches apart to 

deliver chloropicrin and DMDS to an 8 inch depth. This application was followed by an 

application of metam sodium at a 4 inch depth using 12 –inch vertical cultures spaced 4 inches 

apart. Thirty-two inch wide by 9 inch high raised beds were pressed immediately after the 
Page 6 of 35

metam sodium application. Field 1 was 0.96 acres in size (treated acreage was 0.41 acre) and 

was treated with 299.5 lbs metam sodium per treated acre. The treated beds at field 1 were 

immediately covered with a virtually impermeable film (Blockade). Field 2 was 0.96 acres in 

size (treated acreage was 0.43 acre) and was treated with 306.3 lbs metam sodium per treated 

acre. The treated beds at field 2 were immediately covered with an LDPE film. Field 3 was 0.99 

acres in size (treated acreage was 0.45 acre) and was treated with 295.2 lbs metam sodium per 

treated acre. The treated beds at field 3 were immediately covered with an LDPE film.

All three fields were in close proximity and displayed comparable surface roughness conditions. 

On this basis, one centrally located field was selected to represent wind profiles within the 

treatment zones. Two 2 dimensional sonic anemometer profile wind systems were established at 

Field 2 with coverage at 0.3, 0.6, 0.9, 1.8, 2.4, and 3.0 m above ground level (for both wind 

sensors and thermocouples). In addition, a 3-dimensional (3D) sonic anemometer (installed at 

approximately 3.0 m above ground level) was established on the field after the application at 

field 2 to document 3-dimensional turbulence. The average temperature throughout the study 

ranged from 3.6-16.5 oC and wind speeds ranged from approximately calm conditions to 10 m/s.

Soil samples were collected at two points during the study; prior to application and following the 

completion of the study air sampling. Core samples were collected at five depths at a minimum 

of two locations across each field (0-15 cm, 15-30 cm, 30-46 cm, 46-61 cm, and 61-76 cm). The 

preapplication soil samples from each field were analyzed for texture, bulk density, organic 

matter, and soil moisture while the post-study samples were analyzed for soil moisture only. The 

soil at Fields 1 and 2 was classified as a loamy sand soil and the soil at Field 3 was classified as a 

sandy soil. The water content of the soil relative to field capacity was approximately 70% across 

the 0 to 9” depth. Soil organic content of the soil was 0.7% across the 0 to 12” depth. Soil 

temperature ranged between 10 (50°F) and 21oC (70°F) at the 6 to 9” depth throughout the study 

duration.

Off-site air sampling was conducted via eight samplers surrounding the field at 12 meters from 

the edge of the field. The intake height was approximately 1.5 m above ground level to 

approximate the human breathing zone. Off-site sampling was conducted prior to the on-field 

sampling and during the first period (i.e., during the application). ). On-site air samples were 

collected on sampling masts placed at the approximate center of each of the test fields shortly 

after the passage of the application rig. Air sampling tubes were placed at 0.3, 0.9, 1.8, and 3.0 

m above the field on the on-site air sampling masts. Off-cite sampling at each field was 

terminated approximately six hours after the start of the application. A total of 416 Charcoal and 

312 XAD-4 sorbent tubes were analyzed for the on-field sampling portion of the study. Field 

fortification samples were analyzed to ensure proper analysis of air concentration field samples 

in the study. All fortification sample recoveries were greater than (>) 90%, therefore no 

adjustment to air concentration sample analysis was necessary. 

Flux rates were calculated via on-field flux data except during the fumigant application where 

the primary method to compute flux rates was the back-calculation method. The flux profiles 

were calculated based on the field conditions including the application rates used to make the 

applications in the study. For the purposes of completing the PERFUM analyses, these flux 
Page 7 of 35

profiles were subsequently adjusted to the maximum application rate for metam sodium of 320 lb 

metam sodium per treated acre (see Tables 3 - 5).

Table 3. Flux Calculations for Field 1 (Bedded Shank InjectionBlockade VIF Tarp) at Tifton, GA (MRID 47820001)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study 

Reported Flux

(ug/m2-s) (ug/m2-s)

1

1

2/7/2009 16:30 - 21:30 5 1.006 0.940

2 2/7/2009 21:30 - 3:30 6 1.044 1.645

3 2/8/2009 3:30 - 9:30 6 3.132 3.822

4 2/8/2009 9:30 - 15:30 6 4.449 3.352

5 2/8/2009 15:30 - 21:30 6 1.096 1.899

6 2/8/2009 21:30 - 3:30 6 3.947 6.694

7 2/9/2009 3:30 - 9:30 6 10.975 9.290

8 2/9/2009 9:30 - 15:30 6 16.513 10.587

9 2/9/2009 15:30 - 0:30 9 0.414 1.287

10 2/10/2009 0:30 -12:30 12 11.267 4.601

11 2/10/2009 12:30 -0:30 12 2.624 4.338

12 2/11/2009 0:30 -12:30 12 7.097 4.762

13 2/11/2009 12:30 -0:30 12 1.145 1.266

14 2/12/2009 0:30 -12:30 12 2.937 5.098

15 2/12/2009 12:30 -0:30 12 1.934 3.173

16 2/13/2009 0:30 -12:30 12 1.234 0.594

17 2/13/2009 12:30 -0:30 12 1.088 1.104

18 2/14/2009 0:30 -12:30 12 1.453 1.439

19 2/14/2009 12:30 -0:30 12 1.045 1.299

20 2/15/2009 0:30 -12:30 12 1.386 2.258

21 2/15/2009 12:30 -0:30 12 0.652 0.823

22 2/16/2009 0:30 -12:30 12 1.476 0.775

23 2/16/2009 12:30 -0:30 12 0.084 0.157

24 2/17/2009 0:30 -12:30 12 0.469 0.153

25 2/17/2009 12:30 -0:30 12 0.050 0.086

26 2/18/2009 0:30 -12:30 12 0.908 0.500

27 2/18/2009 12:30 -0:30 12 0.268 0.229

28 2/19/2009 0:30 -6:30 6 1.047 1.257

29 2/19/2009 6:30 - 12:30 6 1.985 2.423

30 2/19/2009 12:30 - 0:30 12 0.130 0.179

31 2/20/2009 0:30 - 12:30 12 0.469 0.460

322

2/20/2009 12:30 - 0:30 12 0.027 0.030

1

 Indirect flux calculation method was used.

2

 Measurement at levels filtered, poor regression fit
Page 8 of 35

Table 4. Flux Calculations for Field 2 (Bedded Shank InjectionLDPE Film) at Tifton, GA (MRID 47820001)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study Reported 

Flux

(ug/m2-s) (ug/m2-s)

1

1

2/7/2009 18:30 -

22:30 5 39.632 40.700

2 2/7/2009 22:30 - 3:30 6 38.739 55.255

3 2/8/2009 3:30 - 9:30 6 35.184 43.213

4

2

2/8/2009 9:30 - 15:30 6 55.159 48.845

5 2/8/2009 15:30 - 21:30 6 10.591 19.291

6 2/8/2009 21:30 - 3:30 6 4.962 7.549

7 2/9/2009 3:30 - 9:30 6 3.772 3.001

8 2/9/2009 9:30 - 15:30 6 8.033 4.401

9 2/9/2009 15:30 - 0:30 9 2.936 9.305

10 2/10/2009 0:30 -12:30 12 5.110 2.029

11 2/10/2009 12:30 -0:30 12 2.385 3.993

12 2/11/2009 0:30 -12:30 12 5.980 3.806

13 2/11/2009 12:30 -0:30 12 0.519 0.636

14 2/12/2009 0:30 -12:30 12 1.187 1.842

15 2/12/2009 12:30 -0:30 12 0.876 1.342

16 2/13/2009 0:30 -12:30 12 1.154 0.555

17 2/13/2009 12:30 -0:30 12 0.408 0.416

18 2/14/2009 0:30 -12:30 12 0.461 0.432

19 2/14/2009 12:30 -0:30 12 0.182 0.241

20 2/15/2009 0:30 -12:30 12 0.212 0.295

21 2/15/2009 12:30 -0:30 12 0.160 0.187

22 2/16/2009 0:30 -12:30 12 0.212 0.108

23 2/16/2009 12:30 -0:30 12 0.136 0.245

24 2/17/2009 0:30 -12:30 12 0.113 0.038

25 2/17/2009 12:30 -0:30 12 0.057 0.094

26 2/18/2009 0:30 -12:30 12 0.260 0.132

27 2/18/2009 12:30 -0:30 12 0.147 0.031

28 2/19/2009 0:30 -6:30 6 0.071 0.029

29 2/19/2009 6:30 - 12:30 6 0.134 0.030

30 2/19/2009 12:30 - 0:30 12 0.173 0.031

31 2/20/2009 0:30 - 12:30 12 0.309 0.026

3232/20/2009 12:30 - 0:30 12 0.153 0.028

1

 Indirect flux calculation method was used.

2 Delta flux calculation method was used.

3 Measurement at levels filtered, poor regression fit
Page 9 of 35

Table 5. Flux Calculations for Field 3 (Bedded Shank InjectionLDPE Film) at Tifton, GA (MRID 47820001)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study Reported 

Flux

(ug/m2-s) (ug/m2-s)

1

1

2/7/2009 18:30 -

22:30 5 4.516 6.780

2

1

2/7/2009 22:30 - 3:30 6 8.562 6.780

3 2/8/2009 3:30 - 9:30 6 22.967 27.724

4 2/8/2009 9:30 - 15:30 6 32.866 24.092

5 2/8/2009 15:30 - 21:30 6 9.989 20.440

6

2

2/8/2009 21:30 - 3:30 6 1.851 1.968

7

2

2/9/2009 3:30 - 9:30 6 3.541 1.352

8

2

2/9/2009 9:30 - 15:30 6 13.366 7.461

9 2/9/2009 15:30 - 0:30 9 1.498 4.239

10 2/10/2009 0:30 -12:30 12 4.126 1.439

11 2/10/2009 12:30 -0:30 12 1.608 2.683

12 2/11/2009 0:30 -12:30 12 4.200 2.226

13 2/11/2009 12:30 -0:30 12 0.784 0.913

14 2/12/2009 0:30 -12:30 12 0.396 0.609

15 2/12/2009 12:30 -0:30 12 0.575 0.786

16 2/13/2009 0:30 -12:30 12 0.710 0.351

17 2/13/2009 12:30 -0:30 12 0.355 0.369

1822/14/2009 0:30 -12:30 12 0.755 0.682

19 2/14/2009 12:30 -0:30 12 0.074 0.100

20 2/15/2009 0:30 -12:30 12 0.146 0.211

21 2/15/2009 12:30 -0:30 12 0.109 0.128

22 2/16/2009 0:30 -12:30 12 0.386 0.188

23 2/16/2009 12:30 -0:30 12 0.110 0.217

2422/17/2009 0:30 -12:30 12 0.151 0.051

25 2/17/2009 12:30 -0:30 12 0.064 0.108

26 2/18/2009 0:30 -12:30 12 0.369 0.179

27 2/18/2009 12:30 -0:30 12 0.153 0.026

28 2/19/2009 0:30 -6:30 6 0.195 0.026

29 2/19/2009 6:30 - 12:30 6 0.205 0.216

30 2/19/2009 12:30 - 0:30 12 0.153 0.028

31 2/20/2009 0:30 - 12:30 12 0.042 0.027

3232/20/2009 12:30 - 0:30 12 0.025 0.028

 1

 Indirect flux calculation method was used.

2 Delta flux calculation method was used.

3 Measurement at levels filtered, poor regression fit
Page 10 of 35

MRID 47813901 Study - Monitoring 1,3-Dichloropropene, Chloropicrin, and Methyl 

Isothiocyanate Emissions from Shank Applications at Three Sites Near Duette, Florida 

(Sponsored by USDA, ARS Area-Wide Pest Management Program for Methyl Bromide 

Alternatives and Florida Specialty Crop Foundation)

In MRID 47813901, the study authors monitored for 1,3-dichloropropene, chloropicrin, and 

methyl isothiocyanate during three separate bedded shank injection applications. The test site for 

this study was located in Duette, Florida and the field work was conducted in January of 2009. 

At fields 1 and 2, chloropicrin was co-applied with 1,3-dichloropropene as a pre-bed application 

using 3 swept back shanks spaced 12 inches apart to deliver chloropicrin and 1,3-

dichloropropene to an 8 inch depth. Separate delivery lines were used to carry each fumigant 

from their respective cylinder to the shank. On a separate tractor metam potassium was applied 

into the pressed bed at a 4 inch depth via a 12 inch culture spaced 4 inches apart. The beds were 

then immediately pressed following the metam potassium application. The application at field 3 

did not include 1,3-dichloropropene. Field 1 was approximately 1 acre in size (treated acreage 

was 0.357 acre) and was treated with 311.0 lbs metam potassium per treated acre. The treated 

beds at field 1 were immediately covered with a metalized plastic film (Canslit, 1.25 mil). Field

2 was approximately 1 acre in size (treated acreage was 0.357 acre) and was treated with 300.1 

lbs metam potassium per treated acre. The treated beds at field 2 were immediately covered with 

a virtually impermeable plastic film (Guardian, Olefinas, 1.2 mil). Field 3 was approximately 1

acre in size (treated acreage was 0.357 acre) and was treated with 305.8 lbs metam potassium per 

treated acre. The treated beds at field 3 were immediately covered with a metalized plastic film 

(Canslit, 1.25 mil).

All three fields were in close proximity and displayed comparable surface roughness conditions. 

On this basis, one centrally located field was selected to represent wind profiles within the 

treatment zones. Two 2 dimensional sonic anemometer profile wind systems were established at 

Field 2 with coverage at 0.3, 0.9, 1.8, and 3.0 m above ground level (for both wind sensors and 

thermocouples). In addition, a 3-dimensional (3D) sonic anemometer (installed at approximately 

3.0 m above ground level) was established on the field after the application at field 2 to 

document 3-dimensional turbulence. The average temperature throughout the study ranged from 

3.6-16.5 oC and wind speeds ranged from approximately calm conditions to 9 m/s.

Soil samples were collected at two points during the study; prior to application and following the 

completion of the study air sampling. Core samples were collected at five depths at a minimum 

of two locations across each field (0-15 cm, 15-30 cm, 30-46 cm, 46-61 cm, and 61-76 cm). The 

preapplication soil samples from each field were analyzed for texture, bulk density, organic 

matter, and soil moisture while the post-study samples were analyzed for soil moisture only. The 

water content of the soil relative to field capacity was 245% at Field 1, 207% at Field 2, and 

228% at Field 3 across the 0 to 6” depth. Soil organic content of the soil was 0.94% at Field 1, 

1.38% at Field 2, and 1.26% at Field 3 across the 0 to 6” depth. Soil temperature ranged 

between 7 and 22oC at the 6 to 9” depth throughout the study duration.

Off-site air sampling was conducted via eight samplers surrounding the field at 12 meters from 

the edge of the field. The intake height was approximately 1.5 m above ground level to 

approximate the human breathing zone. Off-site sampling was conducted prior to the on-field 
Page 11 of 35

sampling and during the first period (i.e., during the application). On-site air samples were 

collected on sampling masts placed at the approximate center of each of the test fields shortly 

after the passage of the application rig. Air sampling tubes were placed at 0.3, 0.9, 1.8, and 3.0 

m above the field on the on-site air sampling masts. A total of 342 Charcoal and 342 XAD-4 

sorbent tubes were analyzed for the study. Field fortification samples were analyzed to ensure 

proper analysis of air concentration field samples in the study. Field recovery analysis was 

conducted and subsequent adjustments were made to the air concentration analysis as 

appropriate. 

Flux rates were calculated via on-field flux data except during the fumigant application where 

the primary method to compute flux rates was the back-calculation method. The flux profiles 

were calculated based on the field conditions including the application rates used to make the 

applications in the study. For the purposes of completing the PERFUM analyses, these flux 

profiles were subsequently adjusted to the maximum application rate for metam potassium of 

320 lb metam potassium per treated acre (see Tables 6-8).

Table 6. Flux Calculations for Field 1 (Bedded Shank Injection-Canslit 

Metalized Film) at Duette, FL (MRID 47813901)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study Reported 

Flux

(ug/m2-s) (ug/m2-s)

1

1

1/14/2009 9:30 - 15:30 6 0.870 0.950

2 1/14/2009 15:30 - 21:30 6 0.732 0.534

3 1/14/2009 21:30 - 3:30 6 0.448 0.372

4 1/15/2009 3:30 - 9:30 6 0.381 0.319

5 1/15/2009 9:30 - 15:30 6 0.563 0.334

6 1/15/2009 15:30 - 21:30 6 0.636 0.688

7 1/15/2009 21:30 - 3:30 6 0.483 0.357

8 1/16/2009 3:30 - 13:30 10 0.548 0.350

9 1/16/2009 13:30 - 1:30 12 0.558 0.603

10 1/17/2009 1:30 - 13:30 12 0.434 0.284

11 1/17/2009 13:30 - 1:30 12 0.370 0.579

12 1/18/2009 1:30 - 13:30 12 0.933 0.458

13 1/18/2009 13:30 - 1:30 12 2.068 1.436

14 1/19/2009 1:30 - 13:30 12 1.242 0.942

15 1/19/2009 13:30 - 1:30 12 2.219 1.415

16 1/20/2009 1:30 - 13:30 12 1.037 0.862

17 1/20/2009 13:30 - 1:30 12 0.283 0.309

18 1/21/2009 1:30 - 13:30 12 0.257 0.194

19 1/21/2009 13:30 - 1:30 12 0.118 0.175

202

1/22/2009 1:30 - 13:30 12 0.276 0.359

21 1/22/2009 13:30 - 1:30 12 0.433 0.536

223

1/23/2009 1:30 - 13:30 12 3.827 0.562

 1

 ISCST3 flux calculation method was used.

2 Calculated as per registrant as average of flux from period before and period after

3 Registrant used flux value from previous period due to poor regression fit
Page 12 of 35

Table 7. Flux Calculations for Field 2 (Bedded Shank InjectionGaurdian, Oledfinas Film) at Duette, FL (MRID 47813901)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux Study Reported Flux

(ug/m2-s) (ug/m2-s)

1

1

1/14/2009 9:30 - 15:30 6 4.670 3.630

2

2

1/14/2009 15:30 - 21:30 6 10.432 2.102

3 1/14/2009 21:30 - 3:30 6 1.720 1.603

4 1/15/2009 3:30 - 9:30 6 1.182 1.157

5 1/15/2009 9:30 - 15:30 6 2.464 1.544

6 1/15/2009 15:30 - 21:30 6 1.816 2.371

7 1/15/2009 21:30 - 3:30 6 1.117 0.881

8 1/16/2009 3:30 - 13:30 10 1.191 0.759

9 1/16/2009 13:30 - 1:30 12 1.276 1.640

10 1/17/2009 1:30 - 13:30 12 0.973 0.667

11 1/17/2009 13:30 - 1:30 12 1.280 2.119

12 1/18/2009 1:30 - 13:30 12 2.199 1.139

13 1/18/2009 13:30 - 1:30 12 4.275 3.625

14 1/19/2009 1:30 - 13:30 12 2.564 2.015

15 1/19/2009 13:30 - 1:30 12 10.119 6.247

16 1/20/2009 1:30 - 13:30 12 1.032 0.782

17 1/20/2009 13:30 - 1:30 12 0.575 0.658

18 1/21/2009 1:30 - 13:30 12 0.339 0.262

19 1/21/2009 13:30 - 1:30 12 0.187 0.292

2031/22/2009 1:30 - 13:30 12 0.187 0.302

2131/22/2009 13:30 - 1:30 12 0.187 0.302

2231/23/2009 1:30 - 13:30 12 0.187 0.292

 1

 ISCST3 flux calculation method was used.

2 Calculated as per registrant as average of flux from period before and period after

3 Registrant used flux value from previous period due to poor regression fit
Page 13 of 35

Table 8. Flux Calculations for Field 3 (Bedded Shank Injection-Canslit 

Metalized Film) at Duette, FL (MRID 47813901)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux Study Reported Flux

(ug/m2-s) (ug/m2-s)

1

1

1/14/2009 9:30 - 15:30 6 15.130 7.190

2

2

1/14/2009 15:30 - 21:30 6 8.890 1.563

3 1/14/2009 21:30 - 3:30 6 2.650 1.725

4 1/15/2009 3:30 - 9:30 6 0.528 0.484

5 1/15/2009 9:30 - 15:30 6 0.655 0.430

6 1/15/2009 15:30 - 21:30 6 0.678 0.819

7 1/15/2009 21:30 - 3:30 6 0.507 0.442

8 1/16/2009 3:30 - 13:30 10 0.333 0.267

9

2

1/16/2009 13:30 - 1:30 12 0.273 0.227

10 1/17/2009 1:30 - 13:30 12 0.213 0.176

11 1/17/2009 13:30 - 1:30 12 0.303 0.583

12 1/18/2009 1:30 - 13:30 12 0.820 0.425

1321/18/2009 13:30 - 1:30 12 0.665 0.436

14 1/19/2009 1:30 - 13:30 12 0.510 0.471

15 1/19/2009 13:30 - 1:30 12 6.233 1.472

1621/20/2009 1:30 - 13:30 12 3.207 0.837

17 1/20/2009 13:30 - 1:30 12 0.181 0.201

18 1/21/2009 1:30 - 13:30 12 0.114 0.127

19 1/21/2009 13:30 - 1:30 12 0.060 0.112

2021/22/2009 1:30 - 13:30 12 0.076 0.123

21 1/22/2009 13:30 - 1:30 12 0.091 0.141

2231/23/2009 1:30 - 13:30 12 0.091 0.139

 1

 ISCST3 flux calculation method was used.

2 Calculated as per registrant as average of flux from period before and period after

3 Registrant used flux value from previous period due to poor regression fit

MRID 48011601 Study- Monitoring of Metam Sodium Airborne Flux for Shank Injection for 

Cultural Practice Applicable to Wisconsin (Sponsored by the Wisconsin Potato & Vegetable 

Growers Association, Inc) 

In MRID 48011601, the study authors monitored for methyl isothiocyanate in fields 1 and 3

during a broadcast shank injection application of metam sodium. In field 2, chloropicrin was 

monitored during a bedded untarped shank injection application.’

The test site for this study was located in Coloma, Wisconsin and the field work was conducted 

in September of 2009. Metam sodium was applied via shank injection at a depth of 5.5 and 9.5

inches. The treated field was meant to receive a 0.25 inch water seal about 6 hours after 

application but a precipitation event occurred resulting in only 0.10 inches of water being applied 

to the field. The two metam sodium applications were sealed mechanically because they were 

broadcast applications. Field 1 was approximately 1 acre in size and was treated with 287.0 lbs 
Page 14 of 35

metam sodium per treated acre. Field 3 was approximately 1 acre in size and was treated with 

270.1 lbs metam sodium per treated acre.

The three fields in this study were all located in the general vicinity with two of the fields being 

part of a common field (Field 1-metam sodium and Field 2-chloropicrin). Field 3 (metam 

sodium) was located approximately 4 miles to the southeast of Fields 1 and 2. Wind speed 

profile data were collected at all three fields to account for potential wind flow differences 

between the geographic locations of all three fields and to account for surface roughness 

differences between the bedded field (Field 2) and the broadcast flat applications on Fields 1 and 

3. This was accomplished by placing 2D sonic anemometer profiles with wind monitoring at 

three levels near the center of Field 2 and Field 3. On Field 1, 3D sonic anemometers were 

placed near the center of the field, with supplementary data available at a third level at a location 

in close proximity to this flat broadcast treatment plot. The temperature throughout the study 

ranged from 6-25 oC and wind speeds ranged from approximately calm conditions to 11 m/s.

Soil samples were collected several days prior to application and following completion of the 

application. Core samples were collected at two depths (0-15 cm and 15-30 cm). The 

preapplication soil samples from each field were analyzed for texture, bulk density, organic 

matter, and soil moisture while the post-application samples were analyzed for soil moisture 

only. The water content of the soil relative to field capacity was approximated to be between 75-

80% at Field 1, 50-55% at Field 2, and 75-80% at Field 3 across the 0 to 6” depth. Soil organic 

content of the soil was 0.7% at Field 1, 0.7% at Field 2, and 1.3% at Field 3 across the 0 to 6” 

depth. Soil temperature ranged between 7 and 24oC at the 3” depth throughout the study 

duration.

Off-site air sampling was conducted via eight samplers surrounding the field at 12 meters from 

the edge of the field. The intake height was approximately 1.5 m above ground level to 

approximate the human breathing zone. Off-site sampling was conducted prior to the on-field 

sampling and terminated approximately 6 hours after the start of application. On-site air samples 

were collected on sampling masts placed at the approximate center of each of the test fields 

shortly after the passage of the application rig. Air sampling tubes were placed at 0.3, 0.9, 1.8, 

and 3.0 m above the field on the on-site air sampling masts. A total of 163 Charcoal and 95 

XAD-4 sorbent tubes were analyzed for the study. Background samples indicated that no crosscontamination occurred during the monitoring. Analytical recovery values were acceptable (i.e., 

> 90%) and no corrections to measured residue values were warranted. Field fortification 

samples were analyzed to ensure proper analysis of air concentration field samples in the study. 

Field recovery analysis was conducted and subsequent adjustments were made to the air 

concentration analysis as appropriate. 

Flux rates were calculated via on-field flux data except during the fumigant application where 

the primary method to compute flux rates was the back-calculation method. The flux profiles 

were calculated based on the field conditions including the application rates used to make the 

applications in the study. For the purposes of completing the PERFUM analyses, these flux 

profiles were subsequently adjusted to the maximum application rate for metam sodium of 320 lb 

metam sodium per treated acre (see Tables 9-10).
Page 15 of 35

Table 9. Flux Calculations for Field 1 (BroadcastShank Injection-Water 

Seal 0.10 inch) at Coloma, WI (MRID 48011601)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study Reported 

Flux

(ug/m2-s) (ug/m2-s)

1

1

9/25/2009 10:30-11:30 1 1.650 1.648

2 9/25/2009 11:30 - 15:30 4 0.906 0.862

3

2

9/25/2009 15:30 - 19:30 4 0.788 0.631

4

2

9/25/2009 19:30 - 23:30 4 1.435 1.345

5 9/25/2009 23:30 - 03:30 4 2.782 2.632

6 9/26/2009 03:30 - 07:30 4 4.628 3.202

7 9/26/2009 07:30 - 11:30 4 5.743 5.174

8 9/26/2009 11:30 - 15:30 4 9.493 8.684

9 9/26/2009 15:30 - 19:30 4 10.857 9.755

10 9/26/2009 19:30 - 23:30 4 8.745 8.028

1139/26/2009 23:30 - 03:30 4 8.388 7.595

12 9/27/2009 03:30 - 07:30 4 5.818 5.277

13 9/27/2009 7:30 - 19:30 12 9.220 8.246

14 9/27/2009 19:30 - 7:30 12 2.156 2.035

15 9/28/2009 7:30 - 19:30 12 1.637 1.573

16 9/28/2009 19:30 - 7:30 12 0.914 0.859

 1

 ISCST3 flux calculation method was used.

2 Slope, intercept and R squared values for concentration calculated from 3 values only due 

to poor regression fit

3 Slope, intercept and R squared values for concentration calculated from 3 values only due 

to missing data
Page 16 of 35

Table 10. Flux Calculations for Field 3 (BroadcastShank InjectionWater Seal 0.10 inch) at Coloma, WI (MRID 48011601)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study Reported 

Flux

(ug/m2-s) (ug/m2-s)

1

1

9/25/2009 10:30-11:30 1 5.930 5.530

2 9/25/2009 11:30 - 15:30 4 1.554 1.492

3

2,3 9/25/2009 15:30 - 19:30 4 2.829 2.227

4 9/25/2009 19:30 - 23:30 4 4.105 3.047

5 9/26/2009 23:30 - 03:30 4 6.107 5.992

6 9/26/2009 03:30 - 07:30 4 4.901 4.395

7 9/26/2009 07:30 - 11:30 4 7.975 7.021

8 9/26/2009 11:30 - 15:30 4 11.684 10.338

9 9/26/2009 15:30 - 19:30 4 9.725 8.676

10 9/26/2009 19:30 - 23:30 4 9.833 10.245

11 9/27/2009 23:30 - 03:30 4 10.476 10.680

12 9/27/2009 03:30 - 07:30 4 7.980 7.479

13 9/27/2009 7:30 - 19:30 12 11.133 10.146

14 9/27/2009 19:30 - 7:30 12 3.351 3.073

15 9/28/2009 7:30 - 19:30 12 2.387 2.204

16 9/28/2009 19:30 - 7:30 12 1.337 1.306

1

 ISCST3 flux calculation method was used.

2 Slope, Intercept and R squared values calculated only for 3 heights as the raw data for 

the uppermost height is missing due to low pressure event at site

3 Calculated as of flux from period before and period after (Interpolation) due to poor 

regression fit

MRID 48005901 Study - Monitoring of Metam Sodium Airborne Flux from Shank 

Injection/Compaction Based on Cultural Practice Applicable to Michigan

In MRID 48005901, the study authors monitored for methyl isothiocyanate from two different 

treatments of metam sodium. Both applications were conducted as untarped broadcast shank 

injection and compaction on October 28, 2009. The two test sites were located in the general 

vicinity of Howard City, Michigan. The sites received concurrent air and soil monitoring to 

maintain similar meteorological and soil conditions. Both fields were applied metam sodium at 

12 inch depth. Field 1 was 0.96 acres and applied at a rate of 318.2 lbs per treated acre. Field 2 

was 0.95 acres with 321.1 lbs per acre applied followed by a 0.33 inch water seal. Both fields 

were disked prior to application to obtain the appropriate field moisture. 

Wind speed profile data were collected on both fields in order to account for potential wind flow 

differences between Fields 1 and 2. 2D sonic anemometer profiles with wind monitoring at three 

levels were placed near the center of each field. On Field 1, 3D sonic anemometers were placed near 

the center of the each field as well to provide backup low-threshold wind monitoring level for each 

field. A standard electronic weather station also was established adjacent to Field 1 to record 

precipitation, solar radiation, relative humidity, wind direction and wind speed. Average maximum 
Page 17 of 35

temperature during the study was ~8°C and average minimum temperatures during the study was 

~13°C.

Soil samples were collected at the test sites. The soil type was characterized as loamy sand and 

sand. Samples were collected several days prior to application for gravimetric analysis and soil 

texture analysis in the range of 0-6 in and 6-12 in. Each soil sample consisted of approximately 

0.5 kg (1.102 pounds) of soil. The soil samples collected for soil texture analysis from each field 

and depth were analyzed for texture, bulk density, organic matter, pH, percent sand, percent silt, 

and percent clay. Organic matter was measured at 1.1- 1.6% and 0.5- 1.3% for field 1 and field 2, 

respectively. Within approximately one hour of each application, soil samples within the layer of 

0-6 in were collected for final gravimetric analysis. Percent field capacity of both fields were 

measured to be within acceptable ranges (60 – 80%) and soil temperature ranged from 4 to 15°C 

(average of 10 °C). 

Off-site air sampling was conducted via eight samplers surrounding each field at 25 meters from 

the edge and corners of the field. The intake height was approximately 1.5 m above ground level 

to approximate the human breathing zone. Off-site sampling was conducted prior to the on-field 

sampling and during the first period (i.e., during the application). On-site air samples were 

collected on sampling masts placed at the approximate center of each of the test fields shortly 

after the passage of the application rig. Air sampling tubes were placed at 1, 3, 6, and 10 feet 

(approximately 0.3, 0.9, 1.8, and 3.0 meters) above the field on the on-site air sampling masts. A 

total of 169 Charcoal sorbent tubes were analyzed for the study. Field fortification samples were 

analyzed to ensure proper analysis of air concentration field samples in the study. All 

fortification sample recoveries were greater than (>) 90%, therefore no adjustment to air 

concentration sample analysis was necessary. 

Flux rates were calculated via on-field flux data except during the fumigant application where 

the primary method to compute flux rates was the back-calculation method. The flux profiles 

were calculated based on the field conditions including the application rates used to make the 

applications in the study. For the purposes of completing the PERFUM analyses, these flux 

profiles were subsequently adjusted to the maximum application rate for metam sodium of 320 lb 

metam sodium per treated acre (see Tables 11-12).
Page 18 of 35

Table 11. Flux Calculations for Field 1 (BroadcastShank Injection and 

Compaction) at Howard City, MI (MRID 48005901)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study Reported 

Flux

(ug/m2-s) (ug/m2-s)

1

1

10/28/2009 17:00 - 21:00 4 0.205 0.340

2 10/28/2009 21:00 - 1:00 4 0.237 0.167

3 10/29/2009 1:00 - 5:00 4 0.167 0.118

4 10/29/2009 5:00 - 9:00 4 0.285 0.250

5 10/29/2009 9:00 - 13:00 4 0.486 0.445

6 10/29/2009 13:00 - 17:00 4 1.542 1.111

7 10/29/2009 17:00 - 21:00 4 1.487 1.516

8 10/29/2009 21:00 - 1:00 4 1.692 1.753

9 10/30/2009 1:00 - 5:00 4 3.181 2.788

10 10/30/2009 5:00 - 13:00 8 0.348 0.349

11 10/30/2009 13:00 - 17:00 4 0.000 0.004

12 10/30/2009 17:00 - 1:00 8 0.000 0.000

13210/31/2009 1:00 - 13:00 12 0.085 0.003

14 10/31/2009 13:00 - 1:00 12 0.006 0.002

15 11/1/2009 1:00 - 13:00 12 0.003 0.008

16 11/1/2009 13:00 - 19:00 6 0.000 0.000

1

ISCST3 flux calculation method was used.

2 Use Field 2 wind speed
Page 19 of 35

Table 12. Flux Calculations for Field 2 (BroadcastShank Injection and 

Compaction- 0.33 inch water seal) at Howard City, MI (MRID 

48005901)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux Study Reported Flux

(ug/m2-s) (ug/m2-s)

1

1

10/28/2009 17:00 - 21:00 4 0.180 0.180

2

2

10/28/2009 21:00 - 1:00 4 0.022 0.021

3

2

10/29/2009 1:00 - 5:00 4 0.011 0.028

4

2

10/29/2009 5:00 - 9:00 4 0.332 0.036

5

2,3 10/29/2009 9:00 - 13:00 4 0.010 0.020

6

4

10/29/2009 13:00 - 17:00 4 0.097 0.200

7 10/29/2009 17:00 - 21:00 4 0.126 0.133

8 10/29/2009 21:00 - 1:00 4 0.193 0.202

9 10/30/2009 1:00 - 5:00 4 0.274 0.250

10510/30/2009 5:00 - 13:00 8 -0.012 0.006

11210/30/2009 13:00 - 17:00 4 0.000 0.000

12210/30/2009 17:00 - 1:00 8 0.000 0.000

13210/31/2009 1:00 - 13:00 12 0.002 0.005

14510/31/2009 13:00 - 1:00 12 0.014 0.003

15 11/1/2009 1:00 - 13:00 12 0.000 0.001

16 11/1/2009 13:00 - 19:00 6 0.000 0.000

1

ISCST3 flux calculation method was used.

2

Slope, Intercept and R squared values for concentration calculated only for 3 heights due 

to poor regression (based on registrants).

3 Use Field 1 wind speed data

4

Slope, Intercept and R squared values for concentration calculated only for 3 heights due 

to poor regression (registrants used 4 heights).

5

Slope, Intercept and R squared values for concentration calculated only for 3 heights due 

to poor regression (registrants used only 2 heights).

MRID 48115101 Study - Monitoring of Metam Sodium Airborne Flux from Shank 

Injection/Compaction Based on Cultural Practice Applicable to Washington State

In MRID 48115101, the study authors monitored for methyl isothiocyanate during a metam 

sodium application at AgriNorthwest near Kennewick, WA. The study was conducted during 

the week of March 21, 2010. Two fields were applied metam sodium via shank injection and 

compaction however field 2 was also applied a 0.25 inch water seal. The water seal was started

6 hours after the completion of the application to represent the lag time that occurs as a result of 

a center-pivot applied water seal. Field 1 was 1.10 acres in size and was treated with 317 lbs 

metam sodium per treated acre. Field 2 was 0.87 acre in size and was treated with 368 lbs

metam sodium per treated acre. 

Wind speed profile data were collected on both fields to account for potential wind flow

differences between Fields 1 and 2. Two-dimensional wind sonic anemometer profiles
Page 20 of 35

were established approximately at the center of each field. In addition, 3D sonic anemometers 

and an electronic weather station (ET-106) were established adjacent to Field 1. The sensor 

heights for the meteorological equipment were set to 0.5, 0.9, 1.8, and 3.0 meters. The 

maximum and minimum air temperature measured during the day was 17°C and 0°C, 

respectively and wind speeds ranged from approximately calm conditions to 13 m/s.

Soil samples were collected in triplicate on March 10, 2010 from 0-6” and 6-12” ranges. Soil 

characterization results demonstrated that both of the fields were uniform across 0 – 12”. 

Percent organic matter in field 1 ranged from 1.55- 1.99% and field 2 ranged from 1.05 – 1.43%. 

Field capacity measured indicated that by March 24, 2010, both fields maintained a field 

capacity with a range of 70 to 80%. Soil temperature ranged between 4 and 14oC at the 3 to 9” 

depth throughout the study duration.

Off-field air monitoring stations were established in eight directions around each field at 

approximately 25 m (+/- .5 m) from the edge of the fields at 0, 45, 90, 135, 180, 225, 270, and 

315 degrees from the center point of the field. The north and south off field monitoring stations 

were established at 35 m from the edge of the field to accommodate for the turning radius of the 

application rig. The intake heights were set to approximately 1.5 m above ground level. Off-site

monitoring was conducted prior to the on-field sampling stations coming on-line following the 

application. A total of 128 Charcoal sorbent tubes were analyzed for the study.

Flux rates were calculated via on-field flux data except during the fumigant application where 

the primary method to compute flux rates was the back-calculation method. The flux profiles 

were calculated based on the field conditions including the application rates used to make the 

applications in the study. For the purposes of completing the PERFUM analyses, these flux 

profiles were subsequently adjusted to the maximum application rate for metam sodium of 320 lb 

metam sodium per treated acre (see Tables 13-14).
Page 21 of 35

Table 13. Flux Calculations for Field 1 (Broadcast Shank Injection and 

Compaction) at Kennewick, WA (MRID 48115101)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux

Study Reported 

Flux

(ug/m2-s) (ug/m2-s)

1

1

3/24/2010 0930 - 1200 2.5 4.776 4.590

2 3/24/2010 1200 -1600 4 2.549 2.219

3 3/24/2010 1600 - 1900 3 2.409 2.096

4 3/24/2010 1900 - 2330 4.5 2.791 2.432

5 3/24/2010 2330 - 0330 4 4.172 3.639

6 3/25/2010 0330 - 0730 4 2.010 1.727

7 3/25/2010 0730 - 1100 3.5 4.776 4.266

8 3/25/2010 1100 - 1500 4 7.253 6.229

9 3/25/2010 1500 -1930 4.5 6.695 5.953

10 3/25/2010 1930 - 2300 3.5 5.046 4.411

11 3/25/2010 2300 - 0300 4 6.656 5.818

12 3/26/2010 0300 - 0700 4 6.012 5.295

13 3/26/2010 0700 - 1900 12 8.195 7.073

14 3/26/2010 1900 - 0700 12 2.187 1.945

15 3/27/2010 0700 - 1900 12 5.832 4.930

16 3/27/2010 1900 - 0700 12 4.563 4.043

1

Since there are fewer than three pairs of measured and modeled values greater than 0.1 

micrograms/cubic meter for both terms, the emission rate for the period in question is 

defaulted by weighted interpolation or conservative diurnal matching. Hence, using the most 

conservative approach, the flux values for this period is used from Period 7 (diurnal 

matching)
Page 22 of 35

Table 14. Flux Calculations for Field 2 (Broadcast Shank Injection and 

Compaction- 0.25 inch water seal) at Kennewick, WA (MRID 48115101)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux Study Reported Flux

(ug/m2-s) (ug/m2-s)

1

1

3/24/2010 0830 - 1200 3.5 0.527 1.710

2

2

3/24/2010 1200 -1500 3 0.527 0.401

3 3/24/2010 1500 -1930 4.5 0.173 0.176

4 3/24/2010 1930 - 00:00 4.5 0.120 0.123

5 3/25/2010 0000 - 0400 4 0.183 0.175

6 3/25/2010 0400 - 0730 3.5 0.267 0.255

7 3/25/2010 0730 - 1100 3.5 0.308 0.269

8 3/25/2010 1100 - 1530 4.5 0.387 0.336

9 3/25/2010 1530 -1930 4 0.297 0.258

10 3/25/2010 1930 - 2330 4 0.153 0.133

11 3/25/2010 2330 - 0330 4 0.213 0.186

12 3/26/2010 0330 - 0700 3.5 0.167 0.146

13 3/26/2010 0700 - 1900 12 0.223 0.197

1423/26/2010 1900 - 0730 12.5 0.237 0.143

15 3/27/2010 0730 - 1900 11.5 0.256 0.271

1623/27/2010 1900 – 0700 11.5 0.788 0.170

1

Since there are fewer than three pairs of measured and modeled values greater than 0.1 

micrograms/cubic meter for both terms, the emission rate for the period in question is 

defaulted by weighted interpolation or conservative diurnal matching. Hence, using the most 

conservative approach, the flux values for this period is used from Period 2

2

 Slope, Intercept and R squared values calculated only for 3 heights due to removal of 

outlier

MRID 47956901 Study - A Trial to Evaluate Concentrations and Emission Rates from the 

Application of Metam Sodium by Shank Injection/Compaction on a Daytime and Nighttime Basis

In MRID 47813901, the study authors monitored for methyl isothiocyanate following an 

application of metam sodium by shank injection and compaction on a daytime and nighttime 

basis. The test site was an agricultural field in San Joaquin Valley of California. The shank 

injection and compaction application were unbedded and conducted on a bare ground field in 

good seedbed condition within designated 2.4 acre each subplots. A water seal at the rate of 0.53 

cm per hour followed the application. A second water seal was applied over a two hour period at 

a rate of 0.53 cm per hour from approximately 20:00 to 22:00 after the completion of each 

application and starting before the first sunset. The metam sodium application was conducted at 

the maximum label rate (75 gallons per acre) which is higher than the typical rate for each 2.4 

acre area. The daytime application (field 1) was conducted from 06:00 to 07:45 and the nighttime 

application (field 2) was applied from 00:20 to 01:35. Field 2 was treated approximately 42 

hours after field 1. The fields were 1.5 km from each other in a west to east orientation. The 

plots were typical of commercial agricultural fields in San Joaquin Valley. 
Page 23 of 35

On-field air sampling was conducted on each of the two fields with sample intakes heights 

established at approximately 0.30, 0.60, 0.9, 1.8, and 3.0 meters above the soil surface. Each 

profile sampling mast was centrally located. Off-field sampling was carried out only during the 

application and water sealing periods at the nighttime application (field 2) and throughout the 

study for the daytime application. Meteorological monitoring was conducted with a 2D sonic 

anemometer profile system established on field 1 to monitor wind speed, wind direction, and 

ambient temperature at 0.5, 0.9, 1.4, 1.8, 2.4, and 3.0 meters above the treated surface. The onfield meteorological profile systems were established approximately 5 meters downwind of the 

concentration profile mast. A standard cup and vane system was established adjacent to field 2. 

Based on flat terrain and near proximity of the two fields, comparable wind speed profiles were 

expected for the two fields. 

Six soil samples were obtained form both fields. Each sample was a composite of three subsamples collected randomly for percent sand, silt, clay, organic matter, and pH. Soil cores were 

taken from the same depths to compute field capacity and bulk density subsequent to the 

compaction. Soil temperature ranged between 15 and 43oC at the 0 to 11” depth throughout the 

study duration. Soil temperature and moisture sensors connected to data loggers were buried at 

depths of approximately 8, 15, 23, and 30 cm in each field. Soil moisture in the upper 15 cm 

during the metam application was 72.5% and 53.7% field capacity or field 1 and 2, respectively. 

Field 2 also had lower soil water content. The second water treatment was applied after three 

periods in field 1 and four periods in field 2. 

MITC samples were collected by charcoal sampling tubes. A total of 12 off-field air sampling 

stations were established 20, 40, or 60 meters from the edge of field 1 and 8 were established 

around field 2. Sampling intake height for the ambient samplers were positioned approximately 

1.5 meters above the soil surface. There were in total 289 on-field samples analyzed and 388 

off-field samples. 

Flux rates were calculated via on-field flux data except during the fumigant application where 

the primary method to compute flux rates was the back-calculation method. The flux profiles 

were calculated based on the field conditions including the application rates used to make the 

applications in the study. For the purposes of completing the PERFUM analyses, these flux 

profiles were subsequently adjusted to the maximum application rate for metam sodium of 320 lb 

metam sodium per treated acre (see Tables 15-16).
Page 24 of 35

Table 15. Flux Calculations for Field 1 (Broadcast Shank Injection and 

Compaction) at San Joaquin Valley, CA (MRID 47956901)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. Flux Study Reported Flux

(ug/m2-s) (ug/m2-s)

1 1,3 7/31/2008 9:30 - 11:30 2 6.190 4.380

2 7/31/2008 11:30 - 15:30 4 2.410 2.428

3 7/31/2008 15:30 - 19:30 4 4.543 4.452

4 2,3 7/31/2008 19:30 - 23:30 4 0.350 0.370

5 7/31/2008 23:30 - 3:30 4 0.589 0.607

6 8/1/2008 3:30 - 7:30 4 0.259 0.268

7 8/1/2008 7:30 - 11:30 4 0.198 0.209

8 8/1/2008 11:30 - 15:30 4 0.360 0.369

9 8/1/2008 15:30 - 19:30 4 0.334 0.342

10 48/1/2008 19:30 - 23:30 4 0.053 0.149

11 8/1/2008 23:30 - 3:30 4 0.278 0.266

12 58/2/2008 3:30 - 7:00 3.5 0.288 0.279

13 48/2/2008 7:00 - 11:30 4.5 0.059 0.291

14 68/2/2008 11:30 - 15:30 4 0.058 0.050

15 8/2/2008 15:30 - 18:30 3 0.093 0.087

16 48/2/2008 18:30 - 23:30 5 0.037 0.050

17 8/2/2008 23:30 - 3:30 4 0.092 0.102

18 48/3/2008 3:30 - 7:30 4 0.077 0.412

19 48/3/2008 7:30 - 11:30 4 0.702 0.197

20 68/3/2008 11:30 - 15:00 3.5 0.063 0.083

21 68/3/2008 15:00 - 19:30 4.5 0.052 0.066

22 68/3/2008 19:30 - 23:30 4 0.031 0.043

23 48/3/2008 23:30 - 3:30 4 0.189 0.322

24 48/4/2008 3:30 - 7:30 4 0.161 0.111

25 68/4/2008 7:30 - 19:00 11.5 0.016 0.022

26 68/4/2008 19:00 - 23:00 4 0.021 0.034

27 68/4/2008 23:00 - 7:30 8.5 0.090 0.114

28 68/5/2008 7:30 - 19:00 11.5 0.021 0.028

29 68/5/2008 19:00 - 23:30 4.5 0.027 0.034

30 48/5/2008 23:30 - 7:30 8 0.232 0.103

31 68/6/2008 7:30 - 19:00 11.5 0.027 0.034

1 No samples collected, application period

2 No samples collected, irrigation period

3

Flux calculated using ISCST3 Modeling

4

Slope, intercept and R squared values for concentration calculated from 3 values only due to 

poor regression fit

5 Calculated as average of flux (Delta method) value of Period 11 & 13 due to off-field 

application contamination

6 Delta method used due to poor regression fit (Refer to Field 1 Delta worksheet for 

calculation details)
Page 25 of 35

Table 16. Flux Calculations for Field 2 (Broadcast Shank Injection and 

Compaction) at San Joaquin Valley, CA (MRID 47956901)

Period 

No. Sample Interval Times

Duration 

(Hrs.)

EPA Est. 

Flux Study Reported Flux

(ug/m2-s) (ug/m2-s)

1 - 10

No samples collected as these correspond to periods 1-10 of the application 

performed in field 1 which were prior to application of field 2.

111,3 8/2/2008 1:00 - 5:00 4 2.36 2.4

12 58/2/2008 5:00 - 7:00 3 39.982812 34.278326

13 8/2/2008 7:00 - 12:00 5 4.9751087 4.8418855

14 8/2/2008 12:00 - 16:00 4 16.814398 16.778182

15 8/2/2008 16:00 - 19:00 3 23.886099 22.910119

16 2,3 8/2/2008 19:00 - 22:30 3.5 2.07 2.7

17 48/2/2008 22:30 - 4:00 5.5 0.580 1.412

18 8/3/2008 4:00 - 8:00 4 2.575 2.738

19 8/3/2008 8:00 - 12:00 4 4.902 4.428

20 58/3/2008 12:00 - 15:30 3.5 7.209 8.085

21 58/3/2008 15:30 - 20:00 4.5 6.461 8.944

22 48/3/2008 20:00 - 00:00 4 4.322 7.781

23 58/4/2008 00:00 - 4:00 4 4.231 5.872

24 58/4/2008 4:00 - 8:00 4 2.514 8.370

25 8/4/2008 8:00 - 20:00 12 3.223 3.633

26 6* see Note 1 2.129 4.106

27 48/4/2008 20:00 - 8:00 12.5 1.036 4.579

28 58/5/2008 8:00 - 19:30 11.5 1.198 1.315

29 6* see Note 1 0.845 1.133

30 8/5/2008 19:30 - 8:00 11.5 0.492 0.950

31 48/6/2008 8:00 - 19:00 11 0.145 0.242

1 No samples collected, application period

2 No samples collected, irrigation period

3 Flux calculated using ISCST3 Modeling

4 Slope, intercept and R squared values for concentration calculated from 3 values only due to 

poor regression fit

5 Slope, intercept and R squared values for concentration calculated from 4 values only due to 

poor regression fit

6 Flux caculated as average of flux from preceding and following periods (Not shown in 

graph)

*Note 1: The explanation for lack of concentration data for Periods 26 and 29 for Field 2 is 

provided in Log Sheet Detailed Description.doc Starting after Period 24 on Field 2 the 

sampling duration time were approximately 12 hours, therefore, the duration for Periods 27 

and 29 were approximately 12 hours for Field 2, but for Field 1 the sum of durations for 

Periods (26 and 27) and (29 and 30) were approximately 12 hours each.
Page 26 of 35

MRID 47956701 Study- Flux Evaluation of a Metam Potassium Application (KAPAM-HL) 

Applied by the Drench Method (Study SEC- 2008D) (Sponsored by Amvac Chemical 

Corporation)

In MRID 47956701, the study authors monitored for methyl isothiocyanate (MITC) following 

the application of metam potassium onto a bedded soil surface using spray mozzles from a tank 

containing product with mixed with water that is pulled behind a tractor. The test site for this 

study was located in Modesto, California and the field work was conducted in August of 2008. 

This study was conducted to identify the flux rates of MITC over a six-day period following the 

application. The single treated field was 2.35 acres in sized based on GPS coordinates. The 

metam potassium (KAPAM-HL) application was applied at a rate o 17.05 gallons per broadcast 

acre. The application resulted in a total volume of 1,895 gallons of solution per acre. A 0.2 inch 

water seal was applied immediately following the application. On the first and second evenings, 

an additional water deal of approximately 0.2 inches of water each was applied. 

Immediately following the application and water seal, air quality and meterological sampling 

equipment was relocated to the center of the treated field. Six MITC monitors were placed in the 

field at heights ranging from 0.3 meters to 3.0 meters above ground level. Meteorlogical profile 

monitoring for wind, temperature, and relative humidity was conducted on the treated field 

downwind (south) center of the field based on the steady flow from the northwest and north 

through the study. Also, a 3D sonic anemometer and standard weather station were positioned to 

document additional weather conditions. The sampling height of the CSAT3 wind speed monitor 

was 6.05 meters, the ET106 solar radiation monitor was set to 2.79 meters, the 2D

meteorological monitors for wind speed ranged from 0.46 meters to 3.07 meters, and the HOBO 

soil temperature sensor was set to 0.61 meters above ground level. The 1.6 meter wind sensor 

was found to produce inconsistent wind data compared to the other 5 wind monitor levels;

therefore, wind speed was computed based on the other five levels. 

Soil samples were collected on a random basis in the treatment zone prior to the application. 

Three subsamples collected with a shovel to the depth of 6 inches were used for each composite 

sample. The composite samples were transferred to a zip-lock bag and numbered 1 through 6, 

along with the location of each sample through GPS readings. The preapplication soil samples 

from each field were analyzed for soil type, percent sand, silt, clay, organic matter, and pH. Soil 

was also continuously monitored by HOBO soil sensors for soil temperature and relative soil 

moisture data within the treatment zone. 

Off-site air sampling was conducted via eight samplers throughout the active application and two 

post-application irrigation sets established approximately 25 to 50 meters from the edges of the 

plots around the field. The intake height was approximately 1.5 m above ground level to 

approximate the human breathing zone. There were 132 on-field samples plus 27 exposed 

fortified samples. On-field profile sampling began after application activities and initial sealing 

ceased. There were a total of 24 off-field samples which began sampling shortly before 

application and through the application period and two irrigation periods (Periods 1, 4, and 10). 

Charcoal tubes were analyzed for the study.
Page 27 of 35

Flux rates were calculated via on-field flux data except during the fumigant application where 

the primary method to compute flux rates was the back-calculation method. The flux profiles 

were calculated based on the field conditions including the application rates used to make the 

applications in the study. For the purposes of completing the PERFUM analyses, these flux 

profiles were subsequently adjusted to the maximum application rate for metam potassium of 

320 lb metam potassium per treated acre (see Table 17).

Table 17. Flux Calculations for Field 1 (Drench and Water Seal) at Modesto, 

CA (MRID 47956701)

Period 

No. Sample Interval Times Duration (Hrs.)

Est. Flux Reported Flux

(ug/m2-s) (ug/m2-s)

1 1,3 8/20/2008 7:30 - 11:30 4:00 121.91 128.32

2 8/20/2008 11:30 - 15:30 4:00 12.60 11.62

3 8/20/2008 15:30 - 19:15 3:45 2.79 2.77

4 2,3 No samples collected 4:00 0.32 0.23

5 8/20/2008 23:15 - 3:15 4:00 2.39 0.04

6 8/21/2008 3:15 - 7:15 4:00 0.24 0.04

7

4

8/21/2008 7:15 - 11:15 4:00 0.94 0.06

8

4

8/21/2008 11:15 - 15:30 4:15 1.29 0.14

9

4

8/21/2008 15:30 - 19:15 3:45 1.34 0.06

10 2,3 No samples collected 4:00 0.03 0.09

11 48/21/2008 23:15 - 3:15 4:00 0.27 0.02

12 48/22/2008 3:15 - 7:15 4:00 0.26 0.03

13 48/22/2008 7:15 - 15:30 8:15 0.25 0.04

14 48/22/2008 15:30 - 23:30 8:00 0.41 0.02

15 48/22/2008 23:30 - 7:30 8:00 0.41 0.03

16 48/23/2008 7:30 - 15:30 8:00 0.40 0.02

17 48/23/2008 15:30 - 23:30 8:00 0.40 0.02

18 48/23/2008 23:30 - 7:30 8:00 0.40 0.02

19 48/24/2008 7:30 - 19:30 12:00 0.40 0.02

20 48/24/2008 19:30 - 7:30 12:00 0.40 0.01

21 48/25/2008 7:30 - 19:30 12:00 0.40 0.01

22 48/25/2008 19:30 - 4:30 9:00 0.40 0.01

1 No samples collected, application period

2 No samples collected, sample time too short

3 Flux calculated using ISCST3 Modeling

4 Delta method used due to poor regression fit.
Page 28 of 35

3.0 PERFUM Modeling

The risk estimates calculated based on the recently submitted monitoring studies are summarized 

in this section. All risk estimates were calculated using the same hazard inputs and PERFUM 

modeling approaches as described in the previous risk assessment for metam sodium (Smith; 

D357118). Tables 18 – 21 provide a comparison of the PERFUM modeling results for the 

recently submitted studies to the studies used in the 2009 risk assessment. The results presented 

in these tables are based on the Ventura weather station for a 40 acre field at the maximum 

application rate.

In the 2009 Metam Sodium RED, there was not specific buffer table developed for shank 

injection broadcast untarped applications without water seals. Since that time, the Agency has 

received three emission studies (MRID 47770001, 48005901, and 48115101) examining 

emissions from three fields using the untarped broadcast shank injection without water seals 

application methodology. HED recommends that these three studies be utilized to develop a

buffer table for this particular application method (see Table 18 and Figure 1). The fields utilized 

in these studies were prepared according to the currently recommended GAPs to ensure 

compliance with the fumigant labels and regulations and to achieve high quality emissions data. 

Table 18: Comparison of 40 Acre PERFUM Whole Field Buffer Analyses Using Ventura Meteorological Data for Five

Metam Sodium Broadcast Shank Injection Flux Studies at the Maximum Application Rate of 320 lbs ai/A without water 

seals 1

Percentiles Smith River, CA –

Spray/Rototill/Roll2

Mount Vernon, WA –

Roozen Rig2

Pasco, WABroadcast

Howard City, MIBroadcast Injection 

12” (field 1)

Kennewick, WA –

Broadcast Injection 9”

(field 1)

50 0 65 0 0 0

75 80 350 65 0 5

90 370 1160 290 0 70

95 685 ≥1440 525 5 150

99 1355 ≥1440 1040 85 355

99.9 ≥1440 ≥1440 ≥ 1440 160 605

1 All buffers measured in meters.

2

Previously reviewed study.
Page 29 of 35

Figure 1: Comparison of 40 Acre PERFUM Whole Field Buffer Analyses Using 

Ventura Meteorological Data for Five Metam Sodium Broadcast Shank Injection 

Flux Studies at the Maximum Application Rate of 320 lbs ai/A without water seals

0

10

20

30

40

50

60

70

80

90

100

110

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Distance (m) Percentile

Smith River, CA –

Spray/Rototill/Roll2

Mount Vernon, WA –

Roozen Rig2

Pasco, WABroadcast

How ard City, MIBroadcast Injection

12” (field 1)

Kennew ick, WA –

Broadcast Injection 9”

(field 1) 

In the 2009 Metam Sodium RED, the buffer tables for shank injection broadcast untarped

applications with water seals were developed based on the Bakersfield/Broadcast 

Shank/Intermittent Water Seal emission study. Since that time, the Agency has received four

emission studies (MRID 48011601, 48005901, 47956901, and 48115101) examining emissions 

from six fields using the untarped broadcast shank injection with water seals application

methodology. HED recommends that these four studies be utilized to revise the current buffer 

table for this particular application method (see Table 19 and Figure 2). The fields utilized in 

these studies were prepared according to the currently recommended GAPs to ensure compliance 

with the fumigant labels and regulations and to achieve high quality emissions data. 

Table 19: Comparison of 40 Acre PERFUM Whole Field Buffer Analyses Using Ventura Meteorological Data for Nine

Metam Sodium Broadcast Shank Injection Flux Studies at the Maximum Application Rate of 320 lbs ai/A with water seals 1

Percentiles

Bakersfield, 

CA

Standard 

Water Seal2

Bakersfield, 

CA

Intermittent 

Water Seal2

Lost Hills, 

CA 

Intermittent 

Water Seal2

Coloma, WI 

0.1” due to 

rain (field 1)

Coloma, 

WI 0.1” 

due to rain 

(field 3)

Howard 

City, MI 

0.33” after 

app

(field 2)

San Joaquin 

Valley, CA 

double 

water seal 

(field 1)

San Joaquin 

Valley, CA 

double 

water seal 

(field 2)

Kennewick, 

WA 0.25” 

after app 

(field 2)

50 15 5 10 0 0 0 0 0 0

75 225 125 110 45 45 0 0 30 0

90 ≥1440 315 300 185 240 0 0 235 0

95 ≥1440 450 435 365 475 0 0 555 0

99 ≥1440 890 855 755 970 0 5 1390 0

99.9 ≥1440 ≥1440 1420 1205 ≥1440 0 95 ≥1440 0

1 All buffers measured in meters.

2

Previously reviewed study.
Page 30 of 35

Figure 2: Comparison of 40 Acre PERFUM Whole Field Buffer Analyses Using Ventura 

Meteorological Data for Nine Metam Sodium Broadcast Shank Injection Flux Studies at the 

Maximum Application Rate of 320 lbs ai/A with water seals 

0

10

20

30

40

50

60

70

80

90

100

110

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Distance (m) Percentile

Bakersfield, CA – Standard Water Seal2

Bakersfield, CA – Intermittent Water Seal2

Lost Hills, CA – Intermittent Water Seal2

Coloma, WI – 0.1” due to rain (field 1)

Coloma, WI – 0.1” due to rain (field 3)

How ard City, MI – 0.33” after app (field 2)

Kennew ick, WA – 0.25” after app (field 2)

In the 2009 Metam Sodium RED, there was not specific buffer table developed for shank 

injection bedded tarped applications. Since that time, the Agency has received two emission 

studies (MRID 47820001 and 47813901) examining emissions from six fields using the untarped 

broadcast shank injection without water seals application methodology. HED recommends that 

these two studies be utilized to develop a buffer table for this particular application method (see 

Table 20 and Figure 3). The fields utilized in these studies were prepared according to the 

currently recommended GAPs to ensure compliance with the fumigant labels and regulations and 

to achieve high quality emissions data. 

Table 20: Comparison of 40 Acre PERFUM Whole Field Buffer Analyses Using Ventura Meteorological Data

for Seven Metam Sodium Bedded Shank Injection Flux Studies at the Maximum Application Rate of 320 lbs 

ai/A with Tarps 1

Percentiles

Citra, FL 

LDPE 

Tarp2

Tifton, GA 

Blockade 

Tarp

(field 1)

Tifton, GA 

LDPE Tarp 

(field 2)

Tifton, GA 

LDPE Tarp 

(field 3)

Duette, FL

Metalized 

Tarp

(field 1) 

Duette, FL 

Guardian VIF 

Tarp (field 2)

Duette, FL

Metalized 

Tarp (field 3)

50 50 0 25 0 0 0 0

75 360 55 205 60 0 15 5

90 1240 265 810 340 0 85 70

95 ≥1440 530 ≥1440 670 0 160 135

99 ≥1440 1075 ≥1440 1405 0 365 340

99.9 ≥1440 ≥1440 ≥1440 ≥1440 0 680 615

1 All buffers measured in meters.

2

Previously reviewed study.
Page 31 of 35

Figure 3: Comparison of 40 Acre PERFUM Whole Field Buffer Analyses Using Ventura Meteorological 

Data for Seven Metam Sodium Bedded Shank Injection Flux Studies at the Maximum Application Rate of 

320 lbs ai/A with Tarps 

0

10

20

30

40

50

60

70

80

90

100

110

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

Distance (m) Percentile

Citra, FL – LDPE 

Tarp2

Tifton, GA – Blockade

Tarp (field 1)

Tifton, GA – LDPE

Tarp (field 2)

Tifton, GA – LDPE

Tarp (field 3)

Duette, FL – Metalized

Tarp (field 1) 

Duette, FL – Guardian

VIF Tarp (field 2)

Duette, FL – Metalized

Tarp (field 3)

In the 2009 Metam Sodium RED, there was not specific buffer table developed for drench 

applications. Since that time, the Agency has received one emission study (MRID 47956701) 

examining emissions from one field using the drench with water seal application methodology. 

HED recommends that these two studies be utilized to develop a buffer table for this particular 

application method (see Table 21). The field utilized in this study was prepared according to the 

currently recommended GAPs to ensure compliance with the fumigant labels and regulations and 

to achieve high quality emissions data.

Table 21: 40 Acre PERFUM Whole Field Buffer 

Analysis Using Ventura Meteorological Data for One 

Metam Sodium Drench Study at the Maximum 

Application Rate of 320 lbs ai/A 1

Percentiles Modesto, CA – triple water seal

50 55

75 270

90 685

95 1100

99 ≥1440

99.9 ≥1440

1 All buffers measured in meters.
Page 32 of 35

Appendix A: Metam Sodium/Metam Potassium 

Emission Studies Overview
Page 33 of 35

Appendix A/Table A1: Metam Sodium/Metam Potassium Emission Studies Overview

MRID Location Application Type

Application Rate

(lbs ai/treated 

acre)

Max 1-hr 

flux rate 

(ug/m2-s)

Max Application 

Rate (lbs 

ai/treated acre)

Max Adjusted 

1-hr flux rate 

(ug/m2-s)

% Field 

Capacity

Soil 

Temp 

(oC)

% OM Soil Type

Start Time 

of 

Application

Completion 

Time of 

Application

Time of 

highest 

peak

% Mass 

Loss

Sprinkler Irrigation Studies

45703701 Bakersfield, CA

Solid set sprinkler, standard water seal 

(2 water seals for a 1" total-0.5" after 

app and 24 hours after app)

320 358.1 320 358.1 NA NA NA NA NA NA 20-24 NA

CSREES #74 Bakersfield, CA

Solid set sprinkler, Intermittent water 

seal (6 water seals for a 1.5" total0.25" after app, 4, 11, 24, 30, and 35 

hours after app)

320 54.8 320 54.8 NA ~25 NA Sandy 

loam NA NA 12-16 NA

45703702 San Joaquin, 

CA

Solid set sprinkler, Intermittent water 

seal (5 water seals for a 1.5" total-0.5" 

after app; 0.25" at 8, 24, 30, and 48 

hours after app)

320 48.0 320 48.0 ~60-80 NA NA NA 5:00 11:30 12-16 NA

46969601 Mettler, CA

Solid set sprinkler, double water seal 

(2 water seals for a 0.69" total-0.23" 

after app and 0.46" 8 hours after app)

320 80.7 320 80.7 ~50-75 ~20-25 0.5-0.8 Loamy 

Sand 16:00 22:00 0-4 NA

Broadcast Shank Injection Studies

45703701 Bakersfield, CA Broadcast, standard water seal (0.5" 

after app) 320 118.3 320 118.3 NA NA NA NA NA NA 36-40 NA

CSREES #74 Bakersfield, CA

Broadcast, Intermittent water seal (6 

water seals for a 1.5" total-0.25" after 

app, 6, 11, 24, 30, and 35 hours after 

app)

320 52.4 320 52.4 NA ~25 NA Sandy 

loam NA NA 8-12 NA

45703704 Lost Hills, CA

Broadcast, Intermittent water seal (5 

water seals for a 1.5" total-0.5" after 

app; 0.25" at 8, 12, 30, and 34 hours 

after app)

320 36.3 320 36.3 NA ~27 NA Clay 

Loam 6:50 14:00 4-8 NA

46379201 Mt. Vernon, 

WA Broadcast "Roozen Rig" 320 159 320 159.1 NA NA NA NA NA NA 8-12

47770001 Pasco, WA Broadcast 219 12 320 18.2 NA 7 to 16 NA NA 12:10 12:50 4-8 12.6

48011601 Coloma, WI

Broadcast (Dual Injection at 5.5 and 

9.5"), water seal (0.1" of rain after 

app)

287 9.8 320 10.9 ~75-80 ~13 to 16 0.7 Loamy 

Sand 10:27 10:38 29-33 6.98

48011601 Coloma, WI

Broadcast (Dual Injection at 5.5 and 

9.5"), water seal (0.1" of rain after 

app)

270 10.7 320 12.7 ~75-80 ~13 to 16 1.3 Loamy 

Sand 8:15 8:35 37-41 10.37
Page 34 of 35

Appendix A/Table A1: Metam Sodium/Metam Potassium Emission Studies Overview

MRID Location Application Type

Application Rate

(lbs ai/treated 

acre)

Max 1-hr 

flux rate 

(ug/m2-s)

Max Application 

Rate (lbs 

ai/treated acre)

Max Adjusted 

1-hr flux rate 

(ug/m2-s)

% Field 

Capacity

Soil 

Temp 

(oC)

% OM Soil Type

Start Time 

of 

Application

Completion 

Time of 

Application

Time of 

highest 

peak

% Mass 

Loss

48005901 Howard City, 

MI Broadcast (Injection at 12") 318 2.8 320 2.8 ~60-80 ~7 to 12 1.1-1.6 Loamy Sand/Sand 16:10 16:22 28-32 0.55

48005901 Howard City, 

MI

Broadcast (Injection at 12"), water 

seal (0.33" after app) 321 0.3 320 0.2 ~60-80 ~7 to 12 0.5-1.3 Sand 14:34 14:45 28-32 0.07

47956901 Bakersfield, 

CA

Broadcast (daytime), double water 

seal (0.4" after app, 0.4" at sunset) 317 4.4 320 4.4 ~72 ~27 NA NA 6:00 7:45 0-4 1.2

47956901 Bakersfield, CA Broadcast (nightime), double water 

seal (0.4" after app, 0.4" at sunset) 320 34.3 320 34.3 ~54 ~27 NA NA 0:20 1:35 4-8 12.87

48115101 Pasco, WA Broadcast (Injection at 9") 317 7.1 320 7.1 72.4 ~8 1.6-1.9 NA 9:40 9:55 47-59 6.78

48115101 Pasco, WA Broadcast (Injection at 9"), water seal 

(0.25" after app) 368 1.7 320 1.5 70.9 ~8 1.1-1.4 NA 8:30 8:45 0-4 0.45

Bedded Shank Injection Studies

47131601 Helms, CA Bedded, untarped 294 18.77 320 20.4 NA ~13 8

Sandy 

loam 9:03 10:54 4-8 NA

CSREES #74 Citra, FL Bedded, LDPE tarped 320 174.95 320 175.0 NA ~18 NA Sand 9:30 12:30 4-8 NA

47820001 Tifton, GA Bedded, Blockade Tarped (Field 1) 299.5 16.5 320 17.6 70 ~10 to 21 0.7 Sandy 

loam 12:47 14:20 41-47 5

47820001 Tifton, GA Bedded, LDPE tarped (Field 2) - Bad 

Soil Prep 306.3 55.2 320 57.7 65 ~10 to 21 0.6 Sandy clay loam 15:19 16:47 17-23 13

47820001 Tifton, GA Bedded, LDPE tarped (Field 3) 295.2 32.9 320 35.7 74 ~10 to 21 0.6 Loamy 

sand 17:42 19:58 17-23 6

47813901 Duette, FL Bedded, Metallized tarped (Field 1) 313.6 2.2 320 2.3 142 ~10 to 21 0.94 NA 10:43 11:51 124-136 2.6

47813901 Duette, FL Bedded, Guardian VIF tarped (Field 

2) 302.6 10.4 320 11.0 189 ~10 to 21 1.38 NA 13:22 14:38 6-12 5.5

47813901 Duette, FL Bedded, Metallized tarped (Field 3) 308.4 15.1 320 15.7 171 ~10 to 21 1.26 NA 16:03 16:52 0-6 2.31

Drench Studies

47956701 Modesto, CA Drench, triple water seal (0.2" after 

app, 0.2" at sunset of Day 1 and 2) 164.7 128.3 320 267.8 ~67 ~24 to 27 ~1.3 Sandy loam 7:30 9:45 0-4 37.56

Drip Irrigation Studies

CSREES #74 Citra, FL Bedded, LDPE tarped 383 46.94 320 39.3 NA ~18 NA Sand 9:30 16:00 32-36 NA

45703708 Irvine, CA Bedded, LDPE tarped 320 15 320 14.9 NA NA NA NA 18:20 20:45 0-4 NA
Page 35 of 35

Appendix A/Table A1: Metam Sodium/Metam Potassium Emission Studies Overview

MRID Location Application Type

Application Rate

(lbs ai/treated 

acre)

Max 1-hr 

flux rate 

(ug/m2-s)

Max Application 

Rate (lbs 

ai/treated acre)

Max Adjusted 

1-hr flux rate 

(ug/m2-s)

% Field 

Capacity

Soil 

Temp 

(oC)

% OM Soil Type

Start Time 

of 

Application

Completion 

Time of 

Application

Time of 

highest 

peak

% Mass 

Loss

45703708 Irvine, CA Bedded, untarped (drip lines on soil 

surface) 320 9 320 9.4 NA NA NA NA 18:00 22:00 8-12 NA

Center Pivot Irrigation Studies

47770001 Pasco, WA Center Pviot Irrigation-Drizzle Boom 300 172.1 320 183.8 NA 7 to 16 NA NA 11:35 13:30 0-4 47

Flood Irrigation Studies

47314301 Brawley, CA Flood Irrigation 318 68.34 320 68.8 NA NA NA NA NA NA 5-9 NA

Rotary Tiller and Spray Blade

47572201 Smith River, 

CA Broadcast Spray/Rototill/Roller 320 49 320 49.4 ~30-35 ~19 to 21 ~4 Clay loam/Clay NA NA 4-8 14.1