Appendix 2 

Review of Registrant Proposed Field Adjustment Factors 

1 
A. Methyl Bromide 

Stangellhini (2006a) proposes field adjustment factors for methyl bromide based on 

laboratory and field studies of various application methods. Under Stangellhini’s scheme, 

a field adjustment factor of 100% is assumed for all commodity and space fumigations. 

This is reasonable because nearly all applied methyl bromide from these applications are 

eventually released to the atmosphere. However, Stangellhini’s soil application method 

groupings are inconsistent with those developed in DPR’s analysis of 47 field methyl 

bromide studies (Segawa et al., 2000). We derive field adjustment factor estimates taking 

into consideration data cited in Stangellhini (2006a) and DPR’s extensive methyl 

bromide data set of field studies. The field adjustment factors so derived are consistent 

with the DPR methyl bromide regulations. 

1. Review of the Consortium of Methyl Bromide Registrants proposed 

adjustments 

Stangellhini’s (2006a) proposed field adjustment factors are based on a single soil 

column study (Gan et al., 1997) that is summarized in Yates et al. (1996a): 

Shallow injection (6-15in.), bed or broadcast, no tarp, field adjustment factor = 82% 

Shallow injection (6-15in.), bed or broadcast, LDPE tarp, field adjustment factor = 82% 

Shallow injection (6-15in.), bed or broadcast, HDPE tarp, field adjustment factor = 43% 

Deep injection (20+in.), bed or broadcast, no tarp, field adjustment factor = 38% 

Deep injection (20+in.), bed or broadcast, LDPE tarp, field adjustment factor = 38% 

Deep injection (20+in.), bed or broadcast, HDPE tarp, field adjustment factor = 26% 

Where: 

LDPE = Low Density Polyethylene Film Tarp 

HDPE = High Density Polyethylene Film Tarp. 

The Gan et al. study (1997) included documented analytical methods for bromide ion and 

methyl bromide, frequent sampling and mass balance recoveries near 100%. 

Consequently the study is acceptable in terms of data quality. However, with the 

exception of 30 cm injection depth, the results are single realizations of each test system, 

thus the results are unreplicated. In addition, such column studies are highly controlled 

and do not reflect the variability in emissions typical of field applications. 

1. DPR Methyl Bromide Soil Application Data Set 

Stangellhini’s (2006a) application method groupings are inconsistent with DPR’s 

analysis of the methyl bromide field studies in the DPR database for two reasons: 1) the 

DPR database shows that bed application methods, regardless of the type of tarp used, 

show very high 24 hour emission values and mass loss (81%), and 2) no significant effect 

on the highest 24 hour emissions due to depth of injection could be detected. Barry 

(1999) presents details of the analysis and supports a substantially different structure for 

2 
application method groupings where bed and broadcast represent one level of 

classification, and “tarp” and “no tarp” application methods are a second level of 

classification. No classification based on depth is included because no differences due to 

depth of injection were observed in the highest 24-hour flux. While in concept there 

should be a depth effect, it is likely in practice that application-to-application variability 

at the field level is too large to detect that effect. 

DPR’s data set includes 31 field studies of the application methods consistent with those 

described by Stangellhini. The mean peak 24-hour emissions from these studies are 

similar in magnitude as emissions over the entire loss period (approximately 2 weeks) 

described by Stangellhini (2006a). The DPR mean peak 24-hour emissions (emission 

ratios) are shown below: 

HDPE tarp/broadcast 24-hr emissions (emission ratio) = 24% (n=13, CV = 52%) 

No tarp/broadcast 24-hr emissions (emission ratio) = 37% (n = 8, CV = 47%) 

HDPE tarp/bed 24-hr emissions (emission ratio) = 81% (n = 9, CV = 38%) 

In all cases the first 24 hours following application showed the highest 24-hour emission 

ratio. Since these emissions are for only the first 24 hours and are similar in magnitude to 

the Stangellhini (2006a) proposed field adjustment factors, these results indicate that it is 

likely the Stangellhini (2006a) field adjustment factors are too small. 

2. Methyl Bromide Literature Reported Emissions 

Methyl bromide data potentially appropriate for developing adjustment factors are found 

in 5 journal articles: Majewski et al. (1995), Gan et al. (1996), Yates et al. (1996b), 

Yates et al. (1996c), and Gan et al. (1997). These articles report either direct flux 

(emission) measurements (e.g. aerodynamic method) in the field or soil column results. 

No flux chamber estimates of emissions are used at this time because there are significant 

technical issues associated with flux chamber estimates including: (1) potentially 

significant effects on the local environmental conditions where the chambers are placed 

relative to the field as a whole. This effect may be largest for static chambers but may 

also affect dynamic chambers, (2) the sensitivity of dynamic chamber results to pressure 

gradients created by the air flow, and (3) the very limited coverage of the field by the 

sample chambers which can introduce a high degree of heterogeneity in the flux results 

(Reichman and Rolston, 2002; Majewski et al., 1995; Yates 2006). 

Table 1 summarizes the studies cited above and shows emission estimates for Broadcast 

Tarp and Broadcast Non-tarp methods. Shallow and deep injections are pooled within 

these two categories per the lack of significant difference associated with injection depth 

observed in the DPR data set. The mean emission for Broadcast Tarp application method 

is 40%. The mean emission for Broadcast Non-tarp application method is 66%. 

3. Methyl Bromide Field Adjustment Factor Development 

3 
The mean peak 24-hour emissions (emission ratios) for the three groups in the DPR 

methyl bromide regulations are used as the basis for the DPR field adjustment factors. 

Majewski et al. (1995) conclude that about 50% of the total mass loss occurs in the first 

24 hours for both tarp and non-tarp applications. Thus, the well-characterized DPR 

regulatory emission ratios for Broadcast HDPE Tarp, Broadcast Non-tarp, and Bed Tarp 

can be reasonably doubled to provide an estimate of the field adjustment factor. Due to 

the large initial emission ratio for Bed Tarp, 100% loss should be assumed. This results in 

the following estimates: 

Broadcast Tarp = 48% 

Broadcast Non-tarp = 74% 

Bed Tarp = 100% 

Comparison of these DPR emission estimates with the mean mass loss estimates in Table 

1 indicates that these DPR database derived estimates are within the variation observed in 

the literature values. Use of the DPR database derived field adjustment factors is 

consistent with the methyl bromide regulations and permit conditions. 

The Stangellhini (2006a) proposed generalized adjustment function is reasonable and can 

be implemented to adjust methyl bromide VOC emissions. However, the grouping 

structure and field adjustment factors proposed for soil applications are not consistent 

with the structure supported by analysis of the studies in the DPR methyl bromide data 

set. Thus, the grouping structure has been changed to reflect the actual differences in 

emissions that were detectable in the DPR data set. Emission of 100% of mass applied 

for all applications not made to soil is reasonable. 

The adjustment for both 1990 and 2004 will need to account for fumigations that were 

likely made to beds. Those application records should assume 100% of the mass applied 

is lost. Consistent with the Stangellhini (2006a) proposal, the 1990/91 base year 

adjustment for soil applications not made to beds should assume the non-tarp mass loss of 

74%. This assumption will account for the very permeable LDPE tarps that were in use 

at the time. 

B. Chloropicrin 

The document “Analysis of Chloropicrin emissions in the San Joaquin Valley in 1990 

and 2004” (Stangellhini, 2006b) proposes to adjust chloropicrin VOC emission estimates 

for soil applications according to the proportion of applied mass lost observed in field 

studies of various soil application methods. Emission of 100% of mass applied is 

assumed for all applications not made to soil. The conceptual basis for this proposal is 

sound. However, two of the studies used in the Stangellhini (2006b) proposal, Gillis and 

Smith (2002) and Lee et al. (1994), are not of sufficient quality to be included in the 

estimation of the adjustment factors. The proposed DPR field adjustment factors use 

only data judged acceptable by DPR. 

4 
1. Review of the Chloropicrin Manufacturers Task Force proposed 

adjustments 

The chloropicrin field adjustment factors proposed by Stangellhini (2006b) are: 

Shallow injection (6-15in.), broadcast, no tarp = 62% 

Shallow injection (6-15in.), broadcast, LDPE tarp = 62% 

Shallow injection (6-15in.), broadcast, HDPE tarp = 37% 

Deep injection (20+in.), broadcast, no tarp = 62% 

Deep injection (20+in.), broadcast, LDPE tarp = 62% 

Deep injection (20+in.), broadcast, HDPE tarp = 37% 

Drip-application, surface or buried, HDPE tarp = 9% 

Where: 

LDPE = Low Density Polyethylene Film Tarp 

HDPE = High Density Polyethylene Film Tarp. 

2. Chloropicrin Literature Reported Emissions 

Gao and Trout (2007) used flux chambers to estimate emissions for several chloropicrin 

and 1,3-D application methods, including HDPE tarp, HDPE tarp with pre-irrigation, 

single watering-in, intermittent watering-in, and virtually impermeable film (VIF). Those 

researchers reported problems maintaining a seal between the soil and the chamber. Due 

to these problems the chamber methodology results may not accurately measure 

emissions under field conditions. No flux chamber estimates of emissions are used at this 

time because there are significant technical issues associated with flux chamber estimates 

including: (1) potentially significant effects on the local environmental conditions where 

the chambers are placed relative to the field as a whole. This effect may be largest for 

static chambers but may also affect dynamic chambers, (2) the sensitivity of dynamic 

chamber results to pressure gradients created by the air flow, and (3) the very limited 

coverage of the field by the sample chambers which can introduce a high degree of 

heterogeneity in the flux results (Reichman and Rolston, 2002; Majewski et al., 1995; 

Yates 2006). Predictions of chloropicrin emission reductions due to intermittent 

watering-in methods are subject to considerable uncertainty due to problems noted in Gao 

and Trout (2007). However, the reductions observed for chloropicrin are qualitatively 

consistent with demonstrated reductions in MITC emissions for intermittent watering-in 

methods. 

3. Chloropicrin Field Adjustment Factor Development 

The Stangellhini (2006b) proposed generalized adjustment function is reasonable and can 

be implemented to adjust chloropicrin VOC emissions. However, the grouping structure 

and field adjustment factors proposed for soil application methods are not consistent with 

that proposed by DPR. 

5 
The Beard et al. (1996) study will be used exclusively to produce the DPR field 

adjustment factors for the shank application method. The emissions from Beard et al. 

(1996) are shown in Table 2. Similar to the proposed methyl bromide factors, the 

proposed chloropicrin factors only distinguish between tarp and no tarp. No depth factor 

will be included. All broadcast tarp method mass loss results will be combined to 

produce a mean estimate. Emission of 100% of mass applied for all applications not 

made to soil is reasonable. 

The chloropicrin data set is small and, thus, it is impossible to reliably distinguish 

between emissions for bed and broadcast applications. Thus, no separate field adjustment 

factor for bed methods will be estimated. Instead, based on the known high emission 

characteristics of methyl bromide bed applications (Barry, 1999), the chloropicrin 

emission estimates for bed will be combined with the no tarp method. 

The drip/tarp application method is separated because the emissions appear to be 

substantially lower than the shank methods. Three studies are available to derived a drip 

tarp adjustment factor: Knuteson and Dolder (2000), Rotonardo (2004), and van 

Wesenbeeck and Phillips (2000). 

The Stangellhini (2006b) proposal argues that tarps used in 1990 were LDPE tarps and 

were highly permeable, thus the No Tarp loss rate was assigned to the LDPE 

applications. This assumption is reasonable. 

Based upon the proportional reduction observed for MITC, DPR will assume that 

reduction in chloropicrin emissions for intermittent watering-in is approximately onethird of an untarped application. Other application methods that appear to reduce 

chloropicrin emissions, such as pre-irrigation and VIF may be problematic due to 

labeling requirements and other factors (Gao and Trout, 2007). Therefore, these 

application methods are not recommended at this time. 

The mean field adjustment factor of each group will be used as the DPR estimated field 

adjustment factor value. Results are shown below: 

Broadcast/No tarp & Bed field adjustment factor = 64% (n = 3, CV = 6%) 

Broadcast/Tarp field adjustment factor = 44% (n = 3, CV = 35%) 

Broadcast/Tarp with intermittent watering-in = 20% 

Drip/High permeability tarp field adjustment factor = 12.3 (n = 1, CV = N/A) 

Drip/Low permeability tarp field adjustment factor = 11.8% (n = 2, CV = 27%) 

The CV values for these chloropicrin groups are smaller than those observed for methyl 

bromide. However, this data set is substantially smaller. 

6 
Literature Cited 

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Segawa dated December 2, 1999. California Environmental Protection Agency. 

Department of Pesticide Regulation. Environmental Monitoring and Pest Management 

Branch. 830 K Street, Sacramento, Ca 95814-3510. 

Barry, T. 2006. Development of methyl Isothiocyanate buffer zones using the 

Probabilistic Exposure and Risk Model for Fumigants Version 2 (PERFUM2). 

Memorandum to Charles Andrews dated January 27, 2006. California Environmental 

Protection Agency. Department of Pesticide Regulation. Environmental Monitoring 

Branch. 1001 I Street, P.O. Box 4015, Sacramento, Ca 95812. EM06-05. 

Beard, K.K., P.G. Murphy, D.D. Fontaine, J.T. Weinberg. 1996. Monitoring of potential 

worker exposure, field flux and off-site air concentration during chloropicrin field 

application. HEH 160. Chloropicrin Manufacturers Task Force. Department of 

Pesticide Regulation Registration data volume199-072. 

DPR. 2002. Recommended Permit Conditions for Using 1,3-Dichloropropene Pesticides. 

Department of Pesticide Regulation. Available on-line: 

http://www.cdpr.ca.gov/docs/enfcmpli/penfltrs/penf2002/2002037.htm 

Gan, J. S.R. Yates, D. Wang, and W.F. Spencer. 1996. Effect of soil factors on methyl 

bromide volatilization after soil application. Environ. Sci Technol. Vol 30:1629-1636. 

Gan, J., S.R. Yates, W.F. Spenser, M.V. Yates, and W.A. Jury. 1997. Laboratory-scale 

measurements and simulations of effect of application methods on soil methyl bromide 

emissions. J. Environ. Qual. Vol 26:310-317. 

Gao, S. and T. J. Trout. 2007. Surface Seals Reduce 1,3-Dichloropropene and 

Chloropicrin Emissions in Field Tests. J. Environ. Qual. Vol 36: 110-119. 

Gillis, M. and G.S. Smith. 2002. Chloropicrin emissions and offsite drift from tarped 

and non-tarped fields treated by a drip irrigation application method. Tri-Cal study 

number TC350. DPR registration volume 199-0114. 

Johnson, B. 2006. Calculation of emission potential factors for 1,3-dichloropropene for 

five areas for periods from May 1 through October 31. November 30, 2006 memorandum 

to Randy Segawa. California Environmental Protection Agency. Department of Pesticide 

Regulation. Environmental Monitoring Branch. Sacramento, Ca 95814-3510. 

Knuteson, J.A. and S.C. Dolder. 2000. Field volatility of 1,3-D and chloropicrin from 

shallow drip irrigation application of telone C-35(InLine) to strawberry beds with VIF 

tarp. April 27, 2000. Global Environmental Chemistry Laboratory B Indianapolis Lab, 

Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268-1054. 

Study ID 980070.01. 

7 
Lee, H., K.V. Natta, and M. Gillis. 1994. Chloropicrin workers exposure, flux, and 

offsite monitoring and dispersion mdoelign for tarped broadcast application – pilot study. 

TriCal study number TC246/BR707. DPR registration volume number 199-0079. 

Levine, J., D. Kim, and P. Lee. 2005. Monitoring an untarped bedded drip application of 

metam sodium in Merced Country. California Environmental Protection Agency. 

Department of Pesticide Regulation. Environmental Monitoring Branch. 1001 I Street, 

P.O. Box 4015, Sacramento, Ca 95812. EH05-03. 

Li, L., T. Barry, K. Mongar, and P. Wofford. 2006. Modeling Methyl Isothiocyanate 

Soil Flux and Emission Ratio from a Field following a Chemigation of Metam-Sodium. 

Journal of Environmental Quality Vol 35:707-713. 

Majewski, M.S., M.M. McChesney, J.E. Woodrow, H.H. Prueger, and J.N. Seiber. 1995. 

Aerodynamic measurements of methyl bromide volatilization from tarped and nontarped 

fields. J. Environ. Qual. Vol 24:742-752. 

Merricks, D.L. 1999. Determination of methyl isothiocyanate offsite air movement from 

application of Metam-sodium through shank injection and sprinkler irrigation. 

Agrisearch Incorporated, 5734 Industry Lane, Fredrick, MD 21704-7293. December 14, 

1999. 

Merricks, D.L. 2001. Determination of methyl isothiocyanate offsite air movement from 

application of Metam-sodium through shank injection. Agrisearch Incorporated, 5734 

Industry Lane, Fredrick, MD 21704-7293. March 1, 2001. 

Merricks, D.L. 2002. Determination of methyl isothiocyanate offsite air movement from 

application of Metam-sodium through sprinkler irrigation. Agrisearch Incorporated, 

5734 Industry Lane, Fredrick, MD 21704-7293. January 10, 2002. 

Reichman, R. and D.E. Rolston. 2002. Design and performance of a dynamic gas flux 

chamber. J. Environ. Qual. Vol 31:1774-1781. 

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drip irrigation application, and implied worker inhalation exposures from application of 

chloropicrin by shank injection, drip irrigation systems and at tree replant sites. 

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Registration data volume 199-0112. 

Segawa, R., B. Johnson, and T. Barry. 2000. Summary of off-site air monitoring for 

methyl bromide field fumigations. Memorandum dated January 21, 2000 to John S. 

Sanders. Department of Pesticide Regulation. Environmental Monitoring Branch. 

Sacramento, Ca 95814. 

http://www.cdpr.ca.gov/docs/empm/pubs/tribal/1offsiteMonitMebr-2.pdf 

8 
Spurlock, F. 2002. Summary of 1990-2000 VOC emissions inventory data, memorandum 

to John S. Sanders, February 4, 2002. 

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Valley in 1990 and 2004. Consortium of Methyl Bromide Registrants. Document 

submitted to the Department of Pesticide Regulation in May, 2006. 

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1990 and 2004. Chloropicrin Manufacturers Task Force. Document submitted to the 

Department of Pesticide Regulation in May, 2006. 

Wesenbeeck, I. Van and A. M. Phillips. 2000. Field volatility of 1,3-D and chloropicrin 

from surface drip irrigation application of In-Line to vegetable beds under polyethylene 

tarp. April 28, 2000. Global Environmental Chemistry Laboratory B Indianapolis Lab, 

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Environmental Fate. Department of Pesticide Regulation. Environmental Monitoring 

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95812. EH05-04. 

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bromide from agricultural fields: rate estimates and methods of reduction. In: Seiber, 

J.N., J.A. Knuteson, J.E. Woodrow, N.L. Wolfe, M.V. Yates, and S. R. Yates. Fumigants 

- environmental fate, exposure, and analysis. ACS Symposium Series 652. American 

Chemical Society, Washington, D.C. pp. 116-134. 

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9 
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Technol. 40:3223-3228. 

10 
Table 1. Summary of methyl bromide mass loss estimates from the literature. 

Broadcast Tarp 

Reference Study Type Soil Type Depth (cm) Mass Loss (%) Mean (%) CV JEQ Vol 24:742 Field Silty Clay Loam 25 32 JEQ Vol 25:185 Field Sandy Loam 25 63 JEQ Vol 26:310 Column Sandy Loam 30 43 JEQ Vol 26:310 Column Sandy Loam 30 37 JEQ Vol 26:310 Column Sandy Loam 60 26 

40 

Broadcast Non-tarp 

Reference Study Type Depth (cm) Mass Loss (%) Mean (%) CV JEQ Vol 24:742 Field Silty Clay Loam 25 89 JEQ Vol 26:310 Column Sandy Loam 20 82 JEQ Vol 26:310 Column Sandy Loam 30 71 JEQ Vol 26:310 Column Sandy Loam 60 38 ES&T Vol 30:1629 Column Sandy Loam 30 77 ES&T Vol 30:1629 Column Loamy Sand 30 77 ES&T Vol 30:1629 Column Clay 30 37 

66 

11 
Table 2. Mass loss (% of applied mass) for various chloropicrin application methods. 

Reference Application Method Location Emissions (%) Average (%

Beard (1996) Broadcast/No Tarp Arizona 62.5 Beard (1996) Broadcast/No Tarp Arizona 61.4 64.2 Beard (1996) Bed/Tarp Arizona 68.6 Beard (1996) Broadcast/Tarp Arizona 62.3 Beard (1996) Broadcast/Tarp Washington 33.8 Beard (1996) Broadcast/Tarp Florida 36.5 

44.2 

Rotonardo (2004) Drip/low perm. tarp 15 Knuteson and Dolder (2000) Drip/low perm. tarp California 8.6 11.8 van Wesenbeeck and Phillips (2000) Drip/high perm.tarp Georgia 12.3 12.3 

12