### Appendix 2 Review of Registrant Proposed Field Adjustment Factors

1A. Methyl Bromide

Stangellhini (2006a) proposes field adjustment factors for methyl bromide based on laboratory and field studies of various appli cation 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. Howe ver, Stangellhini’s soil application method groupings are inconsistent with those devel oped in DPR’s analysis of 47 field methyl bromide studies (Segawa et al., 2000). We deri ve 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 ad justment factors so derived are consistent with the DPR methyl bromide regulations.

1. Review of the Consortium of Met hyl Bromide Registrants proposed adjustments

Stangellhini’s (2006a) proposed field adju stment 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 broadcas t, 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) in cluded documented analytical methods for bromide ion and methyl bromide, frequent sampling a nd mass balance recoveries near 100%. Consequently the study is acceptable in term s 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 unreplicate d. In addition, such column studies are highly controlled and do not reflect the variability in emi ssions typical of field applications.

1. DPR Methyl Bromide Soil Application Data Set

Stangellhini’s (2006a) application method groupings are incons istent 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 met hods, 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 dept h of injection could be detected. Barry (1999) presents details of the analysis and s upports a substantially different structure for

2application method groupings where bed a nd broadcast represent one level of classification, and “tarp” and “no tarp” a pplication methods are a second level of classification. No classification based on dept h is included because no differences due to depth of injection were observed in the hi ghest 24-hour flux. While in concept there should be a depth effect, it is likely in practice that application-to-app lication variability at the field level is too large to detect that effect.

DPR’s data set includes 31 field studies of the application me thods 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 DP R 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 (emissi on 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 app lication 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, th ese results indicate that it is likely the Stangellhini (2006a) field ad justment factors are too small.

2. Methyl Bromide Literature Reported Emissions

Methyl bromide data potentially appropriate for developing adjust ment factors are found in 5 journal articles: Maje wski 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 ch amber estimates including: (1) potentially significant effects on the local environmental conditions where the chambers are placed

relative to the field as a whol e. This effect may be larges t 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) th e 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; Majews ki et al., 1995; Yates 2006).

Table 1 summarizes the studies cited above and shows emi ssion estimates for Broadcast Tarp and Broadcast Non-tarp methods. Shallo w and deep injections are pooled within these two categories per the lack of significant difference asso ciated with injection depth

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

is 40%. The mean emission for Broadcas t Non-tarp applicat ion method is 66%.

3. Methyl Bromide Field Adjustment Factor Development

3The 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 applica tions. Thus, the well-characterized DPR regulatory emission ratios for Broadcast HDP E Tarp, Broadcast Non-tarp, and Bed Tarp can be reasonably doubled to provide an estima te 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 wi th the mean mass loss estimates in Table

1 indicates that these DPR data base derived estimates are with in the variation observed in

the literature values. Use of the DPR data base 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 brom ide VOC emissions. However, the grouping structure and field adjustment factors proposed for soil app lications 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 ch anged 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 r ecords should assume 100% of the mass applied is lost. Consistent with the Stangell hini (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 em issions in the San Joaquin Valley in 1990 and 2004” (Stangellhini, 2006b) proposes to ad just chloropicrin VOC emission estimates for soil applications according to the proporti on of applied mass lost observed in field studies of various soil app lication 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.

41. 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.), br oadcast, 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 es timate emissions for several chloropicrin and 1,3-D application methods, including HDP E tarp, HDPE tarp with pre-irrigation, single watering-in, intermittent watering-in, a nd virtually impermeable film (VIF). Those researchers reported problems maintaining a seal between the soil and the chamber. Due to these problems the chamber methodol ogy results may not accurately measure

emissions under field conditions. No flux chamber estimates of emissions are used at this time because there are significan t technical issues associated with flux chamber estimates including: (1) potentially signi ficant 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 dyna mic chambers, (2) the sensitivity of dynamic chamber results to pressure gradients create d by the air flow, and (3) the very limited coverage of the field by the sample cham bers which can introduce a high degree of heterogeneity in the flux results (Reichma n 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 du e to problems noted in Gao and Trout (2007). However, the reductions observed for chloropicr in 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.

5The Beard et al. (1996) study will be used exclusively to produce the DPR field adjustment factors for the sh ank application method. The em issions from Beard et al. (1996) are shown in Table 2. Similar to th e proposed methyl bromide factors, the proposed chloropicrin factors on ly distinguish between tarp and no tarp. No depth factor will be included. All broadcast tarp met hod mass loss results will be combined to produce a mean estimate. Emission of 100% of mass applied for al l applications not

made to soil is reasonable.

The chloropicrin data set is small and, t hus, it is impossible to reliably distinguish between emissions for bed and broadcast applic ations. Thus, no separate field adjustment factor for bed methods will be estimated. Instead, based on the known high emission characteristics of methyl bromide bed app lications (Barry, 1999), the chloropicrin emission estimates for bed will be combined with the no tarp method.

The drip/tarp application method is separa ted because the emissions appear to be substantially lower than the shank methods. Th ree studies are availabl e to derived a drip tarp adjustment factor: Knuteson and Do lder (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 obser ved for MITC, DPR will assume thatreduction in chloropicrin emissions for intermittent watering-in is approximately onethird of an untarped application. Other a pplication methods that appear to reduce chloropicrin emissions, such as pre-irri gation 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 gr oup will be used as the DPR estimated field adjustment factor value. Results are shown below:

Broadcast/No tarp & Bed field adjustme nt factor = 64% (n = 3, CV = 6%) Broadcast/Tarp field adjustment f actor = 44% (n = 3, CV = 35%) Broadcast/Tarp with intermittent watering-in = 20% Drip/High permeability tarp field adjustme nt factor = 12.3 (n = 1, CV = N/A) Drip/Low permeability tarp field adjust ment 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.

6Literature Cited

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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 Ja nuary 27, 2006. California Environmental Protection Agency. Department of Pestic ide 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 Manuf acturers Task Force. Department of Pesticide Regulation Registration data volume199-072.

DPR. 2002. Recommended Permit Conditions for Using 1,3-Dichloropropene Pesticides. Department of Pesticide Re gulation. Available on-line: http://www.cdpr.ca.gov/docs/enfcmpli/penfltrs/penf2002/2002037.htm

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

bromide volatilization afte r 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 ir rigation application method. Tri-Cal study number TC350. DPR registration volume 199-0114.

Johnson, B. 2006. Calculation of emission poten tial factors for 1,3-dichloropropene for five areas for periods from May 1 th rough October 31. November 30, 2006 memorandum to Randy Segawa. California Environmental Prot ection Agency. Department of Pesticide Regulation. Environmental Monitori ng 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 Ch emistry Laboratory B Indianapolis Lab, Dow AgroSciences LLC, 9330 Zionsville Ro ad, Indianapolis, Indiana 46268-1054. Study ID 980070.01.

7Lee, H., K.V. Natta, and M. Gillis. 1994. Chloropicrin workers exposure, flux, and offsite monitoring and dispersion mdoelign for tarped broadcast app lication – pilot study. TriCal study number TC246/BR707. DP R registration volume number 199-0079.

Levine, J., D. Kim, and P. Lee. 2005. Mon itoring an untarped bedded drip application of metam sodium in Merced Country. Calif ornia Environmental Protection Agency. Department of Pesticide Regulation. Envi ronmental Monitoring Branch. 1001 I Street, P.O. Box 4015, Sacramento, Ca 95812. EH05-03.

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Majewski, M.S., M.M. McChesney, J.E. Woodr ow, H.H. Prueger, and J.N. Seiber. 1995. Aerodynamic measurements of methyl bromid e 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 sha nk injection and sprinkler irrigation. Agrisearch Incorporated, 5734 Industry Lane , Fredrick, MD 21704-7293. December 14,

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Merricks, D.L. 2002. Determination of methyl isothiocyanate offsite air movement from application of Metam-sodium through sprinkl er irrigation. Agris earch Incorporated, 5734 Industry Lane, Fredrick, MD 21704-7293. January 10, 2002.

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10Table 1. Summary of methyl bromidemass loss estimates from the literature.Broadcast TarpReferenceStudy TypeSoil TypeDepth (cm)Mass Loss (%)Mean (%)CV (%)JEQ Vol 24:742FieldSilty Clay Loam2532JEQ Vol 25:185FieldSandy Loam2563JEQ Vol 26:310ColumnSandy Loam3043JEQ Vol 26:310ColumnSandy Loam3037JEQ Vol 26:310ColumnSandy Loam60264035Broadcast Non-tarpReferenceStudy TypeDepth (cm)Mass Loss (%)Mean (%)CV (%)JEQ Vol 24:742FieldSilty Clay Loam2589JEQ Vol 26:310ColumnSandy Loam2082JEQ Vol 26:310ColumnSandy Loam3071JEQ Vol 26:310ColumnSandy Loam6038ES&T Vol 30:1629ColumnSandy Loam3077ES&T Vol 30:1629ColumnLoamy Sand3077ES&T Vol 30:1629ColumnClay3037663411Table 2. Mass loss (% of applied mass) forvarious chloropicrinapplication methods.ReferenceApplication MethodLocationEmissions (%)Average (%)CV (%)Beard (1996)Broadcast/No TarpArizona62.5Beard (1996)Broadcast/No TarpArizona61.464.26.0Beard (1996)Bed/TarpArizona68.6Beard (1996)Broadcast/TarpArizona62.3Beard (1996)Broadcast/TarpWashington33.8Beard (1996)Broadcast/TarpFlorida36.544.235.6Rotonardo (2004)Drip/low perm. tarp15Knuteson and Dolder (2000)Drip/low perm. tarpCalifornia8.611.827.2van Wesenbeeck and Phillips(2000)Drip/high perm.tarpGeorgia12.312.3-12