UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C. 20460

										OFFICE OF

										PREVENTION, PESTICIDES

										AND TOXIC SUBSTANCES

MEMORANDUM

Date:		April 18, 2007

Subject:	Risk Mitigation Options to Address Bystander and Occupational
Exposures from Soil Fumigant Applications

From:		Steven Weiss, Chemical Review Manager

Special Review Branch, 

Special Review and Reregistration Division (7508P)

To:		Methyl Bromide Docket (EPA-HQ-OPP-2005-0123)

		1,3-Dichloropropene Docket (EPA-HQ-OPP-2005-0124)

		Metam Sodium/Potassium Docket (EPA-HQ-OPP-2005-0125)

		Dazomet Docket (EPA-HQ-OPP-2005-0128)

		Chloropicrin Docket (EPA-HQ-OPP-2007-0350)

		Iodomethane Docket (EPA-HQ-OPP-2005-0252)

Background

	The Environmental Protection Agency (hereafter referred to as EPA or
the Agency) is opening Phase 5 of the Public Participation Process for
five soil fumigants: methyl bromide (MeBr), metam sodium/potassium,
dazomet, chloropicrin (Pic), and 1,3-Dichloropropene (1,3-D).  The
Agency is also in the process of evaluating the registration of the new
soil fumigant iodomethane.  In 2004 EPA decided it would be appropriate
to review these chemicals as a group to ensure consistency in assessment
methods, and to ensure that the risks and benefits of each fumigant can
be considered in light of the risks and benefits of the others, under
the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), as
appropriate.   EPA is also evaluating applications for registration
actions on several soil fumigant uses that may utilize the risk
mitigation options described in this document.

	This document outlines the risk management options that EPA is
considering to address all risks, but focuses on the acute human
inhalation risks that have been identified in the revised risk
assessments for these six fumigants. EPA seeks public comment on these
risk mitigation options, particularly comments addressing cost,
feasibility, and effectiveness.  

	Soil fumigants are either volatile chemicals that become gases at
relatively low temperatures, around 40 degrees Fahrenheit, or they are
chemicals that react to produce such a gas (e.g., methyl
isothiocyanate).  Soil fumigants are used to control a wide range of
pests including insects, nematodes, fungi, bacteria, and weeds.  Because
of the broad range of pests controlled, soil fumigants are used as part
of the production for a wide variety of crops and provide high benefits
for many growers.  

As gases, however, fumigants move from the soil to the air at the
application site and may pose risks to bystanders who are exposed to
airborne residues that drift off-site.  Bystanders are people who are
not involved in the fumigant application but who live, work, or are
located in nearby areas where they may be exposed to airborne residues
emitted from the application site.  Bystanders include agricultural
workers in nearby fields who are not involved with the fumigant
application.  Incidents of bystander exposure confirm that fumigants
have the potential to move off-site at concentrations which produce
adverse health effects in humans.  

	A glossary of terms applicable to soil fumigation is included in
Appendix A of this document.

Summary of Risks

	Full discussions of the risks to humans from exposure associated with
the six soil fumigants are included in the following documents which can
be found on the federal-wide electronic docket management and comment
system located at   HYPERLINK "http://www.regulations.gov" 
http://www.regulations.gov .

Methyl Bromide: Phase 5 Health Effects Division (HED) Human Health Risk
Assessment For Soil, Greenhouse, and Residential/Structural Uses.  PC
Code: 053201, DP Barcode: D337288, April 10, 2007

Metam Sodium: Revised HED Human Health Risk Assessment for Phase 5; DP
Barcode: D337533, Metam Sodium PC Code: 039003, Metam Potassium PC Code:
039002, MITC PC Code: 068103	

Dazomet: Revised HED Human Health Risk Assessment for Phase 5; DP
Barcode: D306861, Dazomet PC Code: 035602, MITC PC Code: 068103		

Chloropicrin: Revised Health Effects Division (HED) Human Risk
Assessment For Phase 5, PC Code: 081501, DP Barcode: D305336	

1,3-Dichloropropene: Revised Health Effects Division (HED) Human Risk
Assessment For Phase 5, PC Code: 029001, DP Barcode: D337328

Iodomethane: Revised HED Human Health Risk Assessment; DP Barcode:
D325080, PC Code: 000011, January 5, 2006

	The Agency’s risk assessments indicate that the primary risk concerns
for the soil fumigants involve the acute exposures experienced by
handlers, post-application/re-entry workers, and bystanders. Dietary
exposure is negligible since the soil uses of these chemicals are
considered “non-food uses”.  Acute risks to bystanders, during and
after fumigations, may be of concern depending on the level of exposure
and toxicity of the fumigant.  Exposure depends on a number of factors
including application rate, application equipment, weather conditions,
field size and shape, soil characteristics, emission control, and
proximity to the field.  Also, risks to handlers involved in the
application of the soil fumigants and removal of tarps may be of
concern. 

Furthermore, EPA’s Office of Atmospheric Programs (OAP) has estimated
the number of UV-related skin cancer incidences and deaths based on
stratospheric ozone depletion due to methyl bromide’s uses.   OAP’s
assessment is included in the MeBr docket (EPA-HQ-OPP-2005-0123).  It
should also be noted that many of the soil fumigants are contributors to
ground level ozone which has been identified as an air quality concern
in parts of California, and possibly other areas of the United States.  
The Agency seeks comment on areas outside California where VOC emissions
from fumigant and other pesticides are a problem. 

	The reregistration eligibility decision (RED) document for 1,3-D was
completed in 1998. The EPA does not expect any need for additional risk
mitigation solely for 1,3-D.  However, many of the products that contain
1,3-D also contain chloropicrin, and EPA may require measures to
mitigate the risks of chloropicrin use.  Furthermore, many of the
mitigation options being considered for the other fumigants are generic
in nature and would enhance the safety of all soil fumigants, including
1,3-D (e.g.,  site-specific fumigant management plans, notification,
record keeping, etc.).  The Agency seeks comments on potential
advantages and/or disadvantages of requiring these options for 1,3-D as
well. 

Current EPA Mitigation Requirements for Soil Fumigants

	Buffer zones have been used by the EPA to mitigate risks from fumigants
and other types of pesticides.  Currently, 1,3-D, and dazomet product
labels are the only soil fumigants for which the Agency has required
buffer zones.  The experimental use permit (EUP) label for iodomethane
also requires buffer zones.

	All soil fumigant products containing methyl bromide, 1,3-D,
iodomethane, and chloropicrin are currently restricted uses products
(RUP).   Soil fumigant products containing metam sodium/potassium and
dazomet are not currently RUPs.  Handlers involved with the application
of RUPs must be certified applicators, or be working under the direct
supervision of a certified applicator.

	Soil fumigant labels also specify personal protective equipment (PPE)
requirements for handlers as well as entry-restricted periods following
fumigant applications.   

Current State Mitigation Requirements for Soil Fumigants

	Based on EPA’s information to date, only California and Wisconsin
have state regulatory programs requiring buffer zones and other
mitigation requirements that are more protective than what is currently
required by EPA.

	California

	

	California has developed guidance to aid County Agricultural
Commissioners in regulating fumigants.  Since the early 1990s, a major
element of California’s regulatory approach is the use of buffer zones
to protect bystanders and agricultural workers.  Currently, California
has statewide regulations or recommended permit conditions for MeBr,
1,3-D, and metam sodium/potassium to be used by County Agricultural
Commissioners when issuing use permits. Growers and professional
applicators in California must obtain a site-specific permit prior to
conducting soil fumigation.  As part of this permitting process, county
agricultural commissioners define buffer zones and specify other
applicable requirements based on information submitted by applicators. 

	California determines the size of buffer zones depending on the active
ingredient(s) used in the fumigant treatment.  For MeBr, look-up tables
that define buffer distances are based on the application method,
application rate, and field size.  For metam sodium and 1,3-D, current
buffer zone distances are based solely on the application method,
although new buffer zone requirements have been proposed for metam
sodium.  Although chloropicrin also requires a permit prior to
application, there are no statewide buffer zones required.  However,
chloropicrin is often applied in combination with other soil fumigants
(MeBr and 1,3-D); in this case, the buffer zone for chloropicrin is
determined by the buffer zone for the other soil fumigant (MeBr or
1,3-D) with which it was mixed. In cases where chloropicrin is applied
alone, many of the counties in California have opted to use the MeBr
buffer zones, or even larger buffers, even though these are not required
by state regulations.

	California’s Department of Pesticide Regulation (DPR) is in the
process of finalizing an MITC mitigation proposal document. This
document proposes buffer zones similar in structure to MeBr, with
look-up tables containing buffer zones distances that vary depending on
the application method, application rate, and field size. In addition
California County Agricultural Commissioners have the authority to
change the size of the buffer zone specified in look up tables, based on
their assessment of local conditions, worksite plans, and information
from the person seeking a permit.  This type of regulatory
infrastructure is unique to California and is not available to most of
the other states where soil fumigants are used.

   

Wisconsin 

	The Wisconsin Department of Agriculture, Trade and Consumer Protection
(DATCP) has requirements for metam sodium and chloropicrin soil
applications that are more protective than EPA's current requirements. 
In Wisconsin, metam sodium and chloropicrin applications must be done by
certified applicators; at least a 1/4 mile from sensitive sites (e.g.,
schools); the knife rig injection application method may not be used
when soil temperature is too high; and chemigation applications require
pre-notification to county public health authorities and neighbors
within a 1/4 mile of the site.  Wisconsin is also considering whether to
require tarps for certain chloropicrin applications.

	

Risk Management Options

	The Agency is soliciting comments on the risk mitigation options
outlined below which are based on the revised risk assessments, 
California’s guidelines for soil fumigants, EPA’s mitigation measure
requirements for methyl bromide’s commodity uses, and input from
growers, registrants, and other stakeholders.  It is the Agency’s
intent to develop risk mitigation measures that are clear, enforceable
and that reduce acute inhalation and other risks for:

bystanders who live and/or work near fumigation sites;

both handlers involved in the application of fumigants and
cutting/removing tarps; and

workers during reentry to fumigated fields.

	Although reducing risks from inhalation exposure is the focus of the
mitigation options described in this document, EPA expects that
mitigation options that result in reduction of fumigants applied and air
emissions will also reduce:

risks to terrestrial and aquatic organisms, including endangered
species;      

risks associated with poor air quality as a result of volatile organic
compound (VOC) emissions from soil fumigation applications;

risks resulting from stratospheric ozone depletion from MeBr soil
applications; and

other risks resulting from long-term exposure in areas of high use.

		

	At the same time, the Agency is mindful of the importance of soil
fumigation to the production of important food commodities.  Thus, the
Agency’s goal is to reduce risk while maintaining key agricultural
benefits.

	For the following and any other options you would like to suggest,
please provide comments for the following general questions, as
appropriate, and specific questions listed under each mitigation option:

General Mitigation Option Questions

Which fumigant(s), geographic region(s), and crop(s) do your comments
address?

What is the feasibility of implementing this option on a national level?

What are the economic costs and impacts associated with this option?
(e.g., to crop production)

How effectively would this option mitigate the acute inhalation and
other risks associated with soil fumigant applications?

Are there alternative approaches to this option? If so, please describe
and include the rationale for your alternate approach.



	All comments should be submitted to the public docket on the web at  
HYPERLINK "http://www.regulations.gov/"  http://www.regulations.gov/ . 
When submitting, please identify the question(s) to which you are
responding and include discussions, explanations, and references where
possible.	

	The Agency has identified eight mitigation measures that, if
implemented alone or in combination, would directly reduce potential
acute inhalation and other risks associated with soil fumigation
applications:   

buffer zones; 

sealing methods; 

timing of applications; 

application block limitations (e.g., size and proximity); 

respiratory protection;

tarp cutting/removal procedures; 

the entry-restricted period; and 

application method/practice restrictions.  

	In addition, EPA has identified nine mitigation measures that could
affect potential risks indirectly.   These options would facilitate and
ensure compliance, enforcement, and planning of soil fumigant
applications. These additional measures include:

site-specific fumigation management plans (FMPs), 

defining the responsible party, 

certification of FMPs, 

record keeping/reporting/tracking, 

notification/posting, 

classification of fumigants as restricted use pesticides (RUPs), 

good agricultural practices (GAPs), 

fumigation manuals, and 

stewardship programs.

	Most of these measures could be applicable to all of the soil fumigants
(e.g. fumigant management plans). However, some options apply only to
one or a few of fumigants (e.g. water application for MITC-generating
fumigants).

Buffer Zones 

General

	Establishing a buffer zone around a treated field is an effective
method for managing the risks from acute inhalation exposure to
bystanders.  The distance between the application site (i.e., edge of
field) and the bystanders allows airborne residues to disperse before
reaching the bystanders.  The greater the distance, the greater the
potential for residues to disperse, thus decreasing the likelihood that
air concentrations where bystanders are located will cause acute adverse
effects.  EPA’s goal is to determine distances, or buffer zones, which
will adequately protect bystanders from acute exposures, but which are
not so great as to eliminate benefits of soil fumigant use. The distance
or size of the buffer zones would be based on several factors that
include application rates, field size, application equipment/methods,
and emission controls measures (e.g., tarps).   Air monitoring data,
incident reports, and air dispersion modeling based on these factors can
be used to help determine appropriate buffer zones distances.  

	Although no final decisions regarding risk mitigation have been made,
the Agency believes that the use of buffer zones will likely be one of
the most important tools for reducing bystander risk for the soil
fumigants.  EPA recognizes that in some situations large buffer zones
would make the use of soil fumigants impractical for growing various
agricultural crops due to the proximity of homes, occupied areas, and
sensitive sites (e.g., schools).  However, EPA believes that in many
cases buffer zones – even large ones – will not be an impediment for
growers (e.g., for fields where no houses or occupied areas are
typically not in close proximity).   Also, based on California’s
experience, EPA thinks that an approach that gives flexibility to modify
treatment parameters to obtain smaller buffer zones, will also allow
most growers to continue to benefit from the use of soil fumigants
without adversely impacting the health and safety of bystanders and
agricultural workers.  

	Buffer zones, if required, would begin at the start of fumigation and
remain in effect for a specified period, with a minimum of 24 hours. 
The duration of the buffer zone requirement would depend upon when
off-site emissions have declined to a point where bystanders are no
longer at risk.  The Agency is currently analyzing risk assessment
results to determine which fumigants, application methods, and
conditions may warrant buffer zones lasting for longer durations. 

Specific Mitigation Option Questions

Please estimate the quantitative impacts of requiring buffer zones set
at the following distances:  100 feet, 100 to 300 feet, 300 to 500 feet,
500 to 1,000 feet, ¼ to ½ mile, and greater than ½ mile.

As part of the explanation of these impacts, please discuss how the
buffer zone distances listed above would change crop production
practices (fumigation schedules and size of treated fields, crop yields)
and what would be the associated costs?  

What are the costs of leaving areas un-treated as a result of the buffer
zones (e.g. fields near homes)? 

What are the costs of subdividing application blocks to achieve workable
buffers? 

To the extent possible, describe what buffer zone distance is not
feasible and why.  

Please discuss what you would do if new EPA restrictions made it
impractical to continue using the fumigant you are currently using. 
Please identify the next best alternative(s) to your current practice
and what costs would be associated with shifting to alternatives?  

Growers in California and Wisconsin are asked to comment on the
transition process from having no buffers to having buffers. Also,
please provide comments related to cost and feasibility of situations
where bystanders voluntarily moved while buffer zones were in effect to
comply with buffer zone requirements. 

How could you modify practices to get a smaller buffer?  Growers in
California, please comment on modifications that you have made to
achieve smaller buffer zones. 

Growers and/or other stakeholders, please comment on the proximity (e.g.
in meters or feet) of residential or other occupied areas that are
located near fields that are treated with soil fumigants.  Please
comment on the density of these areas within the proximity of
application blocks (i.e., 1 or 2 homes or subdivisions of multiple
houses).

Specify whether fumigated sites are owned or leased by growers.  



Fixed Buffer Zones 

	Fixed buffer zone distances for fumigants and other pesticides have
been used by the Agency in the past.  For example, the current buffer
zone distances required for 1,3-D products range from 100 to 300 feet.  
In this case, the buffer zone size for these products is not adjusted
for rate, field size, or other site conditions.  This type of buffer
zone is more easily understood and easier to enforce than the
scenario-based buffer zones.  The Agency believes that the use of fixed
buffer zone distances may be adequate for some scenarios, especially
when worst case buffer distances are workable for growers.  However, it
would be difficult to implement fixed buffer zone distances for many
fumigant scenarios that are both sufficiently protective and workable.

Scenario-Based Buffer Zones 

	While EPA could establish a nationally uniform buffer zone distance for
all applications of a particular fumigant, the Agency believes that
giving growers the ability to determine buffer zone distances based on
relevant site conditions (application equipment, application rate, field
size, emission control method, etc.) provides flexibility and decreases
the likelihood of overly restrictive buffers based only on worst case
conditions, or buffers which are not adequately protective.  Buffer zone
look-up tables could be provided to determine required distances taking
into account various combinations of mitigation measures.  However, this
flexibility also comes with added complexity in terms of understanding
how to use look-up tables and utilize options for obtaining smaller
buffers, educating growers, devising easily understood labels, and
enforcing these label requirements.   With stakeholder input, the Agency
is considering developing a windows based program with drop-down menus
that would allow users to determine buffer zone distances for various
site conditions based on the same distances in the buffer zone look-up
tables. 

	It is the Agency’s goal to implement an approach that, to the extent
possible, is not only protective of bystanders’ health, but also
provides growers with options for meeting buffer zone requirements. For
example, assume that the required (scenario-based) buffer zone distance
for a given application equipment (e.g., shank injection) using
conventional polyethylene tarps with the maximum application label rate
to a 40-acre application block with fumigant “X” is 500 feet. Also,
an occupied home is located 450 feet to the south of the application
block with no other occupied structures within a mile.  Depending on how
certain changes in the use of the fumigant might affect emissions, the
grower could have the following options to consider:

reduce the application rate to a level that results in a buffer zone
distance less than 450 feet while being still efficacious,

use an alternate sealing method, such as a high barrier film or
metalized tarp, that results in reduced emissions, smaller buffer and
potentially lower application rates,

split the application block into smaller segments and treat on different
days,

treat smaller segment(s) of application block that are closest to the
home first so that the smaller area(s) can be used as buffer when
treating the larger application block later, 

do not treat the 50 foot segment of the application block that is
closest to the home,

provide temporary housing to residents of the home while buffer zone
requirements are in effect,

use an alternate application method with a lower emission potential, or
consider alternate fumigants, other pesticides, or non-chemical
alternatives, or

use dispersion modeling to estimate buffer zone distances based on
refined site- or geographic-specific conditions.	

Specific Mitigation Option Questions

If scenario-based buffer zones were required by the Agency, please
provide increments of application rates and field sizes that should be
reflected in buffer zones look-up tables.

 

Geographic/Site-Specific Buffer Zones 

	The Agency has used air dispersion modeling with empirically-derived
emission data combined with measured meteorological data to help inform
its decision making in determining appropriate buffer zones.  Some
geographical areas of the US may not be reflected in the available
emission and meteorological data sets.  As described in the revised risk
assessments, there is some level of uncertainty when applying the
modeling results to the entire country.  The Agency is considering
allowing site-specific buffer zone distances to be based on the results
of modeling performed using more refined site- or region- specific
conditions (e.g., using local weather data).  This modeling could be
conducted by the fumigator, registrant, grower, or other party according
to detailed guidance provided by EPA.   A fumigation manual is a
possible method for providing guidance on how to perform this modeling. 
 

Minimum Buffer Zones 

	Using both empirical data and computer modeling, the Agency’s risk
assessments show that in some cases target air concentrations will not
be exceeded even without a buffer zone. While the assessments may
indicate instances where no buffer is needed, EPA requests comment on
whether to require a minimum buffer zone for all fumigant uses due to
potential variability in emission rate over a field and other factors
not accounted for by the computer model.

Maximum Buffer Zones 

	The Agency is considering a maximum buffer zone distance based on the
ability to manage and enforce large buffer zones, the need to add a
higher level of certainty to the restrictions by reducing large acreage
applications at the higher rates, and reported incidents involving large
acreage treatments. EPA requests comment on whether to require a maximum
buffer zone distance (e.g., ½ mile) for all fumigant uses (assuming
risks are not concern at that distance).

	

Occupied Structures

	The Agency is considering allowing buffer zones to contain structures
(e.g. homes or other buildings) that are normally occupied if the
responsible party can temporarily relocate occupants who voluntarily
agree to move out of the affected area during period that buffer zones
are required and take steps to ensure that no unauthorized persons enter
the structure during that time period.  

Exemptions  

	The Agency is considering allowing transit activities on streets,
roads, roads within agricultural property, highways, and other similar
sites of travel provided they are not within the minimum buffer zone
distances (as described above in the minimum buffer zone section).   The
Agency believes that to persons traveling through buffer zones for short
durations (beyond the minimum buffer) will not exceed the Agency’s
level of concern.

Specific Mitigation Option Questions

Are there any additional exemptions that the Agency should consider?



Buffer Zones Extending into Adjoining Properties

	There may be situations where the required buffer zone extends onto
adjacent agricultural properties owned by other parties.  If such a
situation exists, the Agency is considering a requirement that the
responsible party receives written permission from the adjacent property
owner for the buffer to extend onto their property and that the
responsible party must verify that there are no locations within the
buffer zone where bystanders are likely to be.

Specific Mitigation Option Questions

What information should be included on a written commitment from
adjacent property owners?

What form should it take?



Work Activity Restriction

	Application sites are often located near properties where agricultural
workers (i.e., bystanders) are present who are not under the control of
the fumigant applicator, grower (who owns, is leasing, or manages the
application site), or designated responsible party.  EPA believes that
the responsible party must take reasonable steps to ensure that persons
other than authorized handlers involved in the fumigation (including
tarp removers) do not enter the buffer zone.  If the responsible party
cannot ensure that unauthorized persons do not enter the buffer zone,
the responsible party will be required to post signs identifying the
boundaries of the buffer zones.

Inner and Outer Buffer Zones

	For methyl bromide, California requires an outer buffer zone based on a
hazard level of concern for a 24-hour exposure period and an inner
buffer based on a 12-hour exposure period.  Only authorized handlers
involved in the fumigant application are allowed to enter the inner
buffer zone while it is in effect.  Agricultural workers are permitted
to enter the area within the outer buffer but outside the inner buffer
provided certain conditions are met (e.g., work activities occur for
less than a specified time duration).  For fumigants with hazard levels
based on 24-hour exposure periods (e.g., MeBr and iodomethane),
establishing an inner buffer zone based on shorter time duration allows
agricultural workers to continue performing work activities without
experiencing exposures exceeding the Agency’s level of concern. 
Currently, risk assessments for fumigants with hazard levels based on
24-hour exposure periods do not estimate distances for shorter exposure
periods.   The Agency is considering modeling buffer zones distances for
inner buffer zones, where applicable (i.e. for fumigants such as MeBr
and iodomethane with hazard levels based on 24-hour exposure periods).  

Specific Mitigation Option Questions

Will having both inner and outer buffer zones be practical and feasible?



  Sensitive Sites

	The Agency believes that it may be prudent to require additional
protective measures for schools, child/adult day care facilities,
hospitals, nursing homes, prisons, and other sensitive sites:  for
example, a prohibition on a fumigation application while school is in
session within a certain distance (e.g., half mile) of the application
block.  Sensitive sites differ from occupied areas (e.g. homes and
businesses) in that their occupants cannot readily evacuate in the event
of mishap, are usually present for extended periods of time, and may
have increased sensitivity to adverse health effects (e.g. occupants of
nursing homes, hospitals, etc.) 

Specific Mitigation Option Questions

Are there areas not identified above that should be considered to be
sensitive sites?

Growers and other stakeholders are asked to comment on the distance of
sensitive sites to fields that are currently being fumigated.



 Sealing Methods

 

Tarps 

	In some cases the use of tarps might significantly reduce the size of
buffer zones because tarps can retain fumigants in the treated soil for
longer periods than fields treated without tarps.  Appendix B contains
some of the currently available data on emission reduction potential of
various tarps.  The revised risk assessment also identified available
flux studies for tarped applications.  Stakeholders are asked to provide
any additional data or citations for data and information not listed in
the risk assessments and Appendix B.  The Agency has drawn the following
conclusions based on available field and laboratory studies:

The use of conventional films such as low density polyethylene (LDPE) or
high density polyethylene (HDPE) in most cases provides a marginal
reduction of emissions for MeBr compared to not using a tarp.

The use of high barrier films (e.g., virtually impermeable film or VIF)
or metalized tarps can result in substantial reductions in MeBr
emissions.

Studies suggest that the use of high barrier films and metalized films
used with strip fumigation applications can allow significant reduction
in application rates of MeBr/chloropicrin with comparable pest control
and yields as typical MeBr/chloropicrin application rates under
conventional polyethylene films.  However, more research is necessary to
quantify the emission reductions.  

Similar rate reductions have been achieved using certain high barrier
films and metalized tarps with the MeBr alternatives - 1,3-D, and
chloropicrin.

By reducing the amount of MeBr that must be applied to the soil, high
barrier films and metalized films directly reduce the potential amount
of volatile MeBr that can be released to the atmosphere.

Use of high barrier films and metalized tarps can reduce ground-level
ozone resulting from soil fumigant use, and may help address air quality
problems in high-use areas.

While high barrier films can cost up to twice as much as the standard
polyethylene film, MeBr/ chloropicrin application rates under high
barrier films can be significantly lower than the conventional
application rates using conventional films resulting in the higher costs
for high barrier films being offset by the savings on MeBr/chloropicrin.

	Improvements in the newest types of high barrier films and the
introduction of the more flexible metalized films appear to have
addressed several previous concerns regarding the handling, tearing, and
soil adhering characteristics of high barrier film products.

Tarps are not typically used with MITC-generating fumigants and data
indicates that available tarps, including high barrier films, would not
effectively reduce MITC emissions. 

	The Agency is aware that the initial costs of using tarps or upgrading
to tarps with increased emission control may be substantial.  However in
some cases this option may enable users to apply lower rates, and
maintain or increase efficacy.  Lower fumigant application rates would
result in smaller buffer zone distances due to lower emissions. 

	There have been concerns that tarps with increased efficiency to
control emissions may also result in increased exposure during tarp
cutting and removing.  California has permeability requirements for
tarps with soil fumigants and prohibits the use of VIF tarps except when
used for research purposes. See the tarp cutting and removal section
below for further discussion on options for mitigating risks for tarp
cutting and removal. 

	The Agency has utilized available emissions data for various types of
tarps to the extent possible, but acknowledges that more data are needed
to better characterize the factors that may contribute to their
effectiveness in terms of emission reduction (i.e., flux rates) and pest
control. There are on-going studies being conducted by USDA’s
Agricultural Research Service (ARS) on the effectiveness of several
commercial tarps across the entire group of soil fumigants.  For more
information on fumigant research being conducted by ARS can be found at:
  HYPERLINK
"http://www.ars.usda.gov/research/programs/programs.htm?NP_CODE=308" 
http://www.ars.usda.gov/research/programs/programs.htm?NP_CODE=308 .

Specific Mitigation Option Questions

Are there other additional data or citations for data and information
related to emission reduction or pest control not listed in the risk
assessments or Appendix B?

For growers that are currently using one or more of these tarps, how did
the use of these tarps affect rates or efficacy? Please specify the
fumigant you applied and whether you used LDPE, HDPE, high barrier
films, or metalized tarps.

Growers that are not using these tarps and researchers, please provide
comments on the feasibility of using tarps or upgrading to tarps that
have increased emission control. Also include information on effect of
tarps on rates and efficacy.

Growers, please comment on potential problems with disposing of used
tarps, including cost and availability of tarps.  Are there any
fees/costs associated with disposal in your area?  Are there any
recycling programs for tarp materials?

EPA understands that historically there have been problems with gluing
VIF sections together.  Have newer generation VIF tarps, metalized
tarps, and glues addressed this problem?

	

Water Applications

	Currently, applying water immediately following an application (and in
some cases again intermittently thereafter) is a method that is used
predominately with the MITC-generating fumigants to reduce emissions. 
As mentioned previously, the Agency has used empirical data to determine
emission rates for various water application methods and to estimate
resulting buffer zone distances.  The Agency believes that water
applications, when feasible and done correctly, may be an effective
means to reduce emissions from MITC- generating fumigants.  

	The Agency is considering the following requirements for water
applications with metam sodium/ potassium:	

a minimum time period that irrigation equipment and water must be
available after the application

a minimum volume of water to be applied within the time period
immediately following application

Specific Mitigation Option Questions

For what types of application methods would water applications
effectively reduce off-site emissions?

Can water applications be effectively used to reduce emission from other
fumigants besides the MITC-generating fumigants? 

Is irrigation equipment available for all crops for which metam
sodium/potassium is used?

If irrigation equipment is available, please describe the associated
costs.  



Compaction Methods

	Other sealing methods such as using rollers or Yetter rigs to close the
chimney created by the injection knives and compact the soil immediately
after injecting fumigants, and using soil amendments to form a reactive
layer on the soil surface may also be effective methods for reducing
emissions.  The Agency has used available empirical emissions data to
the extent possible to evaluate the effectiveness of these methods, but
acknowledges that more data would help characterize the potential
reduction in emissions.  

Specific Mitigation Option Questions

For which fumigants can compaction sealing effectively be used to reduce
emissions? To the extent possible, please cite supporting data and/or
references.

When compaction is used, please provide a detailed description of the
process (e.g., rollers or other devices); amounts of pressure needed;
limitations based on soil type; moisture content; and injector
type/depth.



Timing of Applications

	Generally, less stable atmospheric conditions occur during the daylight
hours and therefore dissipate the fumigant more rapidly than more stable
night time conditions.  The Agency seeks comments and suggestions on
whether application time restrictions would help ensure that periods of
peak emissions do not coincide with stable atmospheric conditions
occurring at night.

Application Block Limits

Multiple Application Blocks

	The Agency is concerned about the potential contribution to bystander
exposure from multiple treated fields that are adjacent to each other or
lie within the same vicinity, if the fields are treated at the same
time.  The Agency is considering a prohibition on fumigating any
application block within a certain distance (e.g. a half mile) of
another application block that has been fumigated within a 24-hour
period, or longer if necessary.  Fumigators, fumigant distributors,
and/or growers would need to ensure that nearby growers are not
fumigating within the same time frames and applicable buffer zones would
still be required.  The fumigation management plan (FMP) and
notification process will need to incorporate this option, if required.
This measure could minimize the potential contribution of multiple
fields to bystander exposure.

Specific Mitigation Option Questions

How could fumigators, fumigant distributors, and/or growers ensure that
nearby growers are not fumigating within the same time frames?



Size of Application Blocks 

	The Agency’s use analysis, included in the docket, provides
preliminary estimates of field sizes currently treated in the US.  The
Agency is considering limiting the size of application blocks for some
use scenarios to reduce the risks to bystanders. 

Specific Mitigation Option Questions

Please describe scenarios that require application blocks of greater
than 40 acres. For these scenarios, would it be feasible subdivide the
application blocks into smaller areas, to be treated on different days?

Please estimate the quantitative impacts of limiting application blocks
to the following sizes:  40 acres, 40 to 60 acres, 60 to 80 acres, and
greater than 80 acres.



Respiratory Protection for Occupational Activities

	Revised risk assessments for MeBr, metam sodium/potasium, dazomet,
chloropicrin, 1,3-D, and iodomethane identify inhalation hazard levels
(i.e., endpoints and uncertainty factors) for occupational risk
assessment.  The revised risk assessments show risk concerns for several
handler scenarios when no respiratory protection is used.  In some cases
inhalation risks can be mitigated with the use of air purifying
respirators equipped with approved respirator cartridge filters. 
However, for scenarios involving air concentrations where these
respirators do not provide adequate assigned protection factors or where
no approved respirator filter exists, the use of self-contained
breathing apparatus (SCBA) may be required to adequately reduce the
risks to handlers.  EPA is considering requiring that labels identify
appropriate respiratory protection based on applicable air concentration
levels and/or specific work activities (e.g. application, tarp cutting,
etc.).  

	Assigned protection factors (APFs) for respirators are used to
determine the reduction of exposure, and are based on the assumption
that users have been fit tested, medically qualified, and trained (these
are not currently required by the Agency).  

	In order to ensure compliance with respirator requirements specified on
labels,  the Agency is considering requiring that occupational and area
air monitoring be conducted to quantify potential exposures.  Of
particular concern are handlers without respiratory protection working
within the buffer zone area.  Such monitoring would need to utilize
appropriate analytical methods, given the specific chemical and
concentration of concern.   For example, monitoring methods would need
to have a limit of quantification (LOQ) that is equal or less than the
exposure level of concern. 

Specific Mitigation Option Questions

To what extent are workers who are currently required to wear
respirators fit-tested, medically qualified, and trained?  Please
specify if fit testing is qualitative or quantitative.

What procedures, if any, should the EPA require to ensure that workers
who are required to wear respirators are fit-tested, medically
qualified, and trained (e.g., require on all labels, recordkeeping,
etc.)?

Fumigators or growers, please describe what air monitoring is currently
performed during and after each fumigation application. Please also
include measurement method(s) as well as LOQ.



Tarp Cutting and Removal

	Fumigant gases that may be trapped under the tarp can be released when
the tarp is cut, particularly when high barrier films are used. 
Handlers cutting and removing tarps may be exposed to air concentrations
that exceed the Agency’s level of concern.  The Agency is considering
requiring the following: a minimum time between application and tarp
cutting (e.g., 7-10 days); use of respiratory protection; or the use of
mechanical devices (e.g. using all-terrain vehicles with cutting
implements attached).  In addition, if tarps are to be removed within 14
days of a fumigation treatment, the Agency is considering the
requirement that tarps be cut (but not removed) at least 24 hours prior
to tarp removal.  The Agency believes that these measures will minimize
handler exposure to remaining fumigant vapors trapped under tarps. 

 Entry-Restricted Period

	The current entry-restricted period for soil fumigants ranges from 2 to
5 days.  All persons, including agricultural workers who are not
involved in the application and tarp removal, are prohibited from
entering the treated area during these periods.  In most cases the
majority of fumigant mass applied using no tarp or under conventional
tarps is emitted during the first 48 hours of an application. However in
some cases, the fumigants being emitted from the treated field may take
much longer (up to a week) to fully off-gas.  For these situations, the
Agency is considering lengthening current entry-restricted periods until
air concentrations in the treated area decline to levels that will not
exceed the Agency’s level of concern.

Specific Mitigation Option Questions

What postapplication activities are performed within the 7 to 10 day
period following fumigant applications?  

What impact, if any would result from extending the current
entry-restricted period?

 

 Application Method/Practice Restrictions

	The Agency is considering prohibiting certain application methods
and/or practices that have been shown to have high emission potential or
that can lead to risks that exceed the Agency’s level of concern
(e.g., overhead sprinkler irrigation under certain application
conditions).  EPA may also prohibit application methods where adequate
emissions data are not available to estimate exposure.  The revised risk
assessments identify these data gaps, where applicable. 

 Site-specific Fumigation Management Plans (FMPs)

	There is risk reduction value in encouraging fumigators to anticipate,
recognize, and evaluate the factors that could lead to bystander
exposures that are of concern.  A valuable supplement to other
requirements is a comprehensive site-specific fumigant management plan. 
FMPs were required by the Agency for methyl bromide’s commodity uses,
and public comments submitted to the docket for this requirement were
generally supportive.  FMPs are also required for the structural
fumigations with phosphine gas.  In addition, FMPs were required as a
condition of an experimental use permit (EUP) granted in 2006 for the
soil fumigant, iodomethane.   It should be noted that soil fumigation
applications are complex operations, and to ensure that all label
requirements are met, EPA believes that FMPs are necessary for adequate
planning, compliance, and enforcement. A sample of elements that the
Agency believes should be included in a comprehensive soil FMP are:

General site information 

Site operator/owner, site address, phone number

Fumigator/applicator information (license #, address, phone, contact
information for person supervising the fumigation, i.e., the responsible
party)

Type of fumigation (e.g., shank, broadcast, raised bed)

Proximity of application block to structures, sensitive sites, and other
nearby application blocks

Map or detailed sketch showing field location, dimensions, property
lines, public roads, water bodies, wells, rights-of-ways inside buffers,
surrounding structures, and sensitive sites (such as homes, schools,
hospitals, employee housing) with distances from the application site
labeled

Application procedures 

Date of fumigant application

Product information (brand name, registration number)

Application rate for each field to be treated

Equipment to be used

Number of acres to be treated

Fumigation window (earliest and latest date of fumigation)

Type of tarpaulin (e.g., HDPE, LDPE, high barrier, metalized tarps) 

Perimeter air monitoring to be done (locations to be monitored, methods,
procedures, and equipment)

Buffer zones 

Show location of buffer zone on map/sketch

Start and stop times for buffer zones

Authorized on-site personnel  

Names of fumigators (for restricted use pesticides, fumigation workers
must be certified applicators, or be working under the direct
supervision of a certified applicator)

Names of other on-site workers and procedures for keeping them out of
treatment area and buffer zone

Personal protective equipment for fumigation workers (selection,
respirator fit-testing, training, medical exams,  maintenance, storage
procedures)

Posting (location of posting signs, procedures for posting and sign
removal)

Notification to neighboring property owners, employers (plans, methods
of notification, procedures, steps to ensure neighboring property owners
keep workers out of the buffer zones, dates and record of notifications)

Tarpaulin repair and response plans

Person(s) responsible

Schedule and procedures for checking tarpaulins for damage, tears, and
other problems

Air monitoring equipment and procedures for testing air concentrations

Respiratory protection devices to be used and procedures for
fit-testing, maintenance, and storage.

Plans for determining when and how repairs to tarpaulins will be made,
and by whom

Minimum time following injection that tarpaulin will be repaired

Minimum size of damage that will be repaired

Other factors used to determine when tarpaulin repair will be conducted

Tarpaulin removal plan

Person(s) responsible

Schedule, equipment and methods used to cut tarpaulins

Aeration plans and procedures following cutting

Schedule, equipment, and procedures for tarpaulin removal

Record keeping procedures

Emergency procedures (evacuation routes, locations of telephones,
contact information for emergency company, local/state/federal contacts,
key personnel and emergency responsibilities in case of an incident,
equipment/tarp/seal failure, odor complaints or elevated air
concentration levels outside buffer zone suggesting potential problems,
or other emergencies).

Site security 

Hazard communication (product labels, material safety data sheets, etc.)

Name, address, contact information, credentials, and signature of
certifying party

	In addition to helping ensure fumigators successfully plan all aspects
of a safe fumigation, FMPs will also likely be a major tool for federal,
state, and local regulators to ensure compliance with labeling and
regulations associated with soil fumigations (see record keeping section
below).

Specific Mitigation Option Questions

Besides California where worksite plans are required to obtain a permit,
to what extent are fumigators currently using FMPs? 



Responsible Party

	For each fumigation event, the Agency is considering requiring that
there be a clear identification of the party who is responsible for
ensuring compliance with label requirements.  In many cases, handler
activities other than the application (e.g. water application, tarp
repair, tarp removal, etc.) are conducted after commercial fumigators
have left the application site.  The responsible party and their
applicable duties that may impact their own risk as well as other
handlers, agricultural workers, and bystanders would need to be
identified in the FMP. 

Specific Mitigation Option Questions

Should the fumigator/applicator be the responsible party for all aspects
of the fumigant application process in regard to label requirements
including tarp cutting and removal?

What are the pros and cons of allowing the responsible party duties to
be shared among different parties (e.g., fumigator, growers, and other
parties)?   



Certification of FMPs

	The Agency is considering requiring that the person supervising the
fumigation, or the responsible party, certify in writing that he/she has
reviewed the FMP and that it addresses all elements required by product
labels, and that all decisions on the fumigation processes, buffer
zones, and PPE are appropriate and protective.  EPA is also considering
allowing state or local governments the option of implementing their own
FMP certification process, or allowing fumigators to either self-certify
or contract a third-party for FMP certification.  The Agency believes
that since most of the states do not have an infrastructure like
California’s with county agricultural commissioners, this option of
allowing self- or third-party certification becomes an important
compliance assurance tool and can be potentially implemented without
placing the burden of reviewing FMPs on states that choose not to assume
the burden.

Record Keeping, Reporting, and Tracking

	There are currently no requirements on EPA labels for applicators or
growers to keep records of applications made. However, many fumigants
are restricted use products (RUPs) and certain records must be kept.
Reporting and tracking of applications as part of a site-specific FMP
could be a major tool for federal, state, and local regulators to ensure
compliance with labeling and regulations associated with soil
fumigations.

Notification/Posting

	If buffer zones are used, bystanders will need to be informed about the
location and timing of the fumigation to ensure they do not enter areas
designated as part of the buffer zone. Furthermore, EPA believes that
bystanders not involved in the fumigation could take other steps to
protect themselves if they were aware of potential risks associated with
soil fumigations that are occurring near where they live and work.  This
can be accomplished by posting signs, as well as through other
communication methods (e.g., verbal and/or written notification). 
Providing access to site-specific fumigation management plans (FMPs) is
one option that may be used to convey useful information to potential
bystanders.  The Agency does recognize that some of the information in
the FMPs may be confidential and other information included in the FMPs
may not be useful to neighbors.  EPA believes the critical information
that must be communicated to all bystanders includes:

Location of the application block including address

Fumigant(s) applied including EPA Registration #

Potential symptoms and adverse health effects from exposure

Applicator license number and contact information

Responsible party(ies) for all aspects of the fumigation process
(including water application and tarp removal)	

Location of buffer zones 

Date/time for start and stop of buffer zones

Entry-restricted period for application block

Emergency procedures and contacts

Notification of local fire departments and first responders

Specific Mitigation Option Questions

What information not listed above should be provided to potential
bystanders?  Include rationale for providing information.

Who should be notified prior to applications?

Where and when should notification be given?

How often should notification be given?

What is the best way to provide this information?



 Restricted Use Pesticides (RUPs)

	All soil fumigant products containing methyl bromide, 1,3-D, and
chloropicrin are currently RUPs.   Soil fumigant products containing
metam sodium/potassium and dazomet are not currently RUPs.  The Agency
is considering making all of the soil fumigants restricted use
pesticides based on the following:

Many of the fumigants or fumigant byproducts (e.g. MITC) are acutely
toxic and trigger RUP classification. 

In order to apply soil fumigants safely and ensure bystanders are not
adversely affected, handlers need specialized training beyond what
labeling can communicate. 

To apply soil fumigants accurately and safely, special equipment is
needed (e.g., chemigation equipment, injection rigs, self-contained
breathing apparatus).

Soil fumigants have the potential to cause profound sub-acute,
sub-chronic, or chronic effects even if the acute toxicity does not hit
RUP triggers.

If any of the soil fumigants are not applied correctly, bystanders may
be exposed to concentrations that exceed levels of concern and/or cause
adverse effects.

There is a history of incidents in which multiple bystanders experienced
illness/injury despite being several hundred to several thousand feet
from the treated area.

The application of soil fumigants can pose hazards for several hours to
several days after application, and so, depending on the situation,
worker and/or area air monitoring may be required to ensure that
exposure limits are not exceeded.

Fumigators need an emergency action plan in case of mishap, or if
weather conditions (e.g., inversion) favor off-site movement of the gas.

	As part of the Agency’s Certification and Training Regulations, EPA
requires pesticide applicators to meet certain training and/or testing
requirements before they use or supervise the use of restricted use
pesticides.   Currently these regulations do not require any training
specifically on the safe handling of soil fumigants.  The Agency
believes that a formal training program may be an effective way to
maximize compliance with labeling requirements, and more importantly
minimize the risk of worker and bystander inhalation exposure associated
with soil fumigations.   The Agency also recognizes that many of the
steps needed to ensure a safe and effective soil fumigation application
are very unique.  A possible option would be to establish a soil
fumigator training and certification category under the Agency’s
Certification and Training Regulations based on training programs
already being used by state agencies, and industry.  Alternatively, EPA
could require registrants to develop training programs as part of
product stewardship (see section below on stewardship).  For example,
EPA would establish criteria for programs and registrants would develop
materials, train/certify applicators that purchase and use their
products.  

 Good Agricultural Practices (GAPs)

	The Agency believes requiring GAPs to be included on labels (e.g., soil
preparation/tilling, target moisture content, temperature, “sealing”
and/or surface compaction, weather criteria, etc.) will minimize
inhalation and other risks from fumigant applications.  Several fumigant
products already incorporate some of these measures on their labels.  

Specific Mitigation Option Questions

The Agency requests specific examples of (1) information where the
employment of GAPs would have prevented incidents, (2) GAP risk
reduction options, as well as (3) ways to make sure GAPs are followed. 
For example, ways to ensure that: the application does not begin at a
calm period; the applicator does not fumigate the soil at too hot of a
temperature; the soil is properly prepared and free of clods; the soil
has proper moisture; end row spillage does not occur; proper
discing/cultipacking is performed; beds are properly formed; end-guns
are turned off for center-pivot applications; and, for sprinkler
applications, nozzle heights are as low as is feasible. 

Should GAPs apply to all, or only some, of the fumigants?

What changes, if any, would result if GAPs were required? 

Should GAPs be advisory or mandatory?



Soil Fumigation Manual

	The Agency is considering developing a manual to provide guidance to
fumigators, growers, and other stakeholders on how to conduct soil
fumigations that are in compliance with EPA labels.  The manual could
potentially include guidance on how to determine buffer zones with
site-specific modeling and monitoring data.   As previously mentioned,
scenario based buffer zones involve some complexity that will require
growers, applicators, and other stakeholders to be adequately educated
on the requirements of the EPA labels.  The Agency is currently
developing a similar manual for MeBr commodity uses. 

Stewardship Program

	The Agency is considering requiring fumigant registrants to conduct a
stewardship program independently or together with the other fumigant
registrants, with the following elements: 

Educational/ training materials in both English and Spanish that are
designed to educate workers regarding work practices that can reduce
exposure to fumigants, including:

Good agricultural practices (GAPs) that reduce emissions and minimize
bystander exposure, 

The recognition of symptoms associated with fumigant exposures,

How to seek medical attention in the event workers experience such
symptoms.

Development of channels for disseminating these training materials to
workers involved in the application of fumigants or in agricultural work
practices that may result in exposure to fumigants and a means of
certifying applicators periodically (e.g. every 2 years).

A description of how and who will conduct the training.

Appendix (A) – Definitions

To aid stakeholders in commenting on this document, definitions for the
following terms are provided:

Application Block: A field or portion of a field treated with a fumigant
in any 24-hour period.

Application Period: In this document, application period refers to the
time required to incorporate a fumigant into the prepared soil. It is
important to note that the time required to apply additional water to
the treated soil to suppress emission of the fumigant into the
atmosphere is not considered part of the application process. It does,
however, fall under the definition of a handler activity.

Buffer Zone: The area that surrounds a pesticide application block in
which certain activities are restricted for a specified period of time
to protect people from potential adverse effects associated with a
pesticide application.

Bystander:  Any person living, working, or located near a fumigant
application that may be exposed to emissions coming off the treated
field.   Bystanders may not know a fumigation application has occurred.
Handlers involved with the fumigation are not bystanders.

Fumigation Handler: Refers to persons assisting the overall operation
including: covering the tarpaulin at the end of the rows (shoveling);
ensuring proper tarpaulin placement, changing cylinders (copiloting);
operating application equipment (driving); supervising; and tarpaulin
cutting and removal.

Good Agricultural Practices (GAPs): Good Agricultural Practices, more
commonly referred to as GAPs, are a set of practices that can help
improve the quality and safety of a pesticide application.  GAPs are
guidelines that can be adapted and/or incorporated into any pesticide
application.

Postapplication Worker:  Postapplication workers re-enter treated fields
after the entry-restricted period has ended to perform various
agricultural work tasks.   Tarp removal and repair are handler
activities and are not considered postapplication works tasks.

Responsible Party:  Person(s) who are responsible for ensuring that all
aspects of the EPA approved product label are adhered to (e.g.,
certification of the fumigant management plan, notification/posting,
supervision of the application, supervision of tarp cutting/sealing,
supervision of water application, removal of posting, etc.)

Sealing Method - Refers to the method used to seal the soil surface
through the use of tarps, compacting the soil, or adding water; and
using specialized application equipment and practices.   Sealing methods
in some cases reduce the rate at which fumigants are emitted from soil.

Sensitive Site: An area designated as sensitive due to the proximity of
occupied sitea (e.g., schools, child day care facilities, hospitals,
nursing homes, prisons, and other sensitive sites) to the application
block to be treated.  Sensitive sites differ from other occupied areas
(e.g. homes and businesses) in that their occupants can not readily
evacuate in the event of mishap, are usually present for extended
periods of time, and may have increased sensitivity to adverse health
effects (e.g. nursing homes, hospitals, etc.). 

Appendix (B) - References for studies on emission reduction of tarps

Fenimore, S.,  Z.Kabir,  H.Ajwa,  O.Dangovish,  K.Roth,  J.Valdez, 
2003.  “Chloropicrin and Inline Dose-Response Under VIF and HDPE Film:
Weed Control Results”,  presented at the 2003 annual International
Methyl Bromide Alternatives and Emissions Reduction Conference.

Gamliel, A.,  A.Grinstein,  M.Beniches,  J.Katan,  J.Fritsch,  P.Ducom. 
1998a. “Permeability of Plastic Films to Methyl Bromide: A Comparative
laboratory Study”.  Pesticide Science. 53  pp.141-148.

Gamliel, A.,  A.Grinstein,  L.Klein,  Y.Cohen,  J.Katan.  1998b. 
“Permeability of Plastic Films to Methyl Bromide”.  Crop Protection.
17  pp.241-248.

Gilreath, J.P.,  J.Noling,  2004.  “Use of Virtually Impermeable
Plastic mulches (VIF) in Florida Strawberry”.  Presented at the 2004
annual International Methyl Bromide Alternatives and Emissions Reduction
Conference.

Gilreath, J.P.,  T.Motis,  B. Santos,  2005.  “Cyperus spp. Control
with Reduced Methyl Bromide Plus Chloropicrin Rates Under Virtually
Impermeable Films in Peppers”.  Crop Protection. 24  pp.285-287.

Gilreath, J.P.,  B.Santos,  J.Mirusso,  J.Noling, P.Gilreath,  2005b. 
“Application Considerations for Successful Use of VIF and metalized
Mulches with Reduced Fumigation Rates in Tomatoes”.  HS287,
Horticultural Sciences Depaartment, florida Cooperative Extension
Service, Institute of Food and Agricultural Sciences, University of
Florida, August 2005.

Hamill, J.E.,  D.Dickson,  L.T-Ou,  L.Allen,  N.Burelle,  M.Mendes, 
2004.  “Reduced Rates of MeBr and C25 Under LDPE and VIF for Control
of Soil Pests and Pathogens”  presented at the 2004 annual
International Methyl Bromide Alternatives and Emissions Reduction
Conference.

Ha, Wonsook, Ajwa, H, “Plastic Film Permeability To Soil Fumigants”
presented at the 2006 annual International Methyl Bromide Alternatives
and Emissions Reduction Conference

Majewski, M.,  M.McChesney,  J.Woodrow,  J.Pruger,  J.Seiber,  1995. 
“Aerodynamic Measurements of Methyl Bromide Volatilization from Tarped
and Nontarped Fields”.   J. Environ. Qual.  24  pp.742-752.

Papiernik, S.,  S.Yates.  2001.  “Transport of Fumigant Compounds
Through HDPE and Virtually Impermeable Films”  presented at the 2001
annual International Methyl Bromide Alternatives and Emissions Reduction
Conference.

Trout, T. “Fumigant Use In California – Response To The Phase-Out”
presented at the 2006 annual International Methyl Bromide Alternatives
and Emissions Reduction Conference

Wang, D.,  S.Yates,  F.Ernest,  J.Gan,  W.Jury,  1997.  “Reducing
Methyl Bromide Emission with a High Barrier plastic Film and Reduced
Dosage.  Environ. Sci. Technol.  31  pp.3686-3691.

Williams, J.,  N.Yang,  R.Cicerone.  1997.  “Summary of Measured
Emissions of Methyl Bromide from Agricultural Field Fumigations from Six
Sites in Irvine, California”  presented at the 1997 Methyl Bromide
State of the Science Workshop, Monterey  Cal.

Williams, J.,  N.Wang,  R.Cicerone.  1999.  “Methyl Bromide Emissions
from Agricultural Field Fumigations in California”.  J. Geophysical
Res.-Atmospheres  104  pp.30087-30096.

Wofford, P.,  R. Segawa,  1998.  “Monitoring Results froom the Tarp
Removal of a Very High Barrier Tarp Application in Santa Cruz County”,
California Department of Pesticide Regulation.

Woods, C.  “Florida research Shows Metalized Bed Covers Can reduce
MeBr Use”,  article based on an interview with Jim Gilreath.  March
23, 2006.

Yagi, K.,  J.Williams,  N.Wang, R.Cicerone,  1993 “Agricultural Soil
Fumigation as a Source of Atmospheric Methyl Bromide”.  Proc. Natl.
Acad. Sci.  90, 8420.

Yagi, K.,  J.Williams, N.Wang,  R.Cicerone. 1995.  “Atmospheric Methyl
Bromide from Agricultural Soil Fumigations”.  Science  267 
pp.1979-1981.

Yates, S.,  J.Gan,  F.Ernst,  A.Mutziger,  M.Yates 1996a.  “Methyl
Bromide Emissions from a Covered Field. 1. Experimental Conditions and
Degradation in Soil”.  J. Environ. Quality  25  pp.184-192.

Yates, S.,  F.Ernst,  J.Gan,  F.Gao,  M.Yates. 1996b.  “Methyl Bromide
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