Revised 9/9/2007 - 1 - Economic Consulting, LLC (Brian D. Adam, Ph.D.)
Cost Comparison of Methyl Bromide and ProFume® for Fumigating a Food Processing Facility
A Report to National Pest Management Association
and Dow AgroSciences
by Brian D. Adam, Ph.D.1
Abstract Costs of fumigating a food processing/warehouse facility using Methyl Bromide and ProFume® are compared using an economic-engineering approach. The two fumigants are also compared for fumigating cocoa beans.
Introduction The purpose of this analysis is to compare the costs of fumigating using methyl bromide
(MeBr) with the costs of fumigating using ProFume® (PF), or sulfuryl fluoride, specifically in
food processing firms and in cocoa bean storage facilities. An economic-engineering approach
is used, estimating costs using engineering and technical specifications. This approach provides
estimates of costs that “typical” firms would face under alternative scenarios, rather than what
particular firms experience under firm-specific situations.
As such, this approach permits comparisons between the two fumigants while holding
other factors constant. Statistical techniques such as econometrics would permit such a
comparison if sufficient data with consistent measurements were available, but since the
number of firms using the two fumigants is low, and the number of fumigations in which those
firms have used PF is very low and under widely varying conditions, the usefulness of
statistical comparisons is likely quite low.
A potential limitation of an economic engineering approach is that, because it is based
on technical and engineering specifications, it may not reflect realities of use in actual
fumigation situations. To provide confidence that the individual cost components reflect the
realities of actual fumigations with these products, the economic engineering estimates are
calibrated based on the reported experiences of companies that have actually fumigated food
1 Professor, Agricultural Economics, Oklahoma State University. Comments by Edmond Bonjour, Gene Harrington, Dan Jenkins, Tom Phillips, and Surresh Prabhakaran are gratefully acknowledged. Any remaining errors are the responsibility of the author.
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processing firms and cocoa bean storage facilities using both MeBr and PF. Additional data
were obtained from distributors of the two fumigants.
As an expansion of the core study, these results are compared with results from
specifications based on laboratory tests and other field tests. These differ from the results of the
fumigator and distributor interviews primarily in the dosage that is assumed to be required for
each of the two chemicals. The purpose of these additional comparisons is to compare the costs
of using these two fumigants should one or more of the parameters change over time, or differ
across users. The research is not intended to provide information about the profitability of
fumigation, so the analysis focused primarily on those components of cost where there were
measurable differences between the two fumigants.
The Approach: From the perspective of the fumigator, the profitability using either fumigant is Revenue
Received from Fumigation minus Cost of Fumigation, where Revenue = Amount received from
the fumigation customer (Client), and Cost = Labor Cost + Equipment Cost + Cost of
Chemicals Used.
Revenue
Revenue received from the Client is composed of the fumigation charge, plus any value to the
Client from any reduction in downtime achieved by using one fumigant over another (to the
extent the Client is willing to pay the fumigator for this added value), and any value the Client
received and is willing to pass on to the fumigator from being able to claim that they use an
“environmentally-friendly” fumigation process.2 The fumigation charge is typically based on a
cost-plus bid by the fumigator, although specific contract provisions (such as whether the
Client or the fumigator pays for costs of extra fumigant needed during the fumigation because
of structural characteristics) differ across fumigating firms.
Since the focus here is on cost of using each fumigant, the revenue received from the
fumigation charge is not included in these calculations. Similarly, any public relations benefits
of using a non-ozone depleting chemical would depend on individual firms’ marketing efforts,
and is not explicitly considered here. 2 One of the fumigating companies interviewed reported that at the same time a food manufacturer announced to the public that it does not fumigate, it was relying on its suppliers to keep its inputs insect-free, which typically required fumigation.
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Costs
Labor Cost
Labor used in a fumigation includes a survey or analysis (screening) of the fumigation site
(typically by a supervisor), then preparation of the facility by workers (including thorough
sealing of vents and other openings; according to firms interviewed, this often can be done
while the plant or warehouse is in operation), the actual fumigation, aeration of the facility after
fumigation, and removal of temporary sealing materials.
All of the fumigators surveyed indicated that these job components differed very little
between the two fumigants. Some indicated that if there were any differences, PF required
more attention to sealing because it is more volatile (technically, it has lower specific gravity –
see Thoms and Phillips – and has a higher vapor pressure). In addition, they indicated that PF
might require more setup time because hoses are inserted into the facility from outside, whereas
MeBr tanks are brought into the facility itself.3 On the other hand, the additional time and effort
required for PF at these stages might be offset by reduced time needed for takedown (since PF
tanks are already outside the facility and don’t need to be taken out of the building).4 Also,
because PF has higher vapor pressure and lower sorption, most of the fumigators reported that
aeration of the facility after fumigation would take less time.
Several noted that if a fumigator has fumigated a particular structure previously, often
this experience can permit the fumigator to reduce the amount of chemical needed, because
leaks have been identified and sealed, or specific problem areas encountered in previous
fumigations can be addressed before the actual fumigation. (Since most of the fumigators
interviewed had less experience with PF, these experience-based adjustments applied primarily
to MeBr fumigations.)
3 However, Thoms and Phillips note that methyl bromide can be introduced into a structure from the outside, and one of the fumigators interviewed reported capability of doing that. 4 The similarity between MeBr and PF fumigations in these kinds of costs is supported by the reported experiences of Subramanyam.
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Equipment Cost
There are some differences in equipment cost between MeBr and PF because PF requires more
specialized equipment. Typically, a computer is needed to calculate dosage of PF using the
Fumiguide®. Strong-walled hoses are needed to introduce PF into the facility. During
fumigation, concentration of PF and MeBr is typically measured using a Fumiscope or similar
device, and a device such as Interscan (PF) or other electronic or tube-type monitor (MeBr) is
used to measure whether fumigant concentrations have decreased sufficiently to permit safe re-
entry of the facility after ventilation. Since a tube-type monitor is the only approved device for
determining re-entry clearance after a MeBr fumigation, the amortized cost of a tube-type
monitor as well as the cost of two tubes at $12/tube (one test in each of two locations) is
included for MeBr.
Cost of Chemicals Used
Cost of chemicals used appears to be the main factor affecting fumigation cost differences,
according to the interviewed firms. PF has specific guidance from Fumiguide® on required
dosage based on half loss time (HLT) – the time during which the initial concentration of the
fumigant is reduced by half (Thoms and Phillips) and a measure of the leakiness of the building
– type of insect, and temperature, which may permit reduction in chemical use compared to
following a blanket dosage rule as the MeBr label specifies. On the other hand, MeBr is
efficacious for most insects at all life stages at the recommended doses. PF’s Fumiguide® has
three choices for fumigators: a “high” dose, which should be nearly 100% effective for all
stages (eggs, larvae, pupae, and adults) of the insect types for which it is approved for use, a
user-defined rate, and Fumiguide’s® “low” dose, which should be effective for all post-
embryonic stages and 50% effective for the egg stage of most species.
Calibration of Economic-Engineering Model
Several sets of data were used to calibrate the model, or specify appropriate parameters and
values for the variables. The most important data set was gathered through telephone interviews
with six fumigators who have used both MeBr and PF and who contacted the author to set up a
phone interview. These roughly hour-long interviews focused on similarities and differences
between methyl bromide and PF in costs of a typical fumigation. Since, as the fumigators
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noted, there really is no typical fumigation, a hypothetical fumigation of a 1Million ft3 food
processing/warehouse facility was considered. The data determined were: labor needed for a
fumigation (setup, fumigation, aeration, and takedown), wages paid for labor, training needed
for workers, differences in dosage and chemical costs, differences in equipment cost and
facility preparation, differences in power use, typical pests targeted, and other relevant
differences as determined by the fumigator.
A second set of interviews was conducted with wholesale distributors of MeBr and PF.
The primary information obtained from these interviews was the wholesale price differences
between MeBr and PF.
The interview data from fumigators and wholesale distributors was supplemented with
information from Dow Agrosciences (cost of equipment used for PF, Fumiguide® dosages for
PF, and field trial data on amount of PF needed for various fumigations), from National Pest
Management Association (recommended dosages for MeBr and data condensed from several
journal articles on efficacy of several fumigants on four stages of various insect species), from
journal articles on the effects of temperature on efficacy of methyl bromide for several species
of insects (Bell, and Vincent, Rust, and Lindgren), and from a presentation by Dr. Bhadriraju
Subramanyam of the Kansas State University Dept. of Grain Science and Industry (efficacy of
low-dose PF fumigations).
Procedures
Representative Firm Costs
The analysis compares PF and MeBr in directly comparable simulations. The primary scenario
compares both fumigants as if they were used to fumigate a food processing/warehouse facility
of 1million ft3 with a fumigant half-loss time of 12 hours.
Fumigation cost
Fumigation cost = Fixed costs + Variable costs
Fixed Costs
Fixed costs = [purchase cost of equipment]/PVIFAni,
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where PVIFAni denotes present value interest factor for an annuity of n years at i percent
interest. PVIFAni = [1 – (1/(1 + i))n]/i, where n is the usable life of the machine and i is the
interest rate on the loan. Dividing by PVIFA allocates the investment cost, including interest
cost, equally over each year of the equipment’s useful life. The yearly equipment cost is
divided by the number of fumigations per year to express equipment cost as equipment cost per
fumigation.
Variable costs
Variable Costs = Labor cost + Training cost + Chemical cost
Labor Cost
Labor cost is specified as [(setup labor hours/worker times number of setup workers x
operating wage rate) + (supervisory labor hours/worker times number of supervisors times
supervisory wage rate) + (fumigation labor hours/worker times number of fumigation workers
times fumigation wage rate) + (aeration labor hours/worker times number of aeration workers
times aeration wage rate)]. If any of these workers must work more than eight hours per day,
they are assumed to receive “time-and-a-half” pay for those hours.
Training cost
Training cost is specified as a combination of an annual training fee (assumed to be
$150/worker) plus an hourly charge for each worker equal to his/her hourly wage rate times the
number of hours of training required per year (assumed to be five hours per worker). The total
training cost for all workers is divided by the number of fumigation jobs per year (assumed to
be 50) to express the training cost as training cost/job.
Chemical cost
Chemical cost is measured for each chemical as dosage in lbs/K ft3 x 1,000 ft3 x cost/lb.
Dosage rates for MeBr are taken from reported experiences of the fumigators interviewed, as
well as from label rates and other data sources. Dosage rates for MeBr are assumed to apply for
temperatures from 70° - 100°F. Dosage for PF is taken from the Fumiguide®, which specifies
dosage for PF according to HLT, temperature, insect, and size of enclosure, from reported
experiences of the fumigators interviewed, and from other data sources.
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Data Data from Phone Interviews with Fumigators Who Have Used Both Chemicals and from Wholesalers of Both Chemicals (Core Model) A key source of data was six fumigators who have used both MeBr and PF and who contacted
the author to set up a phone interview. Another source was two wholesale distributors of each
product who agreed to a telephone interview. Parameters for the core model initially are based
on the data collected from these interviews and data from Dow AgroScience’s Fumiguide® and
their catalog of equipment specifications and cost. Table 1 shows the parameters used in the
core model, based on these data sources.5
The most important differences between cost of fumigations with ProFume and methyl
bromide result from differences in dosage and in fumigant cost. The sections below discuss
these differences.
Fumigant Dosage
The label rate for MeBr is 1 - 3 lbs/K ft3 for processed food. Half of the fumigators interviewed
reported using 1.5 or 2 lbs/K ft3 for a 24-hour exposure time, and half of the fumigators
reported that their standard rate for MeBr was 1 lb/K ft3. This was especially true if they had
previously fumigated a particular facility and repaired any “leaks,” or if they had monitored the
concentration-time (CT) product and found that a lower dose provided effective exposure of
insects to the fumigant. There is also a possibility that a fumigator may need to use a higher
rate of MeBr.
Similarly, PF has a range of possible use rates. Dow Agrosciences’ Fumiguide®
provides a “high dose” rate and a “low dose” rate. The fumigators reported that when using PF
they used Dow Agroscience’s Fumiguide® to calculate dosage. In the Fumiguide®, the
recommended dosage for PF varies by temperature, insect species, and HLT. They reported
good results at label doses (MeBr) and Fumiguide®-recommended doses (PF).
In addition, Dow Agrosciences conducted 96 fumigations at food processing facilities
and warehouses. Their average dosage for these facilities was 2.5 lbs PF/K ft3, suggesting that
as fumigators gain experience with PF, they may find that they will be able to reduce dosage
5 These parameter values reflect industry data at the time of this study. Changes in the industry or economy, including changes in underlying industry structure or changes in regulations or their interpretation, would likely affect these values.
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from the Fumiguide recommendations, adapting it to specific facilities just as they have with
MeBr.6
Table 1. Parameters Used to Calculate Costs of Fumigating a 1 Million ft3 Food Processing Facility Using Methyl Bromide (MeBr) or ProFume (PF)
Parameter MeBr PFParameters:Labor Rates ($/hr)
Setup $18 $18Supervisory $50 $50Fumigation $18 $18
Aeration $18 $15Overtime $28 $28
Hours/WorkerSetup 5 5
Supervisory 15 15Fumigation 24 24
Aeration 12 8Overtime 20 16
# WorkersSetup 4 4
Supervisory 1 1Fumigation 4 4
Aeration 3 3Overtime 1 1
Worker Traininghours per worker per year 5 5
yearly fee per worker $150 $150Interest Rate 10% 10%Temperature (F) 85 85Half-Loss Time (hrs) 12 12Building Size (ft3) 1,000,000 1,000,000Value of Downtime Reduction ($/hr) $0 $0Typical Targeted Pests: weevils, lesser red flour beetle red flour beetleEquipment Life (yrs) 4 4
Purchase Prices ($)Fumiscope $1,333 $1,333
Interscan/electronic monitor $1,000 $3,559Draeger Tube Monitor $215 $0
Heavy-duty hoses, fittings $1,500 $2,480monitoring hoses $475 $475
high-capacity fans ($xxx/fan * n fans) $1,300 $1,300Present Value Factor (PVIFA) 3.170 3.170
Cost of Fumigant ($/lb) $7.00 $5.00 - $7.00Fumigant Dose (lb/1,000 ft3) 1; 1.5; 2 Fumiguide (lo & hi); 2.5
Equivalent fumigation jobs per year 50 50
6 Although it is included here for comparison purposes, none of the fumigators interviewed used the low dose for fumigating processed food. Since the low dose is not sufficient to kill all eggs of some insect species (particularly red flour beetle, a typical pest reported by the fumigators), they reported concerns about the potential for insect population “rebound” and dissatisfied customers.
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The baseline parameters for fumigant dosage are adjusted later in this report according
to different data sources. In particular, fumigators of cocoa beans reported effective use of
lower doses of PF, based upon the recommendation of a Dow AgroSciences representative.7
The fumigators reported that the justification for a lower dosage is that cocoa beans do not
absorb the fumigant as easily and the targeted insects are external feeders, so less chemical is
needed to kill them.
Fumigant Price
Fumigators and distributors reported that differences in price they paid for MeBr and PF ranged
from zero (no difference) to PF $2/lb less expensive than MeBr, with a mean of $0.52 (PF less
than MeBr) and a median of $0.40 (PF less than MeBr). Based on the data on price and dosage,
the most likely combination of these two variables is a PF price that is $0.50 less than the price
of MeBr, a PF use rate of 2.5 lb/K ft3 and a MeBr use rate at 1.5 lb/K ft3.
However, because the number of observations is small, and the range of reported values
is large, presenting the results based on the range of price/quantity observations rather than on
an average of them provides greater confidence in the results. Thus, the wholesale cost of MeBr
is set at $7/lb, and the wholesale cost of PF is varied from $7/lb to $5/lb (a relative difference
of $0 to $2/lb, consistent with the range reported by fumigators and wholesalers). Similarly, the
dosage of MeBr is varied from 1lb/K ft3 to 2 lbs/K ft3, and the dosage of PF is varied from
Fumiguide’s® “low dose” to Fumiguide’s® “high dose.”
Results Figure 1 illustrates the baseline dosages for MeBr and PF by insect species as temperature
varies from 70 – 100°F. Insect species are: Red Flour Beetle (RFB), Indianmeal Moth (IMM),
Confused Flour Beetle (CFB), Sawtoothed Grain Beetle (SGB), Warehouse Beetle (WB),
Mediterranean Flour Moth (MFM), Other Beetle (OB), Other Moth (OM), Granary Weevil
(GW), Rice Weevil (RW), and Lesser Grain Borer (LGB). The dosage for MeBr is the line
labeled by “MeBr,” at an assumed rate of 1.5lbs/K ft3. It is assumed to not vary by insect
species or by temperature.8 If cost per pound is the same for the two fumigants, this graph also
7 Dow AgroSciences confirms that this recommendation is based on experimental data jointly produced with Chocolate Manufacturer’s Association. 8 Vincent, Rust, and Lindgren (1980) report lower efficacy for methyl bromide at temperatures below 4.4°C (40°F). Bell (1988) found somewhat reduced efficacy at temperatures of 25ºC (77°F) for certain species.
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represents the relative chemical costs for the two fumigants for fumigating a 1million ft3
facility.
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
70 75 80 85 90 95 100
Temperatue (F)
lbs.
for 1
M c
u. ft
. war
ehou
se
RFBIMMCFBSGBWBMFMOBOMGWRWLGBMeBr
Figure 1. Dosage of ProFume (Fumiguide high dose) by Insect Species and Methyl Bromide (at label rate of 1.5 lb/1,000 ft3), by Temperature.
ProFume’s Fumiguide indicates that its recommendations for PF for temperatures less than approximately 70°F may not be optimal.
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Equipment Costs
Equipment costs for each fumigant using the parameters specified in Table 1 are shown in
Figure 2 and Table 2. Figure 2 shows the costs on a yearly basis, while Table 2 reports the costs
on a yearly basis and as cost per job, assuming 50 fumigation jobs per year.
$0$500
$1,000$1,500$2,000$2,500$3,000$3,500
Methyl Bromide ProFume
FansDraeger Tubesmonitor hoseshosesInterscan/electronic monitorFumiscope
Figure 2. Equipment Cost per Year for Methyl Bromide and ProFume Fumigation Table 2. Equipment Cost per Year and Total per Job for Methyl Bromide and ProFume Fumigation
Equipment Cost per yr. Methyl Bromide ProFumeFumiscope $421 $421Interscan/electronic monitor $315 $1,123hoses $473 $782monitor hoses $150 $150Tube-type monitor (& two tubes per fumigation) $1,268 $0Fans $410 $410Total per job (50 jobs/yr) $61 $58 Labor Costs
Labor costs for a hypothetical fumigation with each fumigant are shown in Table 3 and Figure
3. The only difference between MeBr and PF is a reduced labor cost for aeration for PF because
its greater vapor pressure and lower sorption likely permits faster aeration of the facility after
fumigation.
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Table 3. Labor Cost per (Hypothetical) Fumigating Job for Methyl Bromide and Profume Labor Cost per job Methyl Bromide ProFume
Setup $360 $360Supervisory $750 $750Fumigating $1,728 $1,728Aeration $648 $432Overtime $864 $864Total $4,350 $4,134
$0
$1,000
$2,000
$3,000
$4,000
$5,000
Methyl Bromide ProFume
OvertimeAerationFumigatingSupervisorySetup
Figure 3. Labor Cost per (Hypothetical) Fumigating Job for Methyl Bromide and Profume Fumigant Cost
These results indicate that PF has a very slight advantage in equipment cost, and a somewhat
larger, though still small, advantage in labor cost. However, the cost of fumigant used in a
typical fumigation is higher for PF than for MeBr for most scenarios. Although the data
indicate that the price per pound of PF is the same or lower than that for MeBr, the data also
indicate that a greater quantity of fumigant is typically used for a PF fumigation than for a
MeBr fumigation.9
9 Although the fumigating companies were not asked about profitability, one of them noted that because more PF fumigant is used in a typical fumigation, its revenues (and profits) are higher fumigating with PF than with MeBr. The markup it charges clients is the same for each chemical, but since the quantity of PF used is higher, the extra revenue received is correspondingly higher. The flip side, of course, is that the client faces higher costs.
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Total Fumigation Costs
To show the fumigation costs under various combinations of fumigation dosage and fumigant
price, Table 4 is arranged so that from left to right the dosage of MeBr varies from 1lb/K ft3 to
1.5lbs/K ft3 to 2 lbs/K ft3, and the dosage of PF varies from Fumiguide’s® “low dose” to Dow
Agroscience’s average field test dose of 2.5 lbs/1M ft3 to Fumiguide’s® “high dose.”
From top to bottom, the price of PF is varied from $7/lb to $5/lb while holding the price
of MeBr constant at $7/lb. Thus, the relative price difference between MeBr and PF varies from
zero (no difference) to PF $2/lb cheaper than MeBr.
For example, when PF costs $5/lb ($2/lb less than MeBr), the use rate for MeBr is
1.5lb/K ft3, and the use rate for PF is the Fumiguide® high dose, then the total fumigation cost
for PF is $19,931. This is 33% higher than the $14,930 cost of a MeBr fumigation.
The difference is smaller if the use rate of PF is lower. In the example above, when the
use rate for PF is reduced to 2.5 lb/1,000 ft3, the cost of a PF fumigation is $16,711. This is
12% higher than the $14,930 cost of a MeBr fumigation.
Conversely, the difference is larger if the relative cost of PF fumigant is higher or if the
use rate of MeBr is lower. For example, if the cost of PF is only $1/lb less than the cost of
MeBr, the use rate of MeBr is 1.5 lb/K ft3, and the use rate of PF is 2.5 lb/K ft3, the total cost of
a PF fumigation is $19,211 and the cost of a MeBr fumigation is $14,930, so that the cost of a
PF fumigation is 29% higher than that of a MeBr fumigation. If the use rate of MeBr is lowered
to 1 lb/K ft3 (while holding other values the same), the cost of a MeBr fumigation drops to
$11,430 and the cost of a PF fumigation is 68% higher than the cost of a MeBr fumigation.
Figure 4 shows these results graphically. Since the values for Equipment and Training
Cost are small and the value for Downtime Cost is zero, these costs are not visible on the graph.
The left-most set of columns shows the cost of a hypothetical fumigation job using MeBr at
three different use rates. The second, third, and fourth sets of columns show the costs of a
hypothetical fumigation job using PF at three different use rates at prices of $7/lb, $6/lb, and
$5/lb, or $0, $1, and $2/lb less than the MeBr price. Table 5 shows the differences between cost
of Pf and MeBr fumigations under these alternative scenarios in percentage form.
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Table 4. Cost of Hypothetical Fumigations for Methyl Bromide and ProFume (Fumigation hours = 24; Downtime Cost = $0/hr; MeBr cost at $7/lb and ProFume cost at $5, $6, and $7/lb; MeBr dose at 1.0 lb, 1.5 lbs, and 2.0 lbs/K ft3; ProFume dose at Fumiguide low, 2.5lb/K ft3, and Fumiguide high)
Cost per Job
Methyl Bromide (1
lb/K ft3)
Methyl Bromide
(1.5 lb/K ft3)
Methyl Bromide (2
lbs/K ft3)ProFume
(low dose)
ProFume (Dow
average - 2.5 lb/K ft3)
ProFume (high dose)
(MeBr $7/lb, PF $7/lb)Equipment $61 $61 $61 $58 $58 $58
Labor $4,350 $4,350 $4,350 $4,134 $4,134 $4,134Training $19 $19 $19 $19 $19 $19
Downtime $0 $0 $0 $0 $0 $0Fumigant $7,000 $10,500 $14,000 $11,452 $17,500 $22,008
Total Cost $11,430 $14,930 $18,430 $15,663 $21,711 $26,219
Equipment $61 $61 $61 $58 $58 $58Labor $4,350 $4,350 $4,350 $4,134 $4,134 $4,134
Training $19 $19 $19 $19 $19 $19Downtime $0 $0 $0 $0 $0 $0Fumigant $7,000 $10,500 $14,000 $9,816 $15,000 $18,864
Total Cost $11,430 $14,930 $18,430 $14,027 $19,211 $23,075
Equipment $61 $61 $61 $58 $58 $58Labor $4,350 $4,350 $4,350 $4,134 $4,134 $4,134
Training $19 $19 $19 $19 $19 $19Downtime $0 $0 $0 $0 $0 $0Fumigant $7,000 $10,500 $14,000 $8,180 $12,500 $15,720
Total Cost $11,430 $14,930 $18,430 $12,391 $16,711 $19,931
(MeBr $7/lb, PF $6/lb)
(MeBr $7/lb, PF $5/lb)
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$0
$5,000
$10,000
$15,000
$20,000
$25,000
$30,000
Methyl
Bromide
(1 lb
/K ft3
) $7/l
b
Methyl
Bromide
(1.5
lb/K ft3
) $7/l
b
Methyl
Bromide
(2 lb
s/K ft3
) $7/l
bProF
ume (
low do
se) $
7/lb
ProFum
e (Dow
avera
ge) $
7/lb
ProFum
e (hig
h dos
e) $7
/lbProF
ume (
low do
se) $
6/lb
ProFum
e (Dow
avera
ge) $
6/lb
ProFum
e (hig
h dos
e) $6
/lbProF
ume (
low do
se) $
5/lb
ProFum
e (Dow
avera
ge) $
5/lb
ProFum
e (hig
h dos
e) $5
/lb
Cos
t of H
ypot
hetic
al F
umig
atio
n
FumigantDowntimeTrainingLaborEquipment
Figure 4. Cost of a Hypothetical Fumigation for Methyl Bromide or ProFume (Fumigation hours = 24; Downtime Cost = $0/hr; MeBr = $7/lb and ProFume cost at $5, $6, and $7/lb; MeBr dose at 1.0 lb, 1.5 lbs, and 2.0 lbs/K ft3; ProFume dose at Fumiguide low, 2.5lb/K ft3, and Fumiguide high)
Revised 9/9/2007 - 16 - Economic Consulting, LLC (Brian D. Adam, Ph.D.)
Table 5. Percent by Which ProFume Fumigation Cost Exceeds Methyl Bromide Fumigation Cost (Fumigation hours = 24; Downtime Cost = $0/hr; MeBr Fumigant cost = $7/lb; MeBr dose at 1.0 lb, 1.5 lbs, and 2.0 lbs./K ft3; PF Fumigant cost = $5, $6, and $7/lb, PF dose at low, Dow average, and high levels )*
% by which PF fumigation cost exceeds MeBr
fumigation cost
ProFume (low dose)
ProFume
(Dow average – 2.5 lb/K cu. ft.)
ProFume (high dose)
PF cost = $7/lb. Methyl Bromide (1 lb / K cu. ft.) 37% 90% 129%
Methyl Bromide (1.5 lb / K cu. ft.) 5% 45% 75% Methyl Bromide (2 lbs / K cu. ft.) -15% 18% 42%
PF cost = $6/lb. Methyl Bromide (1 lb / K cu. ft.) 23% 68% 102%
Methyl Bromide (1.5 lb / 1K cu. ft.) -6% 29% 55% Methyl Bromide (2 lbs / 1K cu. ft.) -24% 4% 25%
PF cost = $5/lb. Methyl Bromide (1 lb / 1K cu. ft.) 8% 46% 74% Methyl Bromide
(1.5 lb / 1K cu. ft.) -17% 12% 33% Methyl Bromide (2 lbs / 1K cu. ft.) -33% -9% 8%
*negative numbers indicate that MeBr cost exceeds PF cost
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Application of Model to Fumigation of Cocoa Beans Fumigation of cocoa beans is sufficiently different from fumigation of food processor facilities
to merit a separate section in this report. Fumigation of cocoa beans requires a lower dosage of
ProFume than fumigation of food processing facilities because cocoa bean fumigation is a
commodity fumigation rather than a space fumigation, and the commodity is taking up a larger
proportion of the fumigated space. The fumigators interviewed reported successful fumigation
with 1 lb/K ft3 of MeBr, and 1.5 lb/K ft3 of PF. According to the fumigators, this dose for PF
was recommended by Dow AgroSciences representatives (see footnote 4).
The fumigators reported very little difference between MeBr and PF in the other
components of the analysis, such as labor cost and equipment cost, so those parts of the
economic-engineering model are transferred directly from the previous section, assuming
fumigation jobs comparable in size to that assumed in the previous section.
Table 6 and Figure 5 show the cost of fumigating cocoa beans using a dose of 1 lb/K ft3
for MeBr and 1.5 lb/K ft3 for PF. When the two fumigants cost the same per pound, a PF
fumigation costs about 29% more. When fumigant costs differ by $1/lb, a PF fumigation costs
16% more, and when the cost difference is $2/lb, a PF fumigation costs 2% more.
Table 6. Cost of a Hypothetical Fumigation for Methyl Bromide or ProFume on Cocoa Beans (Fumigation hours = 24; Fumigant cost = $7/lb for MeBr, $7, $6, and $5/lb for PF; MeBr dose at 1.0 lb/1,000 ft3 and PF at 1.5 lbs./ K ft3)
Cost per
job
Methyl Bromide @ $7/lb
ProFume @ $7/lb
%
Diff.
ProFume @ $6/lb
%
Diff.
ProFume @ $5/lb
%
Diff. Equipment $61 $58 $58 $58 Labor $4,350 $4,134 $4,134 $4,134 Training $19 $19 $19 $19 Downtime $0 $0 $0 $0 Fumigant $7,000 $10,500 $9,000 $7,500 Total Cost $11,430 $14,711 29% $13,211 16% $11,711 2%
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$0
$2,000
$4,000
$6,000
$8,000
$10,000
$12,000
$14,000
$16,000
Methyl Bromide@ $7/lb
ProFume @$7/lb
ProFume @$6/lb
ProFume @$5/lb
FumigantDowntimeTrainingLaborEquipment
Figure 5. Cost of a Hypothetical Fumigation for Methyl Bromide or ProFume on Cocoa Beans (Fumigation hours = 24; Fumigant cost = $7/lb for MeBr, $7, $6, and $5/lb for PF; MeBr dose at 1.0 lb/K ft3 and PF at 1.5 lbs/ K ft3)
As an additional reference point for comparison, since the National Pest Management
Association application for Critical Use Exemption specifies a MeBr use rate of 1.5 lbs/K ft3,
and since the label for MeBr specifies a rate ranging from 1 – 3 lbs/K ft3 for cocoa beans using
a 24-hr exposure, a calculation based on a rate of 1.5 lbs/K ft3, the midpoint of this range, is
evaluated. Table 7 and Figure 6 show the cost of fumigating cocoa beans using a dose of 1.5
lb/K ft3 for both MeBr and PF. When the two fumigants cost the same per pound, a PF
fumigation costs about 1% less. When fumigant costs differ by $1/lb, a PF fumigation costs
12% less, and when the cost difference is $2/lb, a PF fumigation costs 22% less.
Table 7. Cost of a Hypothetical Fumigation for Methyl Bromide or ProFume on Cocoa Beans (Fumigation hours = 24; Fumigant cost = $7/lb for MeBr, $7, $6, and $5/lb for PF; MeBr dose at 1.5 lb/K ft.3 and PF at 1.5lbs./K ft3).
Cost per
job
Methyl Bromide @ $7/lb
ProFume @ $7/lb
%
Diff.
ProFume @ $6/lb
%
Diff.
ProFume @ $5/lb
%
Diff. Equipment $61 $58 $58 $58 Labor $4,350 $4,134 $4,134 $4,134 Training $19 $19 $19 $19 Downtime $0 $0 $0 $0 Fumigant $10,500 $10,500 $9,000 $7,500 Total Cost $14,930 $14,711 -1% $13,211 -12% $11,711 -22%
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$0
$2,000
$4,000
$6,000
$8,000
$10,000
$12,000
$14,000
$16,000
Methyl Bromide@ $7/lb
ProFume @$7/lb
ProFume @$6/lb
ProFume @$5/lb
FumigantDowntimeTrainingLaborEquipment
Figure 6. Cost of a Hypothetical Fumigation for Methyl Bromide or ProFume on Cocoa Beans (Fumigation hours = 24; Fumigant cost = $7/lb for MeBr, $7, $6, and $5/lb for ProFume; MeBr dose at 1.5 lb/K ft.3 and ProFume at 1.5lbs./ K ft3) The key reason for PF being relatively more attractive economically for cocoa beans than for
food processing facilities, compared to MeBr, is because the amount of PF needed for cocoa
beans is substantially lower.
Supplementing with Other Data Report by Dr. Bhadriraju Subramanyam In a report entitled “ProFumeTM Fumigation of Rice Mills in California: Effectiveness and User
Perceptions,” Dr. Subramanyam reports effective fumigations using PF’s low dose. He noted,
though, that in two of three mills, insect populations reached pretreatment levels after two
months. He noted that further research is needed to determine the reason for this population
rebound.
Dow Agrosciences Field Data Fumigation Times of 12 Hours instead of 24 Hours
Since fumigation must be conducted without workers present in the facility, a potential cost of
fumigation is “downtime” for the processing plant or warehouse. If a Client were willing to pay
to reduce this downtime, a fumigator might wish to speed up the fumigating time in order to
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reduce the amount of downtime. The tradeoff is that the concentration of fumigant held in the
facility must be increased to compensate for the reduced time available for the fumigant to kill
insects.
In order to model this, the fumigation time is reduced from 24 hrs to 12 hrs, and the
fumigant dosage is increased accordingly. In the case of PF, Fumiguide is used to adjust the
required amount of fumigant. In the case of MeBr, one could double the fumigant concentration
in order to maintain the same CT (concentration x exposure time), provided that it is
biologically reasonable to assume that mortality remains constant with constant CT, even while
exposure time is reduced. Using this assumption, Table 8 and Figure 7 compare the cost of a
12-hour fumigation for each fumigant with the cost of a 24-hour fumigation.
For MeBr, using the above assumption, switching from a 24-hr fumigation to a 12-hr
fumigation doubles the cost of fumigant, while labor cost is nearly halved. For PF, the switch
raises the cost of fumigant by 83% and nearly halves the labor cost. In order to profitably move
to a 12-hr fumigation, a fumigating company would need to be compensated by a Client for
downtime savings at a rate of $1,375/hr if using PF ($42,726 minus $26,219, divided by 12
hours), and at a rate of $731/hr if using MeBr ($23,702 minus $14,930, divided by 12). If the
cost of PF is $1/lb less than the cost of MeBr, the downtime savings for PF would need to be
$1,159/hr (comparing the cost of a 12-hour high-dose PF fumigation with a $6/lb fumigation
from Table 8, $36,977, with the cost of the same fumigation from Table 4, $23,075, and
dividing by 12 hours).
Although it seems reasonable that shorter fumigation times would provide an economic
benefit to the processors whose facilities are under fumigation by reducing downtime, none of
the fumigators interviewed reported that they could achieve any cost savings or revenue
enhancement from reducing downtime. They indicated that they conduct most fumigations in
such facilities on a holiday weekend when the plant is shut down anyway, so there typically are
no cost savings from shutting down the facility for a shorter period of time.
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Table 8. Comparison of Costs for 24-hour and 12-hour Fumigations for Methyl Bromide and ProFume®: PF Price Equal MeBr Price, and PF Price $1/lb Less than MeBr Price.
Cost per job
Methyl Bromide
(1.5 lb/K cu ft, 24 hrs)
ProFume (high dose,
24 hrs)
ProFume (low dose,
24 hrs)
Methyl Bromide
(3 lbs /K cu ft, 12 hrs)
ProFume (high dose,
12 hrs)
ProFume (low dose,
12 hrs)
ProFume (high dose, 12 hrs, $1/lb
less)
ProFume (low dose,
12 hrs, $1/lb less)
Equipment $61 $58 $58 $61 $58 $58 $58 $58Labor $4,350 $4,134 $4,134 $2,622 $2,406 $2,406 $2,406 $2,406Training $19 $19 $19 $19 $19 $19 $19 $19Downtime $0 $0 $0 $0 $0 $0 $0 $0Fumigant $10,500 $22,008 $11,452 $21,000 $40,243 $17,185 $34,494 $14,730Total Cost $14,930 $26,219 $15,663 $23,702 $42,726 $19,668 $36,977 $17,213
$0$5,000
$10,000$15,000$20,000$25,000$30,000$35,000$40,000$45,000
Methyl Bromide(1.5 lb/K cu ft,
24 hrs)
ProFume (highdose, 24 hrs)
ProFume (lowdose, 24 hrs)
Methyl Bromide(3 lbs /K cu ft,
12 hrs)
ProFume (highdose, 12 hrs)
ProFume (lowdose, 12 hrs)
ProFume (highdose, 12 hrs,
$1/lb less)
ProFume (lowdose, 12 hrs,
$1/lb less)
FumigantDowntimeTrainingLaborEquipment
Figure 7. Comparison of Costs for 24-hour and 12-hour Fumigations for Methyl Bromide and ProFume®.
Revised 9/9/2007 - 22 - Economic Consulting, LLC (Brian D. Adam, Ph.D.)
REFERENCES
Bell, Christopher H. 1988. “Minimum Concentration Levels of Methyl Bromide Required for Full Efficacy Against Seven Species of Stored-Product Beetle at Two Temperatures.” Pesticide Science. 24:97-109.
Subramanyam. Bhadriraju. “ProFumeTM Fumigation of Rice Mills in California: Effectiveness
and User Perceptions.” Unpublished Presentation. Thoms, Ellen M., and Thomas W. Phillips. “Fumigation,” Ch. 20 in Handbook of Pest Control:
Mallis Handbook & Technical; 7th edition (April 1990), pp.1164-1216. Vincent, L. E., M. K. Rust, and D. L. Lindgren. 1980. “Methyl Bromide Toxicity at Various
Low Temperatures and Exposure Periods to Angoumois Grain Moth and Indianmeal Moth in Popcorn.” Journal of Economic Entomology. 73(2):313-7.
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