cost comparison of methyl bromide and profume fumigating a...

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.


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.


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.


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


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,


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.


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.


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.


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.


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.


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.


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.


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.


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)


$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)


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


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%


$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


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%


$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


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


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.


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)


Figure 7. Comparison of Costs for 24-hour and 12-hour Fumigations for Methyl Bromide and ProFume®.


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.

cost comparison of methyl bromide and profume fumigating a...

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