A fumigation service company has identified an effective alternative
treatment to using methyl bromide to control stored-product insects in
flour mills and similar structures (Mueller 1994a). This alternative
treatment combines phosphine, heat, and carbon dioxide to eradicate all
life stages of common stored-product pests, such as the Angoumois grain
moth, red flour beetle, warehouse beetle, and rice weevil (Mueller 1994a).
This treatment using phosphine, heat and carbon dioxide was developed and
is currently used by a fumigation service company in Indianapolis,
Fumigation Service and Supply.
Founded in 1981 by David Mueller, Fumigation Service and Supply (FSS)
provides fumigation services for stored products including flour in mills
and other dried goods (e.g., dog food, pharmaceuticals, and spices) in
processing plants. To educate the community about potential alternatives
to pesticide use, FSS hosts workshops to explain the phosphine, heat, and
carbon dioxide combined treatment method and publishes a newsletter,
Fumigation & Pheromones, which describes the company's research and
educational endeavors (Mueller 1994c). FSS currently employs 20
individuals during the summer and 12 during the winter (Mueller 1994b).
- eradicates all life stages of stored-product insects
- reduces corrosion
- increases penetration
FSS first experimented with methyl bromide alternatives in June 1992 and
currently uses methyl bromide for less than 60 percent of its fumigation
work. FSS plans to eliminate emissions of methyl bromide completely by
January 1, 1997 (Mueller 1994b). In addition, this company is
experimenting with other techniques to replace methyl bromide, such as
combined carbon dioxide and pressure treatments and related innovative
methods to treat commodity imports and exports (Mueller 1994b).
FSS has been fumigating with methyl bromide since the company's
inception. In 1985, the company began treating large food processing
plants, thus increasing its use of methyl bromide. However, FSS became
concerned about the continued availability of methyl bromide, and began to
investigate replacement technologies. Currently, FSS uses methyl bromide
for about 56 percent of its fumigation work, phosphine for about 36
percent, and the combined treatment method for about 8 percent (Mueller
1994b).
The company has been developing the combined treatment over the past
several years, using field trials and laboratory experiments, and has
refined the percentages of phosphine, heat, and carbon dioxide to provide
the best results. The company initially experimented with separate
treatments, but quickly determined that combined methods were more
effective.
The combined treatment consists of 50 to 100 ppm phosphine (9 to 18
percent of the standard phosphine concentration), heat (89.6-98.6øF,
32-37øC), and 4 to 6 percent carbon dioxide. Experiments have shown
that this combined treatment produces 100 percent mortality within 24
hours or less for the egg, larvae, pupae, and adult stages of
stored-product insects, including the Angoumois grain moth, red flour
beetle, warehouse beetle, and rice weevil (Mueller 1994a). The process
relies on heat and carbon dioxide to increase the susceptibility of pests
to phosphine by interfering with insect metabolism (Mueller 1994c).
Using low concentrations of phosphine reduces the chance of corrosion of
metallic materials at facilities, a common problem associated with using
phosphine. In addition, heat and carbon dioxide help reduce moisture,
which tends to contribute to corrosion. Recently, two scientists from
Purdue University were awarded a grant to conduct laboratory research to
vary the percent of carbon dioxide, phosphine, and heat, in an effort to
better understand how this combination technique works. This work is in
progress as of publication of this case study.
FSS has patented their combined treatment technique (Patent Number:
5,403,597; April 4, 1995) and expects few hurdles to commercialization.
Magnesium phosphide, the phosphine releasing agent, is a registered
pesticide product. FSS developed the combined technique based on extensive
knowledge of insect control technologies and Integrated Pest Management
(IPM), as well as extensive testing of various combination techniques
involving heat and inert gases. After fully developing the treatment
specifications, FSS received approval from the EPA to use magnesium
phosphide as part of their patented combined treatment method. FSS has
begun assigning licenses for this combination fumigation technique in
countries in Europe, Asia, and Africa (Mueller 1994b).
FSS has presently completed fourteen applications of the phosphine, heat,
and carbon dioxide treatment on structures, with an efficacy rate of 100
percent (Mueller 1994b). The company performed a large number of
experiments on multiple species of insects to ensure the technique's
effectiveness across a broad range of potential insect pest infestations.
FSS has conducted extensive corrosion and penetration tests to guarantee
that the method works consistently and properly and does not damage
structures or equipment. The penetration experiments test the ability for
the treatment method to permeate depths of flour, while the corrosion
tests examine the resistance of copper to the exposure treatments (Mueller
1994a).
In general, the cost of using the combined treatment is slightly higher
than using methyl bromide because more equipment, labor, and technical
expertise are required. Fumigating costs vary depending on the size of the
facility and the number of times the facility has been treated (see
below). However, treatment costs tend to decrease with repeated treatments
of the same facility. For example, the initial treatment may require a
large input of capital, such as the purchase of thermometers, gas
monitoring equipment, and other electronic devices. In addition, heat and
labor requirements are higher during the first application of the combined
treatment because of the lack of familiarity with the characteristics of
the facility. Mr. Mueller estimates that using the combined treatment is
40 percent more expensive than using methyl bromide the first time a
facility is fumigated, but only 25 percent more expensive for the second
fumigation. Additional applications should continue to reduce application
costs (Mueller 1994b).
Combined Treatment (Phosphine, Heat, CO2)
Cost per 1,000 cubic feet:
First Application - $11.20 14.00
Additional Applications - $10 - 12.50
Methyl Bromide Treatment
Cost per 1,000 cubic feet: $8 - 10
Source: Mueller 1994b.
Mueller. 1994a (April 17-23). A new method of using low levels of
phosphine in combination with heat and carbon dioxide. As presented in
Stored Product Protection: proceedings of the 6th International Working
Conference on Stored-product Protection. Volume I. E. Highley, E.J.
Wright, H.J. Banks and B.R. Champ (eds.). Canberra, Australia.
Mueller. 1994b (December 16, 1994 and February 2, 1995). Personal
communication. David Mueller, Fumigation Services & Supply.
Indianapolis, Indiana.
Mueller. 1994c (spring). Methyl bromide alternative update. David
Mueller, Fumigants & Pheromones. Indianapolis, Indiana.
For more information on this alternative, click
here.
For more information on this material from Fumigation Service &
Supply, Inc. (FSS), an inovator in this field,
click
here. Note that this site is outside of EPA. Therefore, EPA takes
absolutely no responsiblity whatsoever for the content of the web site
information or the opinons expressed in the web site.