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chemicals tabbed as follows:
◆ Fumigants
◆ Aerosols and Micronized Dust
Use the Contents in this section to quickly find the information you
need. The subjects listed in the Contents are also marked on the tabs
in this manual. If the Contents is not specific enough, then turn to the
Index to find the topic and its page number.
Chemical Treatments Overview
2-1-2 Treatment Manual 10/2002-04
PPQ
10/2002-04 Treatment Manual 2-2-1
PPQ
Treatment Manual
2 Chemical Treatments 2
Fumigants
Contents
Fumigants • Methyl Bromide page-2-3-1
Fumigants • Sulfuryl Fluoride page-2-9-1
Fumigants • Phosphine • Tarpaulin (NAP Chamber or Container) page-2-10-1
Introduction
Fumigation is the act of releasing and dispersing a toxic chemical so it
reaches the target organism in a gaseous state. Chemicals applied as
aerosols, smokes, mists, and fogs are suspensions of particulate
matter in air and are not fumigants.
The ideal fumigant would have the following characteristics:
◆ Highly toxic to the target pest
◆ Nontoxic to plants and vertebrates (including humans)
◆ Easily and cheaply generated
◆ Harmless to foods and commodities
◆ Inexpensive
◆ Nonexplosive
◆ Nonflammable
◆ Insoluble in water
◆ Nonpersistent
◆ Easily diffuses and rapidly penetrates commodity
◆ Stable in the gaseous state (will not condense to a liquid)
◆ Easily detected by human senses
Unfortunately, no one fumigant has all the above properties, but those
used by APHIS and PPQ have many of these characteristics.
The toxicity of a fumigant depends on the respiration rate of the target
organism. Generally, the lower the temperature, the lower the
respiration rate of the organism which tends to make the pest less
susceptible. Fumigation at lower temperatures requires a higher
dosage rate for a longer exposure period than fumigation at higher
temperatures.
Chemical Treatments Fumigants
Monitoring of Quarantine Treatments
2-2-2 Treatment Manual 10/2002-04
PPQ
Fumigants vary greatly in their mode of action. Some kill rapidly while
others kill slowly. In sublethal dosages, some fumigants may have a
paralyzing effect on the pest while others will not allow the pest to
recover. Some fumigants have no effect on commodities while others
are detrimental even at low concentrations. Commodities vary in their
sorption of fumigants and in the effort required to aerate the
commodities after fumigation.
Due to the reduction in number of labeled fumigants, there is seldom
a choice in selecting fumigants. When there is a choice, factors such
as the commodity to be treated, pest and stages present, type of
structure, and cost should be considered in selecting a fumigant.
The only authorized fumigants are the following:
◆ Methyl bromide (MB)
◆ Sulfuryl fluoride (SF) (Vikane)
◆ Phosphine (PH) (There are two chemicals used for phosphine,
AP—aluminum phosphide and MP—magnesium phosphide)
Much of the information on fumigants is based on MB with
modification as needed for the other fumigants.
Monitoring of Quarantine Treatments
Monitoring of program fumigations is performed to ensure that
effective fumigant concentration levels are maintained throughout the
treatment to prevent the introduction of quarantine pests. Quarantine
fumigations employing restricted use pesticides require careful
monitoring to assure efficacy and personal safety, to maintain
pesticide residues within acceptable limits, and to preserve commodity
quality. These requirements are included in the fumigant label, and it
is a violation of Federal law to use fumigants and pesticides in a
manner inconsistent with its labeling.
Nonperishable Commodities in Temporary Enclosures
PPQ officers will provide onsite monitoring from introduction of the
fumigant through completion of the 2 hour gas concentration
readings. Half hour and 2 hour readings are required for these
treatments. These readings and general observations permit the officer
to determine how a particular treatment is progressing and to make
necessary corrections to the enclosure or fumigant concentration level.
Perishable Commodities in Temporary Enclosures
The monitoring officer will remain on the site through the entire
fumigation of perishable commodities. Continuous monitoring allows
the officer to alert the pest control operator at any time to implement
Chemical Treatments Fumigants
Monitoring of Quarantine Treatments
10/2002-04 Treatment Manual 2-2-3
PPQ
necessary corrective measures. Due to the nature of the commodity
　
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