9.4 Fumigation Fundamentals & Soil Fumigant Requirements

9.4 Fumigation Fundamentals & Soil Fumigant Requirements

Core Concept: A fumigant is a pesticide that acts as a gas. That single property changes everything. There is no spray pattern to cover and no droplet spectrum to manage - the gas fills the space available to it. The exposure route is inhalation, personal protective clothing is largely irrelevant against it, and the protective strategy is containment plus distance plus monitoring rather than deposition. 40 C.F.R. Sec. 171.103(c)(7) names fumigants explicitly as a competency area for exactly this reason.

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How a Fumigant Differs From a Spray

Common fumigant categories: soil fumigants used preplant against nematodes, soilborne pathogens and weed seeds; stored commodity fumigants used in bins, silos and rail cars; and structural fumigants used against wood-destroying organisms. Structural fumigation in Arkansas is licensed under the separate Arkansas Pest Control Law, not under the 2 CAR pt. 72 agricultural categories.

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The Soil Fumigant Package

Soil fumigant labels carry a set of requirements that go well beyond an ordinary pesticide label.

1. Fumigant Management Plan (FMP)

A written plan prepared before the application and kept on site during the application, then retained as the label directs. It must address, among other elements:

• Site information, including a map of the application block and surrounding areas.
• Applicator and certified applicator information.
• The application method, rate, and equipment.
• Buffer zone size, its boundaries, and the buffer period.
• Posting plan and sign locations.
• Notification of neighbours and of any difficult-to-evacuate sites such as schools, day cares, nursing homes and hospitals within a specified distance.
• Weather conditions that must be met, including a prohibition on application during or before an inversion where the label so states.
• Air monitoring and emergency response procedures, including who is called and how.
• Good agricultural practices for soil condition, moisture and temperature.

A post-application summary documenting what actually occurred is completed after the application.

2. Buffer Zone

A buffer zone surrounds the treated block. Its size is determined from label tables driven by application rate, block size, application method, and soil conditions, and it may be reduced by buffer credits for practices such as using a totally impermeable film (TIF) tarp, deeper injection, or lower application rates. During the buffer period - typically starting at the beginning of the application and running for a set number of hours after it ends - only trained and equipped handlers may be inside, and the buffer zone may not include areas the applicator does not control.

3. Posting

Buffer zone posting signs must be placed at the buffer perimeter, at all points of likely entry, before the application begins, and must remain until the buffer period ends and entry restrictions are lifted. Treated area posting signs carry the standard restricted-entry information.

4. Handler Protection and Monitoring

• Respiratory protection as the label specifies - air-purifying respirators with cartridges rated for that fumigant, or supplied-air / self-contained breathing apparatus at higher concentrations. This requires a documented respiratory protection program: medical evaluation, fit testing, and training.
• Air monitoring with detection appropriate to the fumigant, at the frequency and locations the label specifies.
• Sensory irritation triggers: many fumigant labels require the application to stop and handlers to leave and don respiratory protection if sensory irritation occurs.
• Two-person rule where the label requires it, so no handler works alone in a potential exposure situation.

5. Emergency Preparedness

The FMP must identify the nearest emergency medical facility, the emergency contacts, and the response procedure, and that information must be available on site. This mirrors the Worker Protection Standard duty to make product and exposure information available to treating medical personnel.

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Worker Protection Standard Interaction

• Fumigant applications are expressly named in 40 C.F.R. Sec. 170.405(a)(2), so the Application Exclusion Zone is 100 feet, and the applicator must immediately suspend the application if anyone other than a trained and equipped handler enters it.
• The fumigant label's buffer zone is a separate and usually much larger requirement that sits on top of the AEZ - do not confuse the two.
• Standard WPS decontamination, training and central display obligations apply to fumigation handlers as they do to any other handler.

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Arkansas Framework

• Agricultural soil fumigation falls within the agricultural pest control category under 2 CAR Sec. 72-101, and the applicator must be a licensed commercial, non-commercial, or private applicator as the situation requires.
• Structural fumigation is licensed under the Arkansas Pest Control Law, not the agricultural applicator categories - the same distinction that governs termite, household, and lawn-care work.
• Arkansas record and dealer rules apply as they would to any restricted use pesticide, and the state class designations in 2 CAR pt. 70 apply to any fumigant product the Board has assigned to a class.

[!WARNING] Exam Trap: PPE Does Not Protect Against a Fumigant Gas The most consistently wrong answer on fumigation items is that chemical-resistant coveralls, gloves and boots provide protection. Against a gas they provide almost none - the gas passes through, and in some cases contaminated gloves or boots trap it against the skin. The protections that matter are respiratory protection matched to the fumigant, containment such as a TIF tarp, buffer distance, air monitoring, and time. Some fumigant labels specifically direct handlers not to wear gloves or boots that could trap the gas.