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Container Fumigation Methods

Fumigation involves the release of gaseous chemicals that are toxic towards specific targeted pests. It is applied to containers storing grain or other food commodities for transport to control pest infestation. Methyl bromide and aluminum phosphide are commonly applied fumigants due to their toxicity and penetration properties, but are highly toxic to humans. The effectiveness of the fumigant is dictated by its method of application.

  1. Containers

    • Containers must be properly sealed long enough for the fumigant to take action. They are usually constructed from materials such as fiberglass, wood, steel, concrete or plastic. According to the U.S. Federal Grain Inspection Service, only inspected and certified containers are allowed to be fumigated. Some containers suitable for fumigation include bulk dry-cargo containers, Liquefied Natural Gas (LNG) carriers, and tween deck vessels.

    Surface Treatment

    • This method involves the uniform scattering of fumigant to cover the entire surface of the exposed commodity. The fumigant is applied in granules, pellets, or tablets, provided the dosage is in line with the U.S. Environmental Protection Agency guidelines. The solid fumigant then reacts with moisture in the air to produce the toxic fumigant gas. For example, aluminum phosphide yields toxic hydrogen phosphide, also called phosphine.

    Subsurface Treatment

    • Subsurface treatment consists of submethods that all place fumigants below the commodity surface. The trenched-in method places fumigants in a shallow trench covered with the commodity. Polyethylene tubes are used to apply fumigants into the commodity. Tubes are either 5 feet long in the short probe method or 16 feet in the long probe method. Both are used together in the long probe/short probe combination. The tubing system utilizes 250-foot tubes across the container to ensure uniform fumigant distribution.

    Recirculation System

    • Hydrogen phosphide gas is recirculated throughout the container using perforated tubing and an explosion-proof blower motor. Gas is moved around from high to low concentration areas. Tubing is approximately six inches thick and extends to the commodity surface. The other end is attached to a motor with a blowing rate of around 300 cubic feet per minute. The recirculation system is used together with either the surface or subsurface treatment method.

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