Fumigation, << `fyoo` muh GAY shuhn, >> is a method of killing pests that involves the use of toxic gases. It is widely used to eliminate weeds, nematodes (roundworms), and other pests from cropland. It is also used to protect such foods as grains and spices from rats and insects during storage. Goods shipped between countries often are fumigated to prevent pests and diseases from spreading from one country to another. Houses, apartments, and other buildings are sometimes fumigated to kill cockroaches, termites, and other insects.
The chemicals used in fumigation are called fumigants. They work well only in an enclosed area. For example, stored foods commonly are covered with plastic sheets during fumigation. The sheets trap the gases beneath them, enabling the foods to absorb the fumigants. Some farmland is treated to kill nematodes by injecting fumigants into the soil, which acts as a cover. Plastic sheets are generally used as an additional cover for fields fumigated against weeds, insects, and plant diseases. The sheets are removed about 24 to 48 hours after the fumigants are applied. The fields can be safely planted about one to two weeks later. By then, the gases have been dissipated (released) from the soil.
Fumigants are poisonous to people and must be handled with care. They are usually applied by trained, licensed professionals. Commonly used fumigants include cyanide, formaldehyde, and methyl bromide. Foods that have been fumigated are safe to eat only after the fumigant has been dissipated.
