Which is NOT a disadvantage of fumigants?

Fumigants are a specific category of pesticides that are used to control pests in enclosed spaces. An important characteristic of fumigants is that their application typically requires specialized techniques and equipment, as they must be delivered in gas form to infiltrate the treatment area effectively.

Among the listed options, not being expensive is indeed not a disadvantage of fumigants. In fact, fumigants can vary widely in cost depending on the type of product and the scale of the application. However, the overall perception of fumigants incorporates several challenges. They must be applied in enclosed areas to ensure that the gas remains contained and effective, are often complicated to apply correctly due to the need for proper sealing and monitoring, and can present significant health risks that necessitate the use of full protective gear.

In contrast, considering the cost factor, while fumigants can be viewed as an investment, they often provide a powerful solution when traditional methods are ineffective, making them potentially cost-effective in the long run. Thus, identifying "they are inexpensive" as not being a disadvantage aligns with a nuanced understanding of their application and financial implications in pest control.