What is a major disadvantage of using penta as a wood treatment?

Using penta (pentachlorophenol) as a wood treatment has notable environmental and health concerns, which is why the correct answer highlights its toxicity. Penta is recognized for being harmful to various forms of life, including plants, animals, and humans. Its chemical composition can lead to irritation upon contact and poses risks when inhaled or ingested. This toxicity can create challenges in its use, particularly in areas where the treated wood might come into contact with the environment or where it could affect non-target organisms.

While there may be some characteristics of penta that seem advantageous, such as providing water resistance, these benefits are overshadowed by the significant health and safety risks associated with its use.