With all of these advantages, pet stores often sell prepackaged starter kits for housing small pets complete with a supply of wood chips for bedding. Many people have used cedar and pine chips as bedding for these reasons. These same chemicals can also damage the respiratory tract, causing chronic respiratory disease, and asthma, and some studies have found an association between exposure to some wood dusts and oral cancers. The scientific literature on this topic is extremely clear, and unlike many studies of toxins, most of the scientific evidence regarding wood dust exposure has been conducted in humans rather than in laboratory animals since so many people work in the production of wood products. Keep in mind that the effect on small mammals is likely to be even more pronounced, especially if they are in close, continual contact with wood chips.
Humans also have a relatively poor sense of smell compared with other mammals.
Thus, a nasal or respiratory irritant is much more likely to harm small mammals, which rely on smell for locating food and identifying and interacting with other animals. Exposure to plicatic acid can cause or exacerbate asthma, rhinitis or conjunctivitis in humans and in animals, and the damage can be progressive. Asthmatics who are continuously exposed to cedar, such as in a lumber mill, experience deterioration in their asthma over time. Pine products also include pine resin, also known as rosin or colophony, which is known to pool players and mountain climbers. Plicatic acid has been shown to cause an array of pathological changes consistent with inflammatory and allergic reactions.