- Benzene, commonly found in certain aged books and industrial products, is a well-established carcinogenic chemical.
- It is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC), meaning there is sufficient evidence of carcinogenicity in humans.
- Exposure to benzene primarily affects the bone marrow and can lead to blood disorders such as aplastic anemia and leukemia, particularly acute myeloid leukemia (AML).

While other chemicals listed are hazardous, their carcinogenic profiles differ:
- Formaldehyde is also a known carcinogen but is more commonly associated with resins and embalmment fluids.
- Asbestos is a carcinogen but is predominantly found in insulation and construction materials rather than books.
- Toluene is toxic and affects the nervous system but is not classified as carcinogenic.

Therefore, the correct answer is benzene, notable for its carcinogenicity linked to industrial exposure and certain old paper products.