- Arsenic, a heavy metal historically used in pigments (such as in wallpapers and paints) and bookbinding, is well-known for its toxic effects on the skin.
- Chronic exposure to arsenic can cause characteristic cutaneous lesions, including hyperpigmentation, keratosis, and ulcerations.
- Importantly, arsenic is classified as a Group 1 human carcinogen by the International Agency for Research on Cancer (IARC), meaning it has a definite link to increasing the risk of several cancers, particularly skin cancer, lung cancer, and bladder cancer.

- In contrast, although other heavy metals like lead, mercury, and cadmium have their own toxicities, they are not primarily associated with these specific cutaneous manifestations or as strong a carcinogenic risk in the context provided.

Thus, the correct answer is Arsenic.

Key points:
- Arsenic used historically in pigments and bookbinding.
- Causes characteristic cutaneous lesions: hyperpigmentation and keratosis.
- Classified as a Group 1 carcinogen, increasing risk of skin and other cancers.

Reference: Goldman’s Cecil Medicine, 25th Edition, Chapter 156: Environmental and Occupational Diseases, p. 1204-1206