Final answer:
Tobacco smoke, with its myriad of chemical carcinogens, is a leading cause of head and neck cancers. UV radiation is a key factor in skin cancers, and other substances and pathogens like HPV also contribute to the risk.
Step-by-step explanation:
A leading cause of head and neck cancers in the US is exposure to tobacco smoke, which contains numerous chemical carcinogens. Smoking tobacco not only increases the risk of lung cancer but also significantly raises the possibility of cancers in the mouth, throat, larynx, head, neck, stomach, bladder, kidney, esophagus, and pancreas. Aside from tobacco, other important risk factors include exposure to ultraviolet (UV radiation) from the sun, which is a major contributor to the high incidence of skin cancer, particularly on the head and neck. Moreover, other carcinogens like asbestos, formaldehyde, and certain types of viruses, such as the human papilloma virus (HPV), can also increase the risk of cancer.