Final answer:
Squamous cell carcinoma risk factors include UV light exposure, smoking, personal or family history of skin cancer, precancerous skin lesions, weakened immune system, and exposure to radiation or toxic substances like arsenic.
Step-by-step explanation:
The risk factors for squamous cell carcinoma of the head and neck include a range of environmental and individual behaviors that can increase the likelihood of the development of this type of cancer. Sun exposure is recognized as a significant risk factor, with ultraviolet (UV) light playing a primary role in the development of many skin cancers, including squamous cell carcinoma. Individual behaviors such as smoking can also contribute to risk, with smokers having a significantly higher chance of developing the disease. In terms of individual histories, those with a personal or family history of skin cancer, precancerous skin lesions, or a weakened immune system tend to be at greater risk. Exposure to other forms of radiation or toxic substances, such as arsenic, can also increase the likelihood of squamous cell carcinoma.