Basal and squamous cell carcinomas are most commonly associated with exposure to which of the following?

Basal and squamous cell carcinomas are both types of skin cancer that are primarily linked to exposure to ultraviolet (UV) radiation, particularly UVB rays. These cancers are associated with cumulative sun exposure and are more prevalent in individuals with fair skin who are more sensitive to UV radiation. UVB rays, which are part of the ultraviolet spectrum emitted by the sun, have the energy necessary to damage the DNA in skin cells, leading to changes that can result in cancer.

In contrast, while tobacco smoke is a well-known risk factor for several cancers, particularly those affecting the lungs and oral cavity, it is not primarily associated with skin cancer. Nuclear waste and asbestos exposure are associated with other forms of cancer—like lung cancer and mesothelioma, respectively—but not directly with basal or squamous cell carcinomas. Thus, the connection between UVB radiation and these specific types of skin cancer is well-established in the realm of environmental health and skin oncology.