**7.4 Radiation carcinogenesis**

Radiation is a well-known carcinogen.

Latency: Extremely long latent period is common and It has a cumulative effect. Radiation has also additive or synergistic effects with other potential carcinogenic agents.

Types of radiation: They are divided into two types, namely:

1.Ultraviolet (UV) rays of sunlight, and

2. Ionizing electromagnetic and particulate radiation.

Ultraviolet rays:-. They are derived from the sunlight. Tumors caused: Skin cancer, namely.

1.Squamous cell carcinoma,

2.Basal cell carcinoma, and

3.Malignant melanoma.

They are more common on parts of the body regularly exposed to sunlight and ultraviolet light (UVL).

Risk factors.

The amount of damage incurred depends on:

• Type of UV rays.

◦ Intensity of exposure.

