Definition

• Ultraviolet (UV) light is light consisting of wavelengths between 40 and 390 nm, states the book "Microbiology." UV's wavelengths are shorter than those of visible light (400 to 700 nm), but not as short as those of X-rays or gamma rays.
  
  

Mechanisms

• UV light causes mutations in tumor suppressor gene p53 and release of tumor necrosis factor-α, which may reduce the immune system's surveillance against skin cancer, note Huether and McCance.
  
  

Malignancies

• Incidences of both basal cell carcinoma and squamous cell carcinoma correlate with cumulative exposure to UV light, according to the book "Understanding Pathophysiology."
  
  

Melanoma

• Melanoma also increases with UV-light exposure, but--more so than basal or squamous cell carcinoma--it correlates with episodes of severe, blistering sunburn at a young age, according to Huether and McCance.
  
  

Microbes

• UV light can injure unicellular organisms too, damaging the molecular components of DNA and proteins, notes Jacquelyn G. Black, Ph.D.
  
  

Mitigation

• The atmospheric ozone (O3) layer diminishes UV light's damaging effects on cells, according to the book "Biology."