EFFECTS OF ULTRAVIOLET RADIATION

Henry W. Lim, MD

Co-Chair

National Council on

Skin Cancer Prevention

PRESENTER

• Chairman, Department of Dermatology, Henry Ford Hospital, Detroit, MI

• Photodermatology

DISCLOSURE

• Consultant : La Roche-Posay/L’Oreal, Orfagen, Dow Pharmaceutical Sciences

• Investigator: Johnson & Johnson

ELECTROMAGNETIC RADIATION

ULTRAVIOLET RADIATION

UV λ (nm) Properties

UVC 200-290 Germicidal

UVB 290-320 Sunburn

UVA 320-400 Pigment darkening, tanning

EFFECTS OF UV

• DNA damage• Erythema• Tanning• Vitamin D synthesis• Immunosuppression• Skin cancer

EFFECTS OF UV

• DNA damage

UV AND DNA DAMAGE

UVB:

• Direct effect

• Cyclobutane-pyrimidine dimers

Bolognia, et al. Dermatology. 2008

UV AND DNA DAMAGE(Agar NS, PNAS 4/04; 101:4954; Budiyanto A, P&P10/02; 76:397)

UVA:• Indirect mechanism• Absorption by skin chromophores →

reactive oxygen species → reacts with guanine → oxidative products (8-oxoG, 8-oxo-dG)

• Mutagenic

EFFECTS OF UV

• DNA damage• Erythema

ERYTHEMA

• Primarily the effect of UVB

• Peaks at 24 hrs

EFFECTS OF UV

• DNA damage• Erythema• Tanning

MECHANISMS OF TANNING (Hönigsmann H, PPP 4/02; 18:75)

• UV: activation of tyrosinase• UV DNA damage

nucleotide fragments excised in repair stimulate melanogenesis

ERYTHEMA & TANNING

• UVB: Erythema > tanning

• UVA: Tanning > erythema

• Tanning is an indication that DNA damage has occurred

• There is no “safe tan”

EFFECTS OF UV

• DNA damage• Erythema• Tanning• Vitamin D synthesis– Action spectrum: UVB

EFFECTS OF UV

• DNA damage• Erythema• Tanning• Vitamin D synthesis• Immunosuppression• Skin cancer

UV: IMMUNOSUPPRESSION AND SKIN CANCER

(International Agency for Research on Cancer Working Group on artificial ultraviolet light and skin cancer. Green A, et al.

Int J Cancer 3/07; 120:1116)

• UV: immunosuppressive• Chronic UV exposure:– Photoaging changes– Squamous cell carcinoma– Basal cell carcinoma

• Tanning bed users:– Melanoma– Squamous cell carcinoma

NATURAL AND ARTIFICIAL UV

• DNA damage, immunosuppression, skin cancer

• WHO: UV is carcinogen• WHO: UV tanning beds:

“carcinogenic to humans.” (El Ghissassi F, Lancet Oncol 7/09; 10: 751)

NCSCP RECOMMENDATIONS• To reclassify sunlamps for tanning

as Class II devices

• To impose special controls: user labeling and user registry

• To prohibit use by consumers younger than 18 years

• To require license for facilities at which sunlamps may be used

• To have training and certification of operators

www.skincancerprevention.org