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Overview UV and vitamin D

simple graphic

Consensus

  • UV radiation at the ground consists mainly of UVA, some UVB, and a tiny amount of UVC
  • Sun, sunbeds/tanning beds/some sun bulbs contain both UVA and UVB radiation
  • UVA (315 -400 nm) radiation induces pigment tanning within seconds of UVA and light exposure
    • UVA tanning fades within 2 hours and does not increase melanin in skin
  • UVB (280-315 nm) radiation
    • induces vitamin D synthesis
    • delayed tanning (increases melanin in skin after several days)
    • is mainly responsible for sunburn (erythema), photoaging, photoimmunosuppression
  • Windows (glass) block UVB radiation
  • Modern sunscreens block UVB and UVA, but some of them block UVA poorly or are photo-unstable in this region
  • There has been an increase in melanoma incidence in recent years
  • Tanning beds produce higher levels of UVA radiation than the sun - even at the equator
  • UVB radiation, but not UVA radiation, induces melanoma in genetically modified animals
    • The newest epidemiological evidence suggest that UVA as well as UVB is associated with human melanoma
  • Epidemiological studies published over the last years demonstrated the association between sunbed use and melanoma.
  • Many countries restrict the amount of UVB (vitamin D) from tanning beds (due to mouse study)
  • UVB decreases faster than UVA when far from equator or winter season

Confusion/Disagreement

Sunburn (Erythema), cataracts, and development of skin cancer are related mostly to UVB radiation.
Ban all people under age 18 from using tanning beds

Spectrum

from Mercola

  • Visible: 450 (deep violet) to 700 (deep red)
  • UVA: a small amount gets thru the atmosphere (tan)
  • UVB: a tiny amount gets thru the atmosphere (Vitamin D)
  • UVC: none gets thru the atmosphere

UVB and UVA are very different

UVB UVA
Wavelength 280-315 315-400?
Tan Nope Tan
Vitamin D Vitamin D nope
Sun Screen blocked by sunscreen varies
Tanning salon varies widely
with tubes used
5X more intense
than sun
Thru glass
eye and window
blocked by glass UVA passed by some glass
may destroy some vitamin D
Birds can see nope Many birds can see UVA
Reptile can see Yes reptile Yes reptile
Wrinkle Yes ??
Bleach furniture ?? Yes
Skin Cancer controversy controversy

UV: Different Spectra: UVB = Vitamin D, UVA = Pigmentations

From Tanning Guru
UV: vitamin D, tan @ is.gd/UV_VitD

Hypothesis: UVA decreases vitamin D: many hints

Tanning

Measure UV

UV thru glass

No UVB (Vitamin D) gets thru, but most UVA (Tan) gets thru

uv window glass.jpg

Sunscreens

Increased sunscreen ==> increased melanoma

Melanoma and suncreens Time line -2010

Red = sunlight; other lines = amount of light filtered thru sunscreens

Image

Chart by Wagner and Hollis,  downloaded from Grassroots April 2010 – video expected June

UV Other

Image

See also web

Short url =http://is.gd/UV_VitD

Overview UV and vitamin D        

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