There are few types of wavelength that will damage our skins.
A. UVC (290-200 nm) - is highly carcinogenic, but is mostly absorbed by the ozone-rich
stratosphere.
- with ozone depletion, UVC radiation may become a more important
factor in skin cancer in the future.
B. UVB (315-290 nm) - is responsible for sunburn and can induce skin cancer.
C. UVA (400-315 nm) - There are a long wave and short wave UVA in our life. Longwave UVA is
what we focus, it can pass through Epidermis to Dermis, cause serious
and irreversible damage to the skin.
- is responsible for actinic (aging and darkness) damage to the skin and can act as a
co-carcinogen with UVB radiation.
D. Blue Light – with the longest wavelength, it can pass to the deepest Hypodermis to your skins
, during research, it will cause ROS and RNS in damaging your skin.
※ The oncogenic effect occurs as a result of photochemical damage to epidermal cell DNA
, damage to DNA repair mechanisms and suppression of cell-mediated immunity.
Ps. With the longest wavelength, the more pass your skins. But the energy is lower with wavelength.
Damages
A. UVA – Cause immune resists and related to melanoma.
B. UVB - ① Cause squamous cell carcinoma
② Damaging DNA ⇒ Let pyrimidines from dimer and cyclobutane pyrimidine dimer.
※ The stratum corneum reflects radiation, so reducing the exposure dose.
※ SPF – Sun Protection Factor
↳ only estimate UVB, not UVA
PA – Protection Grade of UVA
↳ only estimate UVA, not UVB
※ Water resist – in water 40 mins, still have SPF function.
Very Water resist – swim 20 mins, 4 times for 80 mins, still have SPF function
There is no “Water Proof” ⇒ Not only one have this classification
Classification
A. Physical Sunscreens = Barrier Sunscreens ⇒ Less Sensitive.
↳ ① Reflect or Block UV and IR
② Only get certified by FDA ingredient ⇒ avobenzone
③ Disadvantage ⇒ Metal may produce free-radical
B. Chemical Sunscreens
↳ ① Absorb UV itself
※ Having sunlight help Vitamin D synthesis
↳ Position ⇒ Keratinocytes
↳ Pro-D3 (7-dehydrocholesterol)
↳ Pro-D3 β ring be photolysis
↳ Pre-D3
↳Thermal Transformation
↳ Vitamin D3
※ Photoaging
↳ Inflammation → sun-burning → cell destroy
↑ ↓ ↑
IL-1.6.8 ↑ → keratinocyte activated, producing free-radical, ex: AP-1
(IL-1α) ↑ → keratinocyte activated, producing free-radical, ex: AP-1
※ Dyspigmentation
↳ UVA ⇒ Stimulate Granulocyte Monocyte Colony Stimulating Factor
↳ Melanin Produced.
↳ Sun exposure increases the activity of melanocytes, the number of melanosomes
produced and the rate of transfer of melanin to the epidermal keratinocytes.
Admin
on Jan th, 2019