Sunscreens are important photo-protective measures.
These are available in different SPF factors.
Higher the SPF the higher sun protection achieved.
SPF is sun protection factor.
It is a measure to assess protection against UVB radiations.
SPF= minimal erythema induced after exposure of sun protected skin
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Minimal erythema induced after exposure of unprotected skin
UVA protection is also important for complete sun protection.
UVA protection is assessed on the basis of persistent pigment darkening (PPD).
It's called UVA -PF ( Ultraviolet A - protection factor).
Two different types of sunscreen :
Chemical and physical sunscreen
(Organic and inorganic)
Avobenzone is most commonly used UVA filter.
Octinoxate is widely used UVB filter.
Inorganic active ingredients :
Titanium dioxide and zinc oxide
These particles available in microfine particles ( nano particles) to avoid refraction of light.
Sunscreen should be applied 2 mg/cm2 to achieve accurate sun protection as labeled on sunscreen with SPF.
Controversies:
1) vitamin D:
With sunscreen application serum vitamin D levels which require sunlight will decrease or not??
The answer is No.
Most of the times people apply sunscreen inadequately so not affecting natural process of conversion of cholecalciferol ( vit D3).
The same UVB radiation is required for vit D synthesis so it's not acceptable to get exposed it to induce photocarcinogenesis.
Instead one can take vit D supplements and must continue photo protection with sunscreen .
2) melanoma and nonmelanoma skin cancer
Is sunscreen usage really helpful in reducing skin cancer on prolonged use??
Answer is yes.
Few scientific studies have established the effectiveness of sunscreen in decreased risk of development of skin cancer.
How often one should apply sunscreen ?
Every 2 hours sunscreen should be reapplied.
As sunscreen do migrate to skin surface through follicular orifice and lead to uneven distribution.
These can be removed with sweat and water. So reapplication is necessary to remain protected all time.
USAN : United States adopted nomenclature is used to name active ingredient of sunscreen .
Till date 16 active ingredients are included in list by FDA.
New generation sunscreen ingredients are more photo-stable one.
Photo allergy risks with active ingredients are relatively low.
