Sun Protection (Classification of Sunscreen and SPF)

Introduction
Skin Damage
Sun Radiation Summary
Sunscreen Defination
Classification Of Sunscreen
Sunscreen Agents
Sun Protection Factor
Sun Protection Factor Classification
When to re-apply the sunscreen

1. Sun protection Classification of Sunscreen And SPF Shivam Pharmaceutical Studies and Research Centre , Anand Prepared by: Rahul Kushwaha

2. Introduction In the past, sun exposure was thought to be a healthy benefit of outdoor activity Overexposure to sunlight is widely accepted as the underlying cause for harmful effects on the skin, eye and immune system Sun protection is essential to skin cancer prevention - about 90 percent of non-melanoma skin cancers and about 86 percent of melanomas are associated with exposure to UV radiation from the sun.

3. Sunlight reaching the surface of the earth contains: ✓ Visible rays ✓ Ultra-violet rays ✓ Infra-red rays UV Rays (particularly wave-length below 320mu) are responsible for most of the therapeutic as well as noxious effects that we attribute to sun-light.

4. SKIN-DAMAGE The UV Spectrum is broken into three parts: ✓ Very High Energy (UVC) ✓ High Energy (UVB) ✓ Low Energy (UVA) Visible and IR radiation don't harm the skin.

5. SKIN-DAMAGE Very High Energy Radiation (UVC) is currently blocked by the ozone layer. High Energy Radiation (UVB) does the more immediate damage. But Lower Energy Radiation (UVA) can penetrate deeper into the skin, leading to longterm damage.

6. Sun Radiation Summary Radiation Type Characteristic Wavelength ( λ ) Effects on Human Skin Visible to Human Eye? UVC ~ 200-290 nm (Short-wave UV) DNA Damage NO UVB ~ 290-320 nm (Mid-range UV) Sunburn DNA Damage Skin Cancer NO UVA ~ 320-400 nm (Long-wave UV) Tanning Skin Aging DNA Damage Skin Cancer NO Vis ~ 400-800 nm None Currently Known YES IR ~ 800-120,000 nm Heat Sensation (high λ IR) NO

7. SUNSCREEN Definition: Sunscreen (also known as sunblock or suntan lotion is a lotion, spray, gel or other topical product that absorbs or reflects the sun's ultraviolet (UV) radiation and protects the skin.

8. IDEAL SUN-SCREEN CHARACTERS: Absorb light preferentially over the range of 280 - 320mu. Resistance to water Preferably odorless, if mild odor: accepted by user. Be non-toxic, non-irritant, non- sensitizing Capable of retaining sunscreening property for several hours Not be rapidly absorbed Be rapidly soluble in suitable vehicles. SUNSCREEN

9. Classification of Sun screen Depending on the mode of action, sunscreens can be classified into: 1) Physical sunscreens (those that reflect the sunlight) 2) Chemical sunscreens (those that absorb the UV light). Physical Opaque formulations containing: titanium dioxide talc, kaolin zinc oxide ferric chloride Icthyol , red petrolatum Mechanism: scatters or reflects UV radiation due to large particle size

10. Classification of Sun screen Chemical Formulations containing one or more: PABA, PABA esters benzophenones cinnamates salicylates digalloyl trioleate anthranilates Mechanism: absorbs UV radiation

11. SUNSCREEN AGENTS PABA(Para-amino benzoic acid) Very effective in the UVB range (200-320 nm) Most effective in conc. of 5% in 70% ethanol Maximum benefit when applied 60 minutes prior to exposure Contact dermatitis can develop. May stain clothin May stain clothing PABA Esters (Padimate A, Padimate O, Glyceryl PABA) Also very effective in UVB range (280-320) Most effective in conc. 2.5-8% in 65% alcohol Less staining

12. SUNSCREEN AGENTS Benzophenones (oxybenzone, dioxybenzone , sulisobensone ) Slightly less effective than PABA Absorbs from 250-400 nm spectrum ( i.e , UVA & UVB). Combined with PABA or PABA ester improves penetration Beneficial in preventing photosensitivity reactions

13. SUNSCREEN AGENTS Cinnamates and Salicylates Minimally effective, absorb UVB spectrum. Generally used in combination with one of the above Anthranilates Minimally effective, absorbs UVA spectrum 250-322 nm. Usually combined with UVB agent to broaden spectrum.

14. Sun Protection Factor The term "sun protection factor" was adopted by the FDA to describe the effectiveness of Sunscreens. SPF is a measure of how much solar energy (UV radiation) is required to produce sunburn on protected skin (i.e., in the presence of sunscreen) relative to the amount of solar energy required to produce sunburn on unprotected skin. As the SPF value increases, sunburn protection increases. SPFdefined as the UV energy required in producing a minimal erythemal dose (MED) on protected skin, divided by the UV energy required to produce a MED on unprotected skin

15. SPF = Broad-spectrum sunscreen gel can protect your skin Sunburn Suntan Photo-aging Dull complexion Skin inflammation and Skin Cancer (more severe cases) Sunscreens have a number written as Sun Protection Factor, i.e. SPF 15, 20, 30 or 50 on the pack  

16. Protection level SPF value Low protection 6,10 Medium protection 15,20,25 High protection 30,40 Very high protection 50+ Sun protection factor classification

17. When to re-apply the sunscreen SPF Tab SPF/time to re-apply the sunscreen [ approx ] 15 After 1 hour 30 After 2 hour 50 After 4 hour 70 After 6 hour If you are exposed to sun and pollution for longer duration then you need to re-apply your sunscreen. SPF wise re-applying time is mentioned in the table:

18. SPF Factor Percentage of UVB Rays Blocked SPF 2 50 % SPF 4 75 % SPF 10 90 % SPF 15 93 % SPF 30 97 % SPF 50 98 % SPF 70 98.5 % SPF 100 99 %