Suncreens 🧴🧴 Flashcards
Describe ideal properties of sunscreens
9
- absorption across harmful UV region (250- 360)
- large molar absorbtivity
- photochemically inert
- totally water insoluble
- non toxic
- non staining
- odourless
- chemically stable and pure
- inexpensive
What does SPF measure?
Sun Protection Factor SPF
measures effectiveness of a sunscreen
SPF = time for MED with sunscreen
Over / time for MED without sunscreen
How do Physical Absorbers work?
Metal oxides..
By reflecting, scattering and absorbing sunlight
How do chemical absorbers work?
Absorb sunlight and dissipate the energy as heat, no net chemical change
Eg. Benziphenones, amino benzoic acid derivatives
What is Nanoparticle toxicity?
Nanopartifles do not penetrate intact skin.
May penetrate damaged skin (eczema)
*TiO2 nanoparticles exposed to UV cab generate hydroxyl radicals that can damage DNA
BUT TIO2 NANOPARTICLES COATED WITH DIMETHICONE OR SILICA TO PREVENT AGGKOMERATION, ALSO INHIBIT FREE RADICAL GENERATION
What factors influence the effectiveness of Sunscreens?
6
- Age of product and expiry date
- Specific ingredients
- Overall formulation
- Water resistance
- Amount of time the sunscreen has been exposed to the sun
- Amount applied
List 3 environmentally unfriendly sunscreen ingredients!!
- Oxybenzone
- Octinoxate
- Butylparaben
Excessive UV Radiation effects what?
- Immune effects
= suppression or cell-immunity - Eyes
= acute conjunctivitis, cataracts or macular degeneration - Cancers of the skin
= sunburn, skim cancers, medication reactions
Role of UV radiation on synthesis of Vitamin D?
What should yhe UV index be to recommend sunscreens?
3 or above
