Sunscreen

Question 1

What effects on the skin does sunlight have (acute and chronic exposure)

Answer 1

Acute exposure (erythema, oedema, tanning, thickening of epidermis/dermis, vitamin D synthesis)

Chronic exposure (photoaging, immunosuppression, carcinogenesis, photodermatoses, photosensitization)

Question 2

UVB rays are responsible for producing sunburn, what do they look like?

Answer 2

UVA (320 to 400 nm), UVB (280 to 320 nm)

Question 3

What type of sunscreen products are available?

Answer 3

• Emulsions
• Oils
• Oils
• Single-phase sprays

Question 4

what is the sun protection factor value (SPF value)

Answer 4

Sunscreen products are classified according to their Sun Protection Factor or SPF value

SPF = MED_protected/MED_unprotected

• The UVR energy required to produce a minimal erythemal dose (MED) on protected skin (with 2 mg/cm² of the sunscreen) divided by the UVR energy required to produce a MED on unprotected skin.
• MED is the smallest dose of UVR (J.m²) that produces redness with clearly defined borders at the exposure site: often measured as exposure time required to cause erythema

Question 5

What is the relationship between SPF and UVB blocking ability?

Answer 5

Question 6

What makes the ideal sunscreen product?

Answer 6

• High SPF and broad UV absorption spectrum
• Cosmetic elegance and water resistant
• Prolonged duration of action
• Limited penetration of sunscreen agents to deep tissues or circulation
• Minimal toxicity, non-allergenic, non comedogenic
• Stable, including photostable

Question 7

What is found in sunscreen products?

Answer 7

Combination of organic and inorganic sunscreens

• Combination of sunscreen actives to provide high SPF and broad spectrum of UV absorption
• Formulations: creams, lotions, oils, sticks, alcohol based sprays, cosmetics and hair treatments
• Toxicity: many reports of local skin reactions; limited information on systemic distribution, toxicology and metabolism
• Risk/benefit ratio in favour of sun protection

Question 8

Properties of sunscreen? What actives are found in it?

Answer 8

Inorganic (physical): zinc oxide and titanium dioxide (TiO₂)

• Block UVA/B through reflection, scattering and absorption

Block UVA/B through reflection, scattering and absorption

• Absorb UVR, chemical excitation – UVR dissipated as longer l energy
• Classified as either UVA or UVB filters with some absorbing in both ranges

Suncreens regulatred by TGA in Australia

Question 9

What are some safety concerns in organic sunscreens?

Answer 9

• Evidence that some organic sunscreens are absorbed via the skin to systemic circulation and excreted in urine
• Concerns of DNA damage to tissues with some sunscreens and UV exposure – in vitro but no long term clinical evidence
• Ideally formulate sunscreen product to prevent skin penetration of actives

Question 10

What are some safety concerns in nanoparticle sunscreens?

Answer 10

• Concerns regarding nanoparticle exposure
• Our systematic studies have shown very limited skin penetration of ZnO NP under in-use conditions (massaging, repeated application, skin flexing) in human volunteers

Question 11

What are some antioxidants in skin protection?

Answer 11

• Antioxidants are included in many skincare and suncare products
• Provide photoprotective effect by neutralising UV-generated free radicals (donate electron) thus preventing tissue damage
• Antioxidants do not become reactive due to loss of electron

Examples: Vitamin A, Vitamin C, Vitamin E, alpha lipoic acid and minerals (selenium)