Sunscreen and Sun care

Question 1

Two main types of sunscreen. State one example of each

Answer 1

1. Chemical (organic): Oxybenzone, octinoxate
2. Physical (inorganic): Titanium dioxide, zinc oxide

Question 2

Types of sunlight that causes skin photoaging and photocarcinoma?

Answer 2

Mainly UVA (UVA1 + UVA2, 320-400 nm) and UVB (290-320 nm)

Question 3

What is SPF?

Answer 3

Level of protection against UVB
(based on ratio of minimal erythema dose on sunscreen-protected skin vs unprotected skin)

Question 4

For daily use, what is the recommended SPF for the sunscreen?

Answer 4

15

Question 5

What does it mean if a sunscreen has “broad spectrum”?

Answer 5

Covers UVB and UVA (UVA1 and UVA2)

Question 6

Three sunscreens that protects against UVA1?

Answer 6

1. Titanium dioxide
2. Zinc oxide
3. Avobenzone (best UVA spectrum, not too good with UVB)

Question 7

State the classification of sunscreen that PABA-derivative falls under. Name one advantage and one disadvantage

Answer 7

Chemical (organic) sunscreen
- Advantage: Lasting protection with good water resistanece
- Disadvantage: Major skin sensitiser

Question 8

State the classification of sunscreen that Benzophenones falls under. Name one advantage and one disadvantage

Answer 8

Chemical (organic) sunscreen
- Advantage: absorbs some form of UVA on top of UVB (but still better at absorbing UVB)
- Disadvantage: reports of sensitivity

Question 9

State the classification of sunscreen that avobenzone falls under. Name one advantage and one disadvantage

Answer 9

Chemical (organic) sunscreen
- Advantage: Best UVA protection (not too good with UVB)
- Disadvantage: Poor skin adherence, hence unpopular for those who sweat a lot

Question 10

State an advantage and disadvantage of physical sunscreens

Answer 10

• Advantage: Suitable for small and prominently exposed areas
• Disadvantage: Discolour clothings, occludes skin

Question 11

What is minimal erythema dose?

Answer 11

Minimum UV radiation dose that produces clearly marginated erythema

Question 12

According to American Academy of pediatrics (AAP), what is the recommendation for sunscreen application for infants and young children?

Answer 12

• Avoid in infants < 6mo
• If required, small amounts of >15 SPF sunscreen can be applied onto small areas
• Use low-sensitising potential sunscreen in view of immature skin barrier
• Physical (inorganic) sunscreen in oil base preferred due to broad spectrum and minimal irritation, sensitisation and penetration