L15: Sunscreens

Question 1

What is the main electromagnetic wave concerned with skin damage from sunlight exposure?

Answer 1

UV light, specifically UV-A and UV-B

Question 2

Which is the main cause of sunburn and skin cancer, UV-A or UV-B?

Answer 2

UV-B

Question 3

Which penetrate deeper into the skin, UV-A or UV-B?

Answer 3

UV-A

Question 4

Which does more damage to the skin, UV-A or UV-B?

Answer 4

UV-A

Question 5

What are some of the natural protective mechanisms against ultraviolet light present in the stratum corneum?

Answer 5

• Scattering and reflection of UV radiation by corneocytes

- Endogenous body antioxidants (eg. carotenoids, urocanic acid and superoxide dismutase)

Question 6

Epidermis absorbs radiation of what wavelength?

Answer 6

< 320nm

Question 7

Which layer of the skin absorbs radiation wavelengths of > 320nm?

Answer 7

Dermis

Question 8

How does tanned skin arise from exposure to ultraviolet rays?

Answer 8

UV rays are absorbed by melanin, causing it to oxidize and result in tanned skin.

This process is called delayed tanning or persistent pigment darkening

Question 9

What is skin colour determined by?

Answer 9

• Mix of carotenoids
• Different types of melanin
• the way that melanin is packaged and distributed in melanosomes

Question 10

What is the relationship between skin pigmentation and incidence of sun-induced skin cancers?

Answer 10

Inverse relationship

Question 11

What causes albino phenotype?

Answer 11

Defective melanocytes, thus unable to produce melanin for photo-protection

Question 12

What are the two types of albinos?

Answer 12

Constitutive and facultative

Question 13

What is skin cancer caused by?

Answer 13

Long-term exposure to the sun and bad sunburns

Question 14

What kind of eye damage can the sun do?

Answer 14

• Cataracts
• Photokeratitis
• Pterygium
• Cancer of the eye

Question 15

What are the 3 main types of skin cancer?

Answer 15

• Basal cell carcinoma
• Squamous cell carcinoma
• Melanoma

Question 16

Can exposure to sun cause allergies?

Answer 16

Yes

Question 17

What are the two main types of sunscreens?

Answer 17

Organic and inorganic

Question 18

What is the MOA of organic sunscreens?

Answer 18

Absorb UV radiation like melanin and transform it into heat

Question 19

Organic sunscreens can offer sufficient protection with just one application throughout the day. True or False?

Answer 19

False. it must be frequently reapplied to maintain protection from the sun.

Question 20

What is the MOA of inorganic sunscreens?

Answer 20

Reflect or scatter UV radiation, absorbing little energy

Question 21

Inorganic sunscreens should be frequently reapplied to confer sufficient protection against the sun. True or False?

Answer 21

False. Their effect lasts longer and do not require frequent reapplication.

Question 22

What are some examples of UVA organic sunscreens?

Answer 22

• Benzophenones
• Avobenzone
• Anthranilates

Question 23

Salicylate is a type of UVB organic sunscreen. True or False?

Answer 23

True.

Question 24

Cinnamate is a type of UVA inorganic sunscreen. True or False?

Answer 24

False. It is a UVB organic sunscreen

Question 25

What are some examples of inorganic sunscreens?

Answer 25

- Titanium oxide | - Zinc oxide

Question 26

What are the advantages of employing nanoparticles in sunscreens?

Answer 26

- Transparent | - Aggregation

Question 27

What are some disadvantages of employing nanoparticles in sunscreens?

Answer 27

- May penetrate into the deeper layers of the skin; may confer side effects that are yet known - Toxic to the environment (as it kills plankton)

Question 28

What does Minimal Erythema Dose (MED) refer to?

Answer 28

Minimum UV radiation dose that produces clearly emarginated erythema in the irradiated site, given as a single exposure TLDR: minimum UV radiation dose to cause sunburn

Question 29

What is the formula for Sun Protection Factor?

Answer 29

MED of protected skin / MED of unprotected skin or Time to produce erythema on protected skin / Time to produce erythema on unprotected skin

Question 30

What does an SPF of 6 mean?

Answer 30

It means that it takes 6 times longer for skin protected with this sunscreen to develop sunburn than normal

Question 31

How much sunscreen should be applied?

Answer 31

Apply 2mg/cm^2 of sunscreen For an average-sized person, this is equivalent to a shot glass

Question 32

What are some disadvantages of water-resistant sunscreens?

Answer 32

- Water dissolves the oily sunscreen film by interacting with the emulsifier - Rubbing removal - Physical degradation

Question 33

What kind of ingredients should after-sun products contain?

Answer 33

- Moisturizer - Anti-inflammatory ingredients - Cooling compounds: Menthol, camphor - Antioxidants: Vit E, Vit C, carotenoids, coenzyme Q10 - Others: Extra virgin olive oil, Aloe, Shea butter

Question 34

What are the protective measures against UV radiation?

Answer 34

- Avoid the sun - Use sunscreens - Wear a hat - Cover up - Wear sunglasses - Avoid artificial tanning

Question 35

What is the upper SPF limit?

Answer 35

50

Question 36

Why is it not recommended for sunscreens to have SPF of > 30?

Answer 36

It offers little additional benefit and may unnecessarily expose users to dangerous levels of chemicals

Question 37

What additional information should water-resistant or sweat-resistant sunscreens provide?

Answer 37

SPF for both before and after being exposed to water or sweat

Question 38

Any tanning product that doesn't contain a sunscreen would have to state on the label that the product does not contain a sunscreen. True or False?

Answer 38

True