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PR2202 > Chapter 5 - Sunscreen > Flashcards

Chapter 5 - Sunscreen Flashcards

1
Q

Compare the wavelength and frequency of UVA and UVB.

A

UVA - Higher wavelength, lower frequency

UVB - Lower wavelength, higher frequency

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2
Q

What type of UV radiation is responsible for sunburn and skin cancer and why?

A

UVB, it has higher energy and therefore does more damage to the skin.

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3
Q

To what extent can UVA and UVB penetrate the skin?

A

UVA - Epidermis to dermis to subcutaneous tissue

UVB - Epidermis to dermis

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4
Q

At the stratum corneum level, how is the skin protected from UV?

A

UV is reflected by the corneocytes.

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5
Q

What causes intermediate pigmentation?

A

Upon UVA exposure, melanin oxidation is triggered leading to intermediate pigmentation

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6
Q

What are the 7 types of natural ultraviolet protective mechanisms of the cutaneous structure??

A

1) Compact horny layers
2) Keratinocyte melanin
3) Carotenoid pigments
4) Urocanic acid
5) Superoxide dismutase
6) Epidermal DNA excision repair
7) Vitamins (C&E) and other antioxidants (glutathione)

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7
Q

How do compact horny layers provide sun protection?

A

Absorbs and scatters UV

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8
Q

How does keratinocyte melanin provide sun protection?

A

1) UV absorbing filter
2) Free radical scavenger
3) Dissipates UV as heat
4) Undergoes oxidation in 300-360 nm range to produce immediate pigment darkening

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9
Q

How do carotenoid pigments provide sun protection?

A

1) Membrane stabilizers

2) Quench oxygen radicals

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10
Q

How does urocanic acid provide sun protection?

A

Oxidized to stabilized UV-induced oxygen radicals

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11
Q

How does superoxide dismutase provide sun protection?

A

1) Oxygen radical scavenger

2) Protects cell membrane from lipoprotein damage

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12
Q

How does epidermal DNA excision repair provide sun protection?

A

Repairs UV-induced DNA damage

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13
Q

How do vitamins and antioxidants provide sun protection?

A

Oxygen radical scavenger

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14
Q

What are the 3 endogenous body antioxidants?

A

Carotenoid pigments, urocanic acid and superoxide dismutase

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15
Q

What wavelengths of UV are absorbed by the epidermis and the dermis?

A

<320 absorbed by epidermis

>320 penetrate dermis

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16
Q

What does UV radiation damage?

A

1) DNA
2) Cell membrane lipids
3) Structural proteins
4) Enzymes

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17
Q

Why is UVB more damaging than UVA?

A

UVB has higher energy and is more carcinogenic as it is able to damage DNA. UVB is more associated with sunburns and redness while UVA is more associated with photoaging.

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18
Q

What does a bad sunburn reaction include?

A

Tenderness, pain, swelling, blistering of the skin. Might also cause fever, chills, and nausea.

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19
Q

What are the solutions to sunburn?

A

Wet compresses and soothing lotions to temporarily relieve the discomfort.

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20
Q

What are the determinants of skin color?

A

Determined by the mix of carotenoids and different types of melanin and also the way the melanin are packaged and distributed in the melanosomes.

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21
Q

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

A

Inverse relationship

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22
Q

Describe the process of immediate pigment darkening (IPD).

A

Upon single exposure to UV, melanin in the melanosome of the basal cell on the epidermis reassemble to form a cap to protect the skin (No new melanin).

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23
Q

Describe the process of delayed tanning (DT) for single UV and repeated UV.

A

Single UV - Attract melanocyte and keratinocyte (melanosomes present inside)
Repeated UV - Increased number and activity of melanocytes and melanosomes; Melanocytes dendrites elongate and branch, accelerating the melanin transfer to keratinocytes

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24
Q

What are albinos especially susceptible to UV damage?

A

Albinos have defective melanocytes and they cannot produce the molecule responsible for photoprotection.

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25
Q

What is the difference between constitutive and facultative albinos?

A

Constitutive - not influenced by external factors

Facultative - due to solar radiation or hormones (skin color)

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26
Q

Which areas of the body are most susceptible to skin cancer?

A

Face, neck, ears, forearms and hand.

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27
Q

What are the 3 types of skin cancer?

A

1) Basal cell carcinoma
2) Squamous cell carcinoma
3) Melanoma

28
Q

Describe the symptoms of basal cell carcinoma.

A
  • Small, shiny fleshy nodule on exposed parts of the body
  • Grows slowly and rarely spread to other parts of the body
  • Can severely damage surrounding skin
  • High cure rate if diagnosed and treated early
29
Q

Describe the symptoms of squamous cell carcinoma.

A
  • Develops on face, ears, lip and mouth
  • Begins as a red scaly patch
  • Has a high cure rate when detected and treated early
  • Spreadable to other areas of the body and can be fatal when untreated.
  • Penetrate to hypodermis
30
Q

Describe the symptoms of melanoma.

A
  • Most dangerous form of skin cancer
  • Usually appears as a dark brown or black lump with irregular edges
  • Sometimes, multicolored with shades of red, blue or white
    If ignored, can spread to other areas, can be fatal
  • Scandinavian paradox (Not only by UV radiation, environmental conditions could also play a part
31
Q

What causes cataracts?

A

Exposure to sun causes cataracts and it is one of the leading causes of blindness

32
Q

What are the 3 types of eye damage that can occur from prolonged exposure to the sun?

A

1) Photokeratitis
2) Pterygium
3) Cancer of the eye

33
Q

Describe the symptoms of photokeratitis.

A
  • Severe pain and reduced vision resulting from exposure only in highly reflective environments (snow blindness- 80% reflected).
  • Appears for a few hours and is reversible
  • Disappears within a day or two.
34
Q

Describe the symptoms of Pterygium.

A
  • Occur because of prolonged exposure to UV.

- Amenable by surgery but tend to recur

35
Q

Describe the symptoms of ‘cancer of the eye’

A
  • Malignant melanoma, cancer of the eyeball.
  • Associated with lifelong exposure to the sun
  • Basal cell carcinoma is common on the eyelids
36
Q

Describe the symptoms of ‘sun allergy’.

A

Occur after short periods of sun exposure due to sensitivity.

  • Intense itching
  • Raised reddish or skin-toned lesions
  • Blisters
  • Chills and nausea
  • Headache
37
Q

What is UV useful for?

A

UV is useful for the production of vitamin D, but prolonged exposure is harmful.
Solution: Frequent short exposure to the sun.

38
Q

How does exposure to UV cause immune system suppression?

A
  • Makes the body more susceptible to infections and cancers
  • Immune systems of dark and light skin people are equally affected
  • Diseases such as cold sore, chicken pox, lupus and genetic problems can be worsened by sun exposure.
39
Q

What is the difference between organic (chemical) and inorganic (physical) sunscreens?

A

Organic - Absorb UV and transform to heat. Needs to be frequently reapplied. Split into UVA and UVB absorbers,
Inorganic - reflect or scatter UV radiation, absorbing little energy. Long lasting effects and have combined effects of UVA and UVB

40
Q

Describe the 3 main constituents of UVA organic sunscreen filters

A

1) Benzophenones: used in low concentration as they are sticky. Higher incidents of allergic contact dermatitis
2) Avobenzone (Parsol): Need frequent reapplication as it is unstable. Incompatible with physical sunscreens. Octocrylene is more stable.
3) Anthranilates (e.g meradimate): Excellent safety profile and low allergenicity.

41
Q

Describe the 3 main constituents of UVB organic sunscreen filters

A

1) PABA derivatives: only in 2% of sunscreens due to allergenicity. Also, stain clothes
2) Salicylates (e.g Octisalate): >50% of secondary sunscreens contain salicylates due to excellent safety profiles (The main role is anti-inflammatory effect)
3) Cinnamates: Most popular, >80% of products with an SPF contain octyl methoxycinnamate (Octinoxate) (primary sunscreens)

42
Q

Describe the 3 main constituents of UVA/UVB inorganic sunscreen filters.

A
  • Helps to block both UVA and UVB.
  • Examples are titanium dioxide or zinc oxide where titanium dioxide is a common coloring agent used in many skin care products including cleansers and sunscreens
43
Q

How is titanium dioxide good as a sunscreen?

A

TiO2 is used as a whitening product and can promote exfoliation and scatter UV

44
Q

What is the inorganic nanoparticle that is becoming commonly used, and what are the concerns?

A

Zinc oxide, colorless when in nanometer scale. Concerns include penetration through the skin when < 13 nm and there an antibacterial but toxic to plankton. A possible advantage is the aggregation of particles when in nano scale.

45
Q

What is erythema?

A

It refers to the redness of the skin or mucous membrane, caused by hyperemia (increased bloodflow) in superficial capillaries

46
Q

What is MED?

A

MED = Minimal Erythema Dose
It is defined as the minimum UV radiation dose that produces clearly emarginated erythema in the irradiated site, given as a single exposure.

47
Q

What is SPF?

A 
SPF = Sun Protection Factor
Formula = MED of protected skin/ MED of unprotected skin
48
Q

How is SPF calculated?

A

The higher the SPF, the more effective in preventing sunburn. It allows the user to stay in the sun for a longer time before getting an erythema. However, the relationship is not linear.

49
Q

Why is a very high SPF bad?

A

More ingredients that are water-insoluble will be required to get a higher SPF. This leads to increased chances of allergy. It is better to apply SPF 30 more often.

50
Q

What is the FDA recommendation of sunscreen application?

A

2mg/cm2, roughly 1 shot glass per average size person. Half the amount used for SPF 30 = (30)^0.5 = 5.5 SPF

51
Q

When are water-resistant sunscreens usually used?

A

When sweat and water contact are common.

52
Q

What are the 6 types of water-resistant sunscreens and the mechanism of efficacy?

A

1) Water-in-oil emulsions: Oil resists removal by water
2) Silicones: Resist water and form thin, no greasy film on skin
3) Acrylate cross-polymers: Prevent water from dissolving the sunscreen (used in TiO2 preparations)
4) Liquid crystals gels: Resist water (used in TiO2 preparations)
5) Phospholipid emulsifiers: Mimic sebum with water-resistant properties.
6) Film forming polymers: Form thick film on the skin.

53
Q

What are the 3 common failures of water-resistant sunscreens?

A

1) Water dissolves the oily sunscreen film by interacting with the emulsifier. (Better to minimize emulsifiers)
2) Rubbing removal: Sunscreen does not stick well to the skin (Poor substantivity)
3) Physical degradation: Water affects water soluble TiO2, leaving behind a film that lacks ingredients required to achieve the labeled SPF.

54
Q

What must a good after sun product contain?

A

A stronger moisturizer (fix water loss) and have anti-inflammatory effects in case of erythema.

55
Q

What are the common components of after sun products?

A

1) Cooling compounds: Menthol or camphor for cooling effect (Soothe and alleviate the sensation of warmth and tenseness of sun-irritated skin)
2) Antioxidants (Not as effective): Vitamin E, C carotenoids, coenzyme Q10
3) Other ingredients: Extra virgin olive oil (EVOO) to reduce ROS-induced DNA damage; ALOE for restorative activity against UVB-induced immune suppression and Shea butter to eliminate superficial irritation and erythema (Both ALOE AND SHEA BUTTER are anti-inflammatory)

56
Q

What is the UV index?

A

The UV index is a number from 0 to 10+ that indicates the amount of UV radiation reaching the Earth’s surface during the hour around noon. The higher the number, to greater exposure to UV radiation (linear scale)

57
Q

What are the recommended UV protection measures for varying UV index/

A

UV 1-2: No protection required
UV 3-7: Seek shade during midday hours. Slip on a shirt, slop on sunscreen and slap on a hat.
UV 8 to 11+: Avoid being outside during midday hours. Make sure you seek shade. Shirt, sunscreen, and hat is a must

58
Q

What does it mean when sunscreen products are labeled as ‘broad spectrum’?

A

Protect against UVA and UVB

59
Q

What are the FDA guidance and ASEAN sunscreen labeling?

A

1) Upper SPF limit is around 50 because anything above 30 offers little additional benefit and may expose users to dangerous levels of chemicals
2) ‘Water-resistant’ and ‘sweat resistant’ must state SPF before and after water or sweat.
3) Any tanning product that doesn’t contain a sunscreen would have to state on the label that it does not contain sunscreen.

60
Q

According to the FDA guidance and ASEAN sunscreen labeling, what are the claims that are not to be made?

A

1) 100% protection against UVA&B
2) Whole day protection (reapplication is not necessary)
3) ‘Sunblock’ (only applicable in Malaysia)
4) ‘Waterproof’ and sweat proof’ claims (Only applicable in Malaysia and Thailand)

61
Q

At what SPF level does claims of UV protection should not be made?

A

SPF <6 (Natual skin protection)

62
Q

What are examples of warning statements for sunscreen?

A

Mandatory: Do not stay too long in the sun, even while using a sunscreen product
Strong recommended warning: Reapply frequently to maintain protection, especially after sweating, swimming o toweling; over-exposure to the sun is a serious health threat

63
Q

What kind of hat is ideal for photoprotection?

A

A hat with a 3-inch brim all around as it can protect areas often exposed to the sun, such as neck, ears, eyes, and scalp or a shade cap with about 7 inches of material draping down the sides and back.

64
Q

What kind of clothes is ideal for protection against the sun?

A

Lightweight, loose-fitting, long-sleeved shirts, pants or long skirts when in the sun
Most materials and colors absorb or reflect UV rays, tightly weaved cloth is the best.

65
Q

What kind of sunglasses can help protect your eyes from sun damage?

A

-Ideal sunglasses should block 99-100% of UVA and UVB radiation (check label)
The intensity of the color is not a good indication as UV protection comes from an invisible chemical applied to the lenses.
Large-framed wraparound sunglasses are best and check protection against High Energy Visible (HEV) light.

66
Q

What are the 2 types of tanning products and why are they bad?

A

Bronzers: made of color additives approved by FDA for cosmetic uses, stain skin when applied and can be washed off
Extenders: When applied to the skin, interact with protein on the surface of the skin to produce color and wears off after a few days. Only color additive is dihydroxyacetone.
Tanning products give a golden color but do not offer sunscreen protection and the chemicals in bronzers may react differently on various areas of your body to produce tan of many shades

PR2202 (19 decks)

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