3 - Sunscreens

Question 1

Drug photosensitisation and photoinduced/photoaggravated dermatoses can be avoided or reduced with sunscreen use

Answer 1

True

Question 2

UV radiation reaching the Earth’s surface can be divided into:

(1) UVB = 290-320 nm
(2) UVA = 320-400 nm

Answer 2

True
UVA can be further subdivided into:
(1) near UVA or UVA II = 320-340 nm
(2) far UVA or UVA I = 340-400 nm

Question 3

The UVB blockers include:

(1) Octinoxate (octyl methoxycinnamate)
(2) Octisalate (octyl salicylate)
(3) Octocrylene
(4) Ensulizole (phenylbenzimidazole sulfonic acid)

Answer 3

True

Question 4

The UVA blockers include:

(1) Oxybenzone (a type of benzophenone)
(2) Meradimate (methyl anthranilate)
(3) Avobenzone (butylmethoxydibenzoylmethane)
(4) Ecamzule (tetraphthalydine dicamphor sulfonic acid)

Answer 4

True

Question 5

The physical blockers include:

(1) Titanium dioxide
(2) Zinc oxide

Answer 5

True

Question 6

The Sun Protection Factor (SPF) is defined as the UV radiation required to produce 1 Minimal Erythema Dose (MED) on protected skin after application of 2mg/cm2 of sunscreen / the UV radiation to produce 1 MED on unprotected skin

Answer 6

True

Minimal erythema dose (MED) =

Question 7

Broad spectrum sunscreen protection is defined as providing protection through the entire spectrum of both UVB and UVA wavelengths

Answer 7

True
UVB = 290-320 nm
UVA = 320-400 nm

Question 8

Water resistant sunscreen products need to maintain the SPF level after 40 or 80 mins of water immersion

Answer 8

True

Question 9

Sunscreens have traditionally been divided into:
(1) chemical absorbers
(2) physical blockers
based on their mechanism of action

Answer 9

True

Question 10

Chemical sunscreens are generally aromatic compounds conjugated with a carbonyl group

Answer 10

True

Question 11

Chemical sunscreens absorb high intensity UV rays, producing excitation to a high energy state; and upon return to ground state, the result is conversion of the absorbed UV energy into longer lower-energy wavelengths such as infrared radiation (heat)

Answer 11

True

Question 12

Physical blockers reflect or scatter UV radiation, however microsized forms of physical blockers (also designated as inorganic particulates) also function in part by absorption

Answer 12

True

Question 13

Para-aminobenzoic acid (PABA) was one of the first UVB chemical sunscreens to be widely available, though historically several problems limited the use of PABA

Answer 13

True

Question 14

Several problems limited the use of Para-aminobenzoic acid (PABA) as it required an alcoholic vehicle

Answer 14

True (also stained clothing, associated with a subjective stinging and allergic contact dermatitis)

Question 15

Several problems limited the use of Para-aminobenzoic acid (PABA) as it stained clothing

Answer 15

True (also required an alcoholic vehicle, caused subjective stinging and allergic contact dermatitis)

Question 16

Several problems limited the use of Para-aminobenzoic acid (PABA) as it caused subjective stinging

Answer 16

True (also required an alcoholic vehicle, stained clothing and caused allergic contact dermatitis)

Question 17

Several problems limited the use of Para-aminobenzoic acid (PABA) as it caused allergic contact dermatitis

Answer 17

True (also required an alcoholic vehicle, stained clothing and caused subjective stinging)

Question 18

Padimate O (octyl dimethyl PABA) replaced the original para-aminobenzoic acid (PABA) as it had greater compatibility in a variety of cosmetic vehicles and had a lower potential for staining or other adverse reactions

Answer 18

True (UVB chemical sunscreen)

Question 19

Despite being a potent UVB absorber, problems with PABA formulations in general have limited their use

Answer 19

True (both PABA and Padimate O, even though Padimate O is the most potent FDA approved UVB absorber)

Question 20

Padimate O (octyl dimethyl PABA) is the most potent FDA approved UVB absorber

Answer 20

True (although the decline in PABA formulations due to allergic contact dermatitis, along with the demand for higher SPF products led to the incorporation of multiple active ingredients in a single product to achieve the desired SPF) - The cinnamates such as Octinoxate (octyl methoxycinnamate) largely replaced PABA derivatives such as Padimate O as the next most potent UVB absorber

Question 21

The cinnamates such as Octinoxate (octyl methoxycinnamate) largely replaced PABA derivatives such as Padimate O as the next most potent UVB absorber

Answer 21

True

Question 22

Octinoxate (octyl methoxycinnamate) is the most frequently used sunscreen ingredient

Answer 22

True (UVB absorber)

Question 23

Octisalate (Octyl salicylate) is used to augment the UVB protection in a sunscreen as salicylates are weak UVB absorbers and are generally used in combination with other UV sunscreens

Answer 23

True

Question 24

Octocrylene is a UVB absorber used in combination with other UV absorbers to achieve higher SPF formulations

Answer 24

True

Question 25

Ensulizole (phenylbenzimidazole sulfonic acid) is a water soluble UVB absorber and is used in products formulated to feel lighter and less oily, such as in daily-use cosmetic moisturisers

Answer 25

True (most chemical sunscreen ingredients are oils soluble in the oil phase of emulsion systems which account for the heavy, greasy properties of many of these products)

Question 26

Although benzophenones are primarily UVB absorbers, it's derivative Oxybenzone also absorbs well through the near UVA/UVA II spectrum (320-340 nm), therefore benzophenones significantly augment the UVB protection of a sunscreen product while expanding into UVA coverage when used in a given formulation

Answer 26

True

Question 27

Meradimate (methyl anthranilate) is a weak UVB filter that absorbs mainly in the near UVA II (320-340 nm) portion of the spectrum

Answer 27

True (it is a less effective sunscreen ingredient and is less widely used)

Question 28

Avobenzone (butylmethoxydibenzoylmethane) provides superior protection through a large portion of the UVA spectrum including majority of the far UVA/UVA I spectrum (340-400 nm)

Answer 28

True (although photostability is a problem with Avobenzone, and it also has the potential to degrade other sunscreen ingredients in products such as the potent UVB cinnamate absorber octinoxate)

Question 29

The photoinstability of Avobenzone can be offset by combining it with Octocrylene (used for photostability)

Answer 29

True

Question 30

Octocrylene is a UVB absorber used in combination with other UV absorbers to achieve photostability

Answer 30

True (classically combined with the UVA absorber Avobenzone to offset Avobenzone's photoinstability)

Question 31

Ecamsule (tetraphthalydine dicamphor sulfonic acid) is a UVA filter with broad absorption profile from 290-390 nm (UVB 290-320 nm, near UVA 320-340 nm and far UVA 340-400 nm) with peak absorption at 345 nm (far UVA wavelength)

Answer 31

True

Question 32

Poor cosmetic acceptance limited the widespread use of the physical blockers titanium dioxide and zinc oxide, until microsized forms became available

Answer 32

True

Question 33

The physical blockers titanium dioxide and zinc oxide are inorganic particulate sunscreens which are reactive and poorly soluble and do not show significant skin penetration

Answer 33

True

Question 34

The ideal sunscreen agent would be: (1) chemically inert (2) safe (3) reflect through the full UV spectrum

Answer 34

True (the physical blockers titanium dioxide and zinc oxide)

Question 35

By reducing the particle size of titanium dioxide to make it more aesthetically acceptable, titanium dioxide functions more by absorption and not simply by blocking (reflecting and scattering) UV radiation, therefore making titanium dioxide less effective in the UVA range than an opaque physical blocker

Answer 35

True (although this microsized ingredient can still be classified as a broad-spectrum agent)

Question 36

Titanium dioxide causes a whitening effect on the skin secondary to pigment residue

Answer 36

True (the net effect might be that the user is inclined to apply the product less heavily, thus effectively lowering the SPF) - hybrid products using a combination of chemical UV absorbers with inorganic particulate blockers may represent a practical compromise

Question 37

Zinc oxide is a physical blocker which offers the same advantages and disadvantages as titanium dioxide, although zinc oxide has more superior far UVA/UVA I protection (specifically 340-380 mm spectrum) than for titanium dioxide, thereby providing more full spectrum protection

Answer 37

True

Question 38

Inorganic particulate microsized sunscreens are not effective in the short wavelength visible range and not suitable for patients with porphyria cutanea tarda or other porphyrias who require optimal photoprotection

Answer 38

True Options for these patients include: (1) protective clothing and sun avoidance (mainstay approach) (2) opaque titanium dioxide or zinc oxide physical blockers

Question 39

SPF 15 products block 93.3% of UVR (UVB) from penetrating the skin

Answer 39

True SPF 15 = 93.3% SPF 30 = 96.7% SPF 50 = 98%

Question 40

Theoretically an SPF 15 sunscreen product allows an individual to remain in the sun up to 15 times longer without burning, compared to what that individual's intrinsic unprotected skin would allow

Answer 40

True (therefore a fair-complexioned individual who usually sunburns in 10 mins without any protection, would theoretically have >2.5 hours of protection from SPF 15)

Question 41

Sunscreens are used for protection from UVR to prevent sunburn

Answer 41

True

Question 42

Sunscreens are used for protection from UVR to prevent skin or lip damage, freckling and skin discolouration

Answer 42

True

Question 43

Sunscreens are used for protection from UVR to prevent skin aging

Answer 43

True

Question 44

Sunscreens are used for protection from UVR to prevent skin cancer

Answer 44

True

Question 45

Sunscreens are used for protection from UVR to prevent phototoxic or photoallergic drug reactions

Answer 45

True

Question 46

Sunscreens are used for protection from UVR to prevent photosensitivity diseases

Answer 46

True

Question 47

Sunscreens are used for protection from UVR to prevent photoaggravated dermatoses

Answer 47

True

Question 48

Sunscreen is contraindicated if there is known sensitivity to any active sunscreen ingredient

Answer 48

True

Question 49

Sunscreen is contraindicated if there is known sensitivity to a vehicle ingredient in the product

Answer 49

True

Question 50

Sunscreen is contraindicated in infants <6 months of age

Answer 50

True (sun avoidance is most appropriate for very young infants)

Question 51

Sunscreen should not be used as the sole component of an overall program of photoprotection

Answer 51

True (a complete program includes protective clothing, shade and sun avoidance)

Question 52

SPF 30 products block 96.7% of UVR (UVB) from penetrating the skin

Answer 52

True SPF 15 = 93.3% SPF 30 = 96.7% SPF 50 = 98%

Question 53

SPF 50 products block 98% of UVR (UVB) from penetrating the skin

Answer 53

True SPF 15 = 93.3% SPF 30 = 96.7% SPF 50 = 98%

Question 54

Product application technique alters SPF

Answer 54

True (in the laboratory, product thickness application is standardised as 2mg/cm2 whereas in the real world the thickness application is closer to 1mg/cm2)

Question 55

SPF 30 sunscreen products provide significantly greater protection than that of the SPF 15 product with respect to sunburn cell production

Answer 55

True (even though the % UVR absorption between SPF 15 and SPF 30 is minute at 93.3% vs 96.7%)

Question 56

The higher the SPF, the greater the near UVA /UVA II (320-340 nm) protection

Answer 56

True

Question 57

Labelled SPF may overestimate the protection as temperate latitudes have a greater proportion of UVA than the solar-stimulated radiation prescribed by regulatory bodies

Answer 57

True

Question 58

A broad spectrum sunscreen has a critical wavelength of >= 370 nm and generally these products will contain either Avobenzone (covers majority of far UVA/UVA I spectrum) or an inorganic particulate physical blocker as an active ingredient

Answer 58

True (the critical wavelength is determined to be the wavelength below which 90% of the total area of UV absorbance resides)

Question 59

Sunscreen vehicles include: (1) Emulsions - oil in water or water in oil (2) Gels -water or alcohol based (3) Sprays (4) Sticks - thickened with waxes and petrolatum (5) Cosmetics - foundation make up

Answer 59

True

Question 60

The most commonly used sunscreens are lotions (oil in water emulsion) and creams (water in oil emulsion)

Answer 60

True

Question 61

Newer ultrasheer sunscreen products use silica as a major vehicle component in the lotion/cream emulsion

Answer 61

True

Question 62

Water based gel sunscreen products rely on limited number of water soluble active sunscreen ingredients such as Ensulizole or trolamine salicylate (both UVB absorbers)

Answer 62

True

Question 63

Sunscreen gel products are easily removed by swimming and perspiration and tend to more readily cause facial or eye stinging

Answer 63

True (though may be favoured by individuals with oily skin or acne)

Question 64

Spray sunscreen products are more convenient to apply but difficult to apply evenly and can produce a discontinuous film, resulting in a less effective sunscreen product

Answer 64

True

Question 65

Sunscreen sticks are helpful for protecting the lips, nose or around the eyes

Answer 65

True

Question 66

Foundation make up, even without sunscreen may provide some protection (SPF 4-5) because of its pigment content

Answer 66

True

Question 67

By raising the level of pigments in foundation make up (including titanium dioxide), or by adding a chemical sunscreen, a higher SPF can be achieved

Answer 67

True

Question 68

By virtue of the opacity of foundation make up, it provides the benefit of some UVA protection

Answer 68

True (functions as a physical blocker that reflects and scatters UVR)

Question 69

The majority of sunscreen adverse reactions are irritant in nature

Answer 69

True

Question 70

Subjective irritation including stinging, burning and itching without associated visible erythema is the most common adverse reaction to sunscreens

Answer 70

True (most frequently experienced in the eye area and stinging sensation can occur even if several hours have elapsed since sunscreen application)

Question 71

An adverse reaction to sunscreen includes Erythema occurring immediately on contact with sunscreen that may represent contact urticaria which may be immunologic (IgE mediated type I allergy) or non-immunologic (due to toxic or direct mast cell degeneration part of the spectrum of subjective irritation)

Answer 71

True (sunscreens do not appear to be associated with an incidence of contact urticaria higher than that of other toiletries or cosmetics)

Question 72

Sunscreens may cause irritant contact dermatitis

Answer 72

True

Question 73

Sunscreens may cause allergic contact dermatitis (true type IV delayed hypersensitivity reactions)

Answer 73

True (though irritation is a more prevalent problem than true allergic contact dermatitis)

Question 74

Virtually all sunscreen ingredients reported to cause allergy may also be photoallergens

Answer 74

True (although relatively uncommon, sunscreen active ingredients seem to have become the leading cause of photocontact allergic reactions)

Question 75

Individuals with eczematous conditions have a significant predisposition to contact or photocontact dermatitis sensitisation because of impaired cutaneous barrier

Answer 75

True

Question 76

Allergic or photoallergic contact dermatitis to sunscreen product should be considered in patients with a photosensitivity condition that suddenly changes or worsens as patients with photosensitivity dermatoses develop the majority of photocontact dermatitis to sunscreens

Answer 76

True (chronically photosensitive patients with eczematous changes who flare despite the use of broad spectrum sunscreen product may need patch testing or photopatch testing with a complete sunscreen series)

Question 77

Sunscreen products may aggravate acne, though this is more related to the vehicle than to sunscreen ingredients

Answer 77

True (sunscreen vehicle ingredient may be comedogenic, but sunscreen oils are typically not)

Question 78

Acne may also be aggravated by UV exposure (acne aestivale) and is not necessarily related to sunscreen product application

Answer 78

True

Question 79

Sunscreen products may cause a form of irritation called contact folliculitis (rapid onset of small follicular papules and pustules shortly after product application), and gel or spray formulation may reduce the frequency of this adverse effect

Answer 79

True

Question 80

UVA varies much less in intensity throughout the day (more constant intensity) than UVB

Answer 80

True

Question 81

Sunscreens are most important from 10am to 4pm when the sun's rays are strongest

Answer 81

True

Question 82

For intermittent casual daily use, an SPF 15 sunscreen is sufficient

Answer 82

True

Question 83

For prolonged recreational exposures, an SPF 30 sunscreen is more desirable especially for fair-skinned individuals

Answer 83

True

Question 84

Sunscreens should be applied 15-30 mins before sun exposure to allow sufficient time of the protection to develop, and then reapplied every 2 hours

Answer 84

True

Question 85

Individuals with polymorphic light eruption, taking photosensitising drugs, whose melasma or lentigines have darken despite sunscreen need better UVA protection through the entire spectrum including far UVA/UVA 1 (340-400 nm) and may benefit from products that contain Avobenzone, Ecamsule, titanium dioxide or zinc oxide

Answer 85

True

Question 86

Subjective stinging in or near the eyes should not be interpreted as a sign of true allergy

Answer 86

True

Question 87

Sunscreens with the chemically inert inorganic particulate materials such as titanium dioxide and zinc oxide as the only active ingredients provides a suitable alternative for patients with sensitive skin, regardless of what kind of sunscreen intolerance they have previously experienced

Answer 87

True

Question 88

Individuals with oily complexions may prefer an oil-free alcohol-based gel or a lighter feeling cosmetic sunscreen moisturiser lotion

Answer 88

True (the oil-free claim refers to the vehicle as the active sunscreen ingredients themselves are oils)

Question 89

The effects of sunscreen use on vitamin D levels in large-scale longitudinal studies are inconclusive

Answer 89

True (patients compliant with sunscreen use may get enough UVR through their sunscreen and non-covered areas to maintain adequate vitamin D levels)

Question 90

For individuals practising vigorous photoprotection, daily intake of vitamin D though diet or supplements of 600IU would seem prudent (800IU for those >70 years old)

Answer 90

True (sunscreen application can inhibit vitamin D synthesis in studies in controlled settings, although large-scale longitudinal studies are inconclusive)

Question 91

Sunless tanners (dihydroxyacetone is the active ingredient) has limited true sunscreen potential of SPF 3 or 4

Answer 91

True (gives a suntanned appearance, but is not sun-protective)

Question 92

Dihydroxyacetone (DHA) in sunless tanners reacts with keratin and the epidermis to form melanoidins as a result of the Maillard or 'browning reaction' in the stratum corneum

Answer 92

True

Question 93

The brown colour obtained on the skin from Dihydroxyacetone (DHA) in sunless tanners absorbed the low end of the visible spectrum with overlap into the far UVA spectrum, and so may provide some UVA I (340-400 nm) protection, although the SPF is only 3-4

Answer 93

True (only provides minimal sun protection, despite the tanned appearance)

Question 94

Because the resultant brown colour from sunless tanners last up to several days, patients need to be reminded that the duration of UV protection (SPF 3-4) is more short-lived than that of the skin colour change

Answer 94

True