Sunscreens:
be sun “SMART” this summer
S: seek shade
M: maintain proper sun protective clothing,
sunglasses, umbrella, hat
A: apply sunscreens, recommended 8
tablespoons daily
R: reapply after every 2 hrs
T: take frequent breaks from prolonged
exposures
The sun is the best source of naturally
occurring vitamin D; however overexposure can lead to some disturbing sun
damages. Before blaming the sun for the harmful outcomes, let's first
understand the spectrum of light that it emits.
UVA light is further divided into two,
UVA I (340nm to 400nm), and UVA II (320nm to 340nm). UVA I is weak and less
potent than UVA II and UVB to cause erythema and melanoma.
Exposure to sunlight rich in UVA and UVB
between 10 am and 4 pm can lead to photosensitivity, photoaging and
photodermatoses as they can penetrate into the deeper layers of the skin. Upon
unprotected exposure to the sun, erythema occurs within 20 to 30 minutes as a
result of oxidation of bleached melanin and dilation of dermal venules. This
eventually begins to fade after 2 to 8 hours. However, pain and edema worsen
after 14 to 20 hours and last 24 to 72 hours due to the dilation of the
arterioles.
Sunscreens:
It is ideal to apply 1oz of sunscreen
per average adult, preferably 20 to 30 minutes (2 hours for para-aminobenzoic
acid PABA and PABA esters) before exposure to the sun. Reapply the sunscreen
after every 2 hours particularly, after swimming, heavy exercise, perspiration
and towelling dry. Consider wearing a Sun Protection Factor (SPF) 30 or above
to minimalize frequent reapplications.
Types: Sunscreens can be either chemical
or physical based upon the ingredients. Chemical sunscreens (PABA, PABA esters,
Cinnamates, Salicylates, Benzophenones, Avobenzone, Phenylbenzimidazole
sulfonic acid, and Ecamsule) absorb UVR. Only benzophenones such as
benzophenone6, oxybenzone, dioxybenzone and mexenone absorb both UVA and UVB.
On the other hand, physical sunscreens (titanium dioxide and zinc oxide)
reflect UVA and UVB.
Take away:
1. If sensitive to sulphonamides,
procaine, benzocaine, or thiazides, avoid PABA and PABA esters.
2. Discontinue use if irritation or rash
occurs.
3. Avoid contact with eyes.
4. Do not use in infants younger than 6
months.
5. Use broad protection water-resistant
sunscreens with SPF 30 and above, which protects against UVA and UVB.
6.
Use shades, hats, sunglasses, and proper clothing when going outdoors.
7.
Apply a combination product of low dose diethyltoluamide (DEET) suitable for 2
hourly application, ensuring maximum sun protection.
8. Regular sunscreen usage reduces the
incidence of melanoma, carcinoma and actinic keratoses.
9. Ensure to use sunscreens while on
photosensitising drugs, immunosuppressants or with photodermatoses or
hyperpigmentation disorders such as vitiligo and albinism.