The best sunscreen for you
is the one that you will use everyday.
But why is sunscreen important?
Sunscreen helps protect against the damaging effects of ultraviolet
radiation from sun exposure. We are
increasingly exposed to UV radiation as we spend more time with outdoor
activities, wear less clothing, and practice more indoor tanning. In addition, the ozone layer is diminishing.
UV exposure has a direct
effect on the incidence of skin cancers.
Skin cancers represent over 50% of cancers in the United States. Melanoma, a deadly form of skin cancer, has
tripled in the past two decades. The
aging population is also increasingly aware of the photo aging effects of sun
exposure that causes premature wrinkles and dyspigmentation.
The UV radiation
wavelength that causes cutaneous damage comprises of UVB (290 nm-320 nm) and
UVA (320 nm- 400 nm). UVB mainly causes
the classic sunburn. UVA can penetrate
window glass and causes deeper damage in the skin. UVA causes tanning and dyspigmentation and is
relatively unchanged by time of day or season.
Because it penetrates deeper into the skin, it can cause more DNA damage
that is related to skin cancers and photo aging.
An ideal sunscreen should
protect against UVB and UVA radiation.
Sunscreens are divided into chemical sunscreens or physical
sunscreens. The physical sunscreens are
titanium dioxide or zinc oxide. Physical
sunscreens protect against UVB and UVA rays.
Most chemical sunscreens protect only against UVB radiation. The SPF factor in a sunscreen measures UVB
protection. For example, if you usually
get burn in 10 minutes without sunscreen, then applying a sunscreen with a SPF
factor of 30 will confer protection for 300 minutes. This assumes that you apply enough sunscreen
at a thickness of 2 mg/cm2 to an area of 50 cm2. For an average adult, a total of 35 ml of
sunscreen for each application is required.
A shot glass is 30 ml. The SPF
factor can be increase by adding chemical sunscreen ingredients.
UVA radiation absorbs at
320-400 nm. The active ingredients that
protect against UVA include titanium oxide, zinc oxide, avobenzone, and
ecamsule (MeroxylTM SX). Trade
names such as HelioplexTM contain avobenzone and oxybenzone and
AntheliosTM SX contains ecamsule, avobenzone, and octocrylene. Recently the FDA started requiring a UVA
rating protection factor on sunscreens similar to current SPF rating for UVB
protection. This rating ranges from “+”
(least effective) to “++++” (most effective).
The effectiveness of
sunscreens not only applies to the active ingredients but also to the correct
application. Sunscreens should be
applied 15-20 minutes before sun exposure and reapplied every 2 hours and after
swimming, towel drying, or sweating.
Sunscreens can be physically rubbed off after these activities.
There are very few adverse
effects from sunscreens. If a person has
sensitive skin then the physical sunscreens like zinc oxide or titanium oxide
are the best choices. Most allergic
reactions to sunscreens are from the chemical sunscreens. Sunscreens have also been implicated in Vit D
deficiency. Currently, there is no
conclusive evidence to support this risk with the regular use of
sunscreen. Studies have shown that even
small amounts of sun exposure can provide adequate vitamin D and that some UV
rays still reaches the skin even when wearing sunscreens.
A comprehensive sun
protection program consists of the right sunscreen, wearing protective clothing
and limiting time out in the sun especially between the hours of 10 AM- 2 PM.
What is the best
sunscreen? There are different
formulations and will depend on the preference of the individual. More expensive sunscreens will contain extra
ingredients for photo aging and will be more cosmetically pleasing. The best
sunscreen is the sunscreen that an individual likes to use and will regularly
apply on their skin.