NEED TO KNOW
ll sunscreens are designed to prevent the
transfer of energy from solar rays to skin.
Results of solar energy striking skin over
time are sunburn, uneven pigmentation, photoaging
and an increased risk of skin cancer. The consistent
application of adequate amounts of sunscreen lessens
all these risks. Even one severe sunburn increases
the risk of skin cancer, so sun-damage prevention is a
very important issue. Ninety percent of nonmelanoma
skin cancer and 65% of melanoma skin cancer
are related to UV exposure. 1 Up to 90% of all skin
changes related to aging are caused by sun exposure. 2
Although clients with darker skin types (Fitzpatrick V
and VI) may have a decreased risk of skin cancer, UV
exposure still significantly increases their chances of
developing the condition.
TYPES OF SUNSCREEN
Although they chemically behave differently, there
are two broad sunscreen classifications, both of which
decrease solar damage by either blocking or absorbing
solar energy transfer: physical sunscreens and
Physical sunscreens. Physical sunscreens help
prevent solar energy from striking the skin. Although
very efficient at deflecting the sun’s rays, a small amount
still penetrate the sunscreen barrier and strike skin
where they can be absorbed. Zinc oxide and titanium
dioxide are physical sunscreens. Physical sunscreens
are inert, meaning they do not react with skin. Because
they do not affect skin negatively and do not cause
skin sensitivity themselves, physical agents are usually
preferred for sun protection.
Chemical sunscreens. There are a large number
of chemical sunscreens. All work by absorbing solar
energy themselves and transforming it into a chemical
reaction, thus preventing transfer of this energy to skin.
After absorption of the sun’s energy into the chemical
sunscreen molecule, one of two things can happen. This
molecule can be chemically transformed via a chemical
reaction into another chemical, which is then very quickly
converted back to the original sunscreen molecule, ready
to absorb another packet of solar energy. This first type of
reaction is the most common.
An alternative chemical reaction can occur, which
produces a toxic byproduct that itself is carcinogenic.
Considerable debate has occurred about how great a
problem these small amounts of toxin really are, and
if they could potentially increase skin cancer risk.
Present consensus is that there is an overall decrease in
skin cancer risk from using sunscreen, even allowing
for the carcinogenicity of the small amounts of
(AND YOUR CLIENTS)
BY CHARLENE DEHAVEN, MD
EVEN ONE SEVERE SUNBURN
INCREASES THE RISK OF SKIN
CANCER, SO SUN-DAMAGE
PREVENTION IS A VERY