Sunscreen - photoprotective products
As presented, exposure to solar ultraviolet radiation can seriously damage
skin. As well as aesthetic damage linked to premature skin aging,
it also carries the risk of skin cancer. The problem
is made worse by the fashion for sunbathing in summer
in certain cultures. In winter, skiing can also
lead to high UV exposure.
Photoprotection - protection
of the skin from UVR - has an important role for
all skins. |
SPFThe ability of a
sunscreen product to absorb radiation is defined by its
sun protection factor (SPF). The SPF of a product is determined by
measuring the time it takes to develop
skin redness (erythema) to a known
amount of radiation. This time is termed the minimum
erythema dose (MED). The MED for a product
containing sunscreen can be measured against one
without, on the same area of skin. Suppose, for
example, that: |
|
|
| MED
with sunscreens |
=
300 secs |
| and |
|
| MED
without sunscreens |
=20
secs |
| then |
|
| the
SPF of this product |
=
300/20 |
| |
=
15. |
|
| An SPF of,
say, 15 is no guarantee, however, that one can stay
in the sun 15 times longer than when not wearing
a sunscreen. |
| |
Sunscreens
The regular, daily use of modern cosmetic products
can potentially be very important for the long-term
health of the skin. Among the most useful ingredients
are sunscreens, which block ultraviolet radiation
absorption by the skin, either wholly or in part.
(Clothing, hats and sunglasses can all act as effective
sunscreens.) The many formulations that are on sale
include lotions, creams, pastes and gels, and rely
on either chemical or physical agents for their
protective action. |
|
