FORMULA ANATOMY DECIPHERED
by Eric S. Abrutyn
Sun Damage Prevention and Repair
Eric S. Abrutyn is a Cosmetics
& Toiletries advisory board
member, and an active member
of both the Society of Cosmetic
Chemists and the Personal Care
Products Council International
Nomenclature Cosmetic
Ingredient (INCI) committee,
where he has served as past chair. Abrutyn
has more than 40 years of experience in personal
care with companies such as Wickhen Products,
Dow Corning and Kao Brands, and specializes in
antiperspirants, functional siloxane, skin and hair
care formulation and innovation management.
After retiring from Kao Brands, Abrutyn founded
TPC2 Advisors Ltd., Inc., a personal care
consultancy.
The importance of sun protection is
known in today’s society better than it
was in earlier decades. Specifically, the
importance of protecting skin from both
UVB radiation (290–320 nm), since it can
cause severe sunburn damage and cancer,
and UVA radiation (320–400 nm),
which penetrates deeper into skin
and produces reactive oxygen species
(ROS) that can cause DNA, cell and
tissue damage, is well-known. UVA
is also noted to induce immune suppression, leading to the development
of malignant melanoma and squamous
tumors, along with photosensitivity,
photodermatoses, photoallergies and
the loss skin elasticity—which can lead
to an increase in wrinkles.
In 1983, L. Kligman wrote about
damage to the human dermis caused
by chronic UV radiation.1 In this study,
researchers exposed hairless mice to
UV radiation and found that repair
can occur if the skin is protected with
sunscreens that provide UVB protection
with an SPF of 6 and 15, in addition to
UVA protection. Repair was found to
occur in situ in severely damaged skin in
the subepidermal reconstruction zones
of new connective tissue, with parallel
collagen bundles and a network of fine
elastic fibers.
Gilchrest also provided a review
of UV radiation damage and clinical
repair.2 According to his review, skin
loses elasticity and its metabolic activity
slows with age. UV radiation exposure
causes thickening of the epidermis
and increased melanogenesis. Further,
massive deposition of abnormal elastic
fibers (elastosis), collagen degeneration,
and twisted dilated microvasculature
can also occur. According to Gilchrest,
the regular use of sunscreens does not
provide full repair but with sun protecting agents, moisturizers and topical
ingredients including retinols and alpha
hydroxyl acids, some repair is possible;
such as keratinocyte ultrastructural
repair. Overall, his review illustrates
the aging processes of UV-exposed
skin and demonstrates that many of
the unwanted changes can be improved
with topical therapy.
A single sunscreen active
is not sufficient to cover
the full spectrum of
UV radiation, which is
necessary to protect
the skin.
Further, work published by de Gruijl
et al. describes the importance of
repair to UV-induced DNA damage
and skin carcinogenesis.3 Mutations
in the genetic coding of protein in
the Hedgehog pathway in basal cell
carcinomas (BCCs) were found to lead
to persistent disturbances that were
passed along to daughter cells—and
solar UVB radiation was a main cause
of these mutations, contributing to skin
carcinogenesis.
It is obvious that UVA and UVB radiation damage human skin. Therefore,
the question of whether UV damaged
skin can be adequately repaired remains
to be answered.
Key Components
for Sun Damage
Prevention and Repair
Sunscreen components: Key to
sun damage prevention are sunscreen
actives that are generally classified
as organic or inorganic UV filters.
Organic UV filters strongly absorb
radiation at specific wavelengths and are
transparent to visible light.4, 5 There are
many efficacious UV filters that can be
incorporated into most sunscreen formulations. Popular UVB filters include
homosalate, octisalate and octocrylene,
while avobenzone is a popular UVA
filter; titanium dioxide, zinc oxide and
oxybenzone can provide both broad-spectrum UVB and UVA protection.
Additionally, a number of effective
UV sunscreen actives are currently
awaiting approval by the US Food and
Drug Administration (FDA), such as
drometrizole trisiloxane, octyl triaz-one, bemotrizinol and diethylamino
hydroxybenzoyl hexyl benzoate. Of
course, a single sunscreen active is not
sufficient to cover the full spectrum of
UV radiation, which is necessary to
protect the skin.
Sunscreen and sun-exposed treatment formulas come in many forms
but two-phase emulsions are the most
popular delivery system. These emulsions can be classified as w/o or o/w,
both having distinct merits such as
versatility of aesthetics or performance
efficacy of sunscreening agents. W/O
emulsions deliver better water resistance
and higher effective-yielding SPF.
Conversely, o/w emulsions are more
widely used due to their lower inherent
cost (higher water content). Lately,
more formulators are creating aerosol
sunscreen sprays because they allow for
quick, clean and easy application. No
matter what type of formulation and
applicator is used, however, the concern
for adequate and effective application by
the consumer remains.
Sun damage repair: Sun damage
repair can be imparted via different
142 | Cosmetics & Toiletries® magazine www.CosmeticsandToiletries.com
Vol. 126, No. 3/March 2011
