From safety and effectiveness to who should use sunscreen and how to apply
it, Canadian dermatologists review the latest evidence and guidelines on the use
The review, published in CMAJ (Canadian Medical Association Journal), recommends
that everyone older than six months of age should use sunscreen to protect
against skin cancer. Most skin cancers develop because of long-term sun
Sunscreen reduces the risk of developing skin cancer by blocking solar radiation
through chemical or physical sunscreen filters such as titanium dioxide and zinc
oxide."Exposure to ultraviolet radiation is directly harmful and has been
associated with the development of skin cancers, which are common in Canada.
High-quality evidence has shown that sunscreen reduces the risk of developing
both melanoma and nonmelanoma skin cancer," writes Dr Megan Sander, a
dermatologist and clinical lecturer at the Cumming School of Medicine,
University of Calgary, Calgary, Alberta, with coauthors.Some key points:
-Prevention -- Evidence from randomized controlled trials indicates that
sunscreen is effective at protecting against skin cancer as well as premature
ageing of the skin.
-Non-White populations -- There is a lack of evidence for the effectiveness of
sunscreen in people with darker skin. Current evidence is mostly limited to
White people, who have a higher rate of skin cancers.
-Babies -- Sun avoidance and protective clothing are recommended for babies.
Sunscreen is not recommended for use before age 6 months because of the
potential for systemic absorption of sunscreen ingredients.
-SPF -- Sunscreens with an SPF sun protection factor of 30 or higher are
recommended in cream or lotion format.
-Spray-on sunscreens are not recommended as they can be dispersed, are flammable
and their effects if inhaled are unknown.
-Harms -- Some people can have skin reactions such as contact dermatitis,
especially to chemical sunscreens, and there is evidence these sunscreens can be
systemically absorbed, although the clinical importance of the absorption is not
-Environmental impact -- Recent evidence indicates that chemical sunscreens can
be detected in water and fish and may contribute to the bleaching of coral
Sunscreen is only one part of a comprehensive photoprotection strategy. It is
important to counsel patients regarding behaviours for avoiding ultraviolet
radiation, including the use of wide-brimmed hats, eye protection (e.g.,
"wrap-around" sunglasses with ultraviolet radiation protection) and seeking
shade when the ultraviolet index is above 3 (usually 11 am-3 pm, April to
September in Canada)," write the authors.Research into the safety of sunscreens
and of new technologies continues. (ANI)