What is the BEST sunscreen for me?

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 (Meroxyl^TM SX).  Trade names such as Helioplex^TM contain avobenzone and oxybenzone and Anthelios^TM 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.