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Writer's picturePat Browne

HOW DO SUNSCREENS WORK?



There are two types of sunscreen products: mineral (physical) or organic (chemical). The active ingredients in sunscreen products protect skin by either absorbing or reflecting UV light. Titanium Dioxide and Zinc Oxide are physical filters (sometimes called sunblocks or mineral sunscreens). These work by creating a physical barrier on the skin to reflect and scatter UV radiation away from the skin. Organic (chemical) sunscreens use ingredients like avobenzone, octisalate, octocrylene, homosalate and others work like sponges to absorb UV radiation. These sunscreens form film that absorbs UV radiation before it penetrates the skin.

 

Both types of sunscreen ingredients have pros and cons. 

 

For example, physical sunscreens are generally well tolerated, even by reactive or sensitive skin, and do not cause irritation, stinging or allergic reactions. But they can be heavy and create a white and/or greasy feeling. Meanwhile, chemical absorber sunscreen ingredients are usually clear and easy to apply, but these are more likely to cause irritation and allergic reactions. 

Many sunscreens use a combination of physical blockers and chemical absorbers to maximize the benefits and reduce the downsides. Additionally, many broad-spectrum sunscreens need a combination of ingredients to protect against UVA and UVB rays, the two types of ultraviolet rays that cause skin damage.

 

Is sunscreen safe?

 

When it comes to sunscreens, the benefit of protection from UV radiation far outweighs any potential risk.

 

UV damage plays a central role in the development of most melanomasbasal cell cancersquamous cell cancers and other less common skin cancers.

 

Dermatologists recommend using a sunscreen with an SPF or at least 30, which blocks 97% of the sun’s UVB rays. High-number SPFs block slightly more of the sun’s UVB rays, but no sunscreen can block 100% of the sun’s UVB rays. No sunscreen – even waterproof – stays on the skin all the time. For the best protection you should reapply sunscreen to all exposed skin every 2 hours. It’s also important to realize that higher SPF sunscreens last the same amount of time as a low-number SPF.

 

Why use a higher number SPF?

 

A high-number SPF does not allow you to spend additional time outdoors without reapplication. As many individuals only apply about 20–50% of the amount of sunscreen needed to achieve the amount of SPF on the label, application of high-SPF sunscreens helps to compensate for under-application. Sunscreen should be reapplied approximately every two hours when outdoors, even on cloudy days, and after swimming or sweating.

 

What is Health Canada’s role?

 

Health Canada tests and approves all sunscreens. Every sunscreen will have a DIN (Drug Identification Number) on the bottle or tube. Health Canada is reviewing not just the safety of the ingredients, but also the effectiveness. To ensure Canadian safety, Health Canada standards for SPF products are very high. All standards are based on scientific evidence for safety and effectiveness.

 

Are there any disadvantages to using sunscreen?

 

Some ingredients in sunscreens could be irritating to especially sensitive or reactive skin. This is generally very rare. If you do have sensitive skin, then look for simple mineral sunscreen which protects the skin by using physical blocker ingredients. 

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