How do sunscreens work?

There are two types of sunscreen ingredients:

  1. Absorbers which absorb most of the UV, and
  2. Reflectors that scatter most of the UV away from your skin.

Some sunscreens utilise both absorbing and reflecting ingredients. Examples of reflecting ingredients include Zinc Oxide and Titanium Oxide. UV absorbers use ingredients such as Oxybenzone, Octocrylene, 4-Methylbenzylidene camphor and Butyl methoxy dibenzoylmethane.

What do SPF numbers mean?

SPF stands for Sun Protection Factor. The SPF is a laboratory derived ratio which measures the increased amount of radiation which causes redness in skin when the sunscreen tested is applied, compared to when it is not used at all. For example if it takes 10 minutes for unprotected skin to show redness, then an SPF30 sunscreen correctly applied, will take 30 times as long or 300 minutes to burn. In reality, it is rare for a person to achieve this exact level of protection as factors like how much you apply, the weather and even your skin type will affect your level of protection. In fact, many Australians apply too little sunscreen. This results in sunscreen users achieving an SPF of between 50-80% less than that specified on the product label.

How Much better are SPF 50+ Sunscreens?

Cancer Council recommends using sunscreens with an SPF of 30 or higher. SPF30 sunscreens filter about 96.7% of UV radiation while SPF50+ sunscreens provide only marginally better protection at 98% . SPF50+ sunscreen does not mean you can stay out of the sun for longer periods of time and you should also use sunscreen in conjunction with other sun protection measures – hats, sunglasses, clothing and shade.

What does broard spectrum mean?

A sunscreen labelled Broad Spectrum offers protection from both UVA and UVB rays. All Cancer Council sunscreens are broad spectrum.

How should sunscreens be best applied?

Sunscreens should be applied on all exposed areas of skin 20 minutes before exposure to UV. It should be applied liberally and evenly to clean, dry skin. You should reapply more regularly if you are swimming, exercising or towel drying.

What causes sunscreen reactions?

Reactions to sunscreen are rare and can be a result of a sensitivity or allergy to any of the many ingredients used in these products. Some people may have reactions to the fragrances, preservatives, UV absorbers or another component of the sunscreen.

Sensitivities to sunscreen are complex, range from mild to severe, and can link to a range of co-factors, including sunlight, other allergens or medications. Some reactions occur soon after applying the sunscreen while others (e.g. allergic reactions) may occur after repeated use. Reactions can also be caused by or made more severe if sunscreen is used with some medications or other topical creams and lotions. Reactions occur in a very low proportion of the population – fewer than 1% of all users – but while uncommon, can be upsetting for those affected.

As with all products, use of sunscreen should cease if an unusual reaction occurs. Individuals or families experiencing reactions should seek a referral to a dermatologist to understand what may have caused the reaction and gain advice on ingredients that should be avoided in the future.

How often should sunscreen be applied?

Cancer Council recommends that sunscreen be reapplied every two hours to ensure that ongoing protection occurs. You should reapply after swimming, exercising or towel drying.

Which of the sun’s rays actually cause skin cancer?

Both UVA and UVB cause skin damage and contribute to premature aging, sunburn and skin cancer. UVA rays penetrate deep into the skin, gradually destroying elasticity and causing premature ageing. UVB rays cause skin damage and can alter the structure of skin cells, and ultimately lead to possible skin cancers. A broad spectrum, SPF30 (or higher) sunscreen will help protect against both UVA and UVB radiation.

Can sunscreens be used on babies?

Cancer Council recommends keeping babies away from direct sunlight as much as possible when UV levels are 3 or above, as their skin is more sensitive than adults’. Plan daily activities to ensure the infant is well protected from the sun and aim to minimise time outside during the middle of the day during the summer period when UV levels are at their strongest.

When this is not possible, ensure that babies are protected from the sun by shade, protective clothing and a hat. Check the infant’s clothing, hat and shade positioning regularly to ensure he/she continues to be well protected from UV.

The widespread use of sunscreen on babies under six months is not generally recommended.

Some parents may choose to use sunscreen occasionally on small parts of their baby’s skin – if that’s the case parents should be careful to choose a sunscreen that is suitable for babies – they may wish to seek the advice of a doctor or pharmacist. Sunscreens for babies usually use reflecting ingredients such as zinc oxide and avoid ingredients and preservatives that may cause reactions in young skin. It’s also important to patch test first.

Can you burn on a cloudy day?

Yes you can, as a significant amount of UV can pass through clouds. It’s important to focus on UV levels, not heat – sun protection is required whenever UV levels are 3 or above.

What other protections should be used other than sunscreen?

Cancer Council recommends people avoid excessive exposure to UV. Sunscreen should never be the first line of defence against sun damage. It is important to wear a broad brimmed hat, protective clothing, sunglasses and make use of shade where possible. Never use sunscreen to extend the time you would normally spend in the sun.

What are the ‘Active Ingredients’ listed on the back of the sunscreen tubes/labels?

These are the ingredients used to absorb and/or reflect the harmful UVA and UVB rays generated by the sun. Some are better at absorbing UVA (eg Butyl Methoxydibenzoylmethane/‘Parsol’ , zinc oxide), while others are better at absorbing UVB (eg Octyl Methoxycinnamate, Titanium Dioxide) and some do both (eg Tinasorb). Most sunscreens use mixtures of UVA and UVB absorbers to optimise their sun protection properties. All sunscreen ingredients used in Australia are approved by the Therapeutic Goods Association.

What are the preservatives listed on the back of the tube/labels of sunscreen and why are they used?

These are ingredients that are necessary to preserve the integrity of the sunscreen cream/lotion. Besides the active ingredients, sunscreens contain moisturisers, water, oils, emulsifiers and various other ingredients which help to maintain the cream emulsion and make the sunscreen pleasant and easy to apply. Without preservatives the sunscreen cream/lotion would support the growth of bacteria which could ‘spoil’ the cream/lotion and/or cause skin infections if they were to contaminate the sunscreen.

Why are there so many different sunscreen types?

There are many sunscreen ingredients available that filter and/or reflect harmful UVA and UVB light generated by the sun. Some chemicals and ingredients absorb harmful rays, some reflect them and some do both. Most sunscreens contain a blend of such chemicals to optimise the SPF 30+ rating (or higher). There are other characteristics such as water resistancy, ease of application, non-greasy, non-irritating, non-whitening, etc that require special formulations with different ingredients, sunscreen actives and preservatives.

How much sunscreen should I apply?

For an adult, the recommended application is 5ml (approximately 1 teaspoon full) for each arm, leg, body front, body back and face (including neck and ears). That equates to a total of 35ml (approximately 7 teaspoons full) for a full body application.

How often should I reapply sunscreen?

Sunscreen should always be reapplied at least every 2 hours. There are variables that can impact the effectiveness of sunscreen once it has been applied. Activities such as swimming, outdoor sports, perspiring, towelling or wiping the body, etc will result in diluting and/or removing sunscreen from the skin. Because sunscreen manufacturers cannot predict the circumstances under which sunscreens will be used, it is recommended that sunscreen be applied every 2 hours irrespective of the water resistance rating of the sunscreen.

What regulations are there for sunscreen in Australia?

The manufacture of sunscreens is strictly regulated by the Therapeutic Goods Administration (TGA) of Australia , and part of this process is that all batches of sunscreen that are produced are thoroughly tested to ensure that the TGA approved formula is adhered to and that the
quantity of approved active ingredients is present before they are released to the public.