Last updated: August 2024
What is sun protection?
Sun protection is aimed at reducing excessive exposure to sunlight. Effective sun protection allows for healthy growth and development as well as enjoyment of outdoor activities but, at the same time, aims to reduce risk of skin diseases and ageing which are related to overexposure to sunlight.
Effective sun protection includes:
- Physical protection of exposed skin such as:
- Wearing tightly woven longer sleeved clothing, broad brimmed hats and sunglasses
- Seeking out shade
- Applying sunscreens
- Rash vests and wetsuits offer the best form of sun protection when swimming or doing other water activities.
- Sun protection is recommended whenever the ultraviolet (UV) index is 3 or higher. Sun exposure in the middle of the day should be avoided as this is when UV radiation is at its highest level.
- For infants, sun protection is best provided with clothing and hats and by avoiding prolonged outdoor exposure during the middle of the day.
Why is sun protection important?
Australia has a very high incidence of skin cancer, both melanoma and non-melanoma, due to everyday sun exposure particularly amongst Australians of Celtic ancestry with fair skin and blue eyes. Sun exposure over time produces premature ageing changes in the skin of all ethnic groups. Consequently, daily sun protection should be used in Australia and New Zealand, particularly during the spring and summer months, where the UV index is often 3 or higher for nearly the entire day. The amount of cloud cover, or temperature, is not a good guide as to how much ultraviolet radiation is reaching our skin and damaging it.
What is ultraviolet energy?
Ultraviolet radiation is energy produced by the sun which is divided into 3 types according to its wavelength – UVB, UVA and UVC.
- UVC is the most dangerous but is currently entirely screened out from reaching the earth’s surface by the ozone layer in the upper atmosphere. Ozone gas also filters out most of the UVA and UVB radiation.
- UVB is more energetic, is blocked by window glass and is the main cause of sunburn.
- UVA is less energetic but penetrates more deeply into the skin. UVA is not blocked by window glass.
Both UVA and UVB radiation contribute to:
- Precancerous changes (sun spots, actinic keratoses) in the skin
- Cancerous changes (basal cell carcinoma and squamous cell carcinoma skin cancers and melanoma) in the skin
- Ageing effects on the skin such as skin dryness, pigmentation and loss of elasticity of the skin (photoaging).
What are sunscreens?
Sunscreens are products (creams, lotions, mists, sprays, gels) applied to the skin to reduce the effect of ultraviolet radiation on the skin. Sunscreens help prevent the development of skin cancer including melanoma. They also help prevent the development and symptoms of photo-sensitising disorders such as photoallergies and phototoxicities. Regular use of sunscreens can help prevent the photodamaging and ageing effects of the sun on the skin.
Sunscreens should be used in conjunction with physical protection and should not be seen as a substitute for physical protection. Avoiding sun exposure, seeking shade and wearing protective clothing (hat, sunglasses, long sleeves) offer the best protection.
How do sunscreens work?
Sunscreens work in 2 ways:
- Reflecting or blocking the light away from the skin (reflectant)
- Absorbing the ultraviolet energy, preventing it from getting into the skin cells (absorbent)
Reflectant sunscreens block UV away from the skin and include zinc oxide and titanium dioxide. How well this is done is dependent on the amount of zinc oxide or titanium dioxide that is applied to the skin. The skin may take on a milky-white appearance when the product is applied although newer formulas have improved this appearance.
Absorbent sunscreen agents absorb UVB or UVA radiation. Most absorbent sunscreens contain a mixture of the following synthetic chemicals – cinnamates, dibenzoylmethanes (salicylates) and benzophenones. Absorbent sunscreens are usually invisible when applied to the skin.
Sunscreen ingredients are mixed in different bases to provide a large variety of available products (creams, lotions, gels, sprays and lip balms). The bases for sunscreens also contain other chemical additives necessary to ensure stability, adequate mixing, a pleasant feel on the skin, a pleasant odour and adequate anti-microbial activity.
No sunscreen will block 100% of UV radiation – there is always some UV that reaches the skin even when the sunscreen has been applied correctly.
What does SPF mean?
SPF stands for Sun Protection Factor.
SPF indicates the amount of UVB radiation that can reach the skin with sunscreen compared with no sunscreen. It is calculated knowing how much UVB radiation is necessary to create redness (burn) of the skin. If you wore SPF 50+, for example, you could stay in the sun 50 times longer before burning compared to if you were wearing no sunscreen at all.
The SPF is determined in scientific laboratory conditions and is regulated in Australia by the Therapeutic Goods Administration (TGA) to ensure strict labelling and safety for consumers. It is important to realise that you cannot depend on the SPF to determine how long you can stay exposed to sunlight or how long before you get sunburnt. In real life the actual SPF of a product is often lower than the formal laboratory testing. All sunscreens, even when applied correctly, will still allow some UV to penetrate the skin.
SPF is the measurement of protection against UVB only. Sunscreens with the same SPF can offer different levels of protection against UVA radiation. Therefore, it is important to choose a sunscreen labelled “broad-spectrum” which protects against both UVA and UVB.
In addition to the SPF and broad-spectrum factors, sunscreens in Australia are also labelled for water resistance. This represents the ability of the sunscreen to remain effective on the skin after repeated or prolonged exposure to water. No sunscreen is “waterproof” and all sunscreens become less effective to some extent after exposure to water. It is always recommended that sunscreens be reapplied after exposure to water to ensure adequate protection.
The Cancer Council recommends Australians use SPF50 or SPF50+, broad-spectrum, water-resistant sunscreen.
How should I apply sunscreens?
It is a known fact that most individuals do not apply adequate amounts of sunscreen, thereby reducing its effectiveness.
Sunscreens should be applied liberally and evenly to clean and dry skin at least 20 minutes before exposure to UV. This allows the product to be evenly dispersed and absorbed into the superficial layers of the skin.
Most products are not visible when applied to skin and as a result small areas can be missed, leading to sunburn appearing in these areas the next day. Care should be taken when applying sunscreens. It is important not to miss your ears, hands and feet and back of the neck. Apply at least 1 teaspoon of sunscreen product to each body part (face, neck and ears, arm, leg, front of body, back). Sunscreen should always be reapplied at least every 2 hours, irrespective of the water resistance of the sunscreen. Swimming, sport, sweating and towel drying can reduce the effectiveness of the sunscreen, so sunscreen should always be reapplied after these activities.
What are the common side effects of sunscreens?
All the synthetic chemicals used in sunscreens have been subjected to extensive testing to determine the risk of side effects. Despite this, problems can occur occasionally with the regular use of sunscreens.
The most common side effect is irritation. Burning, stinging or redness can occur in certain areas of the skin more than others after application of the sunscreen. This is particularly on the face around the eyelids, or occasionally on the hairy forearms of men. This is not an allergy to the sunscreen as the effect only occurs in certain areas, whereas it can be used without any problems on other areas of skin. When irritancy occurs, it is recommended to find an alternative sunscreen that does not irritate the skin.
A true allergic reaction to a chemical in a sunscreen product can occur but is less common. In most cases it is not the synthetic sunscreen chemical itself that is the problem, but more likely one of the other chemicals used in the base such as a perfume or preservative. Professional assessment and patch testing may be useful in identifying the product in the sunscreen that is causing the allergic reaction.
Some sunscreens can cause acne-like eruptions (pimples, folliculitis) when applied to the skin. Again, this is usually caused by the base ingredients of the sunscreen. If you are prone to this problem, it is best to look for gels or lotions or products labelled “oil-free” or “non-comedogenic”.
There are very few reports of chronic or long-term problems related to the regular use of sunscreen. In case of doubt, avoiding the sun by keeping in the shade and/or wearing protective clothing are the best options.
Do sunscreens cause cancer?
To date, there is no scientific evidence to support the claims that synthetic sunscreen chemicals are carcinogenic or have cancer-causing potential.
Despite multiple publications about “nano” particles in magazines and newspapers, no adverse effect of “nano” particles in sunscreens have been demonstrated to date. Because skin cancer and melanoma have been linked to sunlight and solarium UV exposure, the benefits of sun protection are clear.
Are sunscreens safe for young babies?
Because very young babies (less than six months of age) absorb more of any chemical applied to the skin than adults, the widespread regular use of chemical sunscreens is not recommended. However, there have been no reports of side-effects occurring as a result of sunscreen absorption in babies to date.
Can I become deficient in vitamin D if I protect with sunscreen?
In theory yes, but most individuals are not using sunscreens as they should, that is they often do not apply enough product to the skin and reapply as often as recommended. Individuals that are protecting themselves very well because of a history of skin cancer or melanoma, should talk to their doctor about vitamin D deficiency.
Remember sunscreens are only one form of sun protection and cannot be fully relied on to prevent sun damage and skin cancers. Whenever the UV index is 3 or above, all five forms of sun protection should be followed:
- Slip on sun protective clothing
- Slop on SPF50 or SPF50+, broad-spectrum, water-resistant sunscreen
- Slap on a broadbrimmed hat
- Seek shade
- Slide on sunglasses.
| Prof Pascale Guitera | August 2024 |
| Prof Pascale Guitera | July 2022 |
