Cosmetic Surgery & Beauty Magazine #70



According to Williams, scientists use a simple formula

to determine how much sunscreen should be used. ‘As an

example, for a person about 175cm tall and weighing about

82.5kg they will require approximately 40g – almost half a

typical 100g tube, of sunscreen to cover their body to the

same level as is specified in the Australian Standard test

procedure,’ he says.

Using this amount means you are using the effective

level as stated on the label. Using less means you are not

getting the SPF stated on the label.

‘The prudent course is to reapply the sunscreen at

regular intervals to ensure an adequate film is maintained,’

says Williams, who also stresses that using sunscreen is a

filter only.

‘What that means is that the sunscreen continuously

allows the passage of a low level of ultraviolet radiation –

even if it is SPF 30. Reapplication of the sunscreen does not

remove the damage that has already been caused by the


is SPF?

SPF refers to the Sun Protection Factor offered

by various sunscreens. The level of SPF

given to each sunscreen is measured using

a complex mathematical equation, and refers

to the amount of ultraviolet raditation required

to cause sunburn with the sunscreen on, as

a multiple of the amount required without the


Traditionally the SPF is rated for sun damage

by UVB rays only. However, the new legislation

requires the industry to change these standards

and include information about the potential to

protect from UVA radiation, too.

The protection given to individuals by a certain

level of sunscreen will vary depending on:

• the amount applied

• the frequency of application

• the skin type of the user

• immersion in water through swimming

• amount of sunscreen absorbed by the skin.

transmitted radiation,’ he explains. ‘When you reapply the

sunscreen, unlike a cure, you do not “start the clock again.”

So the purpose of reapplying the sunscreen is to ensure

that it is still covering the skin properly. Even if an SPF 30

sunscreen is reapplied regularly, if the intensity of the UV

radiation is high enough and if the skin is exposed for long

enough, invisible damage, or even physical damage in the

form of sunburn, could occur.’

Williams says that another misapprehension is that

the sunscreen starts to work immediately it is applied.

‘All sunscreens in Australia come with the warning that

the sunscreen should be applied 15-30 minutes before

going into the sun and it should read 15-30 minutes before

entering the water,’ he says. ‘This time allows the water in

the product to evaporate and the waterproof sunscreen film

to properly form on the skin surface.’



The mineral zinc oxide has long been known to provide

complete protection from UVB and UVA radiation, and is the

only FDA-approved sunscreen for children under 6 months

of age. However, zinc oxide can leave an undesirable white

residue on the skin.

Modern advances in nanotechnology have meant that

scientists have been able to reduce the particle size of the

zinc oxide to just 80 to 120nm. At this size, the zinc oxide

can sit on the surface of the skin, still working effectively as

a sunscreen, without causing a white appearance.

Nanotechnology, however, has sparked scientific debate

with some fearing the escape of particles into the blood

stream. ‘In early 2009, the Therapeutic Goods Administration

(TGA) conducted an updated review of the scientific

literature in relation to the use of nanoparticulate zinc oxide

and titanium dioxide in sunscreens,’ says Williams.

‘The TGA review concluded that the potential for titanium

dioxide and zinc oxide nanoparticles in sunscreens to

cause adverse effects depends primarily upon the ability of

the nanoparticles to reach viable skin cells; and to date, the

current weight of evidence suggests that titanium dioxide

and zinc oxide nanoparticles do not reach viable skin cells;

rather, they remain on the surface of the skin and in the

outer layer of the skin that is composed of non-viable cells.’

The TGA is continuing to monitor the emerging scientific

literature to ensure appropriate action is taken should any

tangible safety concerns be identified. Currently, however,

no specific warnings about nanoparticles need to be placed

on labels of sunscreens.

In Australia, all active ingredients, such as zinc oxide and

titanium dioxide, must be declared on sunscreen labels, to

help consumers make informed choices. However, it is not

a requirement for sunscreen labels to declare the particle

size of the active ingredients. csbm 95

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