Steve Taylor: Misguided on burning issue

As part of the "Slip, Slop, Slap, Wrap" message, sunscreens are an integral component of the Sun Smart campaign.

Yet consumers have never been adequately informed about the discrepancy between the expected and realised protection which these products provide - not by the Sun Smart campaign, the Cancer Society, the Ministry of Health, the Health Education Council, the Society of Dermatologists or any other official body in New Zealand.

The truth is that, by and large, sunscreens fail to deliver the UV protection they promise, often to a significant extent. And, by and large, this is not due to any deficiency in the products themselves but to the manner in which they are applied by the user.

Research has shown that 92 per cent of a sunscreen's effectiveness depends on how the user applies it - whatever the product, whatever its price, whatever its SPF.

If consumers apply sunscreen at the same rate of application at which the products are applied in the internationally adopted SPF testing system they will achieve the SPF stated on the product.

This is a large amount of product: approximately two finger lengths of product for each of 11 body areas - for example, to each arm.

It equates to about 35-40ml (one third of a standard bottle of sunscreen) for each whole body application for the average New Zealand adult.

However, for more than 25 years medical studies have shown that people apply something between one third and one tenth of that "official" quantity.

Accordingly, the SPF actually achieved on their skin may be no more than a small fraction of the protection they expected.

Is it realistic to expect the public to apply so much sunscreen? Is it not more accurate to say that people are applying the correct amount of sunscreen in that it is an amount with which they feel comfortable and that it is the labelled SPFs on sunscreens that are misleading?

The testing system is an accurate, carefully controlled and reproducible procedure in which a precise quantity of sunscreen is applied to a subject's skin and the product's SPF is then calculated following exposure to a measured quantity of UV. That SPF figure is then quoted on the label of the product.

While it is accurate in the laboratory, its real world relevance can be likened to performing a fuel consumption test on a car when the vehicle is set to run on a rolling road at 30km/h in top gear for several hours and then its fuel consumption calculated.

In such circumstances a 5-litre V8 4WD may achieve a fuel consumption of 95kmpg. Yet in real life an owner would expect to achieve about 25kmpg.

Consumers would obviously be sceptical about an advertised fuel consumption of 95kmpg for such a car, but we take the quoted SPF ratings of sunscreen products at face value.

We trust, intrinsically, the process from which these measures are derived, but they are no more relevant to real world use than the fuel consumption example.

Not only does this mislead the public from an ethical perspective, it also fosters a sense of misguided reassurance about the protection which sunscreens are providing.

The stated performance of sunscreens is also a misconception, which although fully appreciated by officialdom has not been explained adequately to the public.

Why? Is it because it is clear that bodies have been promoting a deceptive message for so long?

Are they potentially liable for the ill-informed use of sunscreens by a trusting public?

The official recommendation to use a sunscreen of SPF 30 or more is yet another misconception. Scientifically it has been shown that for the vast majority of people (90-95per cent) there is no need for an SPF of more than 15 - most of us need less.

The challenge is to ensure that users really do achieve an SPF of about 15.

Once again research has shown that using an SPF 30 product actually delivers a lower SPF on the users' skin than using an SPF 15 product.

Why? Because in order to achieve higher SPF levels, the concentration of active ingredients has to be increased, and as these are inherently oily the product becomes even more challenging and even less cosmetically acceptable to apply.

If the official stance was to follow the dictates of true science it would recommend the use of SPF 15 products which are easier to apply and re-apply.

They are less expensive, expose users to fewer chemicals and actually deliver higher protection.

Over the years, numerous commentators have stated that sunscreens should not be viewed as a "suit of armour" against the sun. Yet in New Zealand, the official bodies responsible for promoting the Sun Smart message have been less than candid about this issue.

Although it may seem to serve the interests of sunscreen manufacturers to promote greater consumption of their products, the fact is that for economic as well as cosmetic reasons few people are prepared to apply so much sunscreen.

The discrepancy between expectation and realisation of sunscreen performance has been known by the medical and scientific community for decades. But it has never been addressed adequately by the health education lobby.

Are official interests being placed ahead of those of the public?

* Steve Taylor is a general practitioner who has developed products including a sunscreen spray.