Simple dosage guide for suncreams will help users
BMJ 2002; 324 doi: https://doi.org/10.1136/bmj.324.7352.1526/a (Published 22 June 2002) Cite this as: BMJ 2002;324:1526All rapid responses
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1. A dosage guide should benefit serious research into the role of
sunscreens in skin cancer.
Would the 'correct' use of modern broad spectrum sunscreens actually
help to reduce the incidence of skin cancer, particularly that of
melanoma? Although it's tempting to think the answer to this question
would be 'Yes', the fact is that at present the answer must be 'Who
knows?'.
Whilst the use of sunscreens does appear to reduce the risk of
squamous cell carcinoma, this is not necessarily the case for basal call
carcinoma, and there have been reports that sunscreen use may be linked
with the development of melanoma, though the evidence for the latter is
conflicting .
Given the inadequate and haphazard manner in which we know that
sunscreens have been used over the years it must surely be difficult to
draw meaningful scientific conclusions about the role of sunscreens in the
prevention (or otherwise) of skin cancer.
With a uniformity of dosage, such as that proposed in the "Two
Fingers - One Finger" suggestion - assuming that the public could be
persuaded to adopt such an idea - it should be possible to be much more
objective about the role of these products in skin cancer.
2. Official oversight? Or dangerous deception?
The "Simple dosage guide for sunscreens" was originally submitted to
the BMJ with the title "Two Fingers to sunscreen? What about One Finger?"
Without some sort of dosage guide for sunscreens, the stated levels of SPF
protection on the products are, at best, misleading - at worst they may
even be dangerous.
The current issue of the Australasian Standard for sunscreens # 2604
(1998) includes the following paragraph in its preface: "The committee
recognised that many people do not apply sunscreens correctly, and (but)
that individual behaviour cannot be addressed within this Standard, and
recommends that the correct use of sunscreens be addressed through public
education." In other words, 'we have a system which works in the
laboratory but if people don't apply the products correctly, well that's
someone else's problem.' And this could be interpreted as not so much an
oversight, as an abrogation of responsibility.
There are 24 organisations whose interests are represented on the
Joint Technical Committee CS/4 which formulated the Australasian Standard
for Sunscreens. Amongst these are the NZ Ministry of Health, the Cancer
Society of NZ, the Measurement Standards Laboratory of NZ, the Cosmetic,
Toiletry & Fragrance Association of NZ, the Australasian College of
Dermatologists, the Australasian College of Occupational Medicine and
numerous high profile Australian organisations.
It seems ironic that one can go into a pharmacy and see hundreds of
vitamin and nutritional products for sale which, scientifically speaking,
fulfil little real need and offer little real benefit to the vast majority
of people. Yet each of these products specifies a dosage for users.
Sunscreens, in contrast, are promoted as an integral part of the world
wide strategy to reduce the incidence of skin cancer, but these products
carry no effective dosage recommendations.
I'm just a GP working in the trenches of general practice. I have no
resources, no research facilities, no budget, no funding. Yet it took 10
minutes and cost nothing to formulate the "Two Fingers" dosage guide. So
why, given the resources of this multi-billion dollar global industry and
the apparent expertise of all those involved, has it taken so long for
some sort of dosage guide to be proposed?
Again, from a GP perspective, it is clear that for subjective,
primarily cosmetic, reasons people do not like applying sunscreens -
especially to those areas most at risk: the head, neck, face, ears, etc.
To try to encourage them to apply One Finger's worth, let alone Two
Fingers' worth will be a challenge indeed.
Despite knowing how inadequately people apply sunscreens the
regulatory emphasis continues to concentrate on the laboratory performance
of sunscreen products - in terms of their SPF. User issues, such as how
best to get these very effective products onto peoples' skin in adequate
concentration are not addressed at all. Yet the best laboratory performing
sunscreen is useless - whilst it remains in its container.
For years there have been calls for a change in the international
testing system to reflect a more realistic application rate amongst the
general public, for example reducing the test application rate from
2mg/cm2 to 1mg/cm2 or even to 0.5mg/cm2, which would more closely reflect
real-world usage. But these calls do not seem to have been heeded. Why not
make it 0.66mg/cm2 as a compromise? That would be cosmetically acceptable
to just about everyone (it would be two digits' worth), and because a
product currently rated at say SPF 30 would automatically become an SPF 10
product, encouragement to reapply the product should fall on much more
receptive ears. If people happened to apply more than two digits' worth -
so much the better, probably.
Here is a global industry comprising manufacturers, marketers, expert
advisors, testing facilities, institutions and attendant regulatory
bureaucracies which appears to be comfortably entrenched in its own status
quo and could, not unreasonably, be seen as representing numerous vested
interests. Its failure to stipulate dosage criteria for sunscreens might
be seen as an official oversight. Less charitably, it could be viewed as
perpetuating a potentially dangerous deception on the public.
Despite the billions of dollars spent on sunscreens around the world
(and these are not inexpensive products for the average working family),
the incidence of skin cancer continues to rise. Although the real answer
about whether sunscreens do, or do not, prevent or contribute to the risk
of melanoma is unclear, I think if I were a part of that industry it would
worry me sufficiently to affect whether I slept easily at night. And I'd
want those questions answered as a matter of urgency.
Steve Taylor - general practitioner
Sunset Road Family Doctors
14/326 Sunset Rd, Mairangi Bay
Auckland 1310, New Zealand
email: steve@dox.co.nz
Competing interests: No competing interests
The suggestions Drs Taylor and Diffey provide are helpful if one
accepts the premise that sunscreens are necessary and should be used to
decrease the incidence of melanoma.
However, there is significant evidence to the contrary. Many
investigators do not believe not suggest a causative association between
sunscreen use and melanoma (1).
There are other factors which also contribute to the effectiveness of
sunscreens in preventing melanoma. (2)
The encouragement of sunscreen use also detracts from the central
cause of melanoma, which is not sun exposure, but an imbalance in the
omega 6 to 3 fat ratio. Epidemiological, experimental, and mechanistic
data implicate omega-6 fat as stimulators and long-chain omega-3 fats as
inhibitors of development and progression of a range of human cancers,
including melanoma (3)
Even the National Academy of Sciences recently concluded that
epidemiological and animal-based investigations have indicated that the
development of skin cancer is in part associated with poor dietary
practices. (4)
Advocating the use of sunscreens rather than exercising judicious
limited progressively increasing exposures until one is able to avoid
sunburn will preclude the population from benefiting from the many well-
documented benefits of sun exposure.
Earlier this year a major peer review journal concluded that ten of
thousands of cancer deaths could be prevented through increased careful
exposure to solar UV-B radiation. (5) There is also strong evidence the
exposure to sunlight is protective against MS (6)
Rather than promote the use of sunscreens and severely limit the
valuable benefits of UV-B radiation it would seem far more prudent to
encourage the judicious use of clothing and timed sun exposure. (7)
References:
1. Br J Dermatol 2002 Apr;146 Suppl 61:24-30
2. J Photochem Photobiol B 2001 Nov 15;64(2-3):105-8
3. Cancer Res 2000 Aug 1;60(15):4139-45
4. Proc. Natl. Acad. Sci. USA, Vol. 98, Issue 13, 7510-7515, June 19, 2001
5. Cancer 2002 Mar 15;94(6):1867-75
6. Occup Environ Med 2000;57:418-421
7. Br J Dermatol 2001 Dec;145(6):1030
Competing interests: No competing interests
Sun Screen Excesses
Sir
I am surprised the two medical scientists fail to mention the dangers
of the application of sunscreens, surely they have investigated this
aspect prior to encouraging use of potentially dangerous sunscreen
practices?
Over the past 5 or 6 years several potentially carcinogenic additives
in sunscreens have already been identified and removed, suggesting that
sunscreens may be at tne heart of skin cancer causation......is it not a
fact that one is far more likely to develop skin cancer if one uses
sunscreen 'protection' than if one does not?
I do not remember any such controversy with coconut oil, in use when
I was a child in the '50s and '60s, the use of which was rapidly
'eradicated' by heavy propaganda stating one 'may cook one's skin using
oils' (despite no scientific evidence for this) when sunscreens came into
fashion through heavy advertising.
A comment on the dangers of sunscreens from the authors would be
useful.
Regards
John H.
Competing interests: No competing interests