Richard M Timms
Do Sunscreens Really Protect Us?
Do Sunscreens Really Protect Us?
Midday, the sun is strong but the surf around the Gower is irresistible. I clutch my
surfboard, deciding today it’s too hot for the neoprene. But should I abandon my
wetsuit? I pause. Courtesy of a family tragedy, I am well aware of the risks of
malignant melanoma. Should I slap on sunscreen? I hesitate. Being a student, I
consider the cost. Is it really worth it? I start thinking about sunscreen protection and
determine to find out more, much more. The result is this essay; and through it I
share with you the fruits of my explorations.
The bounties resulting from my inquiries to be divulged in this essay are: the
risks of sunlight, the uses and abuses of sunscreen, and any identifiable risks of its
use. However, a key theme throughout the essay is an evaluation of the nature of
the available research and evidence.
Do we really need protection from the sun? The answer seems to be “yes” but
with some qualifications. First, UV radiation can result in photoimmunosupression
which could advance the development of cancers. Yet as Schwatz (2002) observes
the exact processes are uncertain and, somewhat counter-intuitively,
photoimmunosuppression appears not to exacerbate infections.
Second, there is the possibility of sunburn, which sometimes merely causes
temporary discomfort, but is also related to longer-term photoaging and
photocarcingenesis. Substantial sunburn in childhood has been linked to malignant
melanoma which is the type of cancer most associated with severe illness and
fatalities. There appears to be a link between malignant melanoma and both a
history of sunburn and intermittent contact with the sun. Nevertheless, again counter-
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Do Sunscreens Really Protect Us?
intuitively, chronic exposure to sunshine appears to reduce the risk of melanoma
(Parkin et al, 2011).
There are various forms of skin cancer. The first is squamous cell carcinoma;
there is evidence that UV screens protect against this. Second is basal cell
carcinoma where the evidence of sun cream’s efficacy is limited. Finally, there is
malignant melanoma but there are doubts about sunscreen’s ability to give
protection from this most perilous form of cancer (Bouknight et al, 2010; Planta,
2011). In a detailed examination of the topic, Burnett and Wing (2011) found that
there were no longitudinal, numerically robust studies to date examining the efficacy
of sunscreen to protect against malignant melanoma.
Although longitudinal studies are desirable, in sunscreen research this is by
no means straightforward. There are the familiar problems, associated with
longitudinal research, of participant withdrawal causing bias (Vestbo et al., 2011).
But in addition there is the further challenge in relation to sun protection that any
current longitudinal research is looking at sunscreen formulations of the 1980s and
1990s. Sunscreen composition and ingredients change over time. For example, antioxidants are now being added to some sunscreens (Wang et al, 2010).
Any new developments may indeed both produce and reduce risks. To give
an instance, in the USA, in June 2011, the Food and Drug Administration introduced
new sunscreen labelling regulations to improve consumer choice and knowledge.
However Diffey (2012) argues the regulations might have an undesirable effect. This
is because, he explains, natural protectors such as clothing and shade protect the
skin through the entire ultraviolet spectrum. Therefore sunscreen should offer a
similarly comprehensive shield and manufacturers have been endeavouring to
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Do Sunscreens Really Protect Us?
provide this. But, according to Diffey (2012), the new labelling regulations give no
inducement to manufacturers to continue to strive for the balanced ideal of protective
ingredients facilitated by modern technology.
Turning now to some of the problems associated with sunscreen use, there is
first an issue common to many protective measures. That is, that despite everyone’s
best efforts, they often are not used correctly. A parallel case is children’s car seats
where even after years of research and advice many adults are inadvertently not
using booster seats safely. For example, O’Neil et al (2009) found 64.8% of 1446
drivers, with 564 children in booster seats had positioned the children incorrectly.
A similar situation of incorrect usage may be occurring with sunscreen. De
Villa et al (2011) found that even research volunteers, who reapplied sunscreen
carefully knowing they would be checked by researchers, did not do so sufficiently
consistently or thickly. For people who try to follow instructions assiduously there are
many immeasurable factors militating against appropriate use. For example, hot
sunny weather is often associated with water, whether cooling off by swimming,
showering or enjoying water-sports. Some sunscreens advertise that they are
“waterproof” but, as I dry myself after an hour or so surfing, I wonder how far sun
creams survive vigorous rubbing with towels.
Rare in discourses of effective sunscreens is their cost, something that
naturally occurs to those of us who are impecunious students. Admittedly, money is
not the only factor against proper use because even wealthier people will disregard
sunscreen guidelines as Buller et al (2012) discovered. Nevertheless, Mahe et al
(2011), looked at the cost around the world and estimated a mean of $238.4 for a
week for a family of four but this could rise to $6396.5. Inevitably poorer families
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Do Sunscreens Really Protect Us?
might well not renew the sunscreen regularly throughout the day because the cost
would be prohibitive.
Next to consider is the question of whether sunscreen, rather than protecting
us, itself poses risks. First, as with many protective measures, we have the tendency
to take more risks if we feel well defended. For example, there is evidence that,
despite the clear benefits of cycle helmets, people wearing them may cycle faster
and take more risks than those without (Phillips et al, 2011). There is a parallel with
sunscreen, with people tempted to stay out for too long in strong sunshine, confident
that the cream will protect them. For example, in their study of sunburn in Swedish
children, Rodvall et al (2010: 275) conclude that sunscreens “may convey false
security”.
Second there is the issue of vitamin D deficiencies which could be caused by
sunscreen. Vitamin D is produced in the skin by ultraviolet B (UVB)-mediated
photolysis of 7-dehydrocholesterol but this process could be blocked by sunscreen.
There is now mounting research to show that vitamin D has an essential role in
maintaining health. It helps to modulate vascular tone, regulate the immune function,
and influence renin and insulin synthesis. There is increased understanding of how
vitamin D defends the body against the development of many forms of cancer
(Holick, 2008).
Lack of vitamin D because of sunscreen blocking UVB penetrating the skin
might not just affect the person using sunscreen. One area of research of increasing
interest is the impact of maternal health on the unborn baby. Foetal malnutrition was
first brought to our attention by research following people born during the famine of
the 1944-45 ‘Dutch Hunger Winter’ (Lumley & Stein, 1997) and the subsequent work
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Do Sunscreens Really Protect Us?
of Barker (1995) . More recently Lapillonne (2010) has reviewed the impact of
maternal lack of vitamin D on foetal health. Vitamin D deficiency may well adversely
influence the formation of the foetal skeleton and foetal ‘‘imprinting” which might
result in susceptibility to chronic disease both soon after birth and in the longer term.
A young, pregnant woman taking care not to put on too much weight by avoiding
highly calorific fats and oils while liberally using high factor sunscreen throughout the
summer might, despite her care and avoidance of risks, be inadvertently be
damaging the health of her unborn baby
It is true that vitamin D can be obtained through diet and supplements.
However, for poorer people, paying for supplements represents an added cost.
Moreover, there are questions about how far pill-type concentrated supplements are
metabolised appropriately by the body. Vitamin D can also be obtained from oily fish
but worldwide fish stocks are in decline. Moderate, sunscreen-free exposure to sun
appears to be a cheaper, environmentally friendly way of obtaining sufficient Vitamin
D.
Sunscreen, however, not only minimises vitamin D manufacture but also limits
production of nitric oxide from L-arginine by nitric oxide synthase in the endothelium.
Nitric oxide has beneficial coronary vasodilator, cardio-protective and
antihypertensive effects. Therefore, lack of exposure to sunlight may increase the
risk of hypertension and ischaemic heart disease. Feelisch et al (2010) advance the
hypothesis that because sun exposure enhances skin activated nitric oxide it
augments cardiac health and is therefore particularly beneficial for older people.
Therefore we might need to distinguish between liberal application of sunscreen to
protect children from sunburn but limited use for older adults whose hearts might
benefit from substantial exposure to the sun.
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Do Sunscreens Really Protect Us?
But having just advised liberal use for children, we proceed with caution
because there are concerns about damaging ingredients contained in sunscreen
itself. Jain and Jain (2010) remark that molecules in sunscreen ingredients can
cause photo-toxic and photo-allergic reactions resulting in skin irritation. This is
particularly true for people with eczema and photodermatoses.
One of the most common sunscreen ingredients is titanium oxide and
concerns have been raised that it might be carcinogenic because high
concentrations of its dust have resulted in respiratory tract cancer in rats (Smijs and
Pavel, 2011). However, there is no evidence of harm if it is applied in cream to the
skin. Zinc oxide is another major ingredient but with few evident risks (Smijs and
Pavel,2011). Both have cosmetic drawbacks leaving a white film on the skin.
Therefore, to overcome this problem, manufacturers have been developing
nanoparticles of approximately 0.20 microns or less, particularly of zinc oxide and
titanium. There are concerns that nanoparticles may penetrate the skin and damage
internal organs, although research indicates that the particles, especially if coated
with dimethicone or silica to improve stability, do not penetrate beyond the stratum
corneum of the skin (Loden et al., 2011, Papakostas et al, 2011). Nevertheless,
Bostrom and Löfstedt (2012) warn that nanoparticles could be absorbed through
lesions. This is important not least because many adolescents and young adults, the
very groups who tend to seek sun-filled holidays and activities, may have acne spots
on the back and face.
There are very many potential ingredients in sunscreen, with some 27
potential UV filters approved for Europe listed by Loden et al (2011). Therefore
ensuring that no sunscreen constituents pose a risk to health requires constant
vigilance. For example, retinyl palmitate, has been suspected of being
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Do Sunscreens Really Protect Us?
photocarcinogenic but this danger has not been established (Burnett & Wang, 2011).
Another ingredient is oxybenzone (benzophenone-3), which has been found to be
absorbed systemically although in humans any effects have been minimal. Rats
given relatively generous portions to eat have shown effects which might damage
reproduction but humans do not usually eat large amounts of sunscreen (Burnett &
Wang, 2011). Although most people do not deliberately ingest it, there are concerns
about younger children whose fingers and thumbs, after having wiped parts of their
body liberally smeared with sunscreen , readily find their way to their mouths.
Sambandan and Ratner (2011) express substantial reservations about
sunscreens which are combined with DEET, an insect repellent, not least because
sunscreen should be reapplied frequently and insect repellents sparingly, so the two
seem ill-matched.
The conclusion of so many papers trying to assess whether the components
of sunscreen are harmful is that there needs to be more research on the topic.
However, it costs money to undertake research and therefore it will only happen if
there are the finances to support it. Clearly in sunscreen research one set of
stakeholders are the sunscreen manufacturers. Understandably, any positive results
in favour of liberal use of sun creams sponsored by the relevant companies might be
regarded with misgivings yet the research may be perfectly valid. A similar area is
that of pharmaceutical company-sponsored research examined by Sergio (2012)
who notes that, to avoid doubts about the research’s credibility, companies
sometimes use independent researchers to publish their papers. Trying to
disentangle whether or not there is undue commercial influence associated with
research extolling sunscreen is challenging in the extreme. Worse still for those of us
seeking reliable knowledge, is the awareness that there is some fraudulent research
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Do Sunscreens Really Protect Us?
(Tavare, 2011). But we will not dwell on the contentious topic of duplicity, which
hopefully is exceptionally rare in sunscreen research.
Even when research is well conducted there is still the question of which
research is published and disseminated. “Grey” or unpublished research is often
ignored (Ahmed et al, 2010). And yet, according to systematic analysis by Hopewell
et al (2007) grey material may impact on the results particularly of meta-analyses.
Additionally, there is a general bias against non-significant findings, and this in itself
may skew our awareness and understanding particularly of scientific knowledge
(Levine et al, 2009).
An absorbing paper by Shalvi et al (2010) demonstrates how capricious can
be the acceptance of papers to peer-reviewed journals including such arbitrary
factors as the month in which a paper is submitted. We simply do not know how
much potentially meaningful research has been left on the shelves of disillusioned
biomedical scientists whose papers have been misunderstood by harassed editors
and rejected before being peer-reviewed.
Even when sound research is widely disseminated, we have to consider how
generalizable the results are. Autier et al (2011) for example point out that while
Green et al (2011) demonstrated that regular sunscreen use can reduce the risk of
developing cutaneous melanoma, this and similar Australian studies involved regular
application of sunscreen by motivated, middle to older aged, light-skinned adults
habitually exposing small areas of skin and living in high sunshine areas. Autier et
al. then explain that for many European people the experience of exposure to
sunshine is that of young people indulging in short but intensive blasts of sunbathing
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Do Sunscreens Really Protect Us?
while on holiday. So we have the drawback of what might be useful evidence for the
efficacy of sunscreens for some populations is of less value for others
So in conclusion, sunscreen has a place in protecting our skin but this is an
area in which there needs to be continuing, independently funded research plus
ways found to access unpublished research. A key need is to explore the protections
and hazards facing different people. For some, particularly older people and those
with darker skins there are risks that sunscreen may be a barrier to the benefits of
sunshine. On the other hand, sunscreen appears to protect others, especially
younger people and those whose skins burn easily. Because I fall into this latter
category, I will use sunscreen whenever clothing and shade are not options. Yet
despite my enquiries, I remain uncertain about many issues such as how to use it
correctly, how much is enough but not too much, and whether any constituents of
sunscreen could cause harm if my skin is damaged. Nevertheless, there is one clear
unambiguous message from the sunscreen research. That is, whatever the degree
of hunger caused by trying to live off an NHS bursary, I should not be eating it!
Word count: 2,467
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