The questionable effectiveness of sunscreen

Adam E Handel a b, Sreeram V Ramagopalan a b

In their Seminar (Feb 20, p 673),1 Vishal Madan and colleagues highlight a rising incidence of non-melanoma skin cancer (NMSC) in several countries. The incidence of NMSC also seems to be increasing in the USA.2 This increase is the reverse of what is expected given the continued increased purchase of sunscreen per head in the USA and UK since the 1990s (figure).3, 4

Figure Full-size image (26K) Download to PowerPoint

Purchase of sunscreen products by volume per head over time in the USA and UK3, 4

The contradiction suggests that increased population exposure to sunscreen does not translate into a reduced risk of skin cancers. This finding is particularly important for public health measures to prevent NMSC (and melanoma). It could be that sunscreens are being improperly used, or that they are ineffective in the prevention of skin cancer, or that other factors not related to ultraviolet (UV) light are leading to an increased risk of NMSC and melanoma.1

Sunscreen has the potential to have negative effects since synthesis of vitamin D relies on UVB radiation.5 Since vitamin D deficiency has been linked to the pathogenesis of many diseases,5 it is crucial that the effectiveness of sunscreens and their use are thoroughly investigated.

We declare that we have no conflicts of interest.

References

1 Madan V, Lear JT, Szeimies RM. Non-melanoma skin cancer. Lancet 2010; 375: 673-685. Summary | Full Text | PDF(932KB) |CrossRef | PubMed

2 Stern RS. The mysteries of geographic variability in nonmelanoma skin cancer incidence. Arch Dermatol 1999; 135: 843-844.CrossRef | PubMed

3 Euromonitor. Cosmetics and toiletries: sun care. http://www.euromonitor.com/Sun_Care. (accessed May 25, 2010).

4 United Nations. World population prospects: the 2008 revision. http://esa.un.org/unpd/wpp2008/index.htm. (accessed May 25, 2010).

5 Holick MF. Vitamin D deficiency. N Engl J Med 2007; 357: 266-281. CrossRef | PubMed

a Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK

b Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital, Oxford, UK