Letters

Simple dosage guide for suncreams will help users

BMJ 2002; 324 doi: http://dx.doi.org/10.1136/bmj.324.7352.1526/a (Published 22 June 2002) Cite this as: BMJ 2002;324:1526
  1. Steve Taylor (steve@dox.co.nz), general practitioner,
  2. Brian Diffey, professor of medical physics
  1. Sunset Road Family Doctors, Mairangi Bay, Auckland 1310, New Zealand
  2. Regional Medical Physics Department, Newcastle General Hospital, Newcastle NE4 6BE

    EDITOR—The sun protection factor (SPF) of a sunscreen is determined after phototesting in vivo at an internationally agreed application thickness of 2 mg/cm2. Yet studies have shown that consumers apply much less than this—typically between 0.5 and 1.5 mg/cm2.1 This has an appreciable effect on protection, with typical application rates achieving a sun protection factor of perhaps one third of that stated on the product.2 This mismatch may be one contributing factor why sunscreens have been reported to be a risk factor in melanoma.3

    No …

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