Assessment of sun exposure in adolescent girls using activity diaries S.S. Sullivan a, *, J.L. Cobb a , C.J. Rosen b , M.F. Holick c , T.C. Chen c , M.G. Kimlin d , A.V. Parisi d a Department of Food Science and Human Nutrition, University of Maine, 5735 Hitchner Hall,Orono, ME 04469, USA b St. Joseph’s Hospital, Bangor, ME, USA c Boston University School of Medicine, Boston, MA, USA d Centre for Astronomy & Atmospheric Research, University of Southern Queensland, Toowoomba, Queensland, Australia Received 26 July 2002; received in revised form 15 December 2002; accepted 15 January 2003 Abstract The objective was to test a method of assessing sun exposure for use in stratifying adolescent girls according to potential for vitamin D 3 synthesis in the skin. Thirty-five girls wore polysulphone ultraviolet (UV) dosimeters and kept diaries of their activities on August 17, 2000. Minutes spent outdoors during each hour of the day were tabulated and adjusted for the fractional strength of ultraviolet B (UVB) radiation relative to peak hour. Total adjusted minutes outdoors were compared with UV dosimeter readings. A series of ampules containing 7-dehydrocholesterol were exposed on a flat plane to further investigate the potential for skin synthesis of previtamin D 3 with a given sun exposure. The correlation between measured UVB exposure and self-reported minutes outdoors adjusted for the time of day was r = 0.64. In vitro previtamin D 3 synthesis at midday was reduced by 50% on a cloudy day compared with a sunny day. © 2003 Elsevier Inc. All rights reserved. Keywords: Vitamin D; Adolescents; Female; Sun Exposure; Ultraviolet Rays * Corresponding author. Tel.: +1-207-581-3130; fax: +1-207-581-1636. E-mail address: susan_sullivan@umenfa.maine.edu (S.S. Sullivan). www.elsevier.com/locate/nutres Nutrition Research 23 (2003) 631– 644 0271-5317/03/$ – see front matter © 2003 Elsevier Inc. All rights reserved. doi:10.1016/S0271-5317(03)00018-6