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Relationship between low ultraviolet B irradiance and higher breast cancer risk in 107 countries. Mohr SB, Garland CF, Gorham ED, Grant WB, Garland FC. Breast J. 2008 May-Jun;14(3):255-60. Epub 2008 Apr 17. PMID: 18422861 DOI: 10.1111/j.1524-4741.2008.00571.x There was a protective effect of UVB irradiance on risk of breast cancer that was independent of fertility rate, proportion of the population overweight, alcohol intake, animal energy intake, and other covariates.

Simulations of ultraviolet irradiances, doses and indices at the Earth's surface at user specified UV wavelengths. A simpler version for non-experts is available at http://nadir.nilu.no/~olaeng/fastrt/fastrt-ez.html

"UV-related web tools maintained by Ola Engelsen * FastRT - Fast simulations of downward UV doses, indices and irradiances at the Earth's surface: http://nadir.nilu.no/~olaeng/fastrt/fastrt.html. * VitD_quartMED - Calculated Ultraviolet Exposure Levels for a Healthy Vitamin D Status: http://nadir.nilu.no/~olaeng/fastrt/VitD_quartMED.html. * VitD - Duration of Vitamin D Synthesis in Human Skin: http://nadir.nilu.no/~olaeng/fastrt/VitD.html. "

"In 1927 a controversy arose in the athletic world. The German Swimmers' Association had decided to use a sunlamp on their athletes to boost performance. Some felt this ultraviolet irradiation constituted "athletic unfairness." In other words, doping."

ncident invasive breast cancer, geographic location of residence, and reported average time spent outside. Millen AE, Pettinger M, Freudenheim JL, Langer RD, Rosenberg CA, Mossavar-Rahmani Y, Duffy CM, Lane DS, McTiernan A, Kuller LH, Lopez AM, Wactawski-Wende J. Cancer Epidemiol Biomarkers Prev. 2009 Feb;18(2):495-507. Epub 2009 Feb 3. PMID: 19190147 doi: 10.1158/1055-9965.EPI-08-0652 In conclusion, region of residence and geographic solar irradiance are not consistently related to risk of breast cancer and may not be sufficient proxy measures for sunlight/vitamin D exposure. The observed association between time spent outside and breast cancer risk support the hypothesis that vitamin D may protect against breast cancer.

Vitamin D production in human skin occurs only when UV radiation exceeds a threshold. From simulations of UV irradiances, the VitD www page ( http://zardoz.nilu.no/~olaeng/fastrt/VitD.html) computes the daily duration of dermal vitamin D production at midday when UV radiation exceeds the required threshold. The daily duration depends on latitude, time, total ozone, clouds, aerosols, surface reflectivity and altitude all of which can be specified by the user

Vitamin D production in human skin occurs only when UV radiation exceeds a threshold. From simulations of UV irradiances, the VitD-ez www page ( http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez.html) computes the daily duration of dermal vitamin D production at midday when UV radiation exceeds the required threshold. The VitD-ez www page is a simplified version of the more complex VitD web page ( http://zardoz.nilu.no/~olaeng/fastrt/VitD.html). The simplified VitD-ez www page is convenient for users unfamiliar to radiative transfer modelling, because the model input is limited and more intuitive.

Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness. Engelsen O, Brustad M, Aksnes L, Lund E. Photochem Photobiol. 2005 Nov-Dec;81(6):1287-90. PMID: 16354110 Vitamin D production in human skin occurs only when incident UV radiation exceeds a certain threshold. From simulations of UV irradiances worldwide and throughout the year, we have studied the dependency of the extent and duration of cutaneous vitamin D production in terms of latitude, time, total ozone, clouds, aerosols, surface reflectivity and altitude. For clear atmospheric conditions, no cutaneous vitamin D production occurs at 51 degrees latitude and higher during some periods of the year. At 70 degrees latitude, vitamin D synthesis can be absent for 5 months. Clouds, aerosols and thick ozone events reduce the duration of vitamin D synthesis considerably, and can suppress vitamin D synthesis completely even at the equator. A web page allowing the computation of the duration of cutaneous vitamin D production worldwide throughout the year, for various atmospheric and surface conditions, is available on the Internet at http://zardoz.nilu.no/~olaeng/fastrt/VitD.html and http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez.html. The computational methodology is outlined here.

In vivo threshold for cutaneous synthesis of vitamin D3. Matsuoka LY, Wortsman J, Haddad JG, Hollis BW. J Lab Clin Med. 1989 Sep;114(3):301-5. PMID: 2549141

Ecological Studies Of Ultraviolet B, Vitamin D And Cancer Since 2000. Grant WB, Mohr SB. Ann Epidemiol. 2009 Mar 6. [Epub ahead of print] PMID: 19269856

Duration of vitamin D synthesis from weather model data for use in prospective epidemiological studies. Edvardsen K, Engelsen O, Brustad M. Int J Biometeorol. 2009 Sep;53(5):451-9. Epub 2009 May 15. PMID: 19444487