In conclusion, adequate levels of vitamin D are essential,
particularly for the elderly. In the light of (a) the fluctuation
of UV radiation due to time of day and season, (b)
a decrease in the capacity for vitamin D, particularly for
the elderly, and above all (c) the proven carcinogenetic
and other harmful characteristics of UV radiation, there
is no such thing as so-called ‘safe sun exposure’, and sun
exposure should not be prolonged in order to increase
vitamin D levels.