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Description / Abstract:
Introduction
Background
Popular attitudes towards sun light exposure have been
ambivalent. Ancient men worshipped the sun as the source of life
(Randle 1997). In the beginning of the 20th century
Finsen was rewarded with a Nobel prize for his work on (sun)light
(Randle 1997). Lack of sunshine was found to be a factor in the
occurrence of rickets. In the second half of the 20th
century a sun tan became a sign of good health but the attention of
the medical and public health community focussed on the negative
side of sun exposure, more specifically on skin cancer and on
keratitis and cataract (Albert and Ostheimer 2002, 2003a,b).
For both the positive and negative (physical) effects of solar
exposure the ultraviolet (UV) component of sunlight is commonly
seen as the causal factor (Gezondheidsraad: Commissie UV-straling
1986, Advisory Group on Non-ionising Radiation 2002). Although the
positive effects of UV exposure were acknowledged, especially with
respect to vitamin D synthesis in the skin and the prevention of
bone disease, public health guidance stressed the carcinogenic
effects of excessive UV exposure and advised avoiding exposing bare
skin to sunlight (WHO 1994, 2002). In recent decades data have
become available that might lead to a reconsideration of the
emphasis on the harmful effects of UV exposure in general and solar
exposure in particular (Lucas et al. 2006b, Grant 2007, Lucas
2007). Technical Committee 6-58 of the CIE has further studied this
issue.
Terms of Reference
The terms of reference of Technical Committee (TC) 6-58
(hereafter denoted as ‘the committee') that compiled the present
report were specified by the International Commission on
Illumination (CIE) as
The fact that man cannot do entirely without UV is accepted by
most scientists active in this field, but is not as well known as
the widely accepted view that UV exposure should be limited to a
sensible level thus avoiding or minimizing risks. The TC will
formulate recommendations for a lower limit of UV exposure
commensurate with good health.
The committee soon realized that defining a minimum exposure
limit of a similar status as UV exposure limits for protection of
workers and the general public (International Non-Ionizing
Radiation Committee of the International Radiation Protection
Association 1989, 1996, International Commission on Non-Ionizing
Radiation Protection 2004) would probably not be feasible. As will
be further detailed below this is due to the dependence of the
(beneficial) effects of UV exposure on constitution, nutrition,
behaviour and location. The committee therefore focussed on
compiling input for scientifically underpinned public health
guidance for solar exposure.
This report considers only exposure to solar UV radiation, the
single UV source to which we are naturally exposed. The radiation
from artificial sources varies greatly between sources, but is
always different to the spectrum of sunlight. Thus the effects, and
balance of positive and negative effects, will be different for
artificial sources than they are for solar radiation.
Report
The present report was developed in three meetings of the
committee in 2005, 2006 and 2007. Furthermore the committee members
prepared reviews of the literature that are reproduced in the
second part of this report (the reviews cover the literature until
2006-2007). The guidance in Part I is based on an assessment by the
committee of the scientific evidence for the various effects of
solar (UV) exposure. In Annex A to Part I recommendations of
otherorganizations are presented. Annex B to Part I
reproduces recommendations from a working group of the
International Agency for Research on Cancer (IARC).