world cancer report - iarc

Fig. 2.37 Deliberate exposure to solar radiation in
order to achieve a sun-tan.
Internalized radionuclides that emit α-particles
and β-particles are carcinogenic to
humans. For most people, exposure to
ionizing radiation from inhaled and tissuedeposited
radionuclides is mainly from
naturally-occurring radon-222. Exposure
to thorium-232, which occurs in soil, is
less common. Cancers associated with
exposure to particular nuclides, usually
in an occupational context, include lung
cancer, bone sarcomas, liver cancer,
leukaemia and thyroid cancer.
The United Nations Scientific Committee
on the Effects of Atomic Radiation [5] has
estimated the lifetime risk of solid cancers
and of leukaemia following an acute
Static direct current (DC) fields
0
Frequency (Hz)
Wavelength (m)
Extremely low
frequencies (ELF)
Superconducting
DC magnets (MRI)
Photon energy (eV)
3x102
Electromagnetic fields and radiation
Fig. 2.38 The spectrum of electromagnetic fields and their use in daily life.
10 6
Mains power
transmission,
distribution
1.2x10 -12
VDUs
and
TVs
whole-body exposure to γ radiation,
together with the corresponding estimated
numbers of years of life lost per radiation-induced
case (Table 2.17). The current
recommendations of the
International Commission for Radiological
Protection are to limit exposures to the
general public to 1 mSv per year, and
doses to workers to 100 mSv over 5
years [6] (1 Sievert equals 1 joule per
kilogram).
Ultraviolet radiation
The major source of human exposure to
ultraviolet radiation is sunlight.
Approximately 5% of the total solar radiation
received at the surface of the
earth is ultraviolet [7]. Intensity of solar
terrestrial radiation varies according to
geography, the time of day and other
factors. The level of skin exposure to
sunlight depends on many parameters
including cultural and social behaviour,
clothing, the position of the sun and the
position of the body. Few measurements
of personal exposure have been
reported. Artificial sources of ultraviolet
radiation are common and such
devices are used to treat a number of
diseases (e.g. psoriasis) as well as for
cosmetic purposes.
3x10 5
10 3
Radiofrequencies
(VLF-VHF)
1.2x10 -9
Broadcast
AM FM TV
3x108
10 0
Microwaves
(UHF-EHF)
Mobile phones
1.2x10 -6
3x10 11
10 -3
1.2x10 -3
Optical radiation
Infrared
Cancer causation
Solar radiation, and specifically the ultraviolet
component of it, causes cutaneous
malignant melanoma and non-melanocytic
skin cancer (Fig. 2.39). Exposure of skin
to ultraviolet radiation causes DNA damage
(Carcinogen activation and DNA
repair, p89) and also the conversion of
trans-urocanic acid to cis-urocanic acid,
which leads to cell injury and ultimately to
cancer. Incidence of skin cancer is
increasing rapidly among fair-skinned
populations [7] (Melanoma, p253). In
Canada, for example, occurrence of this
disease has doubled over the past 25
years. IARC has estimated that at least
80% of all melanomas are caused by exposure
to sunlight. Non-melanocytic skin
cancer, which includes basal cell carcinoma
and squamous cell carcinoma, is the
most prevalent human malignancy: more
people are living with this cancer than any
other. In the USA and Australia, one of
every two new cancers diagnosed is a
non-melanocytic skin cancer. Use of sunlamps
and sunbeds probably causes skin
melanomas in humans.
Electromagnetic fields
Recent years have seen an unprecedented
increase in the number and diversity of
CO 2 laser
3x10 14
10 -6 10 -9 10 -12
1.2x10 0
Ultraviolet
Visible
3x10 17
Ionizing radiation
X-and gamma radiation
1.2x10 3
Diagnostic X-rays
3x10 20
1.2x10 6
Radiation 53