MANAGEMENT OF NORM IN THE PETROLEUM INDUSTRY Akpojevwa Tega Naomi, october 2016 | Page 34

Here, the absorbed energy alone is insufficient to determine the risk and this
must take into consideration how much biological damage is expected from the
absorbed dose. Different types of radiation have different damaging properties
and different tissues have variable susceptibility to damage. Taking these
factors into consideration provides us with the effective dose.
The present model of radiological protection is mainly based on the following
evidence and assumptions:
• Exposure to ionizing radiation, even at low doses, can cause damage to
the nuclear (genetic) material in cells that can result in the development
of radiation induced cancer many years later (somatic effects), heritable
disease in future generations and some developmental effects under
certain conditions.
• Induction of cancer by low-linear energy transfer radiation has been
firmly demonstrated in the dose range of about 100 mGy and higher, and
it was concluded by UNSCEAR that “studies on DNA repair and the
cellular or molecular processes of radiation tumorigenesis provide no
good reason to assume that there will be a low-dose threshold for the
induction of tumours in general.
• Radiation-induced heritable disease has not been demonstrated in
human populations but there is substantial evidence from animal studies
of heritable damage to germ cells (ova and spermatozoa as well as their
precursor cells)
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