MANAGEMENT OF NORM IN THE PETROLEUM INDUSTRY Akpojevwa Tega Naomi, october 2016 | Page 33

In the present framework of radiation protection, effects originated by exposure
of humans to radiation are grouped in:
• Deterministic effects (harmful tissue reactions) due in large part to the killing
or malfunction of cells and in some instances large quantities resulting in organ
damage following high doses
• Stochastic effects, i.e. cancer and heritable effects involving either cancer
development in exposed individuals owing to mutation of somatic cells or
heritable disease in their offspring owing to mutation of reproductive (germ)
cells. This is usually associated with long-term, low-level exposure.
Deterministic effects occur at doses exceeding 0.5 – 1 Gy. These thresholds
vary with dose rate and with radiation quality. The severity of the effect
increases with increasing dose and dose rate. Deterministic effects are mainly
associated with incident scenarios in nuclear industry, industrial and medical
use of high activity sources and X-ray generators and particle accelerators.
Even in worst case scenarios involving NORM in the oil industry, deterministic
effects are never encountered. This is due to the relatively low abundances
actually experienced and the tendency for many NORM to self-absorb, whereby
the bulk mineral matrix and other surrounding material absorb the energy from
underlying decays.
Radiation protection in the field of NORM concerns exclusively an adequate
control of exposure to low doses, a situation where only stochastic effects may
occur.
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