Page 138 - Environmental Control in Petroleum Engineering

The Impact of Drilling and Production Operations 125

Natural and man-made sources of nuclear radiation provide an
average exposure of about 750 mREM/year per person. The natural
background exposure of nuclear radiation varies widely but averages
about 500 mREM/year. This exposure comes from cosmic rays, natur-
ally occurring radioactive elements in the ground, the air (radon and
carbon-14), and from naturally-occurring elements in our bodies and
the foods we eat. Exposure from man-made radiation sources averages
about 250 mREM/year. Man-made sources include medical and dental
X-rays, smoking, color television, and luminous wristwatches. Nuclear
power plants contribute less than 1 mREM/year. Actual exposure levels
for any particular individual vary significantly.
The risks from nuclear radiation can also be placed in perspective
by comparing the estimated loss of life expectancy to that from other
health risks. As seen in Table 3-24, there is a finite risk, but it is small
compared to many other risks.
The International Commission on Radiological Protection has set
recommended exposure limits for radiation. The maximum recom-
mended cumulative exposure to radiation is 5 REM per year. This level

Table 3-24
Estimated Loss of Life Expectancy from Health Risks

Loss of Life
Health Risk Expectancy (days)

Smoking 20 cigarettes/day 2,370 (6.5 years)
Overweight by 20% 985 (2.7 years)
All accidents combined 435 (1.2 years)
Auto accidents 200
Alcohol consumption 130
Home accidents 95
Drowning 41
Safest jobs (teaching) 30
Natural background radiation 8
Medical x-rays (U.S. average) 6
Natural catastrophes 3.5
1 rem occupational radiation dose 1
1 rem/year for 30 years 30
5 rem/year for 30 years 150
Source: Von Flatern, 1993.
Copyright Petroleum Engineer International, with permission.