Radiation

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Absorbed Dose: rad (Roentgen absorbed dose) = absorption of 100 ergs of energy from any radiation in 1 gram of any material; 1 Gray (Gy) = 100 rads = 1 Joule/kg; Exposure to 1 Roentgen approximates 0.9 rad in air.

Biologically Equivalent Dose: Rem (Roentgen equivalent man) = dose in rads x QF, where QF = quality factor. 1 Sievert (Sv) = 100 rems.

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Half Life Calculation

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Ionizing Radiation at the Cellular Level

Causes breaks in one or both DNA strands or;

Causes Free Radical formation

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Exposure Limits

OSHA Limits: Whole body limit = 1.25 rem/qtr or 5 rem (50 mSv) per year.

Hands and feet limit = 18.75 rem/qtr.

Skin of whole body limit = 7.5 rem/qtr.

Total life accumulation = 5 x (N-18) rem where N = age. Can have 3 rem/qtr if total life accumulation not exceeded.

Note: New recommendations reduce the 5 rem to 2 rem.

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External/Internal Exposure Limits for Occupationally Exposed Individuals

Annual Dose Limits

*Effective dose equivalent

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Community Emergency Radiation

Hazardous Waste Sites:

Radiation above background (0.01-0.02 m rem/hr) signifies possible presence which must be monitored. Radiation above 2 m rem/hr indicates potential hazard. Evacuate site until controlled.

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Your Annual Exposure

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HEALTH EFFECTS

Generalizations: Biological effects are due to the ionization process that destroys the capacity for cell reproduction or division or causes cell mutation. A given total dose will cause more damage if received in a shorter time period. A fatal dose is (600 R)

Acute Somatic Effects: Relatively immediate effects to a person acutely exposed. Severity depends on dose. Death usually results from damage to bone marrow or intestinal wall. Acute radio-dermatitis is common in radiotherapy; chronic cases occur mostly in industry.

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ACUTE DOSE(RAD) EFFECT

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Delayed Somatic Effects: Delayed effects to exposed person include: Cancer, leukemia, cataracts, life shortening from organ failure, and abortion. Probability of an effect is proportional to dose (no threshold). Severity is independent of dose. Doubling dose for cancer is approximately 10-100 rems.