Radiation effect

Today I’m going to talk about: Radiation effects

I’ve divided my presentation into one parts:

First I’d like to introduce radiation effects, and second I’ll deal
with the effects.

So, let’s start with introduce radiation effects

Radiation Effects,

effects observed when ionizing radiation strikes living tissue and
damages the molecules of cellular matter. Cellular function may be
temporarily or permanently impaired from the radiation, or the cell may be
destroyed. The severity of the injury depends on the type of radiation, the
absorbed dose, the rate at which the dose wwas absorbed, and the
radiosensitivity of the tissues involved. The effects are the same, whether
from a radiation source outside the body or from material within.

1) Biological,

The biological effects of a large dose of radiation delivered rapidly
differ greatly from those of the same dose delivered slowly. The effects of
rapid delivery are due to cell death, and they become apparent within
hours, days, or weeks. Protracted exposure is better tolerated because some
of the damage is repaired while the exposure continues, even if the total
dose is reelatively high. If the dose is sufficient to cause acute clinical
effects, however, repair is less likely and may be slow even if it does
occur. Exposure to doses of radiation too low to destroy cells can induce
cellular changes that may be de

etectable clinically only after some years.

2) ACUTE EFFECTS

High whole-body doses of radiation produce a characteristic pattern of
injury. Doses are measured in grays or rads, 1 gray being equal to the dose
absorbed when one kilogram of matter absorbs one joule of ionizing
radiation, and 100 rads being equal to 1 gray. Doses of more than 40 grays
severely damage the human vascular system, causing cerebral edema, which
leads to profound shock and neurological disturbances; death occurs within
48 hours. Whole-body doses of 10 to 40 grays cause less severe vascular
damage, but they lead to a loss of fluids and electrolytes into the
intercellular spaces and the gastrointestinal tract; death occurs within
ten days as a result of fluid and electrolyte imbalance, severe bone-marrow
damage, and terminal infection.

3) LATE EFFECTS

Nonmalignant delayed effects of ionizing radiation are manifested in
many orrgans—particularly bone marrow, kidneys, lungs, and the lens of the
eye—by degenerative changes and impaired function; these are largely
secondary to radiation-induced damage to blood vessels. The most important
late effect of radiation exposure, however, is an increased incidence of
leukemia and other cancers. Statistically significant increases in leukemia
and of cancers of the thyroid, the lung, and the female breast have been
demonstrated in populations exposed to relatively high doses (greater than
1 gray).

4) NONIONIZING RADIATION

The radio-frequency radiation, or electromagnetic fields (EMFs), from
sources such as power lines, radar, c
communications networks, cellular
phones, and microwave ovens is nonionizing, and for many years only high
doses of such radiation were known to be harmful, causing burns, cataracts,
temporary sterility, and other effects. In the 1980s and early 1990s,
however, with the proliferation of such devices, the possible effects of
long-term exposure to low levels of nonionizing radiation began to be a
matter of scientific concern and controversy. Subtle biological effects
were reported in some studies, while other studies failed to find these
effects

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