186
12 Health Hazards and Protection
while working in the area where these sources are kept. We must monitor regularly the
amount of radiations received by the body so that we do not exceed the permissible
level of dose.
In conclusion, it can be said that, in spite of having high penetrating power, X - or
γ -rays can still do some damage to the human body. Among the particulate radiations,
high energy β-particles can do localized damage to the human body. Therefore, we
shall have to prescribe a minimum permissible amount of electromagnetic radiation,
which can be tolerated by the human body.
12.4 Internal Absorption
Internal damage to the human body is caused by the radiation emitted from radioactive material taken into the body by inhalation, ingestion, absorption through the skin
or through an open wound etc. γ -emitting isotopes if taken within the body, produces
relatively less damage to the cell, because most of the radiation comes out of the body
(due to its high penetrating power), without causing any appreciable damage to the
tissue present inside the body. On the other hand, α-particles or β-particles, having
less penetrating power can do large amount of damage to the cell present inside the
human body. α-particles, in fact, the most hazardous, because they produce a high
degree of localized damage. Hence, as a rule, maximum precautions should be taken
to avoid ingestion of any type of radioactive materials inside the human body. However, the physiology of the human body is such that, most materials (either radioactive
or non-radioactive) taken by the human body, are also discarded or excreted out of
the body by the ongoing biological process. The body retains some materials for a
longer duration and some for a short duration. This is measured by the biological
half-life, which is the time needed by the biological process to eliminate the material to its half concentration. This biological process, thus, helps us to eliminate
the radioactive isotopes from the body.
Nevertheless, we have to be careful working with radioactive material emitting
especially weak β-particles or α-particles and its chemical nature. There are certain
radioactive isotopes which are concentrated in a particular part of the body and cause
a localized damage. For example,
90 Sr and
89 Sr being chemically similar to calcium,
are carried along with calcium into the body and deposited in the bone. Because
calcium is used for the bone formation, and thus
90 Sr and
89 Sr are retained within
the body for a very long period in the bone. Since bone marrows are responsible for
the production of red/white blood corpuscles, any radioactive material following the
path of bone fixation process will create extensive damage to the activity of bone
marrow cells.
There are also radioactive isotopes which are diluted throughout the body and
cause a genetic hazard (a hazard caused to the human cell such that its effect is
carried over to the next generation). For example,
137 Cs, which follows the chem-
12 Health Hazards and Protection
while working in the area where these sources are kept. We must monitor regularly the
amount of radiations received by the body so that we do not exceed the permissible
level of dose.
In conclusion, it can be said that, in spite of having high penetrating power, X - or
γ -rays can still do some damage to the human body. Among the particulate radiations,
high energy β-particles can do localized damage to the human body. Therefore, we
shall have to prescribe a minimum permissible amount of electromagnetic radiation,
which can be tolerated by the human body.
12.4 Internal Absorption
Internal damage to the human body is caused by the radiation emitted from radioactive material taken into the body by inhalation, ingestion, absorption through the skin
or through an open wound etc. γ -emitting isotopes if taken within the body, produces
relatively less damage to the cell, because most of the radiation comes out of the body
(due to its high penetrating power), without causing any appreciable damage to the
tissue present inside the body. On the other hand, α-particles or β-particles, having
less penetrating power can do large amount of damage to the cell present inside the
human body. α-particles, in fact, the most hazardous, because they produce a high
degree of localized damage. Hence, as a rule, maximum precautions should be taken
to avoid ingestion of any type of radioactive materials inside the human body. However, the physiology of the human body is such that, most materials (either radioactive
or non-radioactive) taken by the human body, are also discarded or excreted out of
the body by the ongoing biological process. The body retains some materials for a
longer duration and some for a short duration. This is measured by the biological
half-life, which is the time needed by the biological process to eliminate the material to its half concentration. This biological process, thus, helps us to eliminate
the radioactive isotopes from the body.
Nevertheless, we have to be careful working with radioactive material emitting
especially weak β-particles or α-particles and its chemical nature. There are certain
radioactive isotopes which are concentrated in a particular part of the body and cause
a localized damage. For example,
90 Sr and
89 Sr being chemically similar to calcium,
are carried along with calcium into the body and deposited in the bone. Because
calcium is used for the bone formation, and thus
90 Sr and
89 Sr are retained within
the body for a very long period in the bone. Since bone marrows are responsible for
the production of red/white blood corpuscles, any radioactive material following the
path of bone fixation process will create extensive damage to the activity of bone
marrow cells.
There are also radioactive isotopes which are diluted throughout the body and
cause a genetic hazard (a hazard caused to the human cell such that its effect is
carried over to the next generation). For example,
137 Cs, which follows the chem-