http://www.ck12.org Chapter 24. Nuclear Chemistry
Effects of Radiation
Radiation can seriously harm living organisms, including humans. In order to better understand how nuclear
radiation causes damage on the cellular level, we should first understand the basics of how the cell works. DNA
in the nucleus is responsible for protein synthesis and for the regulation of many cellular functions. In the process
of protein synthesis, DNA partially unfolds to produce messenger RNA (mRNA). The mRNA leaves the nucleus
and interacts with ribosomes, transfer RNA, amino acids, and other cellular constituents in the cytoplasm. Through
a complex series of reactions, proteins are produced to carry out a number of specialized processes within the
organism. Anything that disturbs this flow of reactions can damage to the cell.
FIGURE 24.13
The most harmful situation is when nuclear radiation does something to alter the structure of the DNA. If this
prevents the production of a crucial protein, the cell will malfunction or die. In an even worse scenario, some
changes to DNA will cause the cell to become cancerous. In acancer cell, the control processes that regulate cell
growth and division are not working properly. As a result, they grow and divide rapidly, often interfering with the
functioning of nearby healthy cells. For example, over time internal radon exposure can lead to the development of
lung cancer. This is especially problematic for smokers, who already have exposed their lungs to significant amounts
of carcinogens. Tissue damage is also common in people with severe exposure to radiation.
Radioisotopes in Medical Diagnosis and Treatment
Radioisotopes are widely used to diagnose, and sometimes treat, various diseases. For diagnosis, the isotope is
administered to the patient and then located in the body using a scanner of some sort. The source of the decay
product (often gamma emission) can be located by the scanner, and a map of where the isotope was transported in
the body can be generated. This information is often very valuable for diagnosing certain medical problems.
For example, a radioactive isotope of iodine (I-131) is used in both the diagnosis and treatment of thyroid cancer.
The thyroid will normally absorb some iodine to produce iodine-containing thyroid hormones. An overactive thyroid
gland will absorb a larger amount of the radioactive material. If this is the case, more and more radioactive iodine can
be administered, where it will cluster in the diseased portion of the thyroid tissue and kill some of the nearby cells.
Cancer treatments often cause patients to feel very sick, because while the radiation treatment kills the unwanted
cancer cells, it causes damage to some healthy cells in the process.
Technetium-99m is perhaps the most widely used radioisotope in diagnosis and treatment (the “m” stands for