Effects of Nuclear Radiation Exposure
Ionizing radiation and disrupted chemical bonds
A radiation source can be external such as an x-ray machine or nuclear reactor leakage, or internal such as via an injected radioisotope. How radiation impacts living tissue is a complicated matter being affected by several variables including radiation shielding, tissue type, proximity, and length of exposure. So while the effects themselves are difficult to dissect, isolate, and predict, we can make some broad and reliable observations of how the human body can be affected.
Let's first look at the problem on a molecular level, which is where most important health related effects occur. All functions within living tissues are molecular processes. Cellular compositions and structures are best understood on a molecular level. Indeed it is the interaction of cells at the chemical (molecular) level which is the key to proper human body function, to life itself.
However, the molecular structure within cells are vulnerable to changes. When this occurs we call this mutation, when one or many alterations in the inherited nucleic acid sequence (DNA and RNA) are damaged or altered in an unpredictable way.
Effects of high level ionizing radiation on living cells
When dosages are large, and intense cell damage can be swift and quite harmful, manifesting in the worst case cell death. The cell may stop functioning entirely (requires 100 gray or 10,000 rads) or become unable to divide and reproduce (mitotic shutdown) which requires a dose of 2 gray or 200 rads). When cell reproduction ceases or is interrupted, those parts of the body which require active cellular reproductive activity such a bone marrow, will case function and over time bring death.
• Very high dose (100 gray or 10,000 rad): An exposure to the entire body will bring death within forty-eight hours.
• Mean lethal dose (2 gray or 200 rad): Causes reproductive death of cells.
• Low doses (2.5 - 5 gray or 250 rad to 500 rad): A whole-body dose will bring death in few weeks.
• Lower and/or more localized doses (100 rads – 199rads): Specific symptoms will arise due to the loss of cells. Burns caused by beta radiations, for example.
• Very low doses (30-50 Rads): The apparently safe levels though some sicknesses like nausea may occur, which most probably, has psychosomatic origins. However, children and pregnant mothers are always vulnerable.
Mutation rates are proportional to dosage. For that reason no amount of radiation can be considered entirely safe, all ionizing radiation carries with it some risk.
Chronic radiation sickness
The most sever effect of radiation exposure is radiation sickness usually caused by chronic exposure to radiation particles with a long half-life such as Cesium (Cs-137). This particle is a common waste contaminant produced by nuclear reactors and can contaminate water, food, and the environment for decades.
The dose and duration of a radiation determines the intensity of radiation sickness. Symptoms may consist of appetite loss, low grade fever, weakness, fatigue, inflammation, dehydration and fainting. The more intense effects can be anemia, hair loss, bruises and burns.
When dosage is lower, the effects may not be apparent for many years, but can be no less serious. Cancer is the most common effect of radiation exposure, with birth defects being another. Both high level and low level exposure can be devastating to human health.