Answer to Question #217043 in Atomic and Nuclear Physics for Maddy

Question

Explain why the risk of detriment to a person due to being exposed to a radioactive substance is impacted by the quantity of the sample, its half-life and means of exposure

(proximity vs contact on exterior of the body vs administered internally). 

Answer 1

"Radiation exposure" refers to the situation where the body is in the presence of radiation. 

There are two types of radiation exposure, "internal exposure" and "external exposure." 

External exposure means to receive radiation that comes from radioactive materials 

existing on the ground, suspended in the air, or attached to clothes or the surface of the 

body ("External Exposure and Skin"). 

Conversely, internal exposure is caused (i) when a person has a meal and takes 

in radioactive materials in the food or drink (ingestion); (ii) when a person breathes in 

radioactive materials in the air (inhalation); (iii) when radioactive materials are absorbed 

through the skin (percutaneous absorption); (iv) when radioactive materials enter the body 

from a wound (wound contamination); and (v) when radiopharmaceuticals containing 

radioactive materials are administered for the purpose of medical treatment. Once 

radioactive materials enter the body, the body will continue to be exposed to radiation until 

the radioactive materials are excreted in the urine or feces (biological half-life) or as the 

radioactivity weakens over time ( "Internal Exposure"). 

The difference between internal exposure and external exposure lies in whether the 

source that emits radiation is inside or outside the body. The body is equally exposed to 

radiation in both cases