Answer to Question #4263 Submitted to "Ask the Experts"

Category: Industrial Radiation — Industrial Applications

The following question was answered by an expert in the appropriate field:


What industrial uses are made of the radioisotope americium-241? Are there any concerns regarding its chemical properties?


Americium-241 (241Am) is used in many detectors to measure (1) smoke in homes, (2) toxic lead in old wall paint, (3) the thickness of foil and paper while in production, and (4) water moisture or hydrocarbons (oil) in soil. The first three industrial sources use the alpha particles or low energy x rays emitted from a sealed Special Form source of 241Am; while the water/oil gauges mix 241Am with beryllium in a sealed source to produce neutrons.

The chemical properties of the 241Am are of concern if the sealed source leaks and is ingested. 241Am behaves chemically like calcium and will go to the bones, thus causing the major portion of a person's radiation dose (exposure). The physical properties (specifically particle size) are of concern if the sealed source leaks and 241Am prticles are released into the air. The particle size helps to determine how much 241Am might be inhaled and where it might be deposited in the lungs, both affecting the persons ultimate radiation dose.

241Am has a 437.2 year half-life and its radiological effects far outweigh its chemical toxicity.

You should also look at the Centers for Disease Control and Prevention's website and search "americium" for more information.

John P. Hageman, MS, CHP

Answer posted on 2 February 2005. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.