Answer to Question #10901 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
I heard about a case involving a worker in the oil fields who picked up a source. His hands then turned black. Could this happen within minutes or would it have been hours, days, or weeks? Are there industrial radiography sources that are strong enough to cause the skin to burn in a short period of time? I can't find any case like this on web searches.
Yes, a person's hand could "turn black" after a very large overexposure, but this would take several weeks to appear. Redness and/or blistering would first appear within days. The International Atomic Energy Agency (IAEA) has a picture of an exposed hand in its Sealed Radioactive Sources booklet. See picture 7 on page 7.
Industrial radiography sources, usually iridium-192 or cobalt-60, are strong enough to cause a skin burn (redness or blistering) and even death. See page 18, "Source Lost in Egypt," and page 19, "Source Lost in Chile," of the above referenced IAEA booklet.
Radiographer accidents have occurred primarily for two reasons. These are (1) when the radioactive source disconnects from its wire-line-drive mechanism or (2) when the radiographer fails to properly make radiation dose-rate measurements (surveys) when approaching the radioactive source. Even if a source disconnect occurs, properly performing a radiation survey would preclude overexposing people. Also, properly performing a radiation survey will assure that radiographers will not overexpose themselves.
Several engineering design improvements have been made in the past few years that have greatly reduced the possibility of a source disconnect. Also, regulations have changed to help assure that radiographers are not overexposed. These include (1) requiring two-person teams to perform radiography, (2) requiring two calibrated radiation survey meters be used during radiography, (3) requiring the radiographers to wear an alarming dosimeter when performing radiography, (4) requiring radiographers to be trained, tested, and licensed to become qualified radiographers, and (5) requiring higher security measures to prevent the loss or theft of radiography sources.
The best protection to assure that no one ever gets overexposed to radiation is to always properly perform radiation surveys.
John Hageman, CHP