Answer to Question #11222 Submitted to "Ask the Experts"

Category: Nuclear Medicine Patient Issues — Therapeutic Nuclear Medicine

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


A friend's husband had radioiodine treatment. I'm not sure of the dose. They didn't follow rules and he sat out on the couch (didn't stay in isolation much).

I don't think he's great at washing hands either. If his wife happened to touch surfaces in the house then got in my mom's car, would my mom's car have it in there? I have a newborn and my mom was at my home holding my baby and sitting on my furniture.

I am worried sick that she has brought radioactive contamination into my house. Does radioiodine cross-contaminate from surface to surface? If so, how do you ever rid your house of it? I want to know:

  1. If he urinated, didn't wash his hands, and touched their phone, then his wife touched the phone and got in my mom's car, is my mom's car now contaminated? Did my mom now bring it into my home?
  2. Does radioiodine travel from surface to surface? And if it does move from surface to surface, how do you ever get rid of it? I know it has an eight-day half-life, but if it goes from the phone to the remote controller for the TV, won't the eight days start again on the new surface? I'm worried sick over this, please help. 

Let me first say that you should not be worried about your house being contaminated with radioactivity that would cause any harm or risk to you or your family from the 131I treatment your friend's husband received.  

While small amounts of the radioiodine can be transferred from the patient to another surface, this does not necessarily present a risk to another person unless they were to ingest the radioactive material. In your situation, it is highly unlikely that the wife of the patient could pick up contamination from touching objects in her house and then transfer that contamination to your mom's car, and that your mom could then transfer it to your house.

With respect to your question on how does the radioactivity ever go away, all of the radioiodine (no matter where it is or how often it gets moved around) continuously decays at a rate such that half of it goes away every eight days. So the general rule of thumb is that after three months, all of the radioactivity is gone.

Please let me if you have any questions or need clarification. Thanks for using our service.

Michael Sheetz, MS, CHP, DABMP

Answer posted on 26 May 2015. 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.