Radium Dichloride Problem

[EAKS]

Hi all,

 

I'm a clinical medical physicist with limited chemistry knowledge and I'm hoping you guys can point me in the right direction with my problem.

 

A new treatment, radium dichloride (223 Ra), is being rolled out across my country but I'm unsure that the risks to staff have been properly managed. If you didn't already know, 223 Ra is an alpha emitting source and hence very dangerous if inhaling or ingesting.

 

My main concern is whether the radium / radium dichloride could evaporate or vapourise from the solution in the event of a spill. I've tried finding data for it's vapour pressure as I believe this to be a useful metric in answering the question. I've only found one value from a dubious looking source.

 

I'm hoping that radium dichloride acts like sodium chloride in that it stays behind in the solution while the water evaporates but I need to be able to prove that and I'm uncertain of how to proceed.

 

I'm sorry if this isn't clear, please feel free to ask questions to improve the clarity of the problem.

 

Best Wishes,

 

EAKS

[StringJunky]

This is the Bayer literature for the injectable version:

 

Medical Use of Radium-223 Chloride,Advisory Committee on the Medical Uses of Isotopes PDF Download

 

It melts at 900^oC.

Edited June 5, 2015 by StringJunky

[EAKS]

Thank you for your answer.

 

Your link doesn't work for me but I've googled the title and found the document you are refering to. Unfortunately, the information in it doesn't answer my question.

 

There seems to be a lack of information from Bayer on the possibility of inhalation and ingestion of radium dichloride. I imagine everything is fine but it worries me it isn't being addressed in the literature they have made available.

Edited June 5, 2015 by EAKS

[StringJunky]

From that PDF link:

 

In Summary, Standard Radiation Safety Practices are Adequate for Safe Handling of Radium-223 Chloride

 

Radium-223 chloride is a ready-to-use radiopharmaceutical solution for injection which can be used as an out-patient treatment

Compared to other radiopharmaceuticals, administered activity and associated dose rates are considerably lower

The presence of some photon (x and γ) emissions allows for measurement of the In Summary, Standard Radiation Safety Practices are Adequate for Safe Handling of Radium-223 Chloride product with standard instrumentation

The risk of radiation exposure is minimal when using established standard radiation safety practices and hygiene measures

Some drug specific information, e.g. dose preparation, will be provided to safely administer Ra-223 chloride

Over 1000 patients have been treated in clinical studies without any radiation safety incidents

[EAKS]

I'm sorry but 'In Summary, Standard Radiation Safety Practices are Adequate for Safe Handling of Radium-223 Chloride' doesn't answer my question.

 

I'll refine my question to make it clearer. l'm asking for a scientific explanation for 'can Radium Dichloride, that is dissolved into water, evaporate or vapourise into an environment of standard conditions (25 C, 1 atm etc)?'

 

I imagine the answer lies in vapour pressure etc. Thinking about it, I'm also concerned about a potential reaction taking place between the radium ions and whatever the spill has landed on. Similar to how salt water is more corrosive than fresh water.

Edited June 5, 2015 by EAKS

[StringJunky]

The intermolecular forces in RaCl₂ are ionic, which means that they are extremely stable at S.T..P. With a M.P. of 900^oC as well, the vapour pressure will be minute, if measurable at all, at room temp. I don't think it's mentioned because it's not, even faintly, an issue. It will just behave like sodium chloride solution if you dropped it on the floor; the water will evaporate, leaving the solid on the floor.

[John Cuthber]

Volatility isn't an issue.

Dust is.

[StringJunky]

Volatility isn't an issue.

Dust is.

True. An injectable unit exposes a patient to a maximum dose of 3.5 MBecq or 95 microCuries. Is that going to be a significant hazard dropped on the floor?

[John Cuthber]

Page 80 of this

https://www.orau.org/ptp/Library/NBS/NBS%2069.pdf

says that (way back in 1959 when standards were generally less stringent) the maximum permitted concentration of 223 Ra in air was about 10^-9 µCi per cc

I think that's 10^-6 µCi per litre so the 100 or so µCi you are talking about could render 100,000 cubic metres of air unbreathable- or it might stick to the floor and never get within striking distance of any human.

 

It's impossible to say which.

 

What you need to do is ensure that, if it gets spilled, there is a suitable clean-up procedure in place.

 

Looking on the bright side, radium chloride is likely to act like barium chloride which is hygroscopic.

It will absorb water from the air so it will tend to stay slightly damp (It's difficult to assign bulk properties like that when you are only talking about micrograms of material.) so it's less likely to forma a dust.