Answer to Question #6432 Submitted to "Ask the Experts"

Q

For the purposes of chemical decontamination at the first-responder level, the use of cold water has been the standard since at least 1989 (when I started). The use of warm or hot water has been discouraged as it "opens the pores," increasing surface area and increasing exposure. Or, at least, that is what I have always been told. Nobody has ever been able to cite a report or study that indicates this is the case. It would seem to make more sense to use warm or hot water as most compounds are more soluble, oils are less viscous, and in the event of exposure the pores may already be opened as a stress or exertional response.

I suspect that if there were studies performed, they would go back to nuclear applications, as it would be far easier to determine retention of contaminants in this field than with ordinary contaminants such as oils, salts, etc. Are there any good studies, publications, reports, etc., that show that cold water is best for radiological decontamination, or is this simply something someone made up as a "common sense approach" with no basis in fact?

A

This is a good question. Like you, I have received guidance on this, but I have not seen anything in a peer-reviewed journal. Here's what I've heard:
Use of very warm or hot water can open the pores, giving surface contamination a chance to enter into the skin and making it more likely that it will be absorbed (or at least it will give a high radiation dose to the skin).

Use of very cool or cold water can cause the pores to shut completely, trapping any particles that have already entered them.

Use of excessive force can cause abrasion, giving contamination access to the bloodstream—or even scrubbing particles into the blood.

For these reasons, the "standard" guidance I have heard is to use cool to warm water and gentle soaps or detergents and to try not to abrade the skin.

NCRP Report 65 (Management of Persons Accidentally Contaminated with Radionuclides) has guidance on skin decontamination (pp. 113-118), but does not seem to address water temperature—although it does discuss a lot of decontamination techniques.

So—I'm not sure if this helps or not. If not, please let me know and I'll see what more I can find. Perhaps readers of this information can shed some light on this discussion.

P. Andrew Karam, PhD, CHP