Recently there were some questions raised about the use of Hexafluorine 
for
decontaminating HF from skin.  The questions were based on studies 
published
from a Swedish group.  I asked Dr. Alan Hall, an expert on the 
physiology of
HF burns to comment.  Here is Dr. Hall's response.
 

Answer:

 

            Two recent publications by a Swedish group reporting studies 
in
rats question whether the active, amphoteric, hypertonic, specific
hydrofluoric acid (HF) eye/skin decontamination solution, 
Hexafluorine=AE
(Laboratoire Prevor, Valmondois, France) is appropriate for use in 
emergent
decontamination of such splashes (H=F6jer et al, 2002; Hult=E9n et al, 
2004).

 

            In both these studies, 50% HF was applied to the skin of 
rats
and left in place for 3 minutes.  Then after a 30-second waiting period
either nothing was done (control groups) or attempted
decontamination/treatment with water only, Hexafluorine only, or water +
2.5% calcium gluconate gel was carried out.  End points in the first 
study
were burn severity and in the second study were effects on some 
electrolyte
disturbances found in HF poisoning (hypocalcemia, hyperkalemia).  These
studies found that there was little difference between water and
Hexafluorine decontamination, while water + calcium gluconate produced
better results.

 

            It must be noted that at the time decontamination/treatment 
was
started, these animals all had well-developed HF burns, indicating that
tissue death had occurred at the time the interventions were begun.
However, the purpose of decontamination is, if possible, to prevent 
burns or
at least decrease their severity.  The first study has been critiqued in 
a
Letter to the Editor (Hall et al, 2003) with an accompanying reply by 
the
authors (H=F6jer et al, 2003).

 

            What critique can be made of these studies?  First, these 
are
not studies of decontamination, but rather of burn treatment.  Neither 
water
nor Hexafluorine are burn treatments; they are decontamination 
solutions.
Beginning decontamination at a time when tissue death has already 
occurred
biases the studies.  The manufacturer of Hexafluorine recommends it be 
used
as soon as possible after exposure, not 3.5 minutes later.  Exposure to 
50%
HF causes nearly immediate pain, and it would be unlikely that an 
exposed
worker would wait for 3.5 minutes to attempt decontamination with 
whatever
is at hand.  Secondly, both these studies did not include a Hexafluorine 
+
calcium gluconate group or a calcium gluconate alone group.  Without the
inclusion of these two groups, it might easily be questioned whether all
that was studied in these rats was the effect of calcium gluconate, a
well-proven treatment for HF burns.

 

            Based on preliminary experiments using immature domestic 
pigs
done by Laboratoire Prevor and Honeywell, the major North American and
European HF manufacturer, using 49% HF, there was already irreversible 
skin
tissue damage after only a 30-60 second exposure.  No decontamination
measure can be expected to be efficacious once tissue death has 
occurred.

 

            Studies carried out by the Hexafluorine manufacturer in a 
rabbit
model with 70% HF skin exposure showed that water decontamination 
resulted
in very severe burns with a very rapid onset, water + calcium gluconate
resulted in less severe burns with a more delayed onset, and 
Hexafluorine
decontamination resulted in no burns at all (Josset et al, 1992).

 

            The discrepancies between these studies raise the issue of 
the
problems associated with animal models.  What, therefore, is the 
published
occupational experience with Hexafluorine decontamination in HF exposed
humans?

 

            Five workers with exposure to 20% (or less) HF developed no
burns following Hexafluorine decontamination (Hall et al, 2000).  German
metallurgy workers (N = 11) exposed either to pickling acid (6% HF/15%
nitric acid or 40% HF) developed no burns and had no lost work time
following Hexafluorine decontamination (Mathieu et al, 2001).  Swedish
metallurgy workers (n = 16) exposed to pickling acid or higher
concentrations up to 70% (n = 2) developed no burns and no systemic
toxicity; lost work time was minimal due to worker observation in 
hospital
rather than burns (Soderberg et al, 2004).  It is of note that this 
company
decided to switch from using water decontamination to Hexafluorine 
because
of very severe burns and systemic poisoning in a worker splashed with 
70%
HF, decontaminated with water, and initially treated with topical 
calcium
gluconate (Soderberg et al, 2004).

 

            So what can we conclude from this very brief review?  First, 
we
are called upon to decontaminate (and then treat if necessary) humans, 
not
rats, pigs, or rabbits.  The animal evidence is conflicting, reflecting
different study designs and differences in the skin between these 
species
and humans.  Second, while human data are limited, in part thanks to
effective safety measures that prevent HF eye/skin exposures, what data 
are
available show that Hexafluorine is quite effective at preventing HF 
burns
in humans when used as a decontamination solution as quickly as possible
following the exposure (as recommended by the manufacture).  

 

Third, whatever decontamination solution is used, certainly any patient 
who
develops pain, erythema, edema, frank burns, or any signs of HF systemic
toxicity should be treated by a qualified physician with either iced
benzalkonium chloride (Zephiran=AE) soaks (as recommended by some HF
manufacturers and occupational physicians) or calcium gluconate, either
topically, by subcutaneous injection, by intravenous Bier block,
intra-arterially, or intravenously, depending on the injured area and
severity of the burn or systemic toxicity, as clinically indicated.

 

Alan H. Hall, M.D.*

ACS/DCHAS Member

President and Chief Medical Toxicologist

Toxicology Consulting and Medical Translating Services, Inc.

Elk Mountain, WY

and

Clinical Assistant Professor of Preventive Medicine and Biometrics

University of Colorado Health Sciences Center

Denver, CO

 

* Dr. Hall is a consultant to Laboratoire Prevor, Valmondois, France.

 

REFERENCES

             

1.                  Hall AH, Blomet J, Gross M, Nehles J:  Hexafluorine 
for
emergent decontamination of hydrofluoric acid eye/skin splashes.
Semiconductor Safety Association Journal 2000; 14:30-33.

2.                  Hall AH, Blomet J, Mathieu L:  Topical treatments 
for
hydrofluoric acid burns:  A blind controlled experimental study 
[Letter]:  J
Toxicol - Clin Toxicol 2003; 41:1031-1032.

3.                  H=F6jer J, Personne M, Hult=E9n P, Ludwigs U:  
Topical
treatments for hydrofluoric acid burns:  A blind controlled experimental
study [Letter]:  J Toxicol - Clin Toxicol 2003; 41:1033-1034.

4.                  Hult=E9n P, H=F6jer J, Ludwigs U, Janson A:  
Hexafluorine
vs. standard decontamination to reduce systemic toxicity after dermal
exposure to hydrofluoric acid.  J Toxicol - Clin Toxicol 2004; 
42:353-361.

5.                  Josset P, Blomet J, Lym SK, Jahan D, Meyer MC:
Theoretical and experimental evaluation of decontamination measures for
burns with hydrofluoric acid.  Proprietary data of Laboratoire Prevor,
Valmondois, France:  Laboratoire Prevor, 1992.

6.                  Mathieu L, Nehles J, Blomet J, Hall AH:  Efficacy of
Hexafluorine for emergent decontamination of hydrofluoric acid skin and 
eye
splashes.  Vet Human Toxicol 2001; 43:263-265.

7.                  Soderberg K, Kuusinen P, Mathieu L, Hall AH:  An
improved method for emergent decontamination of ocular and dermal
hydrofluoric acid splashes.  Vet Human Toxicol 2004; 46:216-218. 

 

       I have reviewed the performance of Hexafluorine when used 
promptly on
moderate acid strength burns and it is exceedingly effective.  
Similarly,
the product Diphoterine is exceedingly effective on deconning moderate
strength corrosives (other than HF).

 

You can review the Skin/Eye decon symposium presentations from the SF 
ACS
meeting at

http://membership.acs.org/c/chas/sfpresents.htm

 

Prevention is best; then decon is NOT needed.

 

Neal Langerman, Ph.D.

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NEAL LANGERMAN
ADVANCED CHEMICAL SAFETY, Inc.
7563 CONVOY Ct
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