WNS nylon decontamination discussion

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Re: WNS nylon decontamination discussion

Postby NZcaver » Mar 30, 2009 4:40 pm

cavedoc wrote:Run it back a few times and you see that the number goes back down before its catastrophic break.

Yeah I noticed that the first time, but I figured I'd use the approximate peak load just to make things simpler.

I agree it's close to expected performance. I'd like to see a repeat on a piece that had sat around in his garage for a month after its bleach exposure. But it's a great start.

Agreed.
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Re: WNS nylon decontamination discussion

Postby Tiggertim » Apr 2, 2009 8:06 pm

I'm really concerned that the caving community is being asked to use decontamination procedures that could be fatally dangerous. Studies by the UIAA have shown that exposure to bleach is the most common cause (after mechanical damage) of rope failure. Do not expose any of your safety critical gear like ropes, harnesses, safety cords etc to bleach. You'll find that this conclusion is supported by all the major gear manufacturers and is published on some of their websites (e.g. Petzl, Blue water etc). I'm going to start asking people I cave with 2 questions: firstly have they have cleaned their caving gear and secondly have they used bleach on any of the ropes etc. If the answer to the second question is yes then I won't be using that rope!
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Re: WNS nylon decontamination discussion

Postby ek » Apr 2, 2009 10:24 pm

Can you provide a specific citation to support the claim that bleach exposure is the most common chemical cause of rope failure? I find this hard to believe--the common belief among rope users is that ALL sport rope failures have either been caused to the rope being cut over a sharp edge, or by prior exposure of the rope to sulfuric acid.

However, ropes are probably not often intentionally exposed to bleach. Even if no ropes have failed due to bleach exposure, that doesn't mean that they won't soon, if people are decontaminating with bleach.
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Re: WNS nylon decontamination discussion

Postby ron_miller » Apr 2, 2009 11:18 pm

Tiggertim wrote:I'm really concerned that the caving community is being asked to use decontamination procedures that could be fatally dangerous . . .


While I'm not saying that everyone should go out and repeatedly bleach their ropes and gear, note that the CMC Rescue publication referenced in the first post on this thread indicated that their testing on nylon kernmantle rescue (static) rope found a 2% strength loss when rope was immersed for 10 minutes in a 10% bleach solution (that's 1 part household bleach to 9 parts water), then rinsed for 10 minutes with water, and tested 14 days later. Undiluted bleach was of course more problematic, with a 14% strength loss when they used straight bleach in the above protocol.

As various posters have noted, additional testing is needed to know whether that strength loss might increase over time, and whether that 2% strength loss happens every time a rope is disinfected.

Given those findings, I would definitely be very interested in seeing the UIAA report that you referred to.

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Re: WNS nylon decontamination discussion

Postby Carl Amundson » Apr 3, 2009 10:03 am

Is there any more information out there on the use of hot water as a decon procedure?
I have heard that hot water may be as effective (or better because is will not damage the nylon) as bleach.
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Re: WNS nylon decontamination discussion

Postby ron_miller » Apr 3, 2009 11:25 am

junkman wrote:Is there any more information out there on the use of hot water as a decon procedure?
I have heard that hot water may be as effective (or better because is will not damage the nylon) as bleach.


There was a news article published a couple of days ago that indicated the fungus is killed at temperatures of 100 degrees F or higher. Unfortunately, the article did not indicate how long this temperature must be maintained, nor did it state whether this kills all forms of the fungus, including the spores.
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Re: WNS nylon decontamination discussion

Postby Carl Amundson » Apr 3, 2009 11:35 am

ron_miller wrote:
junkman wrote:Is there any more information out there on the use of hot water as a decon procedure?
I have heard that hot water may be as effective (or better because is will not damage the nylon) as bleach.


There was a news article published a couple of days ago that indicated the fungus is killed at temperatures of 100 degrees F or higher. Unfortunately, the article did not indicate how long this temperature must be maintained, nor did it state whether this kills all forms of the fungus, including the spores.

Thanks for the link to the article.
If I'm reading this correctly, a blacklight will kill the fungus:

"So far, Stone said he has learned the fungus:
Dies in temperatures near 100 degrees Fahrenheit.
Can survive indirect sunlight but dies when exposed to direct ultraviolet light.
Can be killed with some disinfectant products, such as Lysol.
"
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Re: WNS nylon decontamination discussion

Postby ek » Apr 3, 2009 1:55 pm

Please note that the claim that incident UV kills the fungus appears to be falsified by actual laboratory testing with the fungus:
Finally, the NWHC lab has also done some examining of the decontamination protocols,
and has determined that the product Pure Green 24 is ineffective on this fungus, that UV
light in a laboratory is unsatisfactory, and that 10% bleach works fine. Of course, this is
bad news for rope, so alternatives are being explored. Dr. Hazel Barton stepped forward
to assist in the analysis of ropes and other caving textiles, which has been welcomed by
Dr. Blehert. Samples from various manufacturers have been sent to Dr. Barton, and we
are working to provide funding for that effort.
(p.4, March 2009 Research Status Report}

I would suggest that any decontamination modality unsuccessful in laboratory conditions is extremely unlikely to be successful when applied to caving gear, and that any decontamination modality successful in laboratory conditions still might not be successful when applied to caving gear. This is one reason why Hazel Barton's study on the effectiveness of various decontamination procedures on actual caving gear is so important.
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Re: WNS nylon decontamination discussion

Postby Carl Amundson » Apr 3, 2009 2:06 pm

ek wrote:Please note that the claim that incident UV kills the fungus appears to be falsified by actual laboratory testing with the fungus:
Finally, the NWHC lab has also done some examining of the decontamination protocols,
and has determined that the product Pure Green 24 is ineffective on this fungus, that UV
light in a laboratory is unsatisfactory, and that 10% bleach works fine. Of course, this is
bad news for rope, so alternatives are being explored. Dr. Hazel Barton stepped forward
to assist in the analysis of ropes and other caving textiles, which has been welcomed by
Dr. Blehert. Samples from various manufacturers have been sent to Dr. Barton, and we
are working to provide funding for that effort.
(p.4, March 2009 Research Status Report}

I would suggest that any decontamination modality unsuccessful in laboratory conditions is extremely unlikely to be successful when applied to caving gear, and that any decontamination modality successful in laboratory conditions still might not be successful when applied to caving gear. This is one reason why Hazel Barton's study on the effectiveness of various decontamination procedures on actual caving gear is so important.


I find it interesting that nothing is mentioned in this report about hot water killing the fungus.
Ward Stone (Wildlife Pathologist ) says that the fungus dies in temperatures near 100 degrees Fahrenheit.
It just shows how fluid this information is.

Hot water is much preferable to bleach for the decon of vertical gear and rope IMHO.
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Re: WNS nylon decontamination discussion

Postby ek » Apr 3, 2009 2:27 pm

The melting and softening point of nylon 6 and nylon 6,6 (those are the two chemically different types of nylon)--as well as polyester--are both higher than 100 C. Liquid water heated over 100 C (e.g. in an autoclave) might harm nylon, but normal hot water won't. Of course, it will cause accelerated shrinkage of nylon (but not polyester, which does not chemically absorb water to a significant amount). It may also remove internal lubricants.

Unfortunately, it may not kill spores of the fungus, even if the fungus cannot otherwise survive high temperatures. In addition, the standard exposure interval of 10 minutes could potentially not be long enough, too.
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Re: WNS nylon decontamination discussion

Postby Carl Amundson » Apr 3, 2009 2:38 pm

The article said 100 degree Fahrenheit (37.8 degree Celsius).
This is a much lower temperature then 100 degree Celsius.
100 degree Fahrenheit should not significantly shrink the rope and will do far less damage then bleach.

At this point we need the scientists to come out and say whether hot water will do the job or not.
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Re: WNS nylon decontamination discussion

Postby Scott McCrea » Apr 3, 2009 2:54 pm

I'm beginning to think that "decontamination" is the wrong word and goal. "As clean as possible" sounds much more attainable and realistic.
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Re: WNS nylon decontamination discussion

Postby ek » Apr 3, 2009 2:58 pm

junkman wrote:The article said 100 degree Fahrenheit (37.8 degree Celsius).
This is a much lower temperature then 100 degree Celsius.
100 degree Fahrenheit should not significantly shrink the rope and will do far less damage then bleach.

At this point we need the scientists to come out and say whether hot water will do the job or not.

My reference to 100 C has nothing to do with that article. It has to do with the fact that it's the boiling point of water under 1 atmosphere of pressure, so ANY temperature water is unlikely to harm nylon. I am not advocating actually putting gear in boiling water. If you DID do that (and I'm not saying you should), you'd have to worry about the possibility of contact with or other exposure to a heating element or other heat source of too-high temperature (unless you can make the heating element have a constant temperature of 100 C).

100 F water will still shrink nylon at a higher rate than lower temperature water, like that which you'd ordinarily encounter in a cave. But of course you're right...generally colder water causes less shrinkage than hotter water.

By the way, it's worth mentioning that there are two considerations for decontamination--whether or not it is officially approved, and whether or not it actually works. Now that a study (by Hazel Barton) is being performed to assess and scientifically report the latter, hopefully that will influence the former.

Many officially approved decontamination modalities, e.g. 70% isopropyl alcohol, are completely untested with respect to effectiveness at eliminating the Geomyces fungus associated with WNS. In addition, while 10% bleach has been shown to kill the fungus in the laboratory, my understanding is that we still don't know if it is effective at killing the fungus when it is impregnated in textiles. So even the bleach might not work.

Scott McCrea wrote:I'm beginning to think that "decontamination" is the wrong word and goal. "As clean as possible" sounds much more attainable and realistic.

No, I think the issue of whether or not the fungus is killed is a consideration, which means that this is not simply cleaning but disinfection as well.
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Re: WNS nylon decontamination discussion

Postby icave » Apr 3, 2009 3:49 pm

Shouldn't we at first be sure that it's the fungus we need to be disinfected from, or are we just following the government agiencies in putting the cart in front of the horse? Don't get me wrong, I think we need to be studying how to disinfect gear from the fungus, but don't think of it as a way to disinfect gear from WNS until the two have been definatively linked.
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Re: WNS nylon decontamination discussion

Postby ek » Apr 3, 2009 4:09 pm

This is perhaps not in disagreement with you, icave, since you did say that you think we should be studying how to get rid of the fungus. But to elaborate on the reason for that:

We'll get results way faster if multiple studies are performed in parallel. Since there is presently no other candidate for the infectious agent besides the Geomyces fungus, it makes sense to study how to kill/eliminate that fungus from caving gear, even as we are waiting for confirmation (in the form of formal publication of Blehert's study--see cavergirl's post about this).

icave, you're right that we shouldn't be confident in our decontamination protocols until we know that the fungus is the infectious agent. That would be one of many reasons not to be confident in them. Other reasons would include the that:

(1) there is no completed study testing them (or any other procedures) on actual materials that people actually bring into caves,

(2) many if not all decontamination procedures consistent with them might be dangerous to load-bearing textiles (and there are no conclusive studies to show otherwise...except perhaps for 70% isopropyl alcoho--isopropyl alcohol is endorsed by the NFPA to speed drying of nylon and polyester ropes--but which would probably be prohibitively expensive for most cavers or organizations to use to wash all load-bearing textile items), and

(3) the people who drafted the FWS protocols don't actually know what they mean themselves--Jeremy Coleman (at the New York Field Office) has diligently consulted with the other co-originators of those protocols and explained to me that due to extensive outside consultation, none of them can answer the question as to whether or not woolite or ivory snow qualify as "conventional detergents." (If that question could be answered in the affirmative for either, then a re-usable manufacturer-approved decontamination procedure for decontaminating load-bearing textiles, consistent with the FWS decontamination protocols, would exist. Of course, just because it would be consistent with the FWS protocols still doesn't mean it would actually work...)
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