WNS nylon decontamination discussion

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WNS nylon decontamination discussion

Postby ron_miller » Feb 11, 2008 12:55 am

Regarding concerns about using 1:10 household bleach-to-water solutions to decontaminate vertical gear, this issue has come up previously in the context of rescue workers needing to decontaminate rope and webbing materials following exposure to human pathogens.

CMC Rescue issued a technical advisory in 1999 that covers this issue. The document is available here: http://newyorksearchandrescue.org/downl ... %20Web.pdf

CMC tests on nylon rope reportedly found minimal impact on rope strength when following standard decontamination procedures.
In one test, ropes were immersed in a 1:10 bleach/water solution for 10 minutes, followed by a 10 minute rinse. After 14 days, the reported strength loss was 2%.

In a CMC test conducted similarly except using straight household bleach, the strength loss after 14 days was 13%.
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Re: Fungus serious threat to NE bats

Postby NZcaver » Feb 11, 2008 10:13 am

ron_miller wrote:Regarding concerns about using 1:10 household bleach-to-water solutions to decontaminate vertical gear, this issue has come up previously in the context of rescue workers needing to decontaminate rope and webbing materials following exposure to human pathogens.

Ron,

Without straying too far off track, is there any chance this strength loss could be cumulative?

I'm thinking of how a tiny drop of sulphuric acid will only weaken a rope marginally at the time, but a week/month/year later that point in the rope might be a fraction of it's original strength. I wonder if bleach has a similar effect?
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Re: Fungus serious threat to NE bats

Postby Carl Amundson » Feb 11, 2008 12:07 pm

NZcaver wrote:
ron_miller wrote:Regarding concerns about using 1:10 household bleach-to-water solutions to decontaminate vertical gear, this issue has come up previously in the context of rescue workers needing to decontaminate rope and webbing materials following exposure to human pathogens.

Ron,

Without straying too far off track, is there any chance this strength loss could be cumulative?

I'm thinking of how a tiny drop of sulphuric acid will only weaken a rope marginally at the time, but a week/month/year later that point in the rope might be a fraction of it's original strength. I wonder if bleach has a similar effect?

I will have to admit I'm VERY hesitant about cleaning my vertical gear and rope with bleach.
With no causal agent, no source, and no transport mechanism identified for this outbreak it seems like an undo risk.
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Fungus serious threat to NE bats

Postby ron_miller » Feb 11, 2008 12:21 pm

NZcaver wrote:
ron_miller wrote:Regarding concerns about using 1:10 household bleach-to-water solutions to decontaminate vertical gear, this issue has come up previously in the context of rescue workers needing to decontaminate rope and webbing materials following exposure to human pathogens.

Without straying too far off track, is there any chance this strength loss could be cumulative?


I wouldn't be too surprised if it is in fact cumulative, but the point is that each cleaning event with bleach will have very little effect on strength.

If this sub-thread generates more activity, I would suggest moving it off to its own thread to keep attention on this thread focused on the main issue.

Cheers,

Ron

2/12/08 note: edited post to reflect the fact that the CMC tests apparently did not comprise 14 daily bleach/rinse cycles, but rather one cycle, then testing 14 days later.
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Re: Fungus serious threat to NE bats

Postby NZcaver » Feb 11, 2008 2:38 pm

ron_miller wrote:I wouldn't be too surprised if it is in fact cumulative, but the point is that each cleaning event with bleach will have very little effect on strength. Based on the test data, it takes 14 washes to reduce strength by a total of 2%. Although it is certainly speculative to do so, dividing 2% by 14 yields a strength loss of 0.14% per wash.

Sorry, I did a poor job of wording my last post.

What I meant was (for example) a rope exposed once to bleach and then left to sit for a year. Tested the same day it was exposed, the reduction in strength might be 2%. But tested a year later, could it by then have lost most of it's MBS? This "strength loss over time" issue has apparently been proven ropes exposed to acid, so I was wondering if bleach could cause a similar effect.
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Re: Fungus serious threat to NE bats

Postby VACaver » Feb 11, 2008 4:11 pm

As a FAA Master Parachute Rigger, I would NOT use bleach on any vertical gear. Bleach + nylon do not mix...no matter what the concentration.

Some other way of disinfecting should be used.
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WNS nylon decontamination discussion

Postby wyandottecaver » Feb 11, 2008 5:37 pm

there has been a fair amount of discussion regarding decontaminatin of caving equipment in relation to White Nose Syndrome. This is a attempt at cleaning up that thread. The FWS and others mentioned using a 10% bleach solution which evidence suggests may lead to long term damage.

An idea I would like comment on. the boiling point of water is listed as 212 deg F and the melting point of nylon is listed as a range between 374 deg and 663 deg F. would gently boiling water damage nylon caving gear like rope and harnesses?
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Re: Fungus serious threat to NE bats

Postby wyandottecaver » Feb 11, 2008 5:41 pm

I started a WNS nylon decontamination discussion under Rope to try and keep the threads cleaner. In that post I ask about the possibility of using gently boiling water as the boiling point seems to be about 100 deg lower than the lowest temp given as a nylon melting point. granted damage may occur BEFORE melting...just curious if anyone knows?
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Re: WNS nylon decontamination discussion

Postby Scott McCrea » Feb 11, 2008 6:36 pm

So far, nothing has convinced me to try to sterilize my vertical gear. I will do my best to limit the potential spread of a potential hazard to potentially at risk caves. Eventually, if evidence is presented that proves some of the speculation, I will probably replace all my gear. WNS could be a windfall for caving gear vendors.
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Re: WNS nylon decontamination discussion

Postby wyandottecaver » Feb 11, 2008 6:44 pm

hmmm well 97% mortallity at 4 caves last year for a total of 8-11,000 bats and 9 infected sites this year with no way to know yet if people can or cant carry it accidently on gear convinced me :) but reasonable people can agree to disagree
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Re: WNS nylon decontamination discussion

Postby Carl Amundson » Feb 11, 2008 7:45 pm

wyandottecaver wrote:hmmm well 97% mortallity at 4 caves last year for a total of 8-11,000 bats and 9 infected sites this year with no way to know yet if people can or cant carry it accidently on gear convinced me :) but reasonable people can agree to disagree

To date there has been no causal agent, no source, and no transport mechanism identified for this outbreak.
We don't know of this caused by warm winters or contamination of some sort.
I have seen an email that suggested that the bat fungus was found in a cave that has been closed to cavers for years.

Using chemicals on our nylon vertical gear & rope that we know will damage them is still a hard sell for most of us.
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Re: WNS nylon decontamination discussion

Postby adleedy » Feb 11, 2008 8:13 pm

exactly, While im concerned for the bats, I still have not been convinced that this requires my gear to be cleaned with ANYTHING, that may question its integrity. Spray it off with a water hose...Yes, Bleach or any other chemicals...NO
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Re: WNS nylon decontamination discussion

Postby wyandottecaver » Feb 11, 2008 9:02 pm

I am certainly not saying cavers should use harmful chemicals/methods on their gear. I certainly haven't used anything myself yet and won't use bleach on life support gear at all...of course I also have stopped caving in bat caves entirely and I am in Indiana. The point was to discuss possible ways gear could be decontaminated without creating a hazard for the users!

The more basic issues that concern me are:
1) gear decon, closing caves, avoiding caves with bats, avoiding caves in NY and VT, etc is an outgrowth of the idea that *if* there is an agent that we *can* transport we should do everyhing possible to prevent that.

If we find out in 1 year that it was something unaffected by caving activities we will have lost nothing but some time underground in caves we can visit later. If we find out in a year that it was something that could be carried by caving then we might have helped exterminate the bats in every cave we visited.

2) having caves become infected that are not visited by humans does not mean we can't spread it. It just means something else for sure can.

As a wildlife biologist who has managed major bat hibernacula I respect the opinions of a certain non-bat scientist that global warming is the culprit...it doesn't mean I consider that opinion supported by the facts or biology we *do* know about let alone my own first hand observations :)

getting back on track, I am curious about boiling water...anyone know?
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Re: WNS nylon decontamination discussion

Postby ron_miller » Feb 12, 2008 12:07 am

Apologies in advance to anyone upset or annoyed by this rephrased cross-post from the Bats forum, but it seems that actual data on the bleach issue is germane enough to this new thread to warrant repeating it here.

Regarding concerns about using 1:10 household bleach-to-water solutions to decontaminate vertical gear, this issue has come up previously in the context of rescue workers needing to decontaminate rope and webbing materials following exposure to human pathogens. CMC Rescue issued a technical advisory in 1999 that covers this issue. The document is available here: http://newyorksearchandrescue.org/downl ... %20Web.pdf . From this document:

With the increasing concern for personal safety when dealing with bloodborne pathogens, a procedure was needed to decontaminate rope and harnesses that was not in conflict with safe washing of these products. For an answer, we contacted the engineering staff at Wellington Commercial Cordage.

Rope that has come into contact with blood or other body fluids can be cleaned using chlorine bleach per your department’s protocols for decontaminating equipment. Wellington said that the small amount of bleach specified in most decontamination protocols would have minimal effect on the rope’s fibers. This would hold true for harnesses and other web products although some minor discoloration may occur.


CMC tests on nylon rope reportedly found minimal impact on rope strength when following standard decontamination procedures. In one test, ropes were immersed in a 1:10 bleach/water solution for 10 minutes, followed by a 10 minute rinse. After 14 days, the reported strength loss was 2%.

In a CMC test conducted similarly except using straight household bleach, on the other hand, the strength loss after 14 days was 13%.

NZcaver expressed a concern that damage to the fibers could continue after the exposure, in other words, that the fibers could continue to weaken over time. I have no specific data to refute that, but if that were the case, it would seem that we'd have seen that effect by now in firefighting and rescue equipment that has been decon'ed for years using this 1:10 bleach solution in accordance with the 1999 CMC advisory.

If anyone has any additional actual data regarding effects of decontaminating nylon rope and/or webbing using dilute bleach solutions, I'd be very interested in seeing that.

2/12/08 note: edited post to reflect the fact that the CMC tests apparently did not comprise 14 daily bleach/rinse cycles, but rather one cycle, then testing 14 days later.
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Re: WNS nylon decontamination discussion

Postby NZcaver » Feb 12, 2008 12:17 am

Ron, thanks for the good information. I just moved the recent posts over from the fungus thread, but you beat me to it by reposting your earlier data. No harm done.

Wyandotte, thank you for starting this new thread.
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