Read up on the guidelines of using UV to treat water.
I have read the medical docs and this is what I have found.

UV-A is not effective against all organisms. The SODIS system doesn't make sense and I suspect it is not very successful. I wouldn't rely on it.

Steripen uses UV-B which does not penetrate clear plastic or glass. It reflects off the surface.
This explains why you don't go blind by looking at the bottle while using a Steripen.
Look it up.

And as stated, there is a reason why beer bottles are tinted. Beer(and food) in clear bottles goes bad much quicker from bacteria growth when exposed to sunlight. I won't go into the biology as to why.
You can look this up as well.

One of the guidelines of using UV-B to treat water is to avoid direct sunlight for long periods after treating.

The Steripen docs even mention this fact.

> UV-treated water must therefore not be exposed to visible light for any significant period
> of time after UV treatment, before consumption, to avoid ingesting reactivated and
> dangerous microbes.

I don't know who put that in Wikipedia, but it sounds like crap to me. Bugs don't recover that easily from having their DNA damaged.

Yes, UV 'sterilises' the bugs so they cannot multiply in your gut. That is standard, normal, and sufficient. That is what the EPA requires.

Cheers

Edited by rcaffin on 02/27/2012 15:15:37 MST.

"UV-A is not effective against all organisms. The SODIS system doesn't make sense and I suspect it is not very successful. I wouldn't rely on it."

Just so nobody jumps to conclusions based on your first stament there, UV-C is not effective against all organisms either. I'm currently tasked with finding cost effective ways of removing and treating waste in developing nations and one of my biggests obstacles is Helmenth eggs. UV light is completely inneffective at treating them.

Also the SODIS method has been proven effective and is recommended by the WHO.

Edited by 7sport on 02/27/2012 15:30:49 MST.

Dude, it's sourced from a peer-reviewed journal.

Qiu X, Sundin GW, Chai B, Tiedje JM (November 2004). "Survival of Shewanella oneidensis MR-1 after UV Radiation Exposure". Applied and Environmental Microbiology 70 (11): 6435–43. doi:10.1128/AEM.70.11.6435-6443.2004. PMC 525172. PMID 15528503.

So does anyone know how long it takes for genetic reactivation after a Steripen dose?

We talkin' minutes, hours, days? I highly doubt it is of any concern because any treated water usually gets consumed within 12 hours. If I collect water in the morning, it is often gone by at least dinner time, if not earlier.

Edited by T.L. on 02/27/2012 15:23:40 MST.

> Steripen uses UV-B which does not penetrate clear plastic or glass.
Correction. Steripen, and all other UV systems for treating water (up to the municipal level) use UV-C, at 254 nm. To quote Wikipedia:

"Ultraviolet disinfection of water consists of a purely physical, chemical-free process. UV-C radiation in particular, with a wavelength in the 240 nm to 280 nanometers range, attacks the vital DNA of the bacteria directly. The radiation initiates a photochemical reaction that destroys the genetic information contained in the DNA. The bacteria lose their reproductive capability and are destroyed. Even parasites such as Cryptosporidia or Giardia, which are extremely resistant to chemical disinfectants, are efficiently reduced. "

UV-B is not reliable. It causes sunburn, but does not really sterilise water.

Cheers

For over 40 years I used nothing in many mountain streams, iodine tablets, or occasionally boiled really nasty water. For the past 3 or so years I have used micropur tablets exclusively. Never had a battery failure, light failure, o-ring failure, clogged filter, mechanical failure, or water-born illness. Not to mention the lightness of my purification methods.

:)

The UV light acts on their dna so they don't reproduce. Just like if there was no ozone layer on Earth, we would get a lot more skin cancer (dna mutations).

So the microbes can't be "reactivated".

FWIW, my Steripen Adventurer has worked great, have had it for the past 4 years or so.

I recently printed a small copy of what all the blinking light patterns mean and keep it in my pack.

Steve

Thank you Roger for debunking the myth of the reactivated organisms... Clearly blasphemy.

"I recently printed a small copy of what all the blinking light patterns mean and keep it in my pack."

That's excellent advice. I stored a PDF of the entire operators manual on my iphone and emailed myself a copy too. I do this PDF method with most of the stuff I buy that has any sort of complexity to it (like my altimeter/compass watch for example) just in case I experience a brain fart in the field or in less than ideal situations where I just can't think clearly.

"UV-B is not reliable. It causes sunburn, but does not really sterilise water."

Source?

OK, I'm at work. So don't have all my facts correct. It is UV-C that the Sterpien uses.
And it is a well known fact in the purification world that some chromosomes can be repaired by exposure to visible light for long periods of time.

Visible light also stimulates reproduction of many living organisms.

I will admit that SODIS can work because of the combination of heat and UV-A, but I'd bet the water temp has to be at least 120deg. F or higher.

en.wikipedia.org/wiki/Portable_water_purification

Edited by brooklynkayak on 02/27/2012 16:09:34 MST.

Here's a copy of the article cited by wikipedia...

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC525172/

Try to make sense out of that... I read about half of it and I must say it's pretty confusing. Easy to see where the writer of the wikipedia article got confused.

Here's a couple quotes from the article I liked:
"Our investigation on the sensitivity to DNA-damaging UVC and UVB wavelengths centered on the NER system of MR-1. This system is probably functional, as organisms harboring mutations in NER component genes (e.g., uvrA, uvrB) are typically exquisitely sensitive to UVC (41)."

"Relatively little is known of the interrelationship of genetic systems and mechanisms involved in repairing cellular damage caused by UVR and ionizing radiation in organisms other than D. radiodurans."

"Despite possessing the relevant repertoire of oxidative damage repair genes, the results of our study indicate that S. oneidensis MR-1 is one of the most UVA-sensitive organisms known."

Interpret as you wish, but my understanding is that the cells capable of "reactivating" are highly sensitive to UVC. Maybe I'm wrong but I feel like if you're gonna go slapping sources down like that you ought to at least give them a read first.

Edited by pdcolelli42 on 02/27/2012 16:06:47 MST.

http://www.healthline.com/health-blogs/outdoor-medicine/steripen

Another paragraph from that article.

Solar UV radiation (UVR) is lethal and potentially mutagenic to all organisms at species-specific levels. The stratospheric ozone layer absorbs UVC (<290 nm) effectively; however, both UVA (320 to 400 nm) and UVB (290 to 320 nm) wavelengths penetrate to the earth's surface. UVR-induced damage is greatly dependent on the sources of radiation and the time of exposure. Photons of UVB and UVC wavelengths cause direct DNA damage by inducing the formation of DNA photoproducts, such as cyclobutyl pyrimidine dimers (CPD) and pyrimidine (6-4) pyrimidinone (37). The accumulation of DNA photoproducts can be lethal through the blockage of DNA replication and transcription. UVA can cause photodamage to a variety of molecules as well as physiological processes directly or indirectly by inducing the production of reactive oxygen species (5, 6, 17, 53). Distinct differences between far-UV (UVC) and near-UV (UVB and UVA) damage have been observed in both bacteria and bacteriophages (6).

http://en.wikipedia.org/wiki/Photolyase

Regarding Photolyase, be aware, I suspect it isn't much of a risk, but probably good to not store Steripin treated water on top of an exposed rock for several ours:-)

Edited by brooklynkayak on 02/27/2012 16:27:15 MST.

Read the above posts. Leaving your steripen treated water out in the light indefinitely is no risk. The wikipedia article you linked in the caption under the picture says
"A UV radiation induced thymine-thymine cyclobutane dimer (right) is the type of DNA damage which is undone by photolyase." Referring to UVB damage, the steripen uses UVC.

Edited by pdcolelli42 on 02/27/2012 16:20:51 MST.

“Could there have been some type of malfunction within the lamp that caused UV output reduction in conjunction with a dimmer visible light? Or are the two so exclusive of each other that I'm looking at one hell of a lucky guess? ”

I would not think they are exclusive. The lamp probably puts out (I’m guessing) light in the 150nm to 550nm region. The 150-300nm renders the microbes useless while the longer wavelength allows our eyes to see some of the beam. So if the visible portion dims, most likely the UV portion ‘dims’. And I don’t think steripen uses mercury lamps since we can see some of the radiation.

For the past 18 months--- I’m a steripen Opti user and it has performed great. Of course I can only judge by blue-light strength and how I feel 2 weeks later. I like the quickness over tablets and the weight savings over a filter.

But this lighter version (2.6oz w/ batteries) sure has caught my eye for short trips: http://www.steripen.com/freedom-travel

-Barry
The mountains were made for Teva’s

WOW, six pages and still going strong!

I am pretty sure that if UV were ineffective, there was no way I could have remained free from any water-borne sickness after drinking 3rd and even "4th" world tap water for months at a time -- seven month in my longest stretch. IF UV were ineffective, then hospitals would be the first to know. But I guess some hikers here believe they know much more about the science than hospitals.

My conclusions:

1. Steripen works.
2. Steripen also has quality and reliability issues -- perhaps more with the older models, but still enough of a problem apparently even with current models.

Time to move on (for me anyway)

That freedom must be new. I would love to get my hands on that thing. I've been looking into rechargeable RCR123 batteries and a portable USB charger for them and it ain't easy to find. This little puppy would be lighter and I wouldn't need to fuss with the batteries.

I wonder if I could find anyone to buy my opti :) doubtful that I'd get enough money back to make it worth while.

Edited by pdcolelli42 on 02/27/2012 17:24:13 MST.