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How Safe Is Your Food? Investigating the effectiveness of odor-proof bags
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Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: bags on 04/11/2013 21:01:38 MDT Print View

Nylofume plastic bags are used by the termite tenting industry. It is impervious to the lethal gas so that food can be left within a tented home without contamination. However, they tell you to double-bag your food, just to be safe. If it keeps lethal gas from getting in, then it ought to be good at keeping food scents from getting out.


Stephen M
(stephenm) - MLife

Locale: The Deep Frreze
Re: Re: bags on 04/11/2013 21:15:35 MDT Print View

Fair point Bob.

obx hiker
(obxcola) - MLife

Locale: Outer Banks of North Carolina
nylofume and mylar anti-static bags on 04/12/2013 09:52:11 MDT Print View

The anti-static bags are really interesting. Anyone know of a way to purchase a few bags instead of a case....or want to form a co=operative effort to buy a case? In the cause of science?

Since my aged human nose is obviously the least reliable scientific instrument known to mankind I'm sure you should take the following with several large grains of salt; but here goes.

I've used the opsaks for years and seal them very carefully, yet have noticed a food aroma upon opening my bearicade. I also generally tend to ziplock bag my food, then separate it into meals and days and bag the days inside small 6/gal trash can liners. then all this goes into the opsak.

My last Sierra trip I doubled bagged with nylofume. The nylofume bags have what I believe is a much more reliable and less likely to fail double sealing process of twisting the bag by twirling it about a hundred times and tying off; then twisting the part above the tie again and tying off again. I also bend and tie the 2 ties together. It's easy and fast, doesn't require a smooth flat surface to meticulously press the opening closed and much less prone to user error than the opsak closure. Due to the thin nature of the nylofume you can put a REALLY tight twist on the bags. No testing but it's hard to believe water could penetrate a tightly wound and twice tied off nylofume bag. I suppose I ought to try sinking a bag closed by this method in the tub under water.

There was no detectable odor when opening the bearicade with the food bagged in the nylofume.

BTW the nylofume will not give at ALL. You should squeeze out any extra air before closing it or it will easily burst if pressed down into the bearcan. Learned the usual way..... ;)

PS: Just remembered another observation that lead me to doubt the efficacy of opsaks. I've tried packing them with clothing, sitting on the bag and sealing it to try and make a vaccuum seal. Air always gets in. Maybe That could be a fast test on the nylofume.

Edited by obxcola on 04/12/2013 09:59:49 MDT.

Daniel Fish

Locale: PDX
... on 04/12/2013 10:16:17 MDT Print View


Edited by on 06/09/2013 22:02:19 MDT.

Scott Toraason
OPSAKs on 04/14/2013 13:11:27 MDT Print View

The manufacturer does not claim that OPSAKs are 100% odor proof, that being said the disclaimer hidden below the glowing Backpacker Magazine endorsement for OPSAKs on the their site. However I would agree that the intent of the manufacture is to imply that OPSAK's are odor proof.

No mention is given where the OPSAKs were obtained for the test; I would assume from an authorized dealer. Be that as it may if the OPSAKs were obtained from Amazon or eBay then they are assumed to be defective as posted by a warning on the manufacturer's official website.

(drown) - F - MLife

Locale: Shenandoah
Re: odor proof bags may still do some good on 04/14/2013 13:36:33 MDT Print View

Bears are drawn to human camps by human scents. Once there they scavenge for food. It makes no difference if your OPsak doesn't smell from a mile away, you do, your camp does, and if a bear has leaned to associate those smells to easily obtainable food it will come scrounging around your camp and OPsak or not it will find your cache and your head if your using it as a pillow. Yikes!!!

I use an Ursak or Bearikade always, unless hiking where there are no bears.

Ike Jutkowitz
(Ike) - M

Locale: Central Michigan
re: OPSAK on 04/14/2013 15:49:00 MDT Print View

@Scott- The OPSAKs were purchased online from REI at our expense for the purpose of this study. They arrived sealed in the manufacturer's packaging. I had no reason to suspect they were defective, but after the surprising study results, I individually leak tested each one by inflating with air and compressing them.

I appreciate all the constructive comments. These will help to strengthen future efforts in this area. We hope to begin our second study within the next month. It was intended to be directed more towards law enforcement concerns, but I hope to re-examine some of the findings from the pilot study using more dogs and a number of other odor-proof options. We will also incorporate a negative control (odor-proof bag with a scent packet held over the open mouth of the bag and then withdrawn, leaving the bag empty). This should help to address concerns about dogs targeting some feature of the bags other than the scent contained within, as well as contamination of bag exteriors with scent.

Hopefully at the end of all of this, we will also have enough bags left to do a small scale (e.g. 12 bags per group) in situ study with both positive and negative controls.

Luke Schmidt
(Cameron) - MLife

Locale: The WOODS
Re Re Opsak on 04/14/2013 16:26:08 MDT Print View

"We will also incorporate a negative control (odor-proof bag with a scent packet held over the open mouth of the bag and then withdrawn, leaving the bag empty). This should help to address concerns about dogs targeting some feature of the bags other than the scent contained within, as well as contamination of bag exteriors with scent."

Have you considered just bags that have never been near drugs? I know dogs are trained to look for actual drugs but in the absences of that could they be looking for plastic bags since the two often go together?

Also would it be possible to do a test in an open area to see how fare away the dogs detect drugs in Opsaks, in ziplocks bags, and with no bags. This would answer some of the questions about whether Opsaks help if a bear is farther away.

Willie Evenstop
(redmonk) - F

Locale: Greater Yellowstone Ecosystem
How Safe Is Your Food? Investigating the effectiveness of odor-proof bags on 04/14/2013 16:29:07 MDT Print View

Do the police have an interest in showing the bags to be useless for concealing drugs from their dogs. ?

I think that is going to bias the study.

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: Re: odor proof bags may still do some good on 04/14/2013 16:30:55 MDT Print View

Yeah, that is pretty much how I feel. But, this is not a scientific finding.

I tend to think that bears do not like human body smells, generally. We stink to many wild animals. (Sometimes, I can even smell myself after a few days of hiking in hot sun up in the peaks area. I agree, I stink.) There is nothing scientific about this and *may* offer a hypothesis, or pre-hypothesis conjecture with more refinement and study. Maybe it drives most bears off. Hard to say.

Lets face it, Dr. Jutkowitz is the ONLY study I have seen on this subject. There are a lot of "if's, but's, maybe's surrounding what was done. The scientist is perfectly willing to correct any errors that come out of a public review, do it over including corrections, and, expand it. Well Done, indeed!

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: How Safe Is Your Food? Investigating the effectiveness of odor-proof bags on 04/14/2013 16:33:27 MDT Print View

If the bags were totally effective at blocking odors, then the police would not want to advertise that fact to potential drug smugglers.

If the bags were totally ineffective, then the drug smugglers would read that and move on to some better method of blocking odors.


Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: odor proof bags may still do some good on 04/14/2013 16:35:48 MDT Print View

"We stink to many wild animals."

Well, a black bear does not exactly smell like a rose.

I've been told that the only thing worse than the smell of a bear's body is the smell of a bear's breath.


Gary Dunckel
(Zia-Grill-Guy) - MLife

Locale: Boulder
Vacuum sealing on 04/14/2013 17:54:11 MDT Print View

Ike, I very much appreciated reading your study, and it opened many of our eyes to the reality of conrolling odors in our food supplies. The extensive discussion that followed has been interesting as well.

One thing stood out as curious to me, however. You indicated that the controlled substances were vacuum sealed, and then covered with some sort of canvas, right? I was astounded that the vacuum sealing didn't form a definitive barrier through which odors couldn't penetrate. Is it at all possible that the exterior of the vacuum sealed bags, or the canvas itself, had been contaminated by the handlers when they packaged the controlled substances? Or had the dogs possibly become conditioned to detect the smell of canvas, and not the drugs at all?

I would be very interested in some type of similiar study that involved actual odiferous food (not drugs or canvas) in vacuum sealed Foodsaver bags, to see if food smells can actually penetrate those bags.

All in all, it was a good study, and the results/conclusion seem in fact valid. Thanks for doing this for us, Ike.

Bradley Danyluk
(dasbin) - MLife
Bear attacks on 04/15/2013 10:15:40 MDT Print View


It seems to me that the purpose of proper food storage really has nothing in common with the goal of preventing an attack.

The goal is to keep a bear from stealing your food. That's about it.

Attacking humans is an energy-expensive and risky move for a black bear (even grizzlies only seem to do it defensively).
From what I've read, black bears will very occasionally attack campers inside a tent at night. But these are basically exclusively predatory attacks by starving or deranged bears. Very little to do with stealing your food (even if you kept your food in your tent, it seems to me much more likely the bear will knock down the tent, take the food and run if that is its goal - why bother attack you, unless you try to get in the way?) There are definitely incidental injuries and deaths that occur this way, but I tend to view them not as an "attack" but as a heist mission gone bad, where the thief is forced to maim (or accidentally kills) the guard.

The most dangerous attacks are the ones where the bear's goal is *you*. In that case, it really doesn't matter where your food is or how meticulous your campsite is.

Certainly people should make sure that they are not deluded into believing that proper food storage makes them safe from bears. It makes your food safe from bears... big difference.

Edited by dasbin on 04/15/2013 18:34:26 MDT.

steven franchuk
Re: Odor Proof helps but isn't a comprehensive bear strategy on 04/15/2013 22:48:44 MDT Print View

It seems to me that the purpose of proper food storage really has nothing in common with the goal of preventing an attack.

Daniel, If you look at wikipedia list of fatal bear attacks you will find that none came from Yosemite even though Yosemite bears constantly raided campsites for decades looking for food. When a bear walks into a campsite looking for food they don't want to attack people. Attacking people is just as dangerous to the bear as it is to the person. Most bear attacks o are related to cubs being nearby or when a bear feals threatened by a person. Others atacks have no explaination.

It is well known that yousemite had a lot of bear problems. The bears managed to find way, to get hanging food sacks most of the time. If you were not garding your food there was a good chance the bear would get it. Bears even learned how to break into cars to get food (usually causing extensive damage to the car). That was the past.

Today Yosemite requires all backpackers carry a bear proof canister. The bears quickly learned that they couldn't get into the canisters. Now most Yosemite campers never see a bear. They may walk through the camp at night, but as soon as they see the canister they move on. The bear proof canister is sized so that a bear cannot carry it away. Canister are size so that a bear cannot carry it in its mouth and a bear cannot carry it in its paws.

"to me, the best way to insure the next day's meals is to keep your food with you while you sleep."

Storing food in your tent is the worst thing you can do. That attracts the bear to your tent and increase the chance of bear person encounter. The beast way to insure you have food in the morning is to use a bear proof canister. The only way your food can disappear at night is if another hiker opens your canister steals the food (which has probably happened).

Edited by Surf on 04/15/2013 22:54:17 MDT.

Clayton Mauritzen
(GlacierRambler) - F

Locale: NW Montana
Re: Bear attacks on 04/16/2013 05:50:08 MDT Print View

Bradley, this contradicts the vast majority of research on bear behavior. According to Stephen Herrero (Bear Attacks: Their Causes and Avoidance), most of the predatory grizzly attacks that we have recorded in the Lower 48 and in Canada were caused by bears that had been conditioned to human food. Once bears begin to identify humans as a sources with viable food, their fear of humans and boldness near them increases dramatically, and this leads to much greater chances for a violent encounter. Thus, food storage is an essential component of bear management, especially with grizzlies.

I suggest that you read the above book and corresponding research before recommending courses of action fundamentally in conflict with well-established knowledge.

Edited by GlacierRambler on 04/16/2013 06:23:09 MDT.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Bear attacks on 04/16/2013 14:46:39 MDT Print View

I think you guys need to seperate the discussion into two areas. One is the black bear, and one is the brown bear (grizzly). Those are two completely different animals and they behave differently.


Bradley Danyluk
(dasbin) - MLife
Re: Re: Bear attacks on 04/16/2013 15:34:27 MDT Print View

"most of the predatory grizzly attacks that we have recorded in the Lower 48 and in Canada were caused by bears that had been conditioned to human food."

I can't disagree, having not read that particular book, but my own reading led me to believe that predatory grizzly attacks are a small fraction of bear attacks. Even within the realm of grizzly attacks, most are defensive in nature. Black bear attacks are generally not defensive (they and their cubs tend to just tree themselves when threatened) but a wide variety of abnormal aggressive behaviour which may or may not (likely not) have anything to do with scenting food.
My point is more that, while there are a lot of black bears out there after your food, they tend to be the less-violent sort who are will go after the low-hanging fruit first (the stuff they can get without a fight, that is). There are also a fair number of curious/aggressive black bears interested in *you*, it seems - which has not so much to do with your food.
I've read of a couple cases of predatory grizzly attacks, but they seem to be extremely rare and in nearly every case the bear is starving or injured. I haven't read about this particular link with food scents you mention - it seems a bit odd to me as they tend to devour their victims, which I would suspect is a much greater source of food than what you're carrying.

Edited by dasbin on 04/16/2013 15:35:42 MDT.

Clayton Mauritzen
(GlacierRambler) - F

Locale: NW Montana
Re: Re: Re: Bear attacks on 04/16/2013 19:40:53 MDT Print View

Bob--agreed. In fact, their behavior is dramatically different. However, proper food storage is still an essential component of managing each species.

I don't want to take the thread drift too much further, but I feel that this point does need to be made. It gets to the heart of the OPSak issues.

Tom Clark
(TomClark) - MLife

Locale: East Coast
Re: How Safe Is Your Food? Investigating the effectiveness of odor-proof bags on 04/17/2013 06:32:04 MDT Print View

I'm in the food packaging industry, and just saw this timely article touting a new aroma barrier bag by OdorNo. The company website offers no insight concerning the technology used or data to compare with other options, but I thought I would mention it for consideration. However, the more I read about the little that the company actually says it leaves a bad taste in my mouth.

Here are some quotes from a separate article...

"Not even a dog can smell through my bags," said the colorful Fortune, between laughs and smiles as he demonstrated his product's effectiveness."

" has already begun to order them from us,"