How Safe Is Your Food? Investigating the effectiveness of odor-proof bags

[Mary D]

Does anyone have a pack of beagles or foxhounds or bloodhounds to replicate this experiment with food using several scent hounds? Of course, each dog needs to be tested separately so the pack mentality doesn't affect the results.

Richard, I ran my trials using the doubled freezer bags first. It didn't make any difference. After the first trial, my dog did investigate the OP sack, but walked away after a single sniff. In all trials the dog was in another room while I got things ready.

Ike, the kibble had already been in the single freezer bags for 2-3 weeks. It was because I could clearly smell it myself when walking into the room that I became concerned. I was afraid that if I could smell it that clearly, my dog would attack his pack! I ran the trials two days in a row, so the second day the second freezer bag and the OP sack had been in use for about 24 hours. A week or two would have been better. However, in the field three weeks later, my dog showed no interest until the kibble packages came out of the OP sack at feeding time. Nor did he sniff around his pack during the trip, or during subsequent trips.

[Ben Pearre]

Wonderful work!

This test shows that the bags are permeable to the "illicit" molecules to the point that there's easily enough scent for a trained dog to detect at close range, because the search times are similar. Right? Or does the fact that there were DNFs suggest that the dogs are close to their perception threshold?

Are the times taken by the dogs similar to times taken to find un-bagged goods? That would suggest that (a) the bags do nothing or (b) the times taken are not a great measure of effectiveness.

I'd be curious to see whether bags decrease detection range or probability or etc, and this study doesn't do much to convince me that that won't happen–it defies common sense (but then, so do the data on bike helmets; I'm willing to be told that my common sense is wrong). But then, I haven't encountered many bears–do they just come to where the humans are and then nose around? Or do they smell food from far away? If the former, then perhaps this experiment is more valuable than if the latter?

And how about non-bears? It can be useful to avoid attracting other critters. Does this experiment show that bags won't help there either?

[Scott Toraason]

Where were the OPSAKs obtained for the study?

[Bill S]

In bear avoidance, I would distinguish between avoiding *detection* due to scent, and minimizing attraction due to the same. What this study shows is it's almost impossible to avoid detection.

Even if you want to quibble with the details of the study, it should remind us just how *extremely* sensitive a bear's nose is. When you're dealing with an animal that can smell food–or even the tiniest food residue– from miles and miles and miles away, isn't that kind of daunting and humbling to any effort you might make to conceal your food's scent? Once you really start to think about everything we touch during a typical day–even a day of hiking–you pretty quickly come to the conclusion that you're covered with food residue.

No matter how careful you are, you've gotten something food-like or smellable on you, surely, at some point during the day. All it takes is a speck. Just touching food and then brushing your hand against your bag or yourself an hour later would be enough to register a scent at this level of sensitivity. So it's just not realistic to expect that you'll defeat the bear's nose. It's just not. In my sleeping bag in the woods at night, when I think that I am really just making myself feel better.

Most bear avoidance strategies take two approaches:

1) Reduce the scent you're giving off to make yourself less attractive to the bear.

and

2) Physically prevent the bear from getting to your food in some way. e.g.,, bear bag it, put it in a canister.

If you're being realistic, you don't spend too much time worrying about 1.

Almost all of us smell like food when we go to sleep in the woods, but only a few of us have bear encounters at night or otherwise because of it. We don't know if that's because there's a certain threshhold we crossed–because we smelled *too much* or because of some other opportunistic factor. A lot of the objections to the study argue that there's a threshhold level of smell, and that OP sacks help you avoid that threshhold. To me the jury is still out on that after this study. We still don't know for certain if the OP sacks help you *smell less*, and if that makes any difference. The dogs may have smelled the OP sacks as quickly as the ziploc bags because they were both giving off enough of an odor to make them easily and straightforwardly detectable by a dog's super-nose. But that doesn't mean the OP sack isn't less odorous at a very granular level–and it doesn't tell us if that level of difference might make the bear less inclined to wander into camp.

All I know from my own experience at this point is that why we have bear encounters at night is always somewhat mysterious, because I know that I always smell, but only once in a while do bears wander in to check me out. So ultimately I have to rely on (2), creating a physical barrier to my food, in order to assure it is safe. If what I am really worried about is getting killed by the bear once it wanders in to camp for my food, (2) won't help me with that, but assuming I survive the encounter and the bear doesn't defeat the protection system, I'll still have my food in the morning. In part, the intense interest in the topic is probably because we're afraid of bears, period, and avoiding detection is so important because it assures us we won't have an encounter in the first place.

[Stephen Barber]

What this study shows, bottom line, is O[dor]p[roof] Saks . . .

aren't.

[M B]

Im not sure the study shows anything conclusive. It suggests something, for sure. But further work would be warranted.

Personally, I am quite sure none of the bags are 100% odorproof, I would call any claim to such as false anyway. All plastics are permeable, to some molecules, to some small extent. It is only a matter of time and concentration.

That said, it is very unexpected that simple ziplocks would be statistically no better than more impervious plastics. This does suggest some problem with the testing protocol.

Not to mention that illicit drugs, are not the same as food. Different chemical species involved. Entirely likely that some chemicals are more able to permeate the plastics than others. Perhaps the drug of choice contained a particularly aggressive permeant for the bag material.

There was no control that proved that the loading process did not contaminate the outside of the bags.

The assumption seemed to be made that the only way to contaminate the bags with the odors of the illicit substances, would be to actually touch them with something contaminated.

Not true at all. Odors are vapors, humans can smell ppm quantities of certain things. Dogs can smell quantities so small, we cannot fathom it. The finest scientific instrument cannot even begin to approach a dogs nose.

Simply having odor resistant bags in the vicinity of the samples, even while loading, could have contaminated the outside of them all to the point the dogs could detect them all.

[Bob Gross]

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.

–B.G.–

[Stephen M]

Fair point Bob.

[obx hiker]

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.

[Daniel Fish]

…

[Scott Toraason]

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.

[M G]

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]

@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]

"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.

[Cayenne Redmonk]

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]

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]

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.

–B.G.–

[Bob Gross]

"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.

–B.G.–

[Gary Dunckel]

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]

Daniel,

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.

[steven franchuk]

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).

[MFR]

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.

[Bob Gross]

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.

–B.G.–

[Bradley Danyluk]

"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.

[MFR]

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.

[Author]

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