Wednesday, June 4, 2014

Silly science and the drinking of urine

A friend sent me the following link, having remembered my outdoor education comments that urine was generally sterile, and did not require any particular precautions in the backcountry:

 http://www.outsideonline.com/news-from-the-field/Your-Pee-Isnt-Sterile.html

There are two parts to this story, one which is simply a bad interpretation of mediocre science and the other of which is a genuinely stupid concept which seems to have some traction.

First things first: the bad interpretation of mediocre science.

The article refers to a study presented at a recent medical meeting which actually had nothing to do with the outdoors; it was a study of the urine of women with overactive bladder.  The investigators used what was described as a "cutting edge" method to show that most urine contained bacteria, even if this could not be shown by the conventional method (growing actual bugs from the urine).  The method (hardly "cutting edge"--it's been around for years) actually involved identifying not bacteria themselves but rather traces of their genetic material, DNA.  This is the same methodology which is used in forensics to identify suspects from traces of their body fluids. 

What the investigators actually showed, therefore, was not that bacteria were present in some urine samples but that traces of bacterial DNA were present.  There is a big difference.  This method is so sensitive that it can identify the most miniscule of traces of bacterial DNA. Such material is probably all around us--any living thing can leave such "fingerprints".  

When we talk about something being "sterile", we do not mean the absence of tiny amounts of genetic chemicals.  We mean the absence of viable bacterial which can grow according to usual laboratory methods.  Isolated fragments of DNA cannot reproduce, grow, or cause disease.  Thus, the absence of bacteria growing in standard culture from urine indicates that the urine is "sterile", in spite of any "cutting edge" DNA findings.  

So, the thoughtful, environmentally sensitive camper can continue to relieve himself or herself in the North American wilderness without fretting about spreading disease.  Some have argued that the concentrated salts of urine could have unpleasant environmental consequences, damaging flora or attracting animals.  This may or may not be a concern.  If it is, however, there is an easy solution: pee in streams or other bodies of water!  Heresy, eh?

Now for the genuinely stupid concept.

Apparently, there is a thread in some circles which promotes the drinking of urine as a health or survival technique.  According to the Outside article,  the media's favorite spokesperson for this is apparently a dude named Bear Grylls, who has some sort of reality show Man versus Wild.  In one segment, he is shown in a very hot, dry desert, extolling the benefits of drinking urine as a way of maintaining hydration.

The Outside article used the above study showing urine was "unsterile" as a way of criticizing Grylls.  The problem with the technique, however, has nothing to do with sterility.  It shows an incredible lack of understanding of basic human physiology.

The role of urine is to concentrate and excrete salts in the diet as well as the break down products of protein digestion.   Drinking urine may supply one with some water, but it also puts right back into the body the salt and waste products which are contained in the urine.  These have to be excreted again, but will require more body water in order to make the urine to excrete them a second time.  Thus, drinking urine actually worsens dehydration, even though it puts a bit more fluid into the body. 

This is pretty basic science.  It was shown most elegantly by a chap named James Gamble, who in the 1940s did very careful studies designed to create the optimal life raft ration.  Taking anything other than plain water clearly made one's hydration worse.  Of course, it was "reported" even earlier by Samuel Taylor Coleridge in The Rime of the Ancient Mariner: "Water, water everywhere, but not a drop to drink."

I guess that Bear Grylls doesn't read romantic English poetry.

Tuesday, August 27, 2013

What can they be thinking?

The following item caught my attention recently:

 http://www.huffingtonpost.co.uk/2013/08/06/sunburn-pain-relief_n_3711613.html

The actual scientific study on which the above article was based is published in a very highly respected journal, Proceedings of the National Academy of Sciences:

http://www.pnas.org/content/110/34/E3225.long 

The actual science here is impeccable.  The research reports that a molecule, TRPV4, is involved in producing the pain of sunburn, and that a newly designed compound targeting this molecule inhibited the pain and blistering of sunburn in a mouse model.  The implication is that such a compound could eventually be used to attenuate the burning and blistering of sunburn in humans.

Well, maybe.

The development of sunburn pain, like any pain, is a very complex cascade; this study shows that TRPV4 is an important part of that cascade.  This is exciting new information, which has implications beyond sunburn.  However, there are other well-known components of this cascade, including something called the "prostaglandin pathway." We already know how to inhibit prostaglandin-mediated pain and inflammation: the use of "non steroidal antiinflammatory drugs" (NSAIDS), of which ibuprofen is perhaps best known.  It has been known for a long time that taking ibuprofen or similar agents right after excessive sun exposure markedly reduces pain and blistering. 

The issue is that the pain and blistering of sunburn is really only a small part of the problem.  The UV light which produces the sunburn also damages DNA in cells of the skin.  This damage can ultimately lead to the development of skin cancers such as melanoma.  As I have pointed out in other writings, melanoma caused by sunburn is the most common cause of death in outdoor recreation.  Ibuprofen, or some expensive new TRPV4 antagonist, may well minimize the acute pain of sunburn.  It would do nothing to prevent skin cancer.  Sunburn is our body's way of saying "You jerk!  Don't you know that you are setting yourself up for cancer?"  Why would we want to do anything to take away from this important message?

 

Wednesday, June 19, 2013

Updates and shameless promotion

Despite best of intentions for more regular posts, it's been a pretty dry few months!

Several recent Adirondoc columns are now available through the publications link.

Some time ago, I mentioned Erik Schlimmer's development of a route across the Adirondacks, from Blue Line to Blue Line, which he dubbed the "Trans Adirondack Route."  Erik has now produced a guidebook and video for the route, both of which I highly recommend:  http://www.transadk.com/

I was recently interviewed for a program ("Health Link") discussing the health benefits of wilderness travel.  The link to the interview is: http://blogs.upstate.edu/healthlinkonair/2013/03/28/how-to-prepare-for-hiking-and-mountain-climbing/

Monday, December 31, 2012

Happy New Year!

Looking back over my posts for this year, I realize that I haven't been a very prolific blogger.  Frankly, I can't understand how some folks have the time to keep their blogs so current!  I have, however, continued to keep up my regular column for Adirondac magazine, most of which reads like a blog anyway.  Check out the publication link for some of these.

With winter coming on, the Caribbean cruise industry is in full swing.  I suspect that most readers of this blog don't spend too much time on vessels like the Queen Mary II, but there is actually a very nice wilderness medicine connection.

December was a bad month for cruise ships.  In addition to rather flagrant violation of basic Leave No Trace principles (http://www.foe.org/cruise-report-card), there have been a number of very high profile outbreaks of intestinal infection on some luxury liners:

http://news.sky.com/story/1031527/norovirus-cruise-outbreaks-on-two-ships

How would you like to spend 10 grand or more for a cruise, and wind up puking on the floor of your cabin with the staff forbidden to enter your room?  These are hardly isolated incidents; the Centers for Disease Control and Prevention has a nice summary of reports over the decade:

http://www.cdc.gov/nceh/vsp/surv/gilist.htm

Most of these outbreaks in which the cause could be established were related to Norovirus, a well-described cause of epidemic gastroenteritis.  In addition, however, virtually every other infectious cause of gastroenteritis (including giardiasis) appears on this list.

Where's the backcountry connection?  Believe it or not, there are actually some biologic similarities between cruise ships and backcountry treks.  Both situations take a group of individuals from different backgrounds and locales and put them together for a prolonged period sharing close spaces, eating together, and sharing toileting facilities. 

Epidemiologists have long recognized that such environments are a prime condition for the hand-to-mouth spread of intestinal infections.  Poor hygiene on the part of cruisers leads to surfaces on the ship becoming contaminated, spreading infection.  While this certainly can happen in other public venues such as restaurants and hotels, these do not keep the same group of people in the same environment for several days at a time. Cruise ships do not spend a lot of time worrying about their drinking water; instead, they are compulsive about cleaning surfaces and encouraging their clients to pay attention to personal hygiene.  When outbreaks do occur, the CDC invariably implicates hand-to-mouth spread.

Except in developing countries with no sanitation infrastructure, water is not a very efficient means of spreading intestinal infections.  As the cruise ship experience demonstrates, however, breakdown in personal sanitation is the major way in which such infections spread. 

So, whether your winter travels will be in the Caribbean on a cruise or in the Wind River Range on a trek, enjoy and stay healthy.  In either place, be sure to wash your hands!

Tuesday, August 7, 2012

"Sports Drinks" and the backcountry

The estimable British Medical Journal has just published a provocative expose on the "sports drink" industry.  You know the stuff:  Powerade, Gatorade, etc.  As you're watching the Olympics, no doubt you've caught some screen shots of competitors drinking them and have seen their ads.

The theory behind these products is deceptively simple:  Dehydration leads to decreased athletic performance.  Salts are lost along with water during exercise.  Exercise requires caloric expenditure.  Voila!  Along come products with a perfect balance of water, salt, and carbohydrate.  The products come with an impressive resume of "clinical trials" attesting to their benefit, and are endorsed by a number of athletic organizations.

At first, I wasn't sure that this expose would be of interest to the wilderness traveller.  As a little experiment, however, I checked out "sports drinks" and "electrolyte drinks" on a few of my favorite on-line retailers of backpacking gear:  Campmor, EMS, and REI.  All offer a wide variety of powdered and tablet forms of these for the camper.  EMS, for example, features "GU Electrolyte Brew".  The EMS website claims that the product will "get your system back in balance" and "help you go longer".  Hum...

I urge you to read this report yourself.  It is in the July 18, 2012 issue of the BMJ, which should be available in many university libraries.  Online access is available at:

http://www.bmj.com/content/345/bmj.e4737.pdf%2Bhtml

The quick summary of the report is not pretty.  The real science behind these drinks is almost completely lacking.  Company claims to the contrary, when the medical journal attempted to review these studies it found virtually none of sufficient methodologic rigor to withstand scrutiny.  The few which had been published in journals were overwhelmingly published in very low-impact journals with clear ties to the sports drink industry.  For example, the journal Medicine and Science in Sports and Exercise is published by an organization with long-standing financial relationships to Gatorade, and has a number of "Gatorade affiliated scientists" on its editorial board.

The promoters of these products have largely "invented" dehydration as a common problem in endurance exercise, and have encouraged the promulgation of completely unsubstantiated recommendations for overhydration during sports.  Unfortunately, these are filtering down to youth sports.

Is there a problem with all this?  There is.

First of all, sports drinks contain calories--hundreds per serving.  This may not be a problem for truly active folks, but the average person drinking Gatorade isn't Usein Bolt!  By marketing an image of health and vigorous exercise, companies fool the average (mostly sedentary) user into thinking that he is drinking something other than, essentially, sugar water with a dash of salt.

More importantly, however, the widespread emphasis on sports hydration over the past few years is likely fueling a real problem:  hyponatremia.  This condition, which is basically a fancy name for water intoxication, is a serious cause of death and disability in some endurance sports.  There are at least 16 recorded deaths and over a thousand critical illnesses in marathon running alone attributable to hyponatremia.  Although sports drink makers insist that the salt content of their beverages avoids this complication, this is not correct.  Indeed, an actual scientific study of marathon runners has shown that the volume of liquid consumed, independent of its composition, is the major factor in causing hyponatremia. 

Millions of years of evolution have led to our bodies having an excellent mechanism for preventing dehydration.  The mechanism is "thirst".  Pay attention to it.  When it calls, have a drink.  Of water.  Right from the stream!

Wednesday, May 23, 2012

Just when I thought I'd heard everything....

The things folks do in the backcountry never cease to amaze me.  Check out this recent item from the Albany Times Union regarding some guys who became lost recently in the Adirondacks:

http://m.timesunion.com/tu/db_109215/contentdetail.htm?contentguid=QCPcA8PG&full=true#display

Peeing on each other to stay warm?  Yikees!

Of course, equally important to keeping warm is keeping dry.  This was obviously a counterproductive strategy.  Since their names were used in the article, I suspect that most of their friends have come across this news item.  At least they survived.

This brings to mind an occasional question about hypothermia--is it better to hold onto urine because it is warm, or empty your bladder? (Urinating on another camper is not usually one of the choices.)  The correct answer is that it makes no meaningful difference.  Urine is only warm because the body keeps it heated, so in theory less heat would expended if there were less urine in the bladder to heat.  In the big scheme of things, however, the impact of this on total heat balance would be trivial. More importantly, most people with serious hypothermia are somewhat dehydrated, so the most important thing is to be drinking enough that it isn't possible to hold it! 

Just don't pee on your friends.

Monday, April 9, 2012

The "Trans Adirondack" Route

Erik Schlimmer is a good friend with whom I have guided in Alaska previously. He is one of the few people who approach me in the volume of untreated Adirondack water he has consumed without ill effects!

Erik has a number of "firsts" under his wilderness belt, most of which I would have no desire to duplicate. (Canoeing the lower Hudson? Yuck!) His most recent, however, looks like a lot of fun. He has outlined a 235 mile route which traverses the Adirondack Park. He will be releasing a guidebook early next year (Blue Line to Blue Line) which details the route.

This summer, Erik is working with one of his former students to produce a documentary which will coincide with the launch of his book. Information on the route and the planned documentary is available at:

http://www.kickstarter.com/projects/1559964226/trans-adirondack-route-documentary