Friday, September 11, 2015

More on the dangers of water

Just a day after posting the previous comment, a couple of very pertinent publications came out.

First of all, Wilderness and Environmental Medicine, a wilderness medicine peer-reviewed journal, published a case report of a hiker in the Grand Canyon who appeared to have died from complications of hyponatremia.  She was a 47 year old otherwise healthy woman, who hiked about 10 kg, and was described as drinking "a large amount of water." She had a rapid deterioration in neurologic status, and had findings of brain swelling.  Her serum sodium concentration when measured in the hospital was lowish, although not as low as one would have expected from the description of her medical event.  She had, however, been receiving some intravenous fluid prior to reaching the hospital. 

I am not totally convinced by this case report, largely because of missing data, but the explanation is plausible.  In any case, it is a reminder of what I said earlier:  If one is not thirsty, don't drink!

(This article is not yet available online, but the citation is Wild Environm Med 2015;26:371-374.)

 A second article, actually much more interesting, was also published in the New York Times:

This article, by a physician, reviewed the recent emphasis on increasing water drinking and subtle dehydration and found it bogus.  He reiterated the importance of paying attention to one's own thirst mechanism. 

Wednesday, September 2, 2015

Can water be bad for you?

I am not talking here about water borne illness--anyone reading my publications or blog posts knows my feelings about that!  I am, instead, focusing on problems related to the over-consumption of water from any source. Believe it or not, this is actually a growing problem.  It was nicely reviewed recently in an article in the New York Times:

The physiology here is actually quite simple.  When water is added in excess to the body, it dilutes the amount of sodium in the circulation, a condition called "hyponatremia."  Hyponatremia can cause a host of complications, including devastating and occasional fatal brain injury.

 Fortunately, the body has a couple very effective mechanisms to prevent over-consumption of water.  The first is our thirst mechanism.  Once one has drunk enough water to result in even very minimal hyponatremia, our thirst shuts off and there is simply no desire to drink any more.  Secondly, the kidneys are very good at excreting excessive water; this is why your urine looks so clear after drinking a lot of fluid.

Dangerous hyponatremia can result if we consistently over-ride our thirst mechanism and/or if the ability of the kidney to excrete excess water is impaired.  Vigorous athletic activity can result in both of these.  Hormones produced during exercise may impair kidney water excretion, and admonitions to drink heavily during sport may push us even when our thirst says "no more!"

Most of the reports of this condition have been during endurance sports such as marathon running.  I have not heard of well-documented cases occurring during conventional backcountry travel or hiking. 

One of the lessons of this subject is the importance of listening to one's body.  Fear of dehydration has often led to the admonition for athletes to drink even if they are not thirsty.  This is probably a mistake.  Mild dehydration may impair athletic performance a bit (although even that is debatable), but is rarely fatal.  Probably the best advice is simply pay attention to one's feelings.  If you are thirsty, drink.  If you aren't, don't. 

Thursday, December 11, 2014

Ebola in the Wilderness

Yup.  You read that right.

It was bound to happen.

With all the hullabaloo in the media about the risk of Ebola taking hold in the US "homeland", it was only a matter of time before some started fretting about a participant in an organized camping program or wilderness trek developing the disease.

Over the past few weeks, I have had emailed questions, participated in a discussion regarding the agenda at an upcoming outdoor education meeting, and attended a council meeting--all of which involved the question of whether outdoor education programs should have contingency plans for Ebola.

Gimme a break!

There is no questioning the fact that Ebola is a monumental crisis, a health problem of unimaginable severity with the potential for destabilizing a huge part of Africa.  Its victims die horrible deaths.

Having said that, Ebola will never be anything more than a blip on the screen of health problems in developed areas such as the US.  Its spread depends upon living conditions, health care practices, and severe poverty.  As the past few months have shown, despite some well-publicized imported cases, the disease simply has not taken hold--exactly as the experts (decried by politicians, of course) predicted.  I wrote a piece about this in the Syracuse newspaper:

 There are plenty of things to worry about regarding Ebola, but someone coming down with it in a tent in the North American backcountry is not one. 

As much as I would like simply to laugh this off, there are two things about this which really bother me.

The first is the pitifully narcissistic way in which we look at threats.  Rather than worrying about the fate of hundreds of thousands of unfortunates living in daily fear of this disease, we argue about how it should be handled in US airports.  Rather than aiding local health care workers in areas which are dealing with Ebola every day, we corner the market on protective gear to be stored in hundreds of American hospitals which will never see a case.  "Just in case."

The second is a theme which runs through a lot of my writings on wilderness health and safety.  What is it that seems to cause some wilderness educators to become infatuated with "problems' which are either nonexistent or trivial (wilderness water quality, Ebola), while ignoring issues of demonstrably greater importance (immunizations, hand sanitation)?  

Go figure. 

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:

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:

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: 

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:

I was recently interviewed for a program ("Health Link") discussing the health benefits of wilderness travel.  The link to the interview is:

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 (, there have been a number of very high profile outbreaks of intestinal infection on some luxury liners:

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:

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!