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Backpackers, Don't Listen To Slate: Science Does Support Stream Water Treatment

The risk might be low, but the alternative is maybe months of debilitating diarrhea. It’s your choice. Photo Credit: Timothy Epp/Shutterstock

While we like to think of ourselves as rational creatures, there’s no doubt that human beings are actually quite awful at assessing risk. So I can understand why Ethan Linck thought to contextualize the risk of drinking from backcountry streams with data. “Life is triage, a constant series of negotiations between risks of varying severity,” he wrote. “And how we talk about those risks matters.”

Yes, it does—which is exactly why his piece in Slate last week was so damaging. It was anything but a careful, scientific evaluation of the risks. Wes Siler over at Outside Magazine already pointed out a myriad of issues with the article, but I want to zero in on the actual data, because Linck claimed to be looking at the matter scientifically. Instead, he cherry-picked sources to argue against doing one of the simplest things you can do to protect yourself from some truly awful diseases when you’re backpacking: treating your water.

Last week, @Slate published an article that said backpackers don’t need to filter stream water. That’s simply not true. https://t.co/8JJPQ6Rihj pic.twitter.com/UHa1mgmXeu

— Outside Magazine (@outsidemagazine) February 7, 2018

The Bad

Simply put: when you drink water straight from a stream, river, or lake, you have no idea what’s in it. And that’s bad, because, as epidemiologist Tara Smith, PhD, explained for SELF last month, it can be contaminated with all sorts of nasty things. “These include Giardia, a parasite found in streams and rivers that causes “beaver fever” in campers and hikers, and bacteria like Shigella and Campylobacter that can cause bloody diarrhea,” she wrote.

These organisms exist in waters because they exist in our digestive tracts and those of other animals. So anywhere that there’s poop near water, that water could contain pathogenic strains of Escherichia coli, Salmonella, Campylobacter, Aeromonas, Yersenia enterocolitica, Leptospirosis, Listeria, or Vibrio, in addition to a suite of viruses and protozoan parasites like Giardia and Cryptosporidium. Some of these bugs only cause short-term, if severe, gastrointestinal distress. Others can cause issues that last for weeks, months, or even years.

“Even water that appears pure or clear can be contaminated by people or animals,” explains Jonathan Yoder, MPH, who is deputy chief of CDC’s Waterborne Disease Prevention Branch. I asked Yoder and his colleague, epidemiologist Kathy Benedict, PhD, what their thoughts were on the bold claim that science doesn’t support backcountry water treatment (that “the scientific evidence shows that this mandate [to filter water] rests on a shaky foundation”). Needless to say, they disagreed.

Because appropriately assessing risk requires a clear understanding of what’s at stake, it’s important to point out that with many of these pathogens, we’re not just talking inconvenient cases of the runs. The gastrointestinal symptoms that can occur—intense diarrhea, vomiting—aren’t easily managed by hikers on long trips in the middle of nowhere. “If they have an acute situation, it can actually be quite scary,” says Benedict, “especially if they’re out there by themselves, because they can get themselves into a lot of trouble very quickly.” And people, even people with rapid access to medical care, do sometimes die.

A 3D rendering of Giardia lamblia a protozoan parasite that can set up shop in your intestines and be pretty hard to remove. Image Credit: fotovapl/Shutterstock

A 3D rendering of Giardia lamblia a protozoan parasite that can set up shop in your intestines and get pretty comfortable there. Image Credit: fotovapl/Shutterstock

To his credit, Linck doesn’t exactly downplay the dangers of Giardia or other potential pathogens. But, he argues, that their dangers are not important. It’s totally ok to drink any water you might come across while backpacking (or as the title says, “You Don’t Need to Filter Your Stream Water”) because: “The idea that most wilderness water sources are inherently unsafe is baseless dogma, unsupported by any epidemiological evidence”.

It’s a lovely little straw man that he immediately sets to tearing apart. To paraphrase his argument: everyone says most water is chock full of terrible things. So as long as most water sources are safe, then you’re good to drink from any stream. And look! Here’s a study that says feces contamination was only found in a minority of the sites tested! And one by… a magazine… that says the same thing!

But let’s take a quick look at those sources. The first study examined lakes and streams in Kings Canyon, Sequoia, and Yosemite National Parks looking for feces-associated bacteria (fecal coliform), because where there’s feces, there could be something dangerous in the water. And they found it at 22 of the 55 chosen sites. So yes, that’s a minority, but it’s 40%—and of those, ~16.3% (9) had “higher levels”. And that magazine one? Well, Linck didn’t directly link to it, but Google is a wonderful thing. They surveyed seven locations three times throughout the year for parasites, five of which had at least one test come up positive for either Giardia or Cryptosporidium—just over 71%. But, they claimed, only one had close to dangerous levels. That’s still 1/7—or a little over 14%. It’s a shame that Linck didn’t include the percentages in his article, because for all his talk about appropriately assessing risk, he doesn’t give the information needed to actually do that.

And those studies—if you can really call the magazine investigation that—were conducted in the early 2000s, each testing a miniscule fraction of the waters that are accessed by U.S. hikers every year on a handful of occasions. There is other research he could have cited—like this 2009 study from Georgia, which found 79% of water samples from rivers and streams in southern Georgia over a year tested positive for Salmonella. Or this 2011 one which found “Salmonella, Campylobacter, Staphylococcus aureus, Vibrio vulnificus, and V. parahaemolyticus were widespread—12 of 22 O’ahu streams had all five pathogens.” And even if he didn’t want to count Hawai’i (though it is a U.S. state), then he could have cited this 1987 study in Washington instead, which found Campylobacter at ~36% of sites tested (5 of 14), including a mountain stream. According to the authors, “Campylobacter spp. are widely distributed in central Washington and are present in a variety of aquatic habitats including ponds, lakes, and small mountain streams, which ranged in elevation from 1,460 to 5,400 feet above sea level.”

Even if he just looked at other papers by the same authors as his study, he’d have found this 2004 study, which found that out of 31 backcountry sites, 45% tested positive for fecal coliforms, and just over 25% had high levels. Or this 2006 study which found fecal coliform at 1/15 sites used by backpackers (~6.7%). Or this one from 2008, which found coliform bacteria in 18% of human day use areas, and 14% of backpacker sites. But really, they all tell the same story: one-in-five to one-in-ten sites test positive, which means they might get you sick if you drink their water untreated.

Even the cleanest water can harbor these pathogens. Photo Credit: michaeljung/Shutterstock

Even the cleanest water can harbor these pathogens. Photo Credit: michaeljung/Shutterstock

Of course, even counting every sample in every study I just mentioned, only a tiny fraction of potential hiker drinking sources have been tested, so a lot remains unknown. And because these pathogens are associated with human and animal activities, their presence can be as transient as the wildlife. None of these studies really explains just how variable the risks can be, which is actually something that was noted in that Backpacker article:

“Risk in this area is very hard to quantify,” explains Tod Schimelpfenig, curriculum director for the Wilderness Medicine Institute, of the Wyoming-based National Outdoor Leadership School. “Sample a creek at one point in time and you could have a flush of organisms from an animal that just defecated upstream. Sample it 20 feet upstream 2 hours later and you could find nothing. The risk of drinking untreated water in the wilderness depends entirely on when and where.”

If any conclusions can be drawn, it’s that not all areas carry the same risks, and that even remote streams can harbor dangers. Even if you could assume something like 10%-20% of water sources test positive for fecal contamination (and thus may get you sick)—then, yeah, technically, only a minority of sites are ‘unsafe’ (not that anyone was arguing that most of them were). But just imagine going to a buffet and seeing a sign that said “Nine out of ten of our menu items tested negative for fecal bacteria!”—would you want to eat?

Yoder wouldn’t. Of course, he’s had Giardia before, so he knows exactly what he’d be risking. “I think after you have a one of the more severe diarrheal infections—and I speak from my personal experience—I think you understand that even though you know ninety-nine times out of a hundred, if you drank from that water source, you’re not going to get infected, it’s worth it to protect yourself for that one percent chance.”

The Ugly

While Linck’s prevalence analysis is a straw man at best, he goes on to claim something that’s patently false: that “research to date has failed to demonstrate any significant link between wilderness water consumption and infection with these threats.”

Again, he turns to decades-old data, citing a 1993 study where only 5.7% of backcountry travelers in California’s Sierra Nevada had Giardia, and none of them felt sick. Mind you, he failed to note that more than half of the travelers did purify their water, so they’d have been protected from the parasite. And he didn’t mention that 16.7% of them did return with gastrointestinal illnesses—they just weren’t that one. Then he cites a survey of health departments and a meta-analysis from the same researcher looking at Giardiasis in the US, both of which found that the majority of cases came from non-wilderness sources. But again, that’s a straw man—no one was arguing that backcountry streams were the main source of Giardia infections. That’s like saying most house fires aren’t started by deep-frying a frozen turkey, so by all means, it’s totally safe! And Giardia seems like a very specific hill to die on. What about the myriad of other possible disease agents? Nothing about Campylobacter, Leptosporosis, Shigella, Norovirus, E. coli—and the list goes on.

Heck, if we’re going back decades for our data, why not mention this 1984 study that found people who drank untreated water taken from a stream, river, or lake were about ten times as likely to have Campylobacter jejuni infections than their neighbors who didn’t? Or this 1983 one, which found both Campylobacter jejuni (23%) and Giardia lamblia (8%) in people who came back from Grand Teton National Park with diarrheal disease. They also found that Campylobacter occurred “most frequently in young adults who had been hiking in wilderness areas and was significantly associated with drinking untreated surface water in the week before illness” [emphasis mine]. They even isolated Campylobacter from one of the mountain streams suspected as a source.

You might not realize what has happened upstream. Photo Credit: Ruud Morijn Photographer/Shutterstock

You might not realize what has happened upstream. Photo Credit: Ruud Morijn Photographer/Shutterstock

Or, Linck could have looked at more recent data—like this 2016 study of Giardia outbreaks in the US from 1971-2011, which found six linked to rivers or streams. Or this 2017 study looking at waterborne illness outbreaks in the US in 2013 and 2014, which found another six outbreaks of Giardiasis affecting 91 people which were “caused by ingestion of water from a river, stream, or spring.” And these are just outbreaks where multiple people got infected and sought treatment—they don’t look at the countless individual cases, many of which are not reported to authorities because we don’t go to the doctor for diarrhea unless it’s really bad (diarrheal diseases are notoriously underreported). And it can take a week or more for signs to show in some cases, so you might not even connect your bowel troubles to your recent hiking experience.

Linck does mention a camping related outbreak of Giardia from 1976 which was thought to be waterborne. But he claims, citing a 2004 editorial, that the analysis was wrong. Instead, “the afflicted campers failed to properly wash their hands after using the bathroom.”

“I don’t disagree with the author that, in addition to water treatment, there are other very important things that people can do to stay safe in the backcountry,” says Yoder, “and those include the proper disposal of waste and using good hand-washing hand hygiene, particularly after using the bathroom and before eating before preparing food.”

By pointing to hand-washing, Linck is basically making the turkey argument again; the fact that poor hand-washing also causes outbreaks, maybe even more of them or worse ones, doesn’t mean that drinking untreated water never causes any.

In fact, the idea that every case reported from backpackers comes from poor hygiene instead of streams is not just hard to believe—it’s unsupported by the science. “We have data that there is a risk from backcountry water,” says Yoder. “There certainly are waterborne disease outbreaks—more than twenty that have been reported to CDC—where consumption of water in the backcountry has been linked to illness.”

The Good

The simple fact is, if you drink untreated water, you’re taking on a non-negligible amount of risk. The good news is that risk—however large or small it may be—can be mitigated. And no, not just with fancy filters.

Linck is quick to chastise the outdoors industry for “claiming the average hiker or camper needs a $99.95 microfilter pump to avoid illness and death.” Maybe expensive devices are talked up by their makers (are we really blaming companies for wanting to sell their products?), but luckily, the people that study waterborne diseases and pretty much everyone who has had any kind of training in wilderness survival will tell you that decent water treatment can be done a myriad of ways, many of which are dirt cheap. “Boiling water is one of the most effective ways to inactivate parasites, viruses, and bacteria,” Yoder notes. Or you could get chlorine dioxide tablets that treat a liter of water for about $0.50 each.

Boiling water goes a long way if you're going to be off the grid for awhile. Photo Credit: AlisLuch/Shutterstock

Boiling water goes a long way if you’re going to be off the grid for awhile. Photo Credit: AlisLuch/Shutterstock

Ultimately, the choice of what you drink is yours and yours alone. The point of this isn’t to shame you if you choose to drink untreated stream water—it’s to provide you with what is known from scientific research, rather than hyperbolic rhetoric. Now that you have the information, you can decide to trust in your ability to pick safe water sources, or to take precautions.

As for me, I’ll go with the instincts of the guy who studies these things. Yoder has analyzed the data, and his choice is simple: “I think that having that extra level of protection and making your water safer is worth it, because you’re trading that for more enjoyment out of the backcountry and not having to experience an illness that, at least temporarily, is pretty debilitating.”

It seems like the overwhelming majority of Slate’s twitter followers agree. (Ah, the ratio…)

Actually backpackers, you don’t need to filter stream water. Fresh water is fine to drink: https://t.co/0AqaJFtgKZ pic.twitter.com/QE6NgjZbI1

— Slate (@Slate) February 1, 2018

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10 Ways Space Changes the Body

Former astronaut Mark Kelly (left) poses with his identical twin brother, astronaut Scott Kelly (right). As part of NASA’s Twins Study, Scott spent nearly a year in space, while Mark stayed here on Earth. This gave researchers a chance to study the health effects of long-term spaceflights. (Credit: NASA)

Scott and Mark Kelly are identical twin brothers. Though that alone does not make them unique, what does is the fact that they are also both astronauts. In order to take advantage of the Kellys’ unique situation, NASA scientists decided to conduct a detailed study on the twins, aimed at unraveling how nature versus nurture plays out in space.

As part of NASA’s Twins Study, researchers collected biological samples from each of the Kellys before sending Scott to the International Space Station for a year starting in March 2016. Meanwhile, his brother Mark, who retired as an astronaut in 2011, remained on Earth to serve as the control subject. By analyzing how each twins’ biological markers evolved during the mission, the researchers learned a great deal about how the human body reacts — both physically and mentally — to extended periods of spaceflight.

The NASA Twins Study is made up of ten distinct research projects, which all focus on different aspects of the human body. And last month, after nearly two years of study, the ten separate research teams confirmed their preliminary findings (which were initially released in 2017), as well as presented details on their postflight follow-up results.

Later this year, the findings for each of the various projects will be integrated together and released as one summary paper, which will be followed by several companion papers focusing on the individual studies. In the meantime, here is a summary of the most recent findings for each of the research projects that were carried out as part of the Twins Study.

#1 – Telomeres get longer during spaceflight

Telomeres are the caps that shield the ends of our chromosomes, protecting DNA strands from damage and degradation. In a study led by Susan Bailey of Colorado State University, researchers tracked the length of each twins’ telomeres before, during, and after Scott’s yearlong spaceflight.

The researchers found that Scott’s telomeres significantly increased in length while he was in space, which was not the case with his Earth-bound brother Mark, whose telomeres remained relatively stable. Previous research has shown that longer telomeres are associated with fewer age-related problems.

Though Scott’s telomeres were found to lengthen while he was in space, postflight measurements showed that the telomeres underwent rapid shortening within about 48 hours of landing back on Earth. Eventually, they returned to their preflight lengths. The team believes that the temporary lengthening of Scott’s telomeres could be a side effect of his rigorous exercise routine and restricted, low-calorie diet.

#2 – Decreased body mass and increased folate in orbit

A study conducted by Scott M. Smith of the NASA Johnson Space Center monitored the biochemical profiles of each twin to identify any changes. To do this, his team tracked the brothers’ heights and weights and analyzed their blood and urine samples throughout the duration of the mission.

The researchers not only found that Scott’s body mass noticeably dropped during his time in space, but also that his levels of folate — a beneficial form of folic acid often used to treat anemia — significantly increased.

Much like Bailey’s findings on telomere lengthening, Smith believes the drop in body mass and increase in folate could simply be a result of eating healthier and exercising more often.

#3 – Mentally fit in space, foggy back on Earth

Mathias Basner of the University of Pennsylvania conducted a study that monitored the cognition of both twins over the duration of the mission. By requiring each twin to perform ten different cognitive tests multiple times (preflight, inflight, and postflight), the researchers were able to track how spacefaring Scott’s mental faculties were affected by microgravity.

Using the preflight test results as a baseline, Basner found that Scott’s yearlong mission aboard the ISS did not significantly impair his cognitive abilities while inflight. However, when Scott returned to Earth, the researchers did detect a more pronounced decrease in his speed and accuracy on cognitive tests.

The researchers believe that readjusting to Earth’s gravity may be the cause of Scott’s postflight cognitive decline, but further study is needed to confirm. They also point out that Scott’s performance could have suffered when returning to Earth as the result of a very hectic postflight schedule.

#4 – Flu vaccine stimulates immune system, even in space

To investigate how space affects a human body’s immune system, Emmanuel Mignot of Stanford University conducted a study that introduced the flu vaccine to Scott and Mark on two separate occasions spaced one year apart — during preflight and postflight.

On both occasions, after the vaccines were administered, the twins displayed similar increased immune cell responses to the flu. When the human body is vaccinated against the flu, weakened or dead flu virus cells are injected into the bloodstream. This triggers the body to produce antibodies that seek out and destroy the viral cells, thus preventing any healthy flu cells from multiplying and overwhelming the body’s defenses.

Because the twins showed similar immune responses to both vaccinations, the researchers concluded that being in space does not prevent the flu vaccine from producing the desired immune response.

#5 – Inflammation increases while in space

Mike Snyder of Stanford University carried out a study that investigated whether or not space affects inflammation in the human body. Using blood tests to measure lipids (fats) and cytokines (proteins in the blood that serve as well-known indicators of inflammation), Snyder was able to compare how the inflammatory responses of the brothers differed while Scott was in space.

In this study, the researchers found multiple lines of evidence suggesting that Scott’s body was more prone to inflammation in a microgravity environment than Mark’s was on Earth. For one, the researchers found that Scott had altered levels of a lipid panel taken in space, indicating increased inflammation in his body. The researchers also noted that a certain group of Scott’s cytokines were found to be elevated before the flight, and they remained elevated throughout the mission. Furthermore, another group of Scott’s cytokines spiked just after he returned to Earth. This group of cytokines remained elevated for six months.

Additionally, the study showed that Scott’s body experienced an increase in some proteins that are known to help regulate normal insulin activity. Since inflammation can cause insulin resistance, the increase in Scott’s proteins may have been a counter-measure executed by his body to help combat the insulin resistance associated with inflammation.

#6 – Space affects the microbiome

Inside of each of our guts lives a vast community of microorganisms, known as the microbiome, which plays an important role in our overall health. To study how living in a microgravity environment impacts the microbiome, Fred Turek of Northwestern University monitored the state of each twin’s microbiome before, during, and after the yearlong mission.

The researchers found that the microbiomes of both Scott and Mark were drastically different at all times throughout the project, but the differences were somewhat expected considering microbiomes are very sensitive to environmental variances such as diet and individual immunity. However, the researchers point out that Scott’s microbiome was different in space than it was preflight, displaying a decreased presence of one branch of bacteria known as Bacteroidetes. However, these changes did not persist upon Scott’s return to Earth.

Even though the study showed that Scott’s microbiome changed when switching settings between Earth and space, the changes that were observed were similar to those that would be expected if someone on the ground significantly modified their diet or was exposed to a new environment.

#7 – Spaceflight can trigger gene mutations

Chris Mason of Weill Cornell Medicine used the Twins Study as an opportunity to investigate how space travel can influence genetics. By looking for chemical changes in RNA and DNA through the use of whole-genome sequencing, the researchers showed that Scott experienced hundreds of unique gene mutations compared with his twin.

Though some distinct gene mutations were to be expected, even in twins, the sheer amount of changes surprised the researchers. A few of the gene changes, which were discovered only after Scott returned to Earth, were even found on cell-free DNA and RNA that was circulating in his bloodstream. The researchers believe that these gene changes resulted from the stresses of space travel, which can alter the biological pathways within cells, causing them to eject DNA and RNA. These free-floating DNA and RNA molecules can then trigger the production of new fats or proteins, or even turn specific genes on and off. Though 93 percent of the genes that expressed themselves differently while Scott was in space returned to normal postflight, the researchers found a subset of several hundred “space genes” that remained disrupted after his return.

Of the many gene-induced changes Scott’s body experienced, the researchers found five to be of particular relevance for future missions: (1) Hypoxia, which was likely caused by a lack of oxygen and a surplus of carbon dioxide; (2) Mitochondrial stress and increased levels of mitochondria in the blood, which suggests damage was done to the “power plants” of cells; (3) Telomere lengthening, DNA repair, and DNA damage, which could be a result of living a healthy lifestyle while constantly exposed to radiation; (4) Decreased collagen production, blood clotting, and bone formation, which was likely a combined result of living in microgravity and of fluids shifting around within the body; and (5) Hyperactive immune activity, which may be an effect of living in a new environment.

#8 – Living in space changes how genes are expressed

Similar to the previous project, Andy Feinberg of Johns Hopkins University conducted a study that tracked how each of the twins’ epigenetics (the way that genes express themselves) differed based on their environment.

In two separate populations of white blood cells, Feinberg found multiple regions of the genome where DNA methylation — the process responsible for turning genes on and off — had occurred. These chemical modifications to Scott’s genome were found near two interesting regions. One was close to a gene known to help regulate telomere growth, and another was found near a gene related to collagen production.

Although Scott did experience epigenetic changes during his time in space, the researchers found that the majority of changes were within the expected range of variability for his twin on Earth. However, the results related to telomere growth and collagen production are consistent with the findings of other Twins Study projects.

#9 – Artery walls thicken while in space

Stuart Lee of KBRWyle at NASA Johnson Space Center’s Cardiovascular and Vision Lab performed a study on how inflammation and oxidative stress (damage by free radicals in the air) can impact the structure and effectiveness of arteries. To do this, the researchers examined the twins’ arteries using ultrasound, as well as collected blood and urine samples throughout the mission.

Both during and immediately after the mission, the researchers found that Scott’s inflammation biomarkers were elevated and that the wall of his carotid artery was thicker than it was preflight. Neither of these changes were seen in Mark during his stay on Earth.

At this point, the researchers do not know whether the thickening of Scott’s carotid artery is a temporary and reversible adaptation to living in space, or if it is evidence of permanent and premature arterial aging. Further study is needed to put these findings into clearer focus.

#10 – Proteins that regulate fluids increase while in space

In order to investigate how spaceflight impacts the body’s ability to form and modify proteins, Brinda Rana of the University of California carried out a study that collected urine samples from Scott and Mark before, during, and after the mission. This allowed Rana to identify certain biomarker proteins that are associated with space-related bodily changes, such as muscle and bone loss, metabolic and cardiovascular changes, and the altered regulation of fluids within the body.

The researchers found that while Scott was in space, he excreted some proteins at different concentrations than his Earth-bound brother Mark. In particular, Scott had elevated levels of a protein called aquaporin 2, which helps form the pathways used to carry water through cell membranes in the kidneys. Because aquaporin 2 helps regulate how water is transported within the body, it also serves as a valuable indicator of a body’s overall hydration status.

Notably, the researchers also found that Scott’s increase in aquaporin 2 during spaceflight was correlated with higher levels of plasma sodium — an indicator of dehydration. Though further study is needed, the researchers believe that the increase in aquaporin 2 and plasma sodium may be tied to fluids shifting throughout Scott’s body while he was in a microgravity environment. This is important because, as has been documented with other space-bound astronauts, fluids tend to migrate to the head, causing visual impairment and intracranial pressure.

What’s next?

By taking advantage of an extremely unique opportunity, NASA’s Human Research Program has carried out the first genomic evaluation of the potential risks the human body faces during extended periods of spaceflight. While the results of NASA’s Twins Study are far from conclusive — the sample size is one set of twins and not every variable was strictly controlled for — the study does provide researchers with a wealth of data to guide future studies on the risks of human spaceflight.

As NASA said in a press release, “observations guide development of future hypotheses,” and NASA’s Twins Study has taken the first step to observing how our genomic blueprint is affected by long-term exposure to microgravity and an increased radiation environment. With the information collected as part of this medley of studies, NASA has the preliminary data it needs to inform countless more projects for years to come.

In the meantime, make sure to check back later this year when NASA releases its Twins Study summary paper, which will integrate the results from all ten of the individual studies. Shortly thereafter, each individual study will be releasing its own companion paper.

This post originally appeared in Astronomy.com.

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Chemicals in Non-Stick Pans May Contribute to Weight Gain

Uhoh: Those non-stick pans you love cooking with are often made with a chemical that could contribute to weight gain. (Credit: Shutterstock)

More than 38 percent of American adults and 17 percent of American children are obese. And while there are numerous ways to shed pounds, it’s often difficult for many people to keep them off. It turns out some common items regularly used by people across the world could be the culprit.

A study released Tuesday in PLOS Medicine suggests that perfluoroalkyl substances (PFASs) could be contributing to weight gain and lead to obesity. Since the 1950s, these environmental chemicals have been used in food packaging, non-stick cookware, stain resistant fabrics and carpets, water-repellent clothing, and even some cosmetics. These manmade compounds’ effects on humans aren’t well known, but past studies on animals have shown they may disrupt the endocrine system, or the collection of glands that produce hormones. PFASs have also been linked to cancer, immune issues and high cholesterol.

Down and Up

Over the course of two years, researchers put 621 obese and overweight men and women on energy-restricted diets and tracked their weights. Measuring the plasma concentrations of PFASs, they were able to gather metabolic information including body weight and resting metabolic rate (RMR).

Researchers found that those with higher levels of PFASs at the beginning of the experiment were associated with regaining the pounds they lost, especially in women. Participants lost on average 14 pounds (6.4 kg) in the first six months, regaining almost half of the weight throughout the study. The weight gain could be due to a decline of RMR over the first six months.

“These chemicals may lead to more rapid weight gain after dieting,” Qi Sun, co-author of the study, told the Guardian. “It is very hard to avoid exposure to PFASs, but we should try to. It’s an increasing public health issue.”

With that said, the authors can’t definitively link PFAS chemicals to the weight regain. Some potentially important influences weren’t measured including socioeconomic and psychosocial factors and potential relapses to prior diets weren’t considered. Still, the authors hope this study will lead to further research of environmental chemicals and their possible impact on obesity.

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Man's Chronic Pain Disappears After Vigorous, Cold-Water Swim

(Credit: Shutterstock)

Those polar plunge nuts—you know, the people who strip to their skivvies in February and jump into freezing water—might be on to something.

According to doctors from the United Kingdom, a 28-year-old man who had been complaining of persistent, post-operative pain was cured after jumping into incredibly cold water for a vigorous 60-second, intense swim. Roughly two months prior to his swim, the man had undergone an endoscopic thoracic sympathectomy procedure to treat his severe facial blushing. In this procedure, a portion of the sympathetic nerve trunk is destroyed to treat excessive sweating, blushing and Raynaud’s disease.

The operation went smoothly, but nagging, sharp pain in his chest continued for 10 weeks after the operation. Exercise and movement tended to make things worse, which was bad news for the patient, who has a devoted triathlete. Doctors tried analgesics and other means to control pain with limited success, and when things didn’t work, the patient took a leap of faith.

In a bold attempt to take his mind of pain, the patient decided to go for a swim in the coastal waters of a past triathlon competition. His route was along a rocky, jagged coastline; therefore, there was no dipping his toes in to acclimate to the water. The man had to jump from a rocky outcrop.

“I wasn’t sure if it would help the pain—I just wanted to do it—I thought at best it was a long-shot, but I was desperate to get some relief,” the man told doctors.

When his body slapped into seawater that was 52 degrees Fahrenheit, he had no choice but to swim for safety, or risk hypothermia. He told doctors:

“I initially thought, ‘Damn this is so cold I’m going to die!’ I just swam for my life. Once I was in the water, I had tunnel vision. For the first time in months, I completely forgot about the pain or the fear of shooting pains in my chest if I moved. My entire body tingled with the cold. I just knew if I didn’t keep swimming, I’d soon freeze. After a few moments I actually enjoyed it – it was just an immersive rush of adrenaline. I bet I couldn’t have felt my pain, even if I tried.”

The funny thing is, his pain never returned.

Doctors, of course, dug into the man’s case to see if there was any precedent, but they couldn’t find any in their survey of medical literature. No doubt, ice baths and pool therapy are commonplace in rehabilitation regimens, but swimming in bitter cold water to manage pain appears to be a new one.

The authors considered that this could just be a coincidence, and that there isn’t enough evidence to build a causal relationship between swimming, cold water and pain relief. Maybe it was the placebo effect. Maybe the shock of the water overwhelmed his persistent pain. But if that’s the case, why did the pain remain in remission long after the initial shock of jumping in the water passed? The doctors say they don’t have a clear explanation for why this man’s unorthodox therapy session worked. In a report published Monday in the British Medical Journal, doctors wrote:

“It is possible that the high range of movement involved in swimming manipulated tissues surrounding peripheral nerves in such a way as to mechanically free adhesions and resolve pain. Psychologically, ‘flooding’ with intense activity may have abruptly broken maladaptive cycles of movement avoidance and withdrawal from exercise and its associated pain relieving properties.”

This case, though it may be an outlier, challenges conventional thinking about postoperative treatment and pain management. The doctors say the takeaway here is that more physically aggressive rehabilitation programs may be warranted for certain patients; of course, not everyone can or should jump into bone-chilling water to alleviate postoperative pain. Of course, they’d like to conduct more research into the analgesic effects of forced, cold-water swimming.

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