There are disinfection byproducts in tap water. What happened when Brita, PUR, ZeroWater, and refrigerator water filters were put to the test? 

Though many distrust the safety of tap water, a study of 35 brands of bottled water did not find them to be necessarily safer, cleaner, or of a higher quality than water straight out of the faucet. How much is that saying, though? Two studies published in the 1970s “changed forever the earlier perspective that drinking water safety was only about waterborne disease.” In fact, it was our fight against microbial contaminants that led to a new kind of contamination—in the form of disinfection byproducts.  

The two landmark papers in 1974 solved the mystery of the source of chloroform in drinking water: We met the enemy, and he is us. The chlorination of drinking water—“disinfection [that] is crucial for maintaining the microbiological safety of water”—was interacting with natural organic matter from the water’s source and creating chlorinated compounds that can not only result in off-flavors and smells but also pose a potential public health risk. More than 600 disinfection byproducts have been identified so far. 

After decades of research into the matter, it appears that the life-long ingestion of chlorinated drinking water results in “clear excess risk” for bladder cancer. There is also some evidence of increased risk of certain types of birth defects, but most of the concern has focused on the bladder cancer link. Forty years of exposure may increase your odds of bladder cancer by 27 percent. The Environmental Protection Agency estimated that 2 to 17 percent of bladder cancer cases in the United States are due to these disinfection byproducts in drinking water. However, this assumes the link is one of cause and effect, which has yet to be firmly established. 

The best way to reduce risk is to treat the cause. Countries could prevent the formation of disinfection byproducts in the first place through the better initial removal of source water’s “natural organic matter” (what my grandmother would have called schmutz). Some countries in Europe, such as Switzerland, the Netherlands, Austria, and Germany, have newer, well-maintained drinking water systems that can distribute tap water free from residual disinfectants, but the cost to upgrade the infrastructure of even a small city in the United States could run in the tens of millions of dollars. As the tragedy in Flint, Michigan, revealed, we seem to have trouble keeping even frank toxins out of the tap. 

Nearly 40 percent of Americans use some sort of water purification device. I look at the comparisons of these devices in my video Is It Best to Drink Tap, Filtered, or Bottled Water?. Tap water from Tucson, Arizona, was pitted head-to-head against two of the most common purification approaches—pour-through pitchers and refrigerator filters. As you can see in the graph below and at 2:53 in my video, both fridge filters (GE and Whirlpool) did similarly well, removing more than 96 percent of trace organic contaminants, and edging out the three pitcher filters. ZeroWater caught 93 percent, and PUR pitchers got 84 percent. By the time the filters needed to be replaced, Brita was only catching 50 percent. A similar discrepancy was found between filters from PUR and Brita tested specifically against disinfection byproducts. They both started out about the same at the beginning, but by the end of the filter’s life, PUR appeared to do better, as you can see below and at 3:15 in my video. Reverse osmosis systems can work even better, but the cost, water waste, and loss of trace minerals don’t seem worth it.  

As you can see below and at 3:40 in my video, the annual cost for purifying your water with a pitcher or fridge filter was calculated to be about the same, at only around a penny per cup—with the exception of the ZeroWater brand, which is up to four times more expensive. 

I always figured the “change by” dates on filters were just company scams to get you to buy more replacements, but I was wrong. Because I drink filtered water mostly just for taste, I used to wait until the water started tasting funky. Bad idea. Not only do the filters eventually lose some of their removal capacity, but bacterial growth can build up inside them, resulting in your “filtered” water having higher bacterial counts than water straight out of the tap. You’d be actually making your water dirtier rather than cleaner, so it is important to replace filters regularly. 

As an aside, I used to think the same about the advice to change your toothbrush every three months. Which Big Brush executive thought that one up? But, no, I was wrong again. Toothbrushes can build up biofilms of tooth decay bacteria or become breeding grounds for bacteria to flume into the air with each toilet flush before going back into our mouths. Fun fact: A single flush can spew up “millions of bacteria into the atmosphere” that can settle on your nice, moist toothbrush. The good news is that rather than buying new brushes, you can disinfect the head of your toothbrush with as little as a ten-minute soak in white vinegar or, even more frugally, vinegar diluted by half with water.  

Hydration is important. See related videos below for more information. 

Avoiding waterborne pollutants if possible is also important. See my videos Lead in Drinking Water and Friday Favorites: Benefits of Turmeric for Arsenic Exposure. 

How Many Glasses of Water Should We Drink a Day? Watch the video to find out. 

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Advisories telling pregnant women to cut down on fish consumption may be too late for certain persistent pollutants. 

If you intentionally expose people to mercury by feeding them fish (like tuna) for 14 weeks, the level of mercury in their bloodstream goes up, as you can see in the graph below and at 0:14 in my video Avoiding Fish for Five Years Before Pregnancy. As soon as they stop eating fish, it drops back down such that they can detox by half in about 100 days. (So, the half-life of total mercury in our blood is approximately 100 days.) Even if you eat a lot of fish, within a few months of stopping, you can clear much of the mercury out of your blood. But what about your brain? 

The results from modeling studies are all over the place, providing “some extreme estimates (69 days vs. 22 years).” When put to the test, though, autopsy findings suggest the half-life may be even longer still at 27.4 years. Once mercury gets in our brains, it can be decades before our body can get rid of even half of it. So, better than detoxing is not “toxing” in the first place. 

That’s the problem with advisories that tell pregnant women to cut down on fish intake. For pollutants with long half-lives, such as PCBs and dioxins, “temporary fish advisory-related decreases in daily contaminant intake will not necessarily translate to appreciable decreases in maternal POP [persistent organic pollutant] body burdens,” which help determine the dose the baby gets. 

Consider this: As you can see in the graph below and at 1:32 in my video, an infant may be exposed to a tumor-promoting pollutant called PCB 153 if their mom ate fish. But if mom ate only half the fish or no fish at all for one year, levels wouldn’t budge much. A substantial drop in infant exposure levels may only be seen if the mom had cut out all fish for five years before getting pregnant. That is the “fish consumption caveat.” “[T]he only scenarios that produced a significant impact on children’s exposures required mothers to eliminate fish from their diets for 5 years before their children were conceived. The model predicted that substituting produce for fish would reduce prenatal and breastfeeding exposures by 37% each and subsequent childhood exposures by 23%.” So, “a complete ban on fish consumption may be preferable to targeted, life stage–based fish consumption advisories…” 

If you are going to eat fish, though, which is less polluted—wild-caught or farmed fish? In a recent study, researchers measured the levels of pesticides, such as DDT, PCBs, polycyclic aromatic hydrocarbons, and toxic elements, such as mercury and lead, in a large sample of farmed and wild-caught seafood. In general, they found that farmed fish were worse. Think of the suspect as farmed and dangerous. The measured levels of most organic and many inorganic pollutants were higher in the farmed seafood products and, consequently, so were the intake levels for the consumer if such products were consumed. For example, as you can see in the graphs below and at 3:09 in my video, there was significantly more contamination by polycyclic hydrocarbons, persistent pesticides, and PCBs in all of the farmed fish samples, including the salmon and seabass (though it didn’t seem to matter for crayfish), and the wild-caught mussels were actually worse. If you split adult and child consumers into those only eating farmed seafood or only eating wild-caught seafood, the level of pollutant exposure was significantly worse with the farmed seafood.  

Overall, the researchers, who were Spanish, investigated a total of 59 pollutants and toxic elements. They concluded: “Taking all these data as a whole, and based on the rates of consumption of fish and seafood of the Spanish population, our results indicate that a theoretical consumer who chose to consume only aquaculture [farmed] products would be exposed to levels of pollutants investigated about twice higher than if this theoretical consumer had chosen only products from extractive fisheries [wild-caught fish].” So, when it comes to pollutants, you could eat twice the amount of fish if you stuck to wild-caught. That’s easier said than done, though. Mislabeling rates for fish and other seafood in the United States are between 30 and 38 percent, so the average fraud rate is around one in three.  

In my previous video on this topic, How Long to Detox from Fish Before Pregnancy, I mentioned a study that suggests detoxing from fish for one year to lower mercury levels, but other pollutants take longer to leave our system. 

For optimum brain development, consider a pollutant-free source of omega-3 fatty acids. Check out Should Vegan Women Supplement with DHA during Pregnancy?. 

Aside from pollutants, there are other reasons we may want to avoid excessive amounts of animal protein. See Flashback Friday: The Effect of Animal Protein on Stress Hormones, Testosterone, and Pregnancy.

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What are the effects of chewing gum on hunger and appetite?  

“Horace Fletcher,” proclaimed one of his obituaries in 1919, “taught the world to chew.” Also known as the “Great Masticator,” Fletcher was a health reformer who popularized the idea of chewing each mouthful more than 32 times—“once for every tooth.” It wasn’t put to the test, though, until nearly a century later. In that study, participants were told to eat pasta until they felt “comfortably full” and were randomized to chew each mouthful either 10 times or 35 times before swallowing. The subjects were told the study was about the effects of chewing on mood, but that was just a ruse. The researchers really wanted to know whether prolonged chewing reduced food intake. And, as it turned out, those who chewed more felt full earlier than those who chewed less, such that they ended up eating about a third of a cup less pasta overall. 

If chewing suppresses the appetite in some way, what about chewing gum as a weight-loss strategy? As I discuss in my video How Many Calories Do You Burn Chewing Gum?, an article entitled “Benefits of Chewing Gum” suggested as much by saying that it “may be a useful behavior modification tool in appetite control and weight management,” but it was co-written by the executive director of The Wrigley Science Institute and a senior manager at the Wm Wrigley Jr Company. Why don’t we see what the unbiased science says? 

Big Gum likes to point to a letter published in 1999 in The New England Journal of Medicine. In it, Mayo Clinic researchers claimed that chewing gum could burn 11 calories an hour. Critics pointed to the fact that they didn’t really test “typical” gum chewing; they instead tested chewing the equivalent of four sticks of gum “at a very rapid cadence.” Specifically, the participants were told to chew at a frequency of exactly 100 Hertz (Hz) “with the aid of a metronome” for 12 minutes. That seemed to burn 2.2 calories, hence, potentially 11 calories an hour. 

One might have had more confidence in the Mayo scientists’ conclusion had they not lacked a fundamental understanding of basic units. As defined by Merriam-Webster, hertz is a unit of frequency equal to one cycle per second, so 100 Hz would mean 100 chews per second. (That would be a very rapid cadence!) If it’s true that 11 calories may be burned an hour, though, that means you could burn more calories actively chewing gum while sitting in a chair than you would if you weren’t chewing gum while upright at a standing desk. 

In fact, as you can see in the graph below and at 2:24 in my video, chewing one small piece of gum at your own pace may only burn about three calories an hour, which would approximate the calorie content of the sugar-free gum itself. However, chewing off the calories of a piece of sugar-sweetened gum might take all day. What about the purported appetite-suppressing effect of all that chewing, though? 

The results from studies on the effects of chewing gum on hunger are all over the place. For example, as you can see in the graph below and at 2:50 in my video, one showed decreased appetite, another showed no effect, and yet another even showed significantly increased hunger in women after chewing gum. The more important question, though, is whether there are any changes in subsequent calorie intake. Again, the findings are mixed. 

One study, as you can see in the graph below and at 3:12 in my video, even found that while chewing gum didn’t impact M&M consumption much, it did appear to decrease the consumption of healthy snacks. Interesting, but the researchers used mint gum, and the healthy snacks included mandarin orange slices. So, that may have just been an orange juice-after-tooth-brushing effect.  

It can take an hour before the residual taste effect of mint toothpaste dissipates. This is bad if it cuts your fruit intake, but what about harnessing this power against Pringles? An international group of researchers had people eat Pringles potato chips for 12 minutes, interrupting them every 3 minutes to swish with a menthol mouthwash. As you can see in the graph below and at 3:50 in my video, compared to those in the control groups (swishing with water or nothing at all), the minty mouthwash group cut their consumption by 29 percent. The researchers concluded: “If a consumer finds themselves snacking on too many crisps [potato chips] during a given eating occasion, one potential strategy could be intervening by having a peppermint tea, menthol flavoured chewing gum, or brushing their teeth, to slow down or stop snacking.” 

What we’re wondering about, though, is weight loss. Even if a little tweak like chewing gum can affect the consumption of a single snack, your body could just compensate by eating more later in the day. The only way to know for sure if chewing gum can be used as a weight-loss hack is to put it to the test, which I cover in my video Does Chewing Gum Help with Weight Loss? 

For more information on calories and weight loss, check out related videos below. 

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