EarthTalk®| September 2020

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Being around waterfalls — like this 88-foot doozy along the North Fork of the Nooksack River in Washington State — could help us with a little mental uplift courtesy of the “negative ions” floating around crashing water molecules. Credit: Roddy Scheer.

Dear EarthTalk: Is it true that being around a waterfall makes you feel good? – S.B., Lewiston, ME

The notion of waterfalls making you happy is often viewed as an “old wives’ tale,” but there may be some truth to it given the so-called “negative ions” pervasive in such environments. The collision of water molecules with each other causes water to be positively charged and surrounding air to be negatively charged. According to Pierce Howard, Ph.D., author of The Owner’s Manual for the Brain: Everyday Applications from Mind-Brain Research, it makes sense that waterfalls can make you feel good, given that negative ions hitting our bloodstream can produce biochemical reactions linked to alleviating depression, relieving stress and boosting energy.

“High concentrations of negative ions are essential for high energy and positive mood,” he reports. “Negative ions suppress serotonin levels in much the same way that natural sunlight suppresses melatonin. Hence the invigorating effect of fresh air and sunshine and the correspondingly depressed feelings associated with being closed in and dark.”

“The atmosphere we breathe normally is full of positive and negative ions,” he adds. “Air-conditioning, lack of ventilation, and long dry spells remove negative ions…the best ratios of negative to positive ions are associated with waterfalls and the time before, during and after storms,” says Howard. “The worst are found in windowless rooms and closed, moving vehicles.”

Our love of waterfalls only underscores that people thrive when they are exposed to nature on a regular basis. A 2013 study in the journal Environmental Science & Technology definitively linked exposure to nature directly with improved mental health, comparing the mental health of those who moved from city landscapes to greener, more natural settings with those who relocated in the reverse direction. Researchers found that those who relocated to settings with a higher exposure to nature were noticeably happier during the three-year study period. “[E]nvironmental policies to increase urban green space may have sustainable public health benefits,” they concluded.

In another recent study, researchers sampled the effects of nature on 537 University of Rochester students in both real and imagined situations, and found that individuals who spent time outdoors — or even just imagined themselves in nature — consistently experienced higher energy levels and increased feelings of happiness. Study participants who spent just 20 minutes outdoors a day experienced significant increases in energy levels as well as noticeable mood boosts. Even indoor plants played a role in helping study participants feel more energized.

Another way to look at it would be to consider our sedentary, indoor lifestyle as a drain on our energy reserves and taxing to our mood and general sense of well-being. In the landmark 2005 book Last Child in the Woods, Richard Louv coined the term “nature deficit disorder” to explain how our lack of time outdoors has led to behavioral problems in kids and adults alike. Louv’s prescription? Spend more time outdoors (away from screens) interacting with nature and each other.

In case you needed another reason to get off the couch and out into the woods on a waterfall hike, now you have it. You’ll be sharper. You’ll be more productive. You’ll be invigorated. And you’ll be happier.

Contacts: The Owner’s Manual for the Brain, amzn.to/3gAlLTm; Last Child in the Woods, amzn.to/3kcRb4b; “Green spaces deliver lasting mental health benefits,” medicalxpress.com/news/2014-01-green-spaces-mental-health-benefits.html.


Experts think the benefits of using DEET-based bug repellent to scare off mosquitoes and other biting insects outweigh the health and environmental risks. Credit: Laurie Wilson, FlickrCC.

Dear EarthTalk: Is DEET natural and is it safe to use topically as a mosquito repellent? And which formulations and concentrations are advised? — M. Frey, Milwaukee, WI

DEET (short for “diethyltoluamide”) is a synthetic compound invented by the U.S. Army in 1946 that can be applied topically to repel mosquitos, ticks, fleas, chiggers, leeches and other biting insects. Unlike other repellents which actually deter bugs with smells they don’t like — or even kill them on contact — DEET just makes it harder for pests to smell us so they are more likely to leave us alone.

DEET has been available to the general public since the Army “released” it in 1957, and today it remains most people’s repellent of choice, with 90 percent market penetration in the U.S. An estimated one-third of Americans use DEET to protect them from not only mosquito bites but also mosquito-borne illnesses like Eastern Equine Encephalitis, West Nile Virus, the Zika virus and malaria, not to mention tick-borne illnesses like Lyme disease and Rocky Mountain spotted fever.

DEET is not only effective, it’s also convenient; it is sold in a variety of formulations (liquid, lotion, spray, towelette) ranging in strength from 5-99 percent. The U.S. Environmental Protection Agency (EPA) considers DEET safe to use topically, and has approved 30 companies to sell some 120 different DEET-based repellents online and in store shelves across the U.S. And with 90 percent market penetration for insect repellents, DEET seems to be here to stay.

That said, many of us are still concerned about the safety of DEET for our health and the environment. According to the non-profit Environmental Working Group (EWG), exposure to high concentrations of DEET can irritate the eyes and in very rare cases impair the nervous system, with symptoms including seizures, tremors and slurred speech. But despite these risks, EWG acknowledges that DEET is still probably the safest option for preventing insect-borne diseases.

If you want to use DEET, keep in mind that pediatricians generally recommend not using it on babies up to two months old, but otherwise sticking to concentrations of 10-30 percent for infants and children. The stronger the concentration of the DEET you apply, the longer lasting protection you’ll get from mosquitoes. Consumer Reports found that 99 percent of DEET formulations gave up to 12 hours of protection while lower concentrations (20-34 percent) lasted three to six hours.

If you want to avoid DEET altogether, there are several effective alternatives available, including Picaridin and PMD (AKA Oil of Lemon Eucalyptus). Meanwhile, several botanical oils (castor oil, cedar oil, citronella oil, clove oil, geraniol oil, lemongrass oil, peppermint oil, rosemary oil, soybean oil) are known for repelling insects, but EWG warns most of these are not very effective, won’t last long and could trigger allergic reactions in the user on their own.

To decide what’s best for you and your family given where you live and the risks for insect-borne diseases there, check out the EPA’s “Find the Repellent that is Right for You” search tool which bases its recommendations on your inputs regarding what you are trying to battle, how long you will be outside and potentially exposed, active ingredient preference, and even preferred brand name.

Contacts: EPA’s “Find the Repellent that is Right for You,” epa.gov/insect-repellents/find-repellent-right-you; EWG’s Guide to Bug Repellents, ewg.org/research/ewgs-guide-bug-repellents; “Is DEET Bad for You (and Your Kids)?” health.clevelandclinic.org/is-deet-bad-for-you-and-your-kids/.


Coronavirus could be the knock-out punch for African mountain gorillas already on the brink of extinction. Credit: Francesco Ungaro, Pexels.

Dear EarthTalk: I overheard someone saying the Coronavirus could drive mountain gorillas extinct? Is this because they are susceptible to the virus? — Spencer S., Tukwila, WA

While we don’t know for sure whether mountain gorillas or other great apes are susceptible to coronavirus, no one wants to find out. Damian Carrington reports in The Guardian that the coronavirus could potentially wipe out already threatened populations of chimpanzees, gorillas and orangutans — our closest living relatives with whom we share 98 percent of our DNA.

“Even pathogens producing mild symptoms in humans have been lethal to great apes in the past,” reports Carrington. “The fact that Covid-19 is fatal for some humans leads experts to fear it could potentially prove devastating to great apes.”

To date, no great apes are known to have contracted the coronavirus. Those humans who study and protect them would like to keep it that way. As a result, wildlife tourism across Africa is temporarily shut down. How long “temporary” may be is anybody’s guess at this point, but conservationists fear it could set back their efforts by decades if not put them “out of business”entirely.

“The suspension of ecotourism during the coronavirus pandemic has also meant the main source of revenue for gorilla conservation has been lost and there are fears some of those in surrounding communities who depend on tourists could turn to poaching out of desperation,” reports Jack Losh in The Guardian.

Meanwhile, the story is much the same all across Africa, where governments have suspended all tourism. Ann Gibbons reports for Science that researchers at wildlife reserves across Africa face new challenges in the age of coronavirus. The 130 wildlife rangers at Uganda’s Bwindi Impenetrable National Park are now briefed regularly on how to keep coronavirus away from gorillas and how to monitor wildlife for signs of the sickness.

At another Ugandan reserve, Taï and Kibale, researchers must quarantine for 14 days before they are allowed anywhere near the wild gorilla population under study there, and once researchers can get closer, they still must, in the words of Gibbons, “change their clothes and take their temperatures before they go into the forest, wear masks, and keep their distance.” Researchers there have also tested chimps’ feces for COVID-19 and other viruses.

“Habitat loss and poaching are big threats to the survival of great apes, but viruses are also a concern,” adds Briggs. “Infectious disease is now listed among the top three threats to some great ape groups.” Indeed, past research has shown that chimps can contract the common cold virus, while Ebola is thought to be responsible for thousands of wild chip and gorilla deaths across Africa.

Contacts: “Primatologists work to keep great apes safe from coronavirus,” sciencemag.org/news/2020/05/primatologists-work-keep-great-apes-safe-coronavirus; “Coronavirus poses lethal threat to great apes, experts warn,” theguardian.com/environment/2020/mar/24/coronavirus-poses-lethal-threat-to-great-apes-experts-warn.


Green-minded grocery shoppers spend more time in the bulk aisle than your average consumer given their preference for avoiding disposable packaging on single-use food items and products. Credit: leyla.a, FlickrCC.

Dear EarthTalk: Any tips for reducing the amount of disposable plastic I use for food storage? — J. Spencer, Gaithersburg, MD

Analysts estimate that of the over six billion tons of plastic produced worldwide since the 1950s, we have recycled only 9 percent of it and incinerated another 12 percent. The remaining, some 4.8 billion tons of plastic is either still in use, filling up landfills, or littered into streets, streams and eventually the ocean.

About a third of the plastic produced worldwide is for single-use applications (bottles, bags, utensils, food storage, etc.) — and it is these items that most commonly end up on the side of the road. Researchers discussed in a 2019 paper in Nature that if we do nothing to step up flagging efforts to reduce, reuse and recycle plastics, we could have three times as much of it littered into the global environment by 2060.

So, what’s an environmentally conscious consumer to do? For starters, avoid getting plastic bags at the store. Either bring your own reusable one or if you need to go disposable, at least opt for paper that can be recycled or composted. And if you are food shopping, gravitate toward the bulk items aisle where you can buy just the right amount without unnecessary extra packaging.

Another way to cut down on single use plastic is by ditching plastic straws. Americans go through about 500 million plastic straws daily. Opting for reusable straws (metal, silicone, bamboo or glass, anyone?) — or no straw at all — is one of the simplest ways to cut down on disposable plastic.

According to the non-profit Center for EcoTechnology (CET), the kitchen is one place where you can definitely make some easy adjustments to save plastic. For starters, ditch the plastic wrap; it’s difficult to recycle and can clog recycling processing machines. One great alternative is beeswax paper, which is reusable, washable and compostable. (Make sure to wash it with cold water only so the wax doesn’t melt.)

“Another alternative to plastic wrap is storing your food in glass storage containers or glass jars,” adds CET. “Glass is 100 percent recyclable and can be recycled endlessly without loss in quality or purity.”

Putting dish cloths to use is another way to eschew plastic wrap for keeping produce fresh. Simply wrap up those fruits or veggies in a cloth instead of plastic — or put them in a bowl and cover with a dish cloth and rubber band for a tight seal — and put ’em in the fridge.

One often overlooked environmental downside of the coronavirus situation is that restaurants throw in so much disposable plasticware for to-go and delivery orders — whether customers need it or not. That’s why a coalition of 120 environmental groups recently teamed up to send letters to seven national food delivery companies asking they change their default ordering process to one that does not automatically include utensils, napkins, condiments and straws in order to reduce the tsunami of single-use plastic pollution entering our oceans, landfills and incinerators.

Contacts: Future scenarios of global plastic waste generation and disposal, https://www.nature.com/articles/s41599-018-0212-7; “Zero Waste Substitutes to Eliminate Single Use Plastic in Your Kitchen,” https://www.centerforecotechnology.org/zero-waste-substitutes-to-eliminate-single-use-plastic-in-your-kitchen/; UberEats, GrubHub, Delivery.com, Doordash, Seamless, PostMates & Caviar Asked to “Hold The Single-Use Plastics, Please,” https://seaturtles.org/ubereats-grubhub-delivery-com-doordash-seamless-postmates-caviar-asked-to-hold-the-single-use-plastics-please/.

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