Week of 3/30/2008

Dear EarthTalk: How safe are the fire retardants that are used to quell forest fires across the American West?

—Barbara, Minneapolis, MN

So-called long-term fire retardants—those usually dropped from airplanes over forest fires—are comprised of water mixed with a slurry of chemicals, thickeners and corrosion inhibitors designed to prevent plants on the ground from igniting, keep the ingredients from separating and dispersing during targeted drops, and ensure that the harsh chemicals on board the plane don’t endanger the flight’s safety.

Firefighters sometimes add iron oxide to make the fire retardant turn red when applied so they can see where they have already covered. Ammonium phosphate and ammonium sulfate, known for their use as agricultural fertilizers, are also often added to provide nutrients to help the forest regenerate after a burn.

In recent years, where global warming and droughts have exacerbated forest fires across the American West, federal and state firefighting agencies have upped their cumulative annual use of long-term fire retardants to some 20+ million gallons a year spread across tens of thousands of individual fly-overs.

While such chemicals have been valuable in minimizing the damage of forest fires, their use comes with a price. The nitrogen in ammonium phosphate and ammonium sulfate can wreak terrible havoc on aquatic ecosystems, creating algae blooms that kill fish by choking out their oxygen. A 1998 study by the U.S. Geological Survey’s Northern Prairie Wildlife Research Center, found long-term fire retardants to be "very toxic to aquatic organisms including algae, aquatic invertebrates and fish." The study also said that fire-fighting chemicals "could cause substantial fish kills depending on the stream size and flow rate."

A fire plane dropping fire retardants on a forest fire in Sun Valley, Idaho. Nitrogen in some of these mixtures harms the reproductive capacities of some native plants and creates algae blooms in streams that kill fish by choking out their oxygen.© Getty Images

These chemicals have also been shown to affect some plants" reproductive capacities. One study found that spraying fire retardants in some cases decreased plant species diversity, as weedier species better adapted to make use of excess nitrogen in the soil tended to thrive while native species were not able to compete.

In 2000 the U.S. Forest Service issued guidelines for use of fire retardants by aerial fire fighting crews. While the focus of the document was fire control and safety, it encouraged pilots to avoid applying retardant within 300 feet of waterways or other sensitive areas. The Forest Service acknowledges the risk of using retardants, but believes that their use in moderation is a net gain; as fewer "ground troops" need to be sent in to risky situations while more property can be saved from the ravages of a fast-moving fire.

Fires are actually an essential part of forest ecology and many species of trees and plants thrive in part because of the natural occurrence of fires (sequoia trees, for example, depend upon the high temperatures of forest fires to pry open their cones so new seeds can spring forth and take root). The main reason that such catastrophic, news making fires occur in the first place is that humans have sprawled too closely to the forest edge. This has lead to forest management policies that suppress natural fires, causing large build-ups of tinder-like woody debris that eventually ignites and burns out of control.

CONTACTS: USGS Northern Prairie Wildlife Research Center; U.S. Forest Service Guidelines for Aerial Application of Retardants and Foams


Dear EarthTalk: There are so many energy drinks on the market, but they all seem very high in sugar, coloring and preservatives. Are there any natural versions that offer a healthier kick-start?

—John Hwang, Cambridge, MA

Some 500 new varieties of so-called energy drinks have been introduced in recent years. Most contain excessive amounts of sugar and caffeine and are far from healthy.© aquarelle, courtesy Flickr

Energy drinks constitute one of the fastest growing sectors of the soft drink market across the U.S. and around the world, with some 500 new varieties introduced in recent years. But it’s true that most are far from healthy. Besides containing excessive amounts of sugar and caffeine, which alone can be dangerous to those with diabetes or heart conditions, many also feature a battery of supposedly beneficial herbal supplements (taurine, guarana and ginseng) that are not proven to increase energy and may actually sap energy, being detrimental to bodies overloaded with new and unfamiliar stimuli.

"Most of the energy drinks contain high-tech-sounding ingredients that are not controlled substances, of no value, and potentially harmful" in large amounts, says sports nutritionist Cynthia Sass. "The amount of the stimulants is not always listed on the label, and even when the information is listed, it is hard for consumers to interpret because we are not familiar with these ingredients."

Sass recommends good old fashioned water as the best alternative to energy drinks. Re-hydrating is a great way to stay alert and to move other nutrients through the body. Other tried and true ways to increase energy include maintaining a healthy diet, regular physical activity and, of course, a good night’s sleep.

But what about those times when you really need a boost? Yerba mate tea, which is derived from yerba mate plants that naturally contain caffeine as well as other natural stimulants, is a popular choice. Perhaps part of the reason some people swear by it is that its brewed leaves contain theobromine—also found in cocoa—an alkaloid known to help elevate the mood. Boosters of the drink say it also helps strengthen the immune system, relieve allergies and aid in weight loss.

Not a straight tea drinker? Brewed yerba mate, which has an earthy flavor that some call an acquired taste, is sold commercially not just as tea but also blended in lattes, coffees and energy drinks. Guayaki (available at Safeway, Wegmans, 7-Eleven and elsewhere) is one of a handful of companies paving the way for yerba mate in the U.S. The company sells flavored versions with a hint of cane juice to sweeten it up for otherwise sugar-addicted American consumers.

Another take on healthy energy drinks comes from a handful of companies selling products with vitamins and nutrients instead of caffeine to give drinkers a kick. Zipfizz is a powder that can be mixed in with water and contains a combination of vitamins and minerals that provide the body with electrolytes, antioxidants and vitamin B-12, among other natural, immune-strengthening nutrients. Eniva Vibe, also packed with vitamins and minerals, is another popular new entry into the healthy energy drink market.

As with anything you consume, mileage may vary, so to speak, so experts advise going slow at first to make sure it agrees with you. And if all else fails, remember you can always just go take a nap.

CONTACTS: Cynthia Sass; Guayaki; Eniva Vibe; Zipfizz

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