Most researchers now agree that environmental factors -­ including exposure to chemicals and pollution -­ play a significant role today in determining who gets cancer and who doesn't. (Thinkstock)

With the World Health Organization hinting that cancer could unseat heart disease as the leading cause of death around the world, it’s no surprise that per capita cancer incidence is on the rise globally. In fact, cancer is the only major cause of death that has continued to rise since 1900. While it might depend on whom you ask, most researchers now agree that environmental factors—including exposure to chemicals and pollution—play a significant role today in determining who gets cancer and who doesn’t.

A blue ribbon panel of cancer experts initially convened by President George W. Bush researched hundreds of studies and concluded in 2010 (in its 240-page report, “Reducing Environmental Cancer Risk: What We Can Do Now”) that our exposure to chemicals, pollution and radiation is to blame for the uptick in cancer deaths. “The American people—even before they are born—are bombarded continually with myriad combinations of these dangerous exposures,” the panel reported. “With the growing body of evidence linking environmental exposures to cancer, the public is becoming increasingly aware of the unacceptable burden of cancer resulting from environmental and occupational exposures that could have been prevented through appropriate national action.”

The panel cited grim statistics about cancer’s march, noting that 41 percent of Americans will be diagnosed with cancer at some point in their lives, with 21 percent likely to die from it. Cancer researchers fear that our reliance on chemicals is the main culprit, as borne out by hundreds of studies.

To wit, a 2000 study involving the examination of health records of more than 44,000 pairs of twins across Scandinavia found that “inherited genetic factors make a minor contribution” in causing most cancers but that “the environment has the principle role in causing sporadic cancer.” A 2010 UK study, whereby researchers investigated the level of chemical exposure of more than 1,100 women during their employment history, found that those study subjects who had been exposed to various industrial chemicals and airborne hydrocarbons were at least three times more likely to get breast cancer later on than women with little or no exposure in their backgrounds.

Not everyone agrees. Writing in Forbes magazine, Henry I. Miller and Elizabeth Whelan of the industry-friendly American Council on Science and Health argue that the findings of the presidential panel are based on politics not science: “If the authors had only bothered to consult a standard textbook on cancer epidemiology, they would have learned that lifestyle factors such as smoking, obesity, excessive alcohol consumption and overexposure to sunlight—not chemicals in air, water and food—are the underlying causes of most preventable human cancers.”

While few today would doubt the health risks of such personal lifestyle factors, the President’s cancer panel nevertheless concluded that “the burgeoning number and complexity of known or suspected environmental carcinogens compel us to act to protect public health,” and urged President Obama to use the power of his office to “remove the carcinogens and other toxins from our food, water and air that needlessly increase health care costs, cripple our nation’s productivity, and devastate American lives.”

CONTACTS: President’s Cancer Panel, deainfo.nci.nih.gov/advisory/pcp/; American Council on Science and Health, www.acsh.org.

If you’re interested in cleaning greener, there are many sources of natural cleaning recipes online. Or check out the cleaning products aisle at your local natural food store, where you will find a wide range of cleaning formulations safe for your health and the environment. Pictured: Earth Friendly Products' “Safeguard Your Home” retail pack. (Media credit/Earth Friendly Products)

When it comes to household cleaning products, most mainstream brands make use of chlorine bleach, ammonia or any number of other chemicals that can wreak havoc on the environment and human health.

Ammonia is a volatile organic compound that can irritate the respiratory system and mucous membranes if inhaled, and can cause chemical burns if spilled on the skin. Bleach contains sodium hypochlorite, which can cause eczema and other skin ailments as well as breathing difficulties if inhaled. And when it reacts with other elements in the environment, toxic “organochlorines” can form, damaging the ozone layer and causing health issues such as immune suppression, reproductive difficulties and even cancer.

Fortunately, growing public concern about the health effects of toxic exposure have led to an “explosion of environmentally friendlier and non-toxic products,” says the health information website, WebMD. “There are many products in this category—from laundry detergents and fabric softeners to multi-surface and floor cleaners, to tile and bathroom cleaners—that are…safer for people and the planet.”

WebMD warns that while many are indeed safer, others are “greenwashed,” meaning they are “marketed as natural while still including suspect chemicals.” How does one know? “Get in the simple practice of looking at product labels to see if the cleaning manufacturer is clearly disclosing all ingredients,” reports WebMD. “If it is not…it could mean the manufacturer is trying to hide a particular suspect ingredient.”

Also, just because a product has an eco-certification printed on its label doesn’t necessarily mean it should be trusted. To make sure, check the Eco-Labels section of Consumer Reports’ Greener Choices website, which gives the low-down on what labels really mean and whether they are backed up by government regulations. Another good resource is the U.S. Department of Health and Human Services’ Household Products Database, which provides ingredient lists for thousands of products on U.S. store shelves.

If you want to play it safe and natural when cleaning your home, WebMD suggests using white distilled vinegar—it kills mold and mildew, eliminates soap scum and sanitizes, all in one fell swoop—to clean windows, tile, cutting boards and countertops. Another effective yet gentle natural cleaner for countertops and bathtubs is baking soda, especially when mixed with a few drops of mild soap. Borax can be called in for tougher stains. If you’re interested in cleaning greener, there are many sources of natural cleaning recipes online. Or check out the cleaning products aisle at your local natural food store, where you will find a wide range of cleaning formulations from the likes of Seventh Generation, Ecover, Green Works and Earth Friendly Products (which sells a “Safeguard Your Home” retail pack that includes one each of a window cleaner, an all-purpose cleaner, a dishwashing liquid, an automatic dishwasher gel, a laundry detergent and a fabric refresher), among many others.

CONTACTS: WebMD, www.webmd.com; Greener Choices, www.greenerchoices.org/eco-labels/eco-home.cfm?redirect=1; Household Products Database, hpd.nlm.nih.gov.

Dear EarthTalk: I pruned back an overgrown bush in my back yard last fall and now the soil around it is covered in dandelions and other weeds. Is there any way to get rid of these weeds without resorting to RoundUp and other chemical herbicides? — Max S., Seattle, WA

Weeds are nothing if not opportunistic. While you may not have bargained for getting one form of eyesore (weeds) by clearing another (an overgrown bush), dandelions and other fast-growing, quickly spreading plants know no bounds when some new territory opens up. They will colonize and spread out given the slightest opening—after all, that’s what defines them as weeds.

Of course, conventional herbicides such as Monsanto’s RoundUp will take down the weeds in a jiffy, but the negative effects on people, animals and the environment may be both profound and long-lasting. Independent studies of RoundUp have implicated its primary ingredient, glyphosphate, as well as some of its "inert" ingredients, in liver damage, reproductive disorders and Non-Hodgkin’s Lymphoma, as well as in cardiovascular, gastrointestinal, nerve and respiratory damage.

California’s Department of Pesticide Regulation reports that, year after year, RoundUp is the number one cause of pesticide/herbicide-induced illness and injury around that state. RoundUp is also blamed for poisoning groundwater across the U.S. and beyond, as well as for contributing to a 70 percent decrease in amphibian biodiversity and a 90 percent decrease in tadpole numbers in regions where it is used heavily.

Given that you’ll have to manually remove dead weeds from your yard after applying RoundUp (or any other "post-emergent" herbicide), why not just pull them up by hand in the first place? No doubt, the most eco-friendly way to get rid of weeds is to yank them out without the aid of poisons. Unfortunately, many weeds have long deep roots which need to be pulled completely if you don’t want them to grow back; if need be, use a metal weed puller with a hooked end or a mechanical grabber—available at any local garden supply or hardware store—if you don’t want to have to pull those very same weeds next year.

Garden expert Dean Novosat of the Garden Doctor website suggests giving the weed beds a good watering the night before you pull weeds. "…the soil will be softened and will yield the entire weed plant, root and all," he says. Another way to kill weeds, he says, is by pouring boiling hot water over them.

Of course, once you’ve killed or pulled up all those weeds—and make sure you’re thorough or else it’s waste of time—you’ll want to make sure new ones don’t start showing up in their place. Planting some regionally appropriate and ideally native plants in place of the removed weeds would be a good first step—check with a local nursery about what some good choices might be for your neck of the woods.

Once the area is cleared (and replanted), cover it with three to six inches of mulch. Mulch forms a barrier between the soil and the sun, depriving any new germinating weeds of the sunlight they need to photosynthesize. Mulch is composed of large chunky material such as wood chips and bark nuggets, and works well for weed control also because it is low in nutrients and thus won’t fertilize plant starts below.

CONTACTS: California Department of Pesticide Regulation, www.cdpr.ca.gov; The Garden Doctor, www.the-garden-doctor.com.

Dear EarthTalk: How effective have plastic bag bans and restrictions been on reducing plastic litter and other problems associated with their proliferation? And is it really better to use paper bags, which will just lead to more deforestation? – Peter Lindsey, New Canaan, CT

Plastic bags, first introduced in the 1950s as a convenient way to store food, have since developed into a global scourge, littering roadsides, clogging sewer drains and landfills and getting ingested by animals and marine life. And in recent years we’ve discovered how they are so prolific that they now comprise a significant portion of the plastic and other garbage that has collected in huge ocean gyres far from land.

A few countries around the world—Bangladesh, China, India, Australia, Greece, Ireland, Italy, Israel, South Africa, Taiwan and Mumbai, among others—have taken stands against plastic bags through taxing their usage or banning them outright. The environmental think tank, Worldwatch Institute, reports that China’s decision to ban free plastic bags in 2008 has cut demand by some 40 billion bags, reduced plastic bag usage there by 66 percent, and saved some 1.6 million tons of petroleum.

In March 2007, San Francisco became the first (and is still the only) major U.S. city to implement an across-the-board ban on plastic bags. Large supermarkets and pharmacies there had to ditch plastic shopping bags by early 2008 in favor of paper bags or those made from all-natural biodegradable cornstarch-based plastic. Environmentalists are particularly fond of the latter option for those who don’t bring their own grocery bags, as these cornstarch bags offer the biodegradability of paper without the deforestation as well as the convenience of plastic without the damage to ecosystems. San Francisco officials had originally tried to work with retailers on reducing plastic bag use voluntarily. But after a few years of little or no cooperation, they decided to just institute the ban on anything but biodegradable bags. The result has been a 50 percent drop in plastic bag litter on the streets since the ban took effect.

Los Angeles followed suit and its city council voted in 2008 to ban plastic bags beginning in July 2010—but the ban will only take effect if the state of California doesn’t follow through on a statewide plan to impose a fee on shoppers who request plastic bags. City council members in L.A. hope the ban will spur consumers to carry their own reusable bags and thus reduce the amount of plastic washing into the city’s storm drains and into the Pacific Ocean. Several other U.S. cities, including New York, Philadelphia and Baltimore, have considered outright bans like San Francisco’s, but each settled instead on plastic bag recycling programs in the face of pressure from the plastics industry and retail commercial interests.

While increased demand for paper bags in the wake of plastic bag bans could lead to more deforestation, most paper grocery bags in use today are made from recycled content, not virgin wood. Also, an added benefit of paper over petroleum-based plastic is its biodegradability.

Americans go through some 92 billion disposable plastic bags each year, and only five billion paper ones. If the nation banned plastic bags it is likely that paper varieties would only make up a small part of the difference, in light of the proliferation of reusable canvas shopping bags as well as the availability of biodegradable cornstarch plastic.

CONTACT: Worldwatch Institute, www.worldwatch.org.

SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk, c/o E — The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; earthtalk@emagazine.com. E is a nonprofit publication. Subscribe: www.emagazine.com/subscribe; Request a Free Trial Issue: www.emagazine.com/trial.

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.”

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, www.npwrc.usgs.gov; U.S. Forest Service Guidelines for Aerial Application of Retardants and Foams in Aquatic Environments, www.fs.fed.us/rm/fire/retardants/current/gen/appguide.htm.

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

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, www.cynthiasass.com; Guayaki, www.guayaki.com; Eniva Vibe, www.enivamembers.com/vibe_index.aspx; Zipfizz, www.zipfizz.com.

GOT AN ENVIRONMENTAL QUESTION? Send it to: EarthTalk, c/o E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; submit it at: www.emagazine.com/earthtalk/thisweek/, or e-mail: earthtalk@emagazine.com. Read past columns at: www.emagazine.com/earthtalk/archives.php.