Green Guru
Advice for the eco-minded.
By Starre Vartan
 

In considering the hidden costs that come with shipping fruit—trucking it around the globe in refrigerated containers—I’m wondering whether it’s more energy efficient to eat dried fruit?
—Justin Van Kleeck, Charlottesville, VA

This is indeed a vexing question. The heavy Hawaiian pineapple wins the prize for most fuel used getting it to our plates; in terms of emissions, that translates to about 40 pounds of carbon dioxide for every pound of fruit, or the equivalent of driving a car 80 miles—nearly the distance from New York to Philadelphia. Your logic makes sense; the dehydration process uses little energy and a larger volume of dried fruit can be transported. But here’s the hitch: Even if trucking the fruit is more energy efficient, the jury’s still out on whether switching from whole fruits to dried would be better for the environment—or your health.

If you’re looking at the total energy cost of the fruit we eat, you need to go beyond transportation to also consider the amount of energy required to grow it. Some say the efficiency of large-scale agribusiness far surpasses that of small farms, but the data is lacking. Others say small farms, with their hand tools and more judicious use of petroleum products, take the prize. Marion Nestle, professor of nutrition, food studies, and public health at New York University, says, “I don’t think this question is answerable at the moment. All [the current studies] are theoretical—nobody that I know of is making real measurements.”

Nestle does say eating nonorganic dehydrated fruit could come with some health costs, such as exposure to higher concentrations of pesticides, simply because we tend to eat more dried fruit in one sitting (which also means more calories). All of the ingredients in produce, from sweet flavors to chemicals, become more concentrated when it is dried.

The bottom line is that eating locally grown, in-season food always spares the environmental costs of trucking food long distances, and whether or not it uses less energy overall, it’s a smart way to go for other reasons. You are supporting small farms, preserving your area’s open space, and keeping money and resources in your community.
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After years of hand mowing, I recently switched to a new battery-powered, cordless electric mower. Am I correct in assuming it produces next to no greenhouse gases?
—Tom Sernka, Auburn, WA

Kudos, Tom, for your years of push mowing. Not only does manual labor help keep us couch potatoes fit, but since people-propelled mowers are powered by nary more than a pile of pancakes, it’s the most eco-friendly way to mow.  If you can’t be convinced to eschew your verdant carpet for a self-maintaining habitat of native wildflowers, trees, and shrubs, then an electric mower is the next-best choice.

Electric mowers produce 84 percent less CO2 emissions (the principal greenhouse gas that contributes to global warming) than gas mowers, generating 12 pounds of CO2 a month versus about 75 pounds. That’s because the electricity generated by power plants is created more efficiently than that of individual two-stroke motors (notorious gas wasters). Power plants must also adhere to more stringent air-quality rules.

Even small gasoline engines used in mowers, weed whackers, and leaf blowers are big polluters. “A push mower emits as much hourly pollution as 11 cars, and a riding mower emits as much as 34 cars,” says Enesta Jones, a spokesperson for the U.S. Environmental Protection Agency. These engines spew hydrocarbons and nitrogen oxides into the air, both of which add to ground-level ozone (a main ingredient of smog) and contribute to acid rain and global warming. They also emit carbon monoxide (a poisonous gas), affecting human health. The EPA reports that exposure over time to these nasties can lead to emphysema and chronic bronchitis. Electric mowers are also roughly 30 percent quieter than gas, motoring along at about 56 decibels. So by scrapping your gas mower, you’ll not only help keep the air cleaner, you might also be able to enjoy the sound of birdsong mixed with the hum of that electric engine.
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Is it true that red dye No. 40, often used in hummingbird feeders, is hazardous to hummingbirds?
—Jane O’Malley, Austin, TX

Even if the last thing kids need is to be hopped up on sugary snacks, hummingbirds actually do survive on the sweet stuff, which gives them the quick energy they require to perform their acrobatic high-speed flying maneuvers. Unlike natural flower nectar (the majority of which is clear), commercial hummingbird syrups often contain red food coloring. While no studies have been done on whether red dye No. 40 causes cancer or other diseases in hummingbirds, research shows that the artificial coloring is harmful to other animals, and it is certainly unnecessary to use it.

Hummers consume five times their weight in nectar every day. If they are deriving all or most of their nutrition from a human-provided feeder with red-colored nectar (increasingly likely as they lose habitat), they could be sucking down very high volumes of red No. 40. The World Health Organization estimates that the maximum safe limit of the food coloring is 0.007 milligrams per gram of body weight—12 times the dosage linked to DNA damage in the gastrointestinal systems of lab rats used in a study in Japan. Unfortunately, hummingbirds can devour up to 0.4 grams of it if they are eating solely from a feeder—more than 16 times the recommended level for humans. “The intake per unit of body weight [for the hummingbirds] is huge, compared to body size,” says Sheri Williamson, director of the Southeastern Arizona Bird Observatory.

Williamson suggests making your own sweet nectar. Superfine sugar dissolves easily in water (just be sure the sugar doesn’t contain any extra ingredients like cornstarch or other binders). Whether you mix your own or buy an uncolored pre-made version (look for “dye-free”), remember that hummingbirds are attracted to red flowers, not nectar, so a ruby-painted feeder is all that’s necessary to get their attention—they don’t need colored water, too.

Send your most vexing questions to greenguru@audubon.org.
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