Dear EarthTalk: OK, once and for all, which is more environmentally friendly: paper or plastic at the grocery checkout? And didn’t I just hear that San Francisco has banned plastic bags? -- Brian, Santa Clara, CA

Yes, the city of San Francisco did just recently ban plastic bags. Large supermarkets and pharmacies there must eliminate plastic shopping bags by early 2008 in favor of bags made from either paper or compostable and biodegradable cornstarch. The city’s Board of Supervisors cited the fact that plastic bags are a challenge to recycle and as a result occupy much-needed landfill space, while causing litter problems by easily blowing into trees and waterways, where they can kill birds and marine life.

But just because San Francisco has outlawed plastic bags doesn’t mean that all indications point to paper bags being more green-friendly than plastic. A landmark 1990 study by the research firm Franklin Associates—which factored in every step of the manufacturing, distribution and disposal stages of a grocery bag’s usable life—actually gave the nod to plastic bags.

Franklin’s employed two critical measures in reaching their conclusion. The first was the total energy consumed by a grocery bag. This included both the energy needed to manufacture it, called process energy, and the energy embodied within the physical materials used, called feedstock energy. The second measure used was the amount of pollutants and waste produced.

The Franklin report concluded that two plastic bags consume 13 percent less total energy than one paper bag. Additionally, the report found that two plastic bags produce a quarter of the solid waste, a fifteenth as much waterborne waste and half the atmospheric waste as one paper bag.

Of course, many environmentalists still side with paper as a better choice than plastic at the checkout, mostly for the reasons cited by San Francisco’s Board of Supervisors. Plastic is not biodegradable, it litters our waterways and coastal areas, and has been shown to choke the life out of unsuspecting wildlife. A recent survey by the United Nations found that plastic in the world’s oceans is killing more than a million seabirds and 100,000 marine mammals and sea turtles each and every year. According to the California Coastal Commission, plastic bags are one of the 12 most commonly found items in coastal cleanups. Paper bags do not cause such after-the-fact problems, and are inherently easier to recycle.

But to the non-profit Institute for Lifecycle Environmental Assessment, “paper versus plastic?” is not the question we should be asking ourselves, since the answer is really “neither.” After all, energy and waste issues aside, the manufacture of paper bags brings down some 14 million trees yearly to meet U.S. demand alone, while at the same time plastic bags use up some 12 million barrels of oil each year.

The group urges consumers to “just say no” to both options and instead bring their own re-usable canvas bags, backpacks, crates or boxes to haul away the groceries. Some supermarkets, such as the Albertson’s and Wild Oats chains, even offer a small discount (around five cents) to those who do so. Another benefit of bringing your own, of course, is setting a good example so that other shoppers might do the same.

CONTACTS: Institute for Lifecycle Environmental Assessment, www.ilea.org.

Dear EarthTalk: Is it true that anti-bacterial soaps are no better at preventing infections than plain soaps and that they are actually harmful to the environment? -- Avery Bicks, New York, NY

University of Michigan researchers reviewed numerous studies conducted between 1980 and 2006 and concluded that antibacterial soaps that contain triclosan as the main active ingredient are no better at preventing infections than plain soaps. Further, the team argued that these antibacterial soaps could actually pose a health risk, because they may kill beneficial bacteria and also reduce the effectiveness of some common antibiotics, such as amoxicillin. The study was published in the August 2007 issue of the peer-reviewed journal, Clinical Infectious Diseases.

These findings concur with earlier research conducted by Tufts University’s Alliance for the Prudent Use of Antibiotics. The Tufts study concluded that overuse of triclosan could cause new strains of bacteria to develop, thus “changing the kind of bacteria in our houses to those that may actually be harmful or resistant to antibiotics…” said Tufts’ Dr. Stuart Levy.

According to the non-profit group Beyond Pesticides, laboratory studies have found a number of different strains of mutated bacteria that are resistant to triclosan and to certain antibiotics. The organization also cites reports of triclosan converting into a carcinogenic class of chemicals known as dioxins when exposed to water and ultraviolet radiation. Besides cancer, dioxins have been linked to weakening of the human immune system, decreased fertility, altered sex hormones and birth defects.

If antibacterial hand soap is not effective at reducing infections, consumers may wonder about whether alcohol-based hand sanitizers may do a better job. Combing through different studies on the topic yields mixed conclusions. According to one study conducted at Colorado State University, alcohol-based hand sanitizers were as much as twice as effective as either regular soap or antibacterial soap at reducing germs on human hands.

A Purdue University study, however, contradicts these findings, concluding that while alcohol-based hand sanitizers may kill more germs than plain or triclosan-based soaps, they do not prevent more infections that make people sick. Instead they may kill the human body’s own beneficial bacteria by stripping the skin of its outer layer of oil.

The best advice might just come from a study published in the journal Dairy, Food and Environmental Sanitation back in 1998, which concluded that washing hands thoroughly for 20 seconds or more with plain soap and warm water is by far the most effective way to reduce harmful bacteria, and as such remains our best defense against getting sick.

CONTACTS: Clinical Infectious Diseases, www.journals.uchicago.edu/CID/; Tufts’ Alliance for the Prudent Use of Antibiotics, www.tufts.edu/med/apua/; Beyond Pesticides, www.beyondpesticides.org.

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