Starting soon, Cronig's markets will offer an eco-friendly bagging alternative at the check-out counter: polypropylene shopping bags.

Cronig's bought 5,000 of the bags from 1 Bag at a Time, a company started last year by Aquinnah summer resident Lisa Foster.

"We're hoping that eventually we'll be using less of the paper bags," Cronig's general manager Sarah McKay said. "That will be cost saving for us, but also refuse saving for the Island - less will be ending up at the recycling center or the dump."

The cloth-like bags, sold in four colors, will cost under $5 and have a similar design to the brown paper bags - the logo for Cronig's on one side and Healthy Additions on the other.

If it seems strange that polypropylene - a petroleum product - could be called eco-friendly, Mrs. Foster can explain.

"Each of my bags uses the same amount of petroleum resources as 11 disposable plastic bags," Mrs. Foster said. "But mine is designed to replace hundreds. If you use it twice a week for two to three years, it replaces two to three hundred bags."

Although paper bags are generally considered more environmentally friendly - Cronig's offers only paper at checkout - they contribute more to global warming and cost towns more in disposal than plastic bags.

The process of making a paper bag emits 70 per cent more greenhouse gases, 50 times more water pollutants, and four times more energy than making a plastic bag, according to the Environmental Protection Agency. In addition, disposal costs are higher because they are heavier and bulkier - and they do not always biodegrade in land fills because of a lack of oxygen.

The polypropylene bags have the same design as those used for several years in Europe and Australia. Holding more than a Cronig's paper bag, and as much as four plastic bags, they have hard bottoms so that groceries do not crush together. The handles are long enough to swing onto the shoulder, but short enough to hold at the side without dragging. Unlike canvas, the machine-washable polypropylene bags are water, odor and dirt resistant.

"When she sent us the sample, that was pretty much it," Ms. McKay said of the decision to buy Mrs. Foster's bags.

Ms. McKay also expects the bags will hold more than the regular paper kind. "They're so strong, depending on what it is, you can pack it pretty good. With the paper bags you have to be more careful with how much you put in."

Mrs. Foster, who is a high school English teacher in Los Angeles, Calif., started 1 Bag at a Time after reading an article last year about global warming that predicted a rise in sea level. "I was really depressed about that," Mrs. Foster said. "I thought, ‘Aquinnah will be an island.'"

At the time, Mrs. Foster was living in Australia with her two teenaged children and her husband, a filmmaker, who was shooting a movie. Polypropylene bags are ingrained in grocery shopping culture there.

"You look around and everyone's standing there with their green bags," she said of the Australian grocery stores. Disposable bags were still offered free by the stores, but no one took them, she said.

"It seemed to be such a horrible thing to take a bag," Mrs. Foster said. Even people who forgot their polypropylene bags would not take the free ones. "It was so interesting to see how many people would rather buy another $2 bag and save the embarrassment - or moral choice - of disposing of a bag they didn't need to.

"You really get hooked on them," she added. "My kids would steal them from me and take them to school. My husband was taking them to the gym. I kept having to buy more just so I could go to the market."

When Mrs. Foster learned about the detriments of paper and plastic grocery bags, she was incensed that a reusable bag movement was not taking place in America.

"I was very upset with what I learned about paper bags and how they contribute to global warming," said Mrs. Foster. "I truly believe that Americans do care, but they don't know the issues."

Venting over coffee, a friend in Australia urged Mrs. Foster to try to change the ways of American consumers. When she returned to the United States last summer, Mrs. Foster bought 8,000 of the bags from a company in China - the minimum order. By the time the bags arrived in November, she had sold half of them by cold-calling businesses and appealing to people she knew.

Chilmark resident Mary Steenburgen bought 2,000 for her store in Santa Monica, Calif. The two became acquainted through Mrs. Foster's July book group, which has met at her home in Aquinnah for eight years. The bags are also sold in a few grocery stores across the country, but Cronig's order for 5,000 is the largest so far.

"It was a win-win situation," Ms. McKay said of the decision to place such a large order for Cronig's. "We're very conscious that we live on an Island and that we need to be as environmentally conscious as possible."

Mrs. Foster's venture has been successful enough that she is not going back to teaching in the fall. She has also just hired her first intern - one of her recently graduated students.

Mrs. Foster hopes that the Island's transient summer population could help spread the use of reusable bags.

"This is happening in a community where the potential to spread this message across the country is possible," she said. "While bringing a bag back to the grocery store is a small change, it is a huge shift in consumer thinking. Studies have found that people who begin to use these bags often consider the issue of packaging in a new light."