A Swedish entrepreneur is trying to market and sell a biodegradable plastic bag that acts as a single-use toilet for urban slums in the developing world.

Once used, the bag can be knotted and buried, and a layer of urea crystals breaks down the waste into fertilizer, killing off disease-producing pathogens found in feces.

The bag, called the Peepoo, is the brainchild of Anders Wilhelmson, an architect and professor in Stockholm.

“Not only is it sanitary,” said Mr. Wilhelmson, who has patented the bag, “they can reuse this to grow crops.”

In his research, he found that urban slums in Kenya, despite being densely populated, had open spaces where waste could be buried.

He also found that slum dwellers there collected their excrement in a plastic bag and disposed of it by flinging it, calling it a “flyaway toilet” or a “helicopter toilet.”

This inspired Mr. Wilhelmson to design the Peepoo, an environmentally friendly alternative that he is confident will turn a profit.

“People will say, ‘It’s valuable to me, but well priced,’ ” he said.

He plans to sell it for about 2 or 3 cents — comparable to the cost of an ordinary plastic bag.

In the developing world, an estimated 2.6 billion people, or about 40 percent of the earth’s population, do not have access to a toilet, according to United Nations figures.

It is a public health crisis: open defecation can contaminate drinking water, and an estimated 1.5 million children worldwide die yearly from diarrhea, largely because of poor sanitation and hygiene.

To mitigate this, the United Nations has a goal to reduce by half the number of people without access to toilets by 2015.

The market for low-cost toilets in the developing world is about a trillion dollars, according to Jack Sim, founder of the World Toilet Organization, a sanitation advocacy group.

As far as toilets go, “the people in the middle class have reached saturation in consumption,” said Mr. Sim, who calls himself a fan of the Peepoo. “This has created a new need, urgently, of looking for a new customer.”

Since 2001, his organization has held an annual World Toilet Summit, and Mr. Sims said he was excited that in recent years there had been an emergence of entrepreneurs devising low-cost solutions.

At the 2009 meeting, Rigel Technology of Singapore unveiled a $30 toilet that separates solid and liquid waste, turning solid waste into compost. Sulabh International, an Indian nonprofit and the host of the World Toilet Summit in 2007, is promoting several low-cost toilets, including one that produces biogas from excrement. The gas can then be used in cooking.

But Therese Dooley, senior adviser on sanitation and hygiene for Unicef, said that inculcating sanitation habits was no easy task.

“It will take a large amount of behavior change,” Ms. Dooley said.

She added that while “the private sector can play a major role, it will never get to the bottom of the pyramid.”

A sizable population, poor and uneducated, will still be left without toilets, Ms. Dooley said, and nonprofits and governments will have to play a large role in distribution and education.

Meanwhile, Mr. Wilhelmson is pushing ahead with the Peepoo.

After successfully testing it for a year in Kenya and India, he said he planned to mass produce the bag this summer.