CHARLESTON, S.C. (AP) - South Carolina's pluff mud, the slick, dark muck that will swallow shoes whole, makes up much of the state's coastal marshes. The smell, depending on whom you ask, is either the sweet smell of home or an awful stink.

But the mud holds a secret that could help clean up environmental contamination from polychlorinated biphenyls, PCBs, a pollutant that's known to cause cancer and other serious health problems in animals. It's suspected to do the same in humans.

Harold "Hal" May, a microbiologist at the Medical University of South Carolina in Charleston, began studying how to get rid of PCBs 25 years ago.

He hiked out one day into the mud off a Charleston park and brought back a sample of the dark, strong smelling concoction of decaying plants and animals and all the organisms that feed on them.

That's where he found the bacteria that could help clean up the PCB pollution that's spread around the country and the world, according to a MUSC.

"I went out wading in the water beyond Brittlebank Park and collected some pluff mud. It was pretty smelly, but that's where it came from," May said in a press release from the university.

The United States banned PCBs in 1979, but they are still found in rivers, marshes and contaminated soil, according to the EPA. They were used in electrical equipment, motor oil and insulation, even in floor finish.

"The factories where these were, they would make these things in great big batches and then wash the floors of the plants off into the river next to the plant. The stuff started accumulating in many places around the world doing this kind of thing. That's one big way that it's moved into the environment," May said.

As PCBs make their way through waterways, they're eaten by fish, which in turn can be eaten by humans, MUSC said. And "that can put people's health at risk."

To clean up PCB contamination in waterways, environmental officials can either dredge up the soil and remove it, or cover it up with more soil so it can continue to degrade naturally, according to the National Oceanic and Atmospheric Administration.

Rather than wait for natural bacteria to break down PCBs, May's new invention uses the bacteria from the pluff mud, called "Dehalobium chlorocoercia" or DF-1, to attack the contamination and break the chemicals down faster, MUSC said.

May worked with Kevin Sowers, with the Institute of Marine and Environmental Technology at the University of Maryland in Baltimore, and Upal Ghosh, at the University of Maryland, to develop a new way to break down PCB pollution.

Using the bacteria found in Charleston, with another known bacteria, and pellets that can get into contaminated soil, the researchers have had several successful tests with their new invention from an old marsh bacteria.

"Sowers and Ghosh have started a company called RemBac Environmental, which uses their creation to clean up PCBs. May does not have a stake in it but does have two patents related to the product," MUSC said.

"The company is in its early days, but testing shows it reduced PCBs in a Virginia wetland drainage creek, a Hawaiian atoll and a Michigan river. Testing is currently underway in a Delaware canal," according to the university.

Information from: The State, http://www.thestate.com