They are spongy, soft and, according to a state study, safe.

But not everyone is convinced that playing on an athletic field or playground surfaced with rubber infill is totally safe.

The results of a $245,000 study conducted by the University of Connecticut Health Center; the Connecticut Agricultural Experiment Station; the state Department of Public Health and the state Department of Environmental Protection states that the fields -- on hot, sunny days, they sometimes smell like burning rubber -- do not pose a health risk.

Still the study, released last weekend, recommends better ventilation be used in indoor facilities composed of these materials after finding a higher contaminant level in the lone inside facility tested.

"Developers of new indoor fields should consider alternatives to crumb rubber infill as a cushioning agent," the study suggests.

It also recommends that proper management of stormwater runoff which could contain the tiny rubber pellets is "prudent to address possible environmental effects.

"DEP concludes there is no risk to drinking water from this runoff," the study maintains, "but a potential risk exists for surface waters and aquatic organisms."

So the state suggests that owners of such fields evaluate their stormwater drainage systems.

"What we learned from this study in Connecticut will provide valuable guidance to municipalities, schools and others who are considering installing artificial playing fields," said Dr. J. Robert Galvin, the state's public health commissioner.

The study was done in response to complaints from parents and some legislators over the smell and the safety of the millions of the tiny pellets that cover the fields and cling to clothes, socks and hair.

The state, using money it received as settlements in cases involving environmental violations, sent a team of researchers to four outdoor fields and one indoor field all lined with the rubber infill. They equipped three soccer players with monitoring devices. Those results, along with samples taken from the fields when they were not in use, were analyzed for some 200 chemicals.

"While the indoor findings were below the health risk targets, the elevated contaminant levels suggest a need to ventilate these fields so they be brought to the level of safety outdoors," Galvin said.

The long-term durability and low maintenance costs have made rubber crumb fields a popular alternative to grass. Bunnell High School in Stratford and St. Joseph High School in Trumbull recently installed such surfaces.

But they've also become controversial.

In Westport, the health risks potentially posed by artificial turf fields have been debated for several years since the installation of a synthetic surface for the athletic field at Staples High School in 2006. There are three other artificial turf fields in town.

A group of Westport residents has advocated that play on the artificial surfaces be halted -- or at least be sharply reduced -- pending the outcome of the study assessing possible harmful health effects from the rubber infill.

Ridgefield First Selectman Rudy Marconi saw that firsthand three years ago when plans to use rubber infill in resurfacing Onalfo Field near the Winter Garden Ice Rink divided his town.

"It became very controversial," Marconi said Saturday. The plan was defeated in a referendum.

Still he said he was glad to hear the study is completed and believes the results could help alleviate some parental concerns.

But Marconi warned that this study may not be the final word.

That certainly is the case with those opposed to the creation of such fields, like Nancy Alderman and her nonprofit Environment and Human Health in North Haven, and Penney Burnett, a Stamford resident, who has fought against the use of the artificial turf in her city.

Alderman points out the study shows three stormwater runoff samples taken from the fields contain zinc levels high enough to be toxic to two aquatic organisms. She promised her group will have a more detailed response after analyzing all the study data.

Burnett said the executive summary statements she saw excerpted in EHHI's response made the situation appear worse than she thought.

"I read it today on the zinc toxicity, and it was like, oh my God," she said.

Nor was Burnett surprised by the findings regarding toxic chemicals being released into the air from the rubber crumbs.

"If you are off gassing this stuff on kids, particularly on little kids, it's a problem," she said.

And Marconi? He advised parents and coaches to remain vigilant in supervising the use of rubber infill fields.

The fields, which cost at least $800,000, feel spongy and soft. They are made of tiny pellets manufactured by grinding up old tires.

As a result, these playing surfaces offer more give than the old Astroturf fields which sometimes felt like falling on cement.

"We know that all-terrain tires contain toxic chemicals to allow them to have greater pliability," Marconi said. "We also know these tires get mixed into the manufacturing process of rubber infill."

Then there's the plastic filament used which many believe contains lead.

So he said parents need to check their children's clothing, shoes, socks and require them to bathe or shower after playing on such a surface, under the swings and slides of a children's playground or at an athletic complex.

Additionally Marconi said these rubber surfaces heat up faster than a regular grass field.

"Coaches need to be aware of this," he said. "After several days of 90-degree heat they should check the temperature of the field before allowing any workouts. Of course, they should make sure their players are properly hydrated."

Although Marconi is a big proponent of artificial turf because of its durability and low maintenance, he said his town is looking at other types of designs including one using the by-product of carpet manufacturing.

"Carpets have been deemed safe for the homes for decades," he said. "Maybe that's the way to go."

Staff writer Wynne Parry contributed to this report.