Media reports about possible links between the rubber crumbs in artificial turf and cancer rates in soccer goalies are raising concerns, but so far officials say there are no studies documenting any risk.

Washington State University soccer coach Amy Griffin first raised the concerns when she noticed she was visiting more young soccer goalies in cancer clinics than ever before.

"I've coached for 26, 27 years," she said. "My first 15 years, I never heard anything about this. All of a sudden it seems to be a stream of kids," Griffin told NBC news in a recent report.

That prompted her to put together a list of 38 U.S. soccer players who had recently been diagnosed with cancer. What alarmed her was that 34 of them were goalies.

That caught the attention of Julie Foudy, a former U.S. national team captain and now a journalist for ESPN, who made a documentary on the concerns.

She told CBC News since the documentary aired this week her list of young athletes being treated for cancer has grown to 187 and more than half of them are soccer goalies, and many have lymphoma.

Evidence is anecdotal

Both Foudy and Griffin are quick to acknowledge that all of the evidence is anecdotal and that researchers have not established any scientific links between the rubber crumbs and health effects.

"The turf industry says we are 100 per cent confident in the safety of these fields because the data supports that," says Fordy.

Rubber pellets pop out of the artificial turf behind Portland Timbers midfielder Will Johnson, left, as he slides in on Vancouver Whitecaps midfielder Cristian Techera during an MLS soccer game in Portland, Ore., on July 18. (Don Ryan/AP)

The rubber crumbs are made from recycled car and truck tires that are ground up into rubber crumbs and spread on the turf to give the surface bounce.

She notes 20,000 tires can go into a single field and little is known about the origins of the tires and the chemical compounds they contain.

She notes the pellets can contain up to 27 chemicals of concern — including 11 known carcinogens.

"What we do know is there is a lot of bad stuff in tires. The question is — is it enough that it is harmful to kids?" says Foudy.

Ingestion as a pathway

Foudy says industry studies on the issue have focused on air exposure from gases emitted by the pellets, but not other more direct forms of exposure.

"Science right now says there is not a high enough level of concern, but again you have that big data gap... They are not looking at the other pathways to exposure."

There are concerns goalies, like Vancouver Whitecaps' goalkeeper David Ousted, might be ingesting the pellets during the games. (Darryl Dick/The Canadian Press)

She notes the rubber pellets end up in the eyes and open cuts on players, and particularly in the mouths of goalies, who spend a lot of time diving and catching balls on the ground.

"They haven't been looking at ingestion ... They are eating them. It's in their mouths when they catch a ball."

"Ingestion is the pathway with long-term exposure," said Foudy. "That is the big gap in the studies."

"We had one mum whose son died from cancer, and he'd wake in the morning and think it was sleep in his eyes, and it was turf pellets."

UBC prof echos concerns

At the UBC School of Population and Public Health, associate professor Trevor Dummer agrees the evidence is anecdotal, but it does raise enough concerns to warrant further study.

"Without starting any sort of panic or massive change in behaviour on peoples part, I think this is something that warrants another look at from a scientific perspective, bearing in mind that would be a complicated and expensive study to do," he says.

"It is an area where we should direct some more scientific research, just to look at whether there could be an issue with accidental ingestion and consumption."

Nevertheless Dummer — whose own son plays soccer on artificial turf — says parents and players should not panic.

"I don't think with the current evidence that we have that there is a huge cause for concern, that people should be stopping their children from playing on these pitches. I wouldn't suggest that."

But he says for now, everyone should take some basic precautions.

"You don't want to eat these things. You should shower after you play, wash your hair, things like that, just this sort of sensible advise, to make sure these pellets are not sitting on you for a long time."

Vancouver monitoring the issue

The Vancouver Park Board manages 11 synthetic turf fields in the city. Spokeswoman Margo Harper said the board is aware of the concerns and is monitoring the issue closely.

But for now, they have have found no reason to take action.

"Based on information from Canadian health experts, agencies and independent consultants, there isn't yet enough data to draw any conclusions," said Harper.

Fordy notes California has recently launched a three-year $3-million study on the issue and U.S. senators have called for an Environmental Protection Agency investigation into the safety of the rubber crumbs.

She says for now it is up to parents and communities to make their own decisions, but there are simple precautions players can start taking right away.

"At least wash your hands and at least be aware. I think the public deserves that right, and has a right to know."

To hear the full interview listen to the audio labelled Crumb rubber cancer concerns with the CBC's Stephen Quinn on The Early Edition.