Washington state health officials say artificial turf that contains crumb rubber does not appear to cause cancer.
Crum rubber is commonly made from old tires.
In 2009, Amy Griffin, a coach for the University of Washington’s women's soccer team, became concerned that several goalies had developed blood cancers at around the same time.
She thought crumb rubber could be to blame and she started compiling a list of players who had developed cancer.
The list, which included 53 players from Washington, prompted an investigation by the state.
They looked at a number of the players identified by Griffin to see if they’d developed cancer at a higher rate than normal.
The state released their results on Wednesday.
Lauren Jenks, with the state department of health, said they found lower rates of cancer in the players they studied than they'd expect to see in the general population.
And even though their investigation didn't focus on the safety of crumb rubber, Jenks said the results are reassuring.
"If you're playing on the crumb rubber fields right now, it does not appear to be causing cancer,” she said.
“That's not carte blanche that it's totally safe, I think there are still limitations to what we know. But based on what we know, if you enjoy playing soccer you should continue playing soccer. We know for sure that physical activity and soccer are good for you."
The state's investigation was not designed to look at the causes of cancer in soccer players.
And Coach Amy Griffin says she still has concerns about the use of crumb rubber in artificial turf.
“The more I learn, the more worried I become. Just the mere fact that I know what's in it and I see it break down into dust so that when kids are on it all day the dust is actually sticking on their skin, they look like they're on a coal train, I just can't imagine that that's good for you.”
Studies to date have not shown a connection between crumb rubber and health risks. However, federal agencies say there are gaps in the research and they’re currently evaluating the possible impacts of the substance.
Washington state officials say if you play on crumb rubber, shower after playing and thoroughly clean any cuts or abrasions. They also recommend that people don’t ingest crumb rubber and that they remove their cleats outside so they don’t track recycle rubber into the house.