By Jacqueline Howard, CNN, January 27, 2017

"It's important to note that the investigation was not designed to discover the causes of cancer among the people, nor was it designed to add to our understanding of the risks or benefits of crumb-rubber fields," said Cathy Wasserman, state epidemiologist for non-infectious conditions, in her opening statements about the investigation last week.

In other words, the study wasn't designed to identify whether exposure to tire crumbs caused cancer among some of the players. Rather, the investigation was to determine whether the cancer diagnoses were higher than would be expected and then qualify as a cluster.

"When I keep adding up these things, in my head, it's the one thing that I still don't feel great about," she said of crumb rubber being a possible factor.

"Goalkeepers get it in their sides, hips, elbows, abrasions from sliding on the stuff. So if they have an open sore, not only the black dots but the dust particles that you can't even see when the tire crumb breaks down so small get in there. I'm sure you eat it and inhale it," she said. "Just in a 10-minute warmup, our keepers will hit the ground anywhere from 50 to 100 times."

Since the investigation, Griffin said many more people have reached out to add names to her list.

Now, Griffin's list of soccer players with cancer has grown to 237, she said, and her team still uses two fields, one grass and one artificial.

Vasilis Vasiliou, a molecular toxicologist and professor of epidemiology at the Yale School of Public Health, wants more data.

He said he is partnering with Griffin to conduct additional research to dig deeper into exactly how many chemicals and carcinogens from crumb rubber might end up in athletes' bloodstreams.

"The question for me is, do these chemicals get into the blood of our kids?" Vasiliou said. "We need these comprehensive studies to really give us some answers. We need to know how safe it is for our kids to be playing on these fields."

Vasiliou, along with his colleagues at Yale and researchers at the University of Washington, recently applied for a research grant from the National Institute of Environmental Health Sciences. Their application is scheduled for review in early March, Vasiliou said.

The researchers plan to assess human exposure to chemicals in crumb rubber through analysis of biological samples taken from college soccer players.