WAYCROSS, Ga. - There is a cancer problem in Southeast Georgia. They don't know the cause - but residents have their suspicions.

Janet MacMahan's son died from gastro esophageal junction adenocarcinoma. He was 24. "The water is definitely causing these cancers," she says.

"The six mile radius where four kids were diagnosed at the time my son and two dogs and I," she continues. "We knew it had to be the water."

MacMahan would discover negligible levels of arsenic in her water well. She stopped using it but has not stopped looking for answers.

"The whole time it has been - oh my God - kids are drinking this water," she explains.

- CDC investigation -

In Summer 2015, their fears were heightened. Four children were diagnosed with the same cancer within a 60 day period, in and around Waycross. Five-year-old Gage Walker is on of them. The diagnosis is Rhabdomyosarcoma. It's rare: only 350 cases are diagnosed in the U.S. each year.

Gage recently finished his treatments and has to have CT scans every six weeks. Neighbors say they believe the source of the cancers is environmental.

RELATED | CDC to investigate possible 'cancer cluster' in Southeast Georgia

Last December, the CDC's Agency for Toxic Substances and Disease Registry began its investigation.

Investigators are looking at two locations: the CSX Rice railyard and the former Atlanta Gas Light property. The review of the railyard is complete and now the Atlanta Gas property is under review.

- Silent Disaster -

The community group called Silent Disaster is tracking the cases of childhood cancer in and around Waycross. Last May, the group collected water samples from several locations and sent them to a lab for review.

"We spent about $10,000," explains Joan Tibor of Silent Disaster. They discovered certain chemicals - much to their surpirse.

"We found Lead 210 and Polonium 210 and Radium 226 in that water system," she says. What does that mean? "As as Uranium. Actually all the daughters, all of the breakdowns of Uranium are in that water... it is not good."

Tibor moved out of Waycross after an illness but she has been on a crusade to find out the cause of the cancers in the community.

"We tested at some homes where we knew people were having health problems and they tested over [EPA standard levels]," she continues. "All of the systems that we tested either had Polonium, Lead 210 or Radium over the health parameter."

There is no proof this is related to a source of pollution.

"We don't know the source," Tibor admits, "but we believe we know what triggered the escalation."

The Georgia EPA says small amounts of Radium and Uranium occur in groundwater in certain parts of Georgia and that elevated levels are naturally occurring and not the cause of pollution. Silent Disaster has submitted its findings to the CDC and say they would like them to act on it.

"They're on the clock and I'm raising total hell on Facebook," Tibor says.

- Radiation from groundwater -

It is unclear what the full meaning of their test results is, but it is a fact that long term exposure to high levels of Polonium and Radium will increase the risk of cancer.

"When you throw in Arsenic you multiply, synergistically, the effects of radiation," Tibor explains.

These crusaders say they're not ready to give up on their effort to find out what's causing the rare cancers in their community. And they're not alone.

RELATED | Georgia lawmaker wants Waycross declared a 'cancer cluster'

"Look at the facts around the cases in the Ware County region. It would most likely fit the CDC's definition and you would most likely call this a cancer cluster," Georgia state Rep. Jason Spencer told First Coast News last year.

Media personality and activist Erin Brockovich has also said she is going to investigate the strange illnesses in Ware County and Waycross. Brockovich first rose to fame in 1993 after successfully building a case against Pacific Gas and Electric for drinking water contamination.

The area hasn't been declared one at the time of this writing. The CDC is continuing their investigation of the area and we will continue to cover this story as it develops.

Brockovich posted to Facebook saying she was getting involved: