Parents in one California community are fighting for answers after at least seven children were diagnosed with cancer in the past four years. Earlier this year, they fought to remove a cell phone tower from a local elementary school campus. Now, they're focusing on a chemical in their drinking water supply that's linked to cancer. And Ripon, California, is just one of dozens of cities across the country dealing with the possibly harmful chemical.   

"Until we figure out what is happening in this town, we won't stop," said Kellie Prime, a mother whose son, Kyle, is one of at least seven kids in Ripon who have been diagnosed with cancer in recent years. Prime and another mother successfully had the cell phone tower removed, and have since shifted focus to the drinking water. 

"My gut tells me that something is here that's causing these issues," Prime said.

Ripon was once home to a Nestle plant that used trichloroethylene, or TCE, to decaffeinate coffee until the 1970s.  Nestle discharged the plant's wastewater into the city's sewers. TCE was recently found in one of five city drinking water wells.

The city of Ripon said TCE levels reached 90% of the EPA maximum allowed in drinking water last summer.  The well was turned off four months later.  The city says the water "meets all established drinking water standards," and Nestle said that for more than 30 years, the company has "implemented... cleanup and water protection measures to ensure... levels... do not exceed California standards."

But University of California San Francisco scientist Veena Singla said that when it comes to chemicals like TCE, there are no safe levels of exposure. 
 
"Drinking water standards and guidelines that we have now are many decades old, and they don't account for the latest science that shows pregnant women and children are more susceptible to TCE," Singla said.

Millions of pounds of TCE are used every year for manufacturing and degreasing. The chemical can migrate from industrial sites into surrounding communities through the soil and water, and can even turn into a clear, odorless vapor that moves up into the homes above.

"We know it can cause cancer by any route of exposure," Singla said. "So what that means is whether you breathe it in, whether you drink it in contaminated water… we're concerned about all those exposures."

When asked if she thinks TCE exposure could have caused her son's cancer, Prime said that "I think it needs to be looked into, for sure."  

Last year, CBS News visited Franklin, Indiana, where dozens of kids were diagnosed with cancer. A non-profit found high levels of toxins, including TCE vapor, in homes near an old manufacturing site. Clean up and testing under the EPA is ongoing.

"We used our kids as the canary in the coal mine in our town," said Kari Rhinehart, who lost her daughter to brain cancer.

In White Bear Township, Minnesota, community members diagnosed with cancer and their loved ones were outraged after learning a company that makes fishing sinkers and battery terminal posts admitted TCE had been leaking into the air for years, at points reaching seven times what was allowed. 

In Ripon, families are calling for additional vapor testing. "We have a lot more questions than we do answers -- so until we get those answers to those questions, we are very concerned," Prime said.

Regulators say potential health effects from TCE depend on the amount and length of exposure, and it can be difficult to trace the cause of any one cancer diagnosis.  But Prime says after seeing her son's battle firsthand, she'll do anything to prevent other parents from experiencing the same pain.   

"It was hell… it was life-altering," Prime said. "He's sick every day, losing weight, losing his hair."

Her son is now in remission – but Prime is determined to keep pushing forward. She said she's motivated by "the fight these kids have in them."

"We have to show them that we will fight for them," she said.  

The regional water board has asked Nestle to do additional vapor testing to ensure TCE levels are within new, stricter guidelines set by the state.  Nestle says the work plan has been submitted and approved by the water board.