MANATEE, Fla. -- A group of alumni at Bayshore High School say the school is a cancer cluster. They’ve been taking their concerns to Manatee County and school district officials for nearly 15 years and today their story got national attention on "CBS This Morning."

“I live with the guilt of sending my son to the school. If that is the case then I want answers,” said Liz Reed. Her son Ricky died of a rare form of bone cancer 20 years ago.

He’s one of nearly 500 cases with cancer or autoimmune illnesses including more than 100 deaths and all have some type of connection with Bayshore High School.

Hydrogeologist Dave Woodhouse has been studying the Bayshore case. Does he think there a cancer cluster case at Bayshore High School?

“Yes. Definitely convinced,” said Woodhouse.

Woodhouse says he’s worked more than 100 of these cases over the years, and “This fits the same model so many other cases I’ve worked on.”

First there is the case number, which Woodhouse says is staggering. “This isn’t just a town or a city that has 500 people -- it’s one building. “

There’s also the rare types of cancers seen and the school’s location. Woodhouse says industrial sites up to three miles away injected contaminants into the water from arsenic to chlorinated solvents and heavy metals.

Woodhouse says all that water flowed south under the school and its wells.

“The wells react like straws in the ground bringing up contamination. That water was used in showers, drink, irrigation,” Woodhouse explained.

The school’s story appeared on "CBS This Morning" after the health department said it would request health information from alumni between 1984 and 2012.

“Those results will be inconclusive not reach everyone went to school there,” said Cheryl Jozsa from Orlando.

Jozsa has led the fight for answers after her sister died of a rare type of leukemia in 1999. Her sister Terri was a 1979 Bayshore graduate and one of foyr leukemia cases in her class.

Jozsa said, “My sister was amazing, and had a loving huge heart.”

Jozsa says she has struggled with the county and school district for answers.

She said, “The most frustrating part is for years we’ve been dismissed.”

She hopes national attention will reach alumni before it’s too late because “early detection may help someone’s life.”

Reed wants to spare other families her pain.

“I don’t’ want any parents to go what I went through.”

The group has a Facebook page to keep alumni informed

There are several factors to determine if those who are sick are really part of a cancer cluster or it's just a coincidence.

According to the Centers for Disease Control and Prevention, it's when there's a greater-than-expected number of cancer cases that occurs within a group of people in a geographic area over a period of time.

The American Cancer Society says as many as four of every five suspected clusters are determined not to be connected at all.

Here's how the cases at Bayshore High School measure up against the CDC's criteria.

There are a high number of cancer cases there are about 500 of them.

To be considered a true cluster, all of the cancer cases have to be the same type or the types have to have the same cause.

So far there have been 25 leukemia cases.

But in the bigger picture, more than a hundred patients have died from *different cancers.

The group have all been students at the old school site from the 1970s to 1999, when the school was demolished.

Geographically, these cases have been linked to the site, but no soil samples have shown anything that would have caused cancer.

The cases were generally diagnosed about 20 years after graduation.

Woodhouse says previous soil samples have not been deep enough. He recommends doing rock core testing several hundred feet down and possibly deeper, but first the county should do a seismic survey underground.

The health department will be collecting the health forms through February and expect to have a report ready by next fall.

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