Pat Hannigan can't explain the cancers she and her husband survived.

But, like others in this Hudson River town where drinking water is contaminated with the gasoline additive MTBE, she's trying to connect the dots.

"I tell you, I know we're a small town, but there have been many, many cases of cancer," the 26-year Fort Montgomery resident and melanoma survivor said.

"I think it's really something they should look into."

Twenty-one U.S. senators couldn't agree more.

Last week, following reports that MTBE is a "likely" carcinogen, Senate leaders demanded answers from the federal Environmental Protection Agency.

In a letter to EPA Administrator Stephen L. Johnson, 19 Democrats, one Republican and one independent sought details of an internal study that reportedly concludes MTBE causes cancer.

MTBE, which was put into gasoline to reduce air emissions, has been banned in some states because of contamination to drinking water supplies.

"This is extremely troubling and certainly warrants further investigation and review," the senators wrote.

Key elements of the risk assessment have not been made public, and EPA officials say the nonpeer-reviewed draft represents "incomplete information."

"This draft should not be construed to represent agency determination or policy," spokeswoman Eryn Witcher said.

"It's too early to determine anything."

While some research has linked MTBE to cancer in laboratory animals, no study has ever found the link in humans.

Yet with revelations that the EPA might know more than previously released, residents in some MTBE hot spots are crying foul.

"My health was always good until about a year ago, when I was diagnosed with colon cancer," Pat's husband, Butch, said as he sat outside his Canterbury Road home here.

Empty 5-gallon bottles of Poland Spring Water sat near the front door. "I've always had a healthy lifestyle, so I kind of questioned why I got it.

"But of course, with this whole MTBE thing going on, it's easy to blame that."

Such thinking could become infectious.

And costly.

On Monday, lawmakers abandoned product liability protection for MTBE manufacturers, clearing the way for passage of a sweeping energy bill.

The move also cleared the way for more than 150 lawsuits, including one in Fort Montgomery, filed against petroleum manufacturers nationwide.

John Sarcone is a Westchester County attorney representing the Hannigans and more than 100 others in this Orange County hamlet.

"You have to punish" the manufacturers, Sarcone said of the $27 billion in punitive damages he's seeking on behalf of his clients.

"They knew their product was defective and it would contaminate groundwater, and yet they continued to use it anyway."

Similar cries for compensation are echoing across the country; communities in at least 36 states have water supplies contaminated with the chemical.

In New York, more than 14,000 wells and water systems are tainted.

State health officials say they've never tried to link Fort Montgomery's water woes to cancer.

But Pat, 56, says the evidence is clear: She knows 12 neighbors who've suffered similar maladies and suspects there are more.

Coincidence?

Butch, 51, doesn't think so.

"My train of thought ever since I was diagnosed with cancer has been, what's my long-term costs going to be?" he said.

The day might come when he needs a lawyer to answer his own question.