State researchers have found no increase in cancer cases near a Gilford site where toxic coal-tar waste was dumped in the early 1950s, according to a report released yesterday.

Last winter, a resident of the Liberty Hill area gave the town administrator a survey of local health problems, including 19 cancer cases.

The state Department of Environmental Services started its cancer study from that list, said Dennis Pinski, who supervised the report.

Four properties on Liberty Hill Road are designated by his department as comprising the hazardous waste site, numbered 69, 77, 83 and 87. Keyspan, which took over a company that reportedly dumped the waste in Gilford after a 1952 gas plant explosion in Laconia, recently bought the properties, said Debbie Shackett, interim town administrator. Two houses were built after the dumping, and they have since been razed.

Gary Bernier grew up just down the street, at 41 Liberty Hill Road, with his sister.

He said he remembered throwing rocks into the tar pit in the early 1960s.

His sister, Sylvia Swift, died in June 2006 of brain and lung cancer, 30 years after she quit smoking. His mother died of cancer in 1982, he said, but was a smoker. His father also died of cancer, he said, but his death was not recorded on the survey that the state formed its study around.

Bernier has since moved to Wilmot, where he was diagnosed with non-Hodgkin's lymphoma three years ago.

His family's experience demonstrates shortcomings in the information.

Although people in his family lived near a hazardous waste dump that was unrestricted while he and his sister were young and had a high rate of cancer, they also smoked and may have had a genetic predisposition to the disease.

Pinski said that "cancer clusters" were rare and that it was often difficult to trace the causes of cancer.

"We can never draw a cause and effect," he said. "The numbers get very murky when you start to go from groups to families or households."

In the Liberty Hill study, he said, his department investigated cancer rates at households where the risk of exposure to contaminants from the dumped waste was minimal.

It was necessary to do this, he said, because a larger data set would yield more statistically relevant results.

Bernier was surprised to learn that the state did not find a higher rate of cancer near the site.

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