The study did not prove cause and effect, they said.

He says a study has proved that the move would save the state more than 16 percent on drug costs.

But, she continued, the new study has not yet proved that this is the case.

But he added that such a study might prove "a difficult challenge."

Instead, scientific studies proving that a treatment works are needed.

The new study does not prove that personal care products cause breast cancer.

"No study can prove the absence of an effect," he said in a statement.

Recent genetic studies proved its position as a separate species.

A spokeswoman for the meat industry, however, said the study did not prove cause and effect.

Recent studies have proved that an airport is strongly needed in the county.