The crippling reach of methamphetamine abuse has become the nation's leading drug problem affecting local law enforcement agencies, according to a survey of 500 sheriff's departments in 45 states.

More than half of the sheriffs interviewed for a National Association of Counties survey released Tuesday said they considered meth the most serious problem facing their departments.

"We're finding out that this is a bigger problem than we thought," said Larry Naake, executive director of the association. "Folks at the state and federal level need to know about this."

About 90 percent of those interviewed reported increases in meth-related arrests in their counties over the past three years, packing jails in the Midwest and elsewhere.

The arrests also have swamped other county-level agencies that assist with caring for children whose parents have become addicted and with cleaning up toxic chemicals left behind by meth cookers.

The report comes soon after the White House Office of National Drug Control Policy restated its stance that marijuana remains the nation's most substantial drug problem. Federal estimates show there are 15 million marijuana users compared with the 1 million that may use meth.

Dave Murray, a policy analyst for the White House, said he understands that the meth problem moving through the nation is serious and substantial. But he disagrees that it has become an epidemic.

"This thing is burning, and because it's burning, we're going to put it out," he said. "But we can't turn our back on other threats."

At a conference on the scourge of methamphetamine, one item on the agenda was a tour of a seemingly unlikely place: a burn unit.

Legislators, doctors, social workers and law officials — including the federal government’s second highest-ranking drug czar — walked the halls of Vanderbilt University Medical Center regional burn center, where seven of the 20 patients were injured by fires and explosions in clandestine meth labs.

Vanderbilt doctors told Joseph Keefe, deputy director of the Office on National Drug Control Policy, and the other participants that meth cases are increasingly common and are driving up state medical expenditures. The costs of treating critically injured burn victims typically exceed $10,000 a day each — and most meth patients don’t have health insurance.

“As bad as this may sound, as a burn doctor I almost wish another drug, one less volatile that doesn’t regularly explode during the manufacturing process, would come down the pike to overtake the popularity of meth,” said the center’s director, Dr. Jeff Guy.

Standing in the doorway of one patient’s room Tuesday, Guy told Keefe that the man had spent 45 days in a hospital from an October meth blast and “has gone out and blown himself up again.”