ELKHART, Ind.—The toxic garbage, often in clumps, blends in easily with the more mundane litter along rural roads and highways here: used plastic water bottles, old tubing, dirty gloves, empty packs of medicine. But it is a nuisance with truly explosive potential, and evidence of something more than simply a disregard for keeping the streets clean.

“;The way to get rid of your meth lab these days is to put it in a plastic bag, then throw it out the car window,”; said William V. Wargo, the chief investigator for the prosecuting attorney's office in Elkhart County.

In the last few weeks, as the snow that had obscured the sides of roads, fields and parks has melted, law enforcement officials here have found at least a dozen so-called trash labs, the latest public safety hazard to emerge from the ever-shifting methods of producing methamphetamine.

Each trash lab becomes a crime scene and is proof, officials said, that a new and ever more popular way of making meth does not demand a lot of space or a lot of pseudoephedrine, an essential ingredient. The new method is a quick, mobile, one-pot recipe that requires only a few pills, a two-liter bottle and some common household chemicals.

Law enforcement officials in several states say that addicts and dealers have become expert at making methamphetamine on the move, often in their cars, and they discard their garbage and chemical byproducts as they go, in an effort to destroy evidence and evade the police.

Just as some states had reported progress in stamping out home-based meth labs, this transportable process has presented a new challenge: 65 percent of meth lab seizures in Tennessee, for instance, are now the one-pot, or “;shake-and-bake,”; variety. The number of meth labs seized in Oklahoma last year increased to 743 from 148 just four years ago, largely because of the prevalence of moving labs. In Indiana, the state police reported that meth lab seizures rose nearly 27 percent from 2008 to 2009.

Wargo attributed at least half of the new meth activity in Elkhart County to the easier one-pot arrangements. He began seeing the switch in 2008.

“;We are so under water on this thing,”; he said.

With disturbing frequency, officials in Alabama, Kentucky, Michigan, Tennessee and other states say they, too, are confronting the problem of trashed labs, and are scrambling to identify and clear the debris—which is often tinged with the drug and other noxious chemicals—before the public stumbles upon it.

“;We just drive around, and off the side of the road, there's one, there's one, and there's another,”; said Paul G. Matyas, the undersheriff in Kalamazoo County, Mich. “;We'll spend all day doing nothing but that.”;

Matyas said that someone finding a bottle on the side of the road “;might think somebody didn't drink all the pop out of their bottle.”;

“;Well, that's not pop,”; he said. “;You pick it up and it could explode. Acid could spill and burn you. At one of the sites about a week ago, we found a dead deer, and I know exactly what happened.”;

In some states, officials estimate that the majority of meth lab seizures are now transportable ones, and that over the last two years, the mobile process has supplanted the home-based method of high-yield production that came to be one face of the meth scourge last decade.

“;I scratch my head sometimes,”; said Thomas Farmer, director of the Tennessee Methamphetamine Task Force, adding that sometimes authorities find more than one pot being made on the move. “;We get 10, 15 bottles going at the same time.”;

Authorities say that the mobile method has grown in popularity because it is easier, cheaper and harder to get caught than making it indoors, and that most of the cooks are addicts themselves, not dealers or distributors.

One two-liter bottle might produce about eight grams of meth, enough for the cook to share with his “;smurfers”;—friends or fellow users who make the rounds at stores, each buying small enough amounts of the main chemical ingredients to stay below the radar of law enforcement, often while meth is being made in the back seat.

States like Tennessee had seen a decrease in meth-related arrests and lab discoveries after passing laws cracking down on consumer access to ephedrine and pseudoephedrine, the decongestants found in common cold medicines. But officials there are seeing those numbers rise again, and they say that is partly because of how smurfers are operating across large territories.

“;We thought we had a pretty good grip on it,”; said Darrell Weaver, director of the Oklahoma Bureau of Narcotics and Dangerous Drugs Control. “;We felt like we had it well controlled, but it's a cat-and-mouse game. Now we have seen an increase in methamphetamine labs again.”;

In 2003, Oklahoma seized 1,200 meth labs. After passing one of the first laws in the country limiting access to pseudoephedrine, that number plummeted to 148 in 2006. But by 2009, the number had risen to 743.

Statistics from the federal Drug Enforcement Administration show that the number of meth labs, dumps and equipment found nationally from 2007 to 2008, the most recent data available, rose nearly 15 percent, to 6,783, from 5,910. That came after a nearly 58 percent drop over the three previous years, from 17,356 in 2003 to 7,347 in 2006.

Rep. Mark Souder, R-Ind., who represents the Elkhart area, expressed some of the frustration common among officials who thought they had made good headway against the meth producers through aggressive enforcement of new laws. Souder said he might propose even tighter restraints on the sale of pseudoephedrine.

“;We broke up some of the big labs, and what we have is lot more little points, little pebbles,”; he said. “;They're harder to find. It is very hard to track this new thing we're trying to deal with because it doesn't have a normal distribution network.”;

And when the police do take samples from a trashed lab or stop a car and find a bottle in process, the illegal product confiscated is often too small for state or federal prosecutors to step in.

“;The quantity of the labs is increasing, but the amount of product is not that great,”; Weaver, in Oklahoma, said. “;You used to find pounds of methamphetamine at a lab.”;

The trashed labs can sometimes function like fingerprints, in that they may contain certain telltale signs of a cook's technique. In those cases, it is easier for investigators to connect the dots and bring charges.

“;We have forced them further underground, to come up with other means to do this,”; Farmer, of Tennessee's task force, said. “;I think we are very much still in the game. They know we're out there and after them, on their heels.”;