This Nov. 25, 2013 photo shows certified industrial hygienist Gary Siebenschuh putting on a hazardous materials suit before entering a home that once served as a clandestine methamphetamine lab in Memphis, Tenn. The house was placed under quarantine after a Nov. 6 fire that police said was caused by a meth lab that exploded in the attic of the house. (AP Photo/Adrian Sainz).

MEMPHIS, Tenn. - Tens of thousands of U.S. houses have been used as methamphetamine labs over the last decade, and an industry is developing around cleaning them up.

Many Americans are aware of the production of the highly addictive drug thanks to AMC's hit show "Breaking Bad," which featured a chemistry teacher who turned into a meth cooker and dealer. In real life, cleanup contractors deal with a property when a batch explodes or police raid an operation and shut it down.

However, there is little oversight of the growing industry, opening the door for potential malfeasance. And some homeowners are often reluctant to pay thousands of dollars to make a property safe, so many houses don't get cleaned for years, exposing residents and sometimes even neighbours to harmful chemicals. Many insurance policies do not cover meth cleanup.

To make a meth home safe, a certified contractor must remove and replace all contaminated materials, from walls to carpet to air conditioning vents. Next, a certified "industrial hygienist" tests the home to gauge whether it can be lived in or needs more cleaning.

"You do testing in the front end, so we can find out how much meth is there," said Gary Siebenschuh, whose company, G7 Environmental Services, also does testing for asbestos, mould and other contaminates. "Then the homeowner hires a contractor, and then he cleans it up."

Despite laws requiring landlords to disclose if meth had been made on a property, experts say such disclosures often don't happen.

Exposure to meth residue can cause respiratory problems, and health officials say meth homes pose a threat to public safety. For example, squatters may enter abandoned homes, and children play around them.

Over the last decade, tens of thousands of homes have been used to cook meth, according to federal data. About 25 states have laws related to meth cleanup. Some states, such as Indiana, Kentucky and Tennessee, place meth homes on quarantine lists. Some properties on Tennessee's list date to 2006, underscoring the years it often takes for some properties to be cleaned. Cleanup costs can range from $3,000 to $25,000, depending on the home's size and the amount of contamination.

Joe Mazzuca, CEO of operations for Meth Lab Cleanup LLC, said his business has been growing 30 per cent annually in recent years.

"We consider it to be still in its infancy," said Mazzuca.

Many independent contractors, such as law enforcement officer Don Horne, do meth cleanup as a second job to make extra money.

Horne noted that contractors who offer very low bids may be cutting corners.

One Tennessee hygienist faces federal fraud charges for contracting with home owners to clean up their properties, then illegally certifying that the homes were safe to live in despite not being properly cleaned. Douglas McCasland has pleaded not guilty, and faces trial in June.

With a small staff, Tennessee's meth remediation department acknowledges it does not have the manpower to closely oversee contractors.

Dan Hawkins, head of the state's meth remediation office in Knoxville, says the division received federal funding to operate the website and has about three employees. The state is looking at training more people to oversee and evaluate cleanup jobs.

"We are aware that contractors may run the entire scope, from very good to terrible, and we are evaluating," he said.

News from © The Associated Press, 2013