A big I-Team Investigation uncovers hidden dangers inside Milwaukee area homes. We're not talking about lead paint and pipes, asbestos, or mold. We all know to watch out for those. This is a warning about toxic chemicals that seep into the walls, floors, and ceilings, and stay there for years. The biggest problem: people in our area aren't always warned before they move in.

Two-year-old Isabel couldn't be more proud of her new big-girl room. When her mom, Stacie Ramos, signed the lease on their south side duplex last year, her family asked the landlord about the people who used to live there.

"When we moved in, he told us the recent people who lived here just moved out," recalled Chris Pimentel, a family friend. "There was problems. They didn't tell us what kind of problems."

Big problems. In July 2008, Milwaukee Police found a clandestine methamphetamine lab there. Haz-mat crews in moon suits dismantled it, carrying out all kinds of dangerous chemicals like propane and acetone.

"It does concern me, because we have kids in the house," Pimentel said.

Most concerning, the room where the other tenant used a caustic chemical cocktail to make his meth is now Isabel's bedroom. Her mom had no clue. The landlord, Jeff Wilhelm, never said a word, because he didn't have to. We eventually tracked him down and asked Wilhelm if he thought his new tenants deserved a head's-up.

"I didn't deem it as being any kind of danger, so no, I didn't think it was necessary on our end," Wilhelm said. "We tore everything. I mean, we removed the carpeting, we primed and painted everything."

But all that work might not be enough. First responders who've gone through the DEA's special meth training know those living in former meth labs remain at risk long after haz-mat crews pack up.

"There's residues, there's contaminants throughout that house that nobody may be aware of," said Milwaukee Police Lieutenant John Kaltenbrun. "It especially becomes dangerous for young children."

The question Wilhelm can't answer is how much chemical residue may still be inside the walls and the floors and the ceilings of the south side duplex.

"These labs do use chemicals that get into the environment," said Wisconsin Attorney General J.B. Van Hollen "They can soak into the ground. They can soak into furniture. They get into building materials."

Surprisingly, Van Hollen, the state's top cop, doesn't think the state should make landlords tell tenants if their home was once a meth lab.

"As long as people logically do their jobs as we try to do in the [Wisconsin Department of Justice], the lack of a state mandate, I don't think really makes a difference," Van Hollen said.

Right now, all Wisconsin's Administrative Code says is a landlord must disclose "any structural or other conditions in the dwelling unit or premises which constitute a substantial hazard to the health or safety of the tenant." There is no specific reference to meth or meth labs.

"They should be responsible for telling people, definitely," says state Representative Jon Richards of Milwaukee. "I think so, because, especially when you're renting, you have no idea what went on there before. No idea at all."

Richards, who chairs the State Assembly's health committee, thinks it's about time Wisconsin law got in line with other states, like California and Missouri, which already require landlords to tell prospective tenants about the meth lab before they sign a lease.

"We've been looking at it in terms of how do we put people in jail, how do we get our prosecutors and police more tools to combat the situation, and I think it's time we shift our attention a little bit," Richards said.

Until that happens, tenants, like Ramos and her daughter, have to rely on the landlord rather than the law.

The DEA keeps a registry of all properties in the United States where clandestine meth labs have been found. There are dozens of Wisconsin properties on that list. And while it may seem like an odd question to ask at the time, it can't hurt to ask the landlord directly before you sign a lease.

Link: DEA's National Clandestine Laboratory Register: http://www.justice.gov/dea/seizures/index.html