Jacki Whittaker thought one of the bedrooms in her Melbourne rental home smelt like "cat piss". But the real culprit was something far more sinister.

The previous tenants had been cooking methamphetamine in the bathroom resulting in significant contamination.

Jacki and her two adult children were told by a testing company they must leave immediately because it wasn’t safe to stay in the house.

But no one really knows how many of us are actually at risk from meth residues because even scientists haven’t even worked it out.

In this episode, Hagar Cohen investigates how some operators in an unregulated meth testing industry are scamming the public and profiting from our fear.