A lack of standards or regulations for methamphetamine contamination tests on New Zealand properties has led to dozens of real estate agents conducting the reviews themselves.
Agents and property managers are now being certified to test homes for P, but questions have been raised as to whether a conflict of interest is emerging with those helping to sell property.
Real estate businesses told Seven Sharp independent parties should be testing the homes not their agents or managers, many citing a conflict of interest.
Currently there are no standards or regulations for P testing, which has led to confusing advice for homebuyers and property owners.
The Real Estate Institute of New Zealand said: "Preliminary checks by trained agents or property managers may be logical."
However, the government agency regulating the property industry said agents should stick to providing real estate and not meth testing services and the Property Institute said with such vague rules real estate professionals should steer clear of testing.
Miles Stratford, who runs a company that trains meth testers, has a network of about 300 contractors throughout New Zealand to carry out baseline tests, including agents and property managers.
Real estate professionals are well placed to perform the job, he said, adding the P problem is now so large the property market needs as many trained testers as possible.
"It is a big issue for the country because what we've got is a 15 year plus backlog of properties that've got contamination issues."
A government review is currently under way on the rules of what and how properties are tested, but it is understood the issue of who is testing is not a focus.