High levels of lead have been found in soil under homes in a suburb of Thames in Coromandel already known to have high arsenic levels.
There are about 200 homeowners living in Moanataiari. Since November last year they have been told they cannot eat vegetables grown in their gardens or let children playing outside put soil in their mouths.
The arsenic was discovered late in 2011 by contractors digging up soil during work at a school in the suburb. It is thought to be from mine tailings dumped as landfill 60 to 90 years ago.
New soil tests have now revealed high levels of lead in the soil at residential properties in the eastern part of Moanataiari sub-division.
Thames-Coromandel District Council believes the lead is naturally occurring, but a resident, Dennis Tegg, believes historic gold mining is the real cause. He says the subdivision is built on old mine tailings, which are a far more likely source than the lead paint the council's consultants are suggesting.
The Waikato District Health Board says residents need to take the same precautions with lead as they have been with arsenic.
A full report including management and remediation options is expected from the council later this year.