Planning a vege garden? Get a free soil test to check for lead

A community science project, Soilsafe Aotearoa, is offering the service, which tests for eight contaminants: arsenic, cadmium, chromium, copper, manganese, lead, nickel and zinc.

Lead contamination can be a particular problem in Kiwi backyards. The heavy metal was previously used in house paint and petrol.

Soilsafe Aotearoa is co-led by Dr Melanie Kah and Dr Emma Sharp.

Dr Sharp said lead levels can depend on how well a home’s exterior has been maintained and how close the garden is to a main road.

“The occurrence of other metals may be due to high natural background levels, or … practices, like burning tanalised wood,” she said.

Tanalised wood can leach arsenic and copper into the soil.

The project is run by the School of Environment at the University of Auckland, in partnership with GNS Science and Macquarie University. To date, it’s tested 1570 samples from 339 properties throughout the country.

Results will be collated to provide baseline data on the state of garden soils, Dr Sharp said.

In Australia, a similar study found high levels of lead in 35 percent of homes (particularly in older, painted houses in inner cities).

Last year, there were 111 recorded cases of lead poisoning here. Excessive lead can cause serious health problems, including kidney damage. Children are at higher risk of harm. They absorb more lead than adults and too much can damage their developing nervous system.

How to get your soil tested

To register for the project, visit Soilsafe Aotearoa and enter your details.

You’ll need to collect cricket ball-sized samples of soil from different areas around your house and then send them off for testing. While the test is free, you’ll need to pay postage to the test lab in Dunedin.

Testing takes about eight weeks. If contamination is found, Soilsafe Aotearoa will provide advice on what you should do.