Karen Wakil wanted to start a vegetable garden at her home on Sydney’s upper north shore, but concerned there could be toxic levels of lead in the soil she decided to get some tests done first.
- A Macquarie University study has found about one-fifth of vegetable gardens across Australia are likely to produce food with unsafe lead levels
- The study also found more than a third of homes around the country had garden soils above the Australian residential guideline for lead
- Experts say there are strategies that can be implemented to reduce lead levels
“If we were growing a portion of our family’s food in our own soil, we wanted to be sure that we weren’t creating a risk for our children,” Ms Wakil said.
“We do have some lead flashing on our roofs and the house is old enough to have had lead paint, so I thought there could be some contamination.”
While testing showed Ms Wakil’s soil was safe, her concerns were not unreasonable.
A new study has revealed about a fifth of vegetable gardens across Australia are likely to produce foods with dangerous lead levels.
Macquarie University researchers analysed 17,256 soil samples from more than 3,600 homes around the country.
The results showed 31 per cent of vegetable gardens were unsafe in Sydney, compared with 19 per cent in Melbourne and Brisbane.
The study also found more than a third of homes around the country had garden soils above the Australian residential guideline for lead (300 mg/kg).
“Older, inner-city homes … those that are timber constructed and are painted tend to have higher levels of lead in their soils,” Professor of Environmental Science at Macquarie University Mark Taylor told ABC Radio Sydney.
In Sydney, gardens in inner-city, Leichhardt, Marrickville, Ryde, Burwood and Strathfield were among the most toxic.
Mitigating the risks
Professor Taylor said while the study’s results were sobering, there were strategies that could be implemented to reduce lead levels, including installing raised garden beds and mulching exposed soil.
“If you’re going to grow vegies and you’ve got contaminated soil … you’re better off to mulch all the areas where you’re not going to grow veggies, and then build a raised bed with fresh, clean soil,” he said.
“We know that drip lines are the most contaminated part of a garden’s soil, so it’s important that people are aware of that and they don’t use that as a vegetable garden growing space.”
Some vegetables also pose a higher risk than others.
“Root vegetables and fruiting vegetables are less of a risk than what we see with leafy vegetables.”
Professor Taylor said preventing the migration of contaminated soil or outside dust into the house was also a key to reducing the risk of lead exposure.
“Take your shoes off. If you’ve got a pet, it’s preferable the pet stays outside or stays inside because they’re a really clear vector for the transport [of contaminated soil],” he said.
Macquarie University research assistant Kara Fry added that proper hygiene — including frequent handwashing — also helped.
“If you’ve got young kids, you might like to designate a clean play space for them. That might be a garden bed, like a raised bed with clean purchased soil that they can play in,” she said.