Vegetable gardens with a lead concentration lower than the current Australian soil guideline may produce vegetables that exceed the Australian Food Standard, according to new data modelling from the Macquarie University VegeSafe program.
New research published in October suggests soil with a lead concentration of 270 mg/kg could produce vegetables that exceed the Australian food standard based on 2631 vegetable gardens tested. The current Australian guideline for soils in domestic residences is 300 mg/kg.
The modelling follows research published earlier this year through the VegeSafe program, which sparked conversations surrounding concerns about toxic levels of lead in urban soil across Australia. The research results showed more than a third of Australian homes tested had garden soils above the Australian residential guidelines for lead.
VegeSafe is a community science program run by environmental science staff at Macquarie University which aims to educate but not scare the community about metal contaminants, so they can continue gardening in a safe way.
What’s the big deal with lead?
Lead is a naturally occurring element expected to be found in soil. However, Macquarie University research assistant Kara Fry said lead could have serious neurotoxic effects, particularly for young children.
“During activities like gardening, we can unknowingly ingest or inhalable possibly contaminated soil particles,” she said.
“Soil can be tracked into the home on your shoes and clothes after gardening, and on windy days exposed soil can also be remobilised by wind and enter your home as dust. For young children with frequent hand-to-mouth activity the risk from ingestion is higher. Additionally, home-grown veggies can uptake lead from the soil.”
According to previous research through VegeSafe, older homes, painted homes and inner-city homes are most likely to have high levels of lead.
Miss Fry said: “This is due to the long-lasting impact of legacy contaminants, like emissions from the leaded gasoline era and peeling and flaking lead paint from older, painted homes. Homes that are nearby mining and smelting operations may also be at risk for trace metal contamination.”
How can we keep our veggie gardens safe?
Miss Fry said while lead contamination and the potential risks in your garden could feel “very doom and gloom” there were simple things you could do to reduce your exposure.
“The first is to have your soil tested,” she said. “General good-practice actions like washing your hands after time in the garden, leaving dusty clothes and shoes at the door, installing doormats to prevent soil being tracked into your home and mulching areas of dry, exposed soil can help to reduce your exposure risk.
“Also make sure that home grown produce is thoroughly washed before eating.
“In the event of soil contamination, there are a range of remediation options to suit various budgets and the magnitude of the issue, from planting edible veggies in raised beds, to soil removal and replacement.”
A large part of the VegeSafe program is to educate the community about metal contaminants in their garden soil and how to mitigate these risks, Miss Fry said.
Isabella Signorlie, 25, a relatively new urban vegetable gardener, said she first started her vegetable patch March 2020 and had never heard of vegetable uptake of lead.
She said: “I don’t use raised beds. No, I know nothing about lead in soil.
“I have broccoli and cauliflower growing at the moment, but I do always wash them thoroughly after picking.”
To get your soil tested or learn more about mental contaminants in soil head to:
An interactive map of soil samples can be found here: