Up to 40 per cent of soils sampled showed lead levels three times the recommended Australian guidelines, with older homes in the inner west most at risk.
The information comes from a paper released as part of VegeSafe, an ongoing community science program run by Macquarie University, that measures the contamination levels of soils across Australia.
The paper found the worst area for lead contaminated soil was the former Leichhardt local government area, which includes the suburbs of Balmain, Annandale, Rozelle, Lilyfield, Birchgrove and Leichhardt. Soil samples in the area showed median lead levels to be double the rate deemed safe.
Researcher Marek Rouillon said contamination had been around for decades because of historic pollution from leaded products such as leaded paint and petrol.
“This isn’t a new problem, it’s been accumulating for many years,” he said.
Mr Rouillon said the inner west had the highest risk of contamination because many of the houses in the area were built during a time where high concentration lead paint was used.
Mr Rouillon said that one house in particular recorded a lead reading of 6490mg/kg, more than 20 times the national guideline.
“Your natural background level of lead in 20-30mg/kg.” he said.
“We’ve identified that lead paint is actually causing a lot of the contamination in Sydney,” Mr Rouillon said. “It just so happens these houses are very common in places like Leichhardt and Stanmore.”
Mr Rouillon said that the rise of young families moving into inner city areas presented the greatest risk.
“The biggest concern is for infants and toddlers.” said Mr Rouillon, adding that exposure to lead could lead to “irreversible effects such as loss of IQ
Lead poses a health risk when it is ingested, increasing the amount of lead in the blood.
One pathway to exposure is direct hand-to-mouth contact after touching lead-contaminated soil. Another pathway is lead being absorbed into plants such as vegetables.
According to the paper, almost half of all houses in metropolitan areas grow some form of edible produce and the increased levels of lead contamination in these areas means that many people could be at risk.
Fellow researcher Professor Mark Taylor said that the program was an important way of highlighting a danger in people’s gardens that needed to be addressed.
“Our program is really highlighting the fact we have this legacy contaminant,” Professor Taylor said.
Soil in 15 per cent of gardens surveyed recorded a lead concentration level more than three times the Australian guidelines.
The study surveyed 203 homes from 22 former local government areas in the centre of Sydney.
Participants from the nominated areas were asked to send in soil samples from their gardens, with the soils being tested for a variety of metals including zinc and lead.
The samples were taken from a variety of areas around the house and were benchmarked against the Australian guideline 300mg of lead per kilogram of soil.
Soil samples taken in outer Sydney suburbs such as Palm Beach, Baulkham Hills and Camden were used as a reference point because of the areas’ low levels of lead contamination.
The results showed an increase in lead levels towards the city centre, with the highest concentrations being found in the City of Sydney and Inner West Council areas.
Professor Taylor encouraged people to send in soil samples to test their own gardens for lead contamination.
The testing is free and samples from all across the country are welcome with each participant receiving an individual report with information on their soil benchmarked against Australian standards.
Included in the report is information about how to further avoid soil contamination, with options including soil replacement and raised garden beds.
“The good news is that there are ways people can help themselves,” he said. “Our underlying goal is to ensure the community is better informed so that we all can carry on gardening.”