Many of the metals, including lead, copper, chromium and zinc, remain in parks and gardens at levels considered dangerous to human health.

The extent of the contamination is outlined in a new Macquarie University study that shows for the first time the ongoing environmental and potential health impacts of the city’s industrial past.  

The majority of the contaminants can be directly traced to the city’s former smelting and steel making industries that spread pollution through atmospheric dust and slag waste, a by-product of the metal mining process.  

The study also has significant implications for the future management and notification of environmental risks across the city.

“Newcastle is very similar to other former industrial cities around the world, such as [the former US automotive manufacturing city] Detroit, where there are lots of metals and hydrocarbons left in the soil,” lead author Paul Harvey said.

“The way we look at Newcastle from an environmental management perspective needs to change.”

The three-year study, published in the journal Science of the Total Environment on Wednesday , involved testing 150 soil samples taken from five areas including Carrington, Mayfield, Newcastle and Cooks Hill and Merewether.

Lead was the most abundant metal contaminant found in the soil samples. It was found to exceed Australian Health Investigation Levels in 88 per cent of samples taken from private residences.

The Newcastle Herald has previously reported on the health impacts of lead exposure, which include learning difficulties, behavioural problems and cancer, as part of the award-winning Toxic Truth investigation into the contamination fallout from the former Boolaroo lead smelter.

About 45 per cent of the lead found in the Newcastle study was able to be converted into a form that could be absorbed in the human intestine.

Mr Harvey said it was believed high levels of lead found around Newcastle were most likely the result of lead ore dust that blew across the city as it was being transported from the port of Newcastle to the Cockle Creek lead smelter in the early twentieth century.

The problem was compounded by lead slag smelter waste that was used as clean fill across the city for years.

Significant levels of copper, which can be traced to a former copper smelter that operated in the city prior to the establishment of the BHP steelworks in 1915, were also found

“When we looked at the soil samples under the microscope we saw characteristic particles from from iron, lead and copper smelting. There was an indication that smelter material is quite widespread across the city,” Mr Harvey said.

While the majority of the contamination was found closer to the former industrial sites, significant “hot spots” were located in areas not traditionally associated with industrial activity.

“Industrial slag was a very common source of clean-fill,” Mr Harvey said.

“A lot of it was used around the docklands but it was also used widely across the city.”

In addition to metals, the researchers also tested for carcinogenic polycyclic hydrocarbon compounds, a pollutant commonly associated with steelmaking.

The compound benzo(a)pyrene was found in numerous soil samples at levels that exceeded Australian Health Investigation levels.

“While we have strong evidence linking the presence of contaminating metals in Newcastle’s soils to the city’s legacy industrial activities, the source of these other polycyclic aromatic hydrocarbon contaminants is still unclear,” Macquarie University environmental scientist and study supervisor Mark Patrick Taylor said.  

“They could be present due to steel manufacturing and coal transport practices, as well as incomplete combustion of motor vehicle emissions.”

In addition to creating increased awareness about the pollution risks across the city, the study’s authors have called on state governments to adopt a more coordinated and consistent approach to dealing with legacy pollution issues.

“To do nothing would be disingenuous to the people of Newcastle; ripping up large parts of Newcastle is not an option either, but there are things that can be done at a policy and regulatory level, ” Professor Taylor said.

“If we were talking about redeveloped site that had this sort of pollution on it, the NSW EPA would order a full clean-up be done. But there is an hiatus between new developments and existing developments.”

Mr Harvey said a more robust property pollution certificate system also needed to be introduced.

The certificates, known as section 149 certificates, advise potential property buyers of residual contamination on a property. Hundreds of the certificates have issued for properties surrounding the former Boolaroo lead smelter.

“More title deeds might need to have a section 149 certificate on them indicate that there might be a contamination risk,” Mr Harvey said.

“Maybe we need to review how those notices are put onto title deeds.”

Carrington resident Russell Green said he felt many long-term Newcastle residents  simply accepted high levels of residual pollution as a fact of life.

“I have no doubt that if you were to dig down a bit anywhere around here you would find all sorts of terrible stuff,” Mr Green, whose father was a boilermaker at BHP, said.

“It’s an important subject but I’m not sure it is being taken as seriously as it needs to be. People need more information about how they could be affected.”

He added government pollution policies helped promote community apathy.

“If we were in another country there would be outrage about this sort of pollution. California, for instance, has very strict pollution controls.”

Mr Green said he and his wife Kim were considering a vegetable garden in their backyard.

“It certainly looks like there were vegetables and chickens here once,” he said.

“If we put a garden in it will probably be above ground.”

Mr Harvey said the success of the programs such as Vegesafe, also provided an opportunity to educate residents of potential soil contamination issues.

The Vegesafe program, developed by Macquarie University in 2013, offers free testing of garden soil samples for heavy metals.

More than 6000 samples from 1400 homes from across Australia have been tested to date.

The university has received about 30 samples from Newcastle homes, a number of which contained high levels of lead.

“We need to educate the community about metals in the soil, but we also need to educate people about how to manage those risks,” Mr Harvey said.

If you have a problem on your property then you need to know where you can go to get help to sort those problems out.”  

A NSW EPA spokeswoman said the authority would meet with the report’s author’s in the near future. 

She said Section 149 certificates had been issued to homeowners in areas such as Carrington since 1997. The certificates also offer advice about using raised garden beds for growing food and replacing soils in areas regularly visited by children and pets.

Hunter New England Health public health physician Tony Merritt said the   key determinant of risk is whether the contaminant is capable of getting into children’s bodies in amounts likely to cause health effects.

“Generally, it is only in highly-contaminated environments where there is bare soil, for example no grass, concrete or sand, that lead in soil is of health concern,” Dr Merritt said. 

A recent study of 72 children aged under 5 years in the North Lake Macquarie region, where lead is known to be present in soil from past industrial activities, found all children had a blood lead level below 5 micrograms of lead per deciliter of blood. This included those who played extensively in soil and did not wash their hands before eating.

Blood lead levels of 5 micrograms of lead per deciliter of blood are notifiable under the Public Health Act.