After decades of concern about the health effects of lead pollution, scientists have found the toxic pollutant no longer poses a threat to the air quality in our major cities.
- Concentration of lead in the air in major cities is now largely below limits of detection
- But scientists warn contaminated soil and dust is causing problems in backyards
- Vets say they’re seeing more cases of backyard chickens with lead poisoning
But, perhaps surprisingly, scientists warn that lead is still a problem in the place where most Australians would least suspect it — the humble Aussie backyard.
These were the findings from the first comprehensive snapshot of industrial lead contamination in Australia.
The international team of researchers used everything from lichens to 60 years of South Australian McLaren Vale Shiraz and Cabernet Sauvignon to observe the rise and fall of atmospheric lead.
Professor Mark Taylor from Macquarie University in Sydney led the study, which found lead emissions in the 20th century from sources such as leaded petrol were “massive”.
“There have been really clear signals from lead petrol emissions which peaked in the 1970s and there were peaks of into the atmosphere from the late 19th century when we had a significant number of lead smelters operating out of Broken Hill and Port Pirie,” Professor Taylor said.
“What we see today though is a much cleaner environment with respect to lead. Regulation has reduced concentrations of lead in air largely below limits of detection in our major cities.”
Soils, dust can pose a hazard
But it is not all good news. Scientists warn that lead is still an issue in Australian backyards.
“The problem we are left with is the legacy — soils and dusts which can pose a hazard to communities that live in those particular areas that are highly contaminated,” Professor Taylor said.
The study found the level of contamination in backyards was starting to become evident through chickens. It seems they are the “modern canaries” in the coal mine.
Over the years, lead poisoning was traditionally linked to petrol and paints.
But the soil is proving to be the latest culprit with vets saying they are treating more and more animals, mainly chickens, for lead poisoning.
George Maniatis started getting worried when his chicken’s wing started drooping. (ABC News: Jake Sturmer)
Sydney resident George Maniatis is one of a growing number of Australians with a backyard vegetable garden and his own chickens.
Recently, one got sick.
“She stopped producing eggs, she started to wander around and stumble around like a drunk person. She would drop her wing, stop eating and I started to get worried,” he said.
Mr Maniatis took his chicken to the vet and a blood test confirmed lead poisoning.
“The reading was off the chart,” he said.
“I was kind of shocked because I thought everything was normal.
“I was feeding them well, I was treating them well, but apparently the soil was contaminated.”
More and more cases of poisoned chickens
Specialist bird and exotic animal vet Dr Alex Rosenwax said Mr Maniatis’s experience was not uncommon.
He said he was seeing on average about one animal a week, and as many as two per day during busy times, with lead poisoning.
“I think the trend is moving more towards us seeing cases of chickens,” Dr Rosenwax said.
“We used to see a lot of cases in our parrots when they were chewing on the old paint on the wall in people’s houses.
“But now we seem to see more cases in people’s chickens because the lead dust from people demolishing their houses is more in the soil now.”
A recent study found many of the surveyed Sydney backyards had elevated lead levels in the soil. (ABC News: Jake Sturmer)
More Australians are looking to grow their own vegetables and have backyard chickens, according to a study from the Australia Institute.
It found as many as 48 per cent of metropolitan households grow some form of edible produce.
But lead expert Professor Mark Taylor warned homeowners needed to be careful, especially if they live in the inner city or have homes built before the 1970s.
A recent study by Professor Taylor found 40 per cent of the 200 Sydney backyards he measured had lead levels in the soil above the Australian health guidelines.
“What we see is in the inner part of Sydney — they’re the most contaminated areas — and as you move away from the city centre as road density gets less, as houses get more modern, the contamination gets less,” he said.
“Most people in older houses, lead paint was used at some time on the guttering, even for the walls themselves, [so the soil in that area] tends to be more contaminated.”
But the advice from experts is to carry on gardening, with a few simple precautions.
“We consider the greatest risk is particulates – bits of contaminant sticking to the plant and people not washing the veggies properly,” Professor Taylor said.
“You should be mulching your garden soil, doing a raised bed if it’s contaminated and just reducing exposure to particles and dust that can get on your food and into your house.”
The Environment Protection Authority disputes the findings, saying one of the lead measurements used was inconsistent with the national guidelines.
However, it could not explain how it was inconsistent, only that the lead size fraction used in the study did “not correspond with a human exposure pathway”.
Lead exposure assessment expert Albert Juhasz said Professor Taylor’s findings warranted a closer look.
“If there hasn’t been a comprehensive analysis for the report to understand the reason why that size fraction was used, it’s very easy to come up with a statement to say that was the wrong particle size,” the University of South Australia Associate Professor said.
“If there’s something in the environment and it potentially has got an impact on human health — you’d think that something like that would trigger a response,” he said.
The EPA said it was working with NSW Health and local councils to identify any contamination issues.