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In our recent study we found that 40% of 203 Sydney homes we sampled contain lead in garden soil above the Australian health guideline of 300 milligrams per kilogram (mg/kg).

This presents a hazard because soil lead can adhere to or get absorbed into edible plants. An additional pathway of exposure occurs when contaminated soil dust enters homes and is accidentally ingested. Lead is a potent neurotoxin that affects childhood development.

Urban agriculture and VegeSafe

Urban agriculture is becoming more popular across Australia. Almost half (48%) of all households in metropolitan areas are now growing some form of edible produce.

Most lead contamination is a result of the historical use of lead petrol and lead-based paint (now phased out) and previous industrial emissions. Scientists and regulators are well aware of these legacy issues, but the general public remains underinformed about the potential risks.

To help urban gardeners assess contamination risks associated with their garden soils, we started the community science initiative VegeSafe in 2013. This program offers free soil metal screening to participants.

Each participant receives a formal report on their soil metal results and advice about what to do next if soils contain elevated concentrations of metals. We have provided 5,500 free soil metal tests to over 1,300 homes and community gardens (Australia-wide), the largest program and study of its kind in Australia.

What did we find?

As well as the 40% of Sydney gardens containing soil above the 300 mg/kg Australian health guideline, approximately one in seven homes had soils lead levels greater than 1,000 mg/kg. Soil metal concentrations were typically greatest around drip lines.

Soil lead concentrations were greatest in the City of Sydney and former local government areas of Leichhardt Municipal Council and Marrickville Council, which had mean soil lead concentrations of 883 mg/kg, 960 mg/kg and 689 mg/kg, respectively.

Soil lead concentrations of vegetable garden soils from 141 Sydney homes. Map represents one of four areas around homes (front yard, drip line, back yard and vegetable garden) in this study. Source: Rouillon et al. 2016

Homes with painted exteriors built before 1970 were more likely to have soils contaminated with lead. The highest levels are at homes 80 years or older. This is likely to have been caused by lead-rich paint, which contained up to 50% lead prior to 1970. Lead in paint was reduced to less than 1,000 mg/kg (0.1%) by 1997.

We observed the environmental benefit of the withdrawal of lead from paints and leaded petrol (removed in 2002) in our study. Garden soils at newer homes contain the least lead. Soil lead concentrations decrease with distance from Sydney’s city centre, where there are more old homes and greater density of traffic and industry.

Cross-section schematic of a typical inner-Sydney residential home with median soil Pb (lead) concentrations for painted pre-1970 homes, non-painted pre-1970 homes, post-1970 homes and reference homes. The vegetable garden is displayed at the rear of the back yard, as this was the case for the majority of homes. Source: Rouillon et al. 2016 Public health

Lead exposure is especially detrimental for children because their neurological and skeletal systems are developing. Adults are also adversely affected, with studies showing increased blood pressure and hypertension associated with sub-clinical exposures.

Toxicological evidence also shows that exposure reduces semen quality and extends the time to pregnancy. In short, lead is detrimental to all human systems and exposures should be avoided or minimised at all times.

Our study demonstrates lead contamination in garden soils is greater at painted homes than non-painted homes. Many pre-1970 Australian homes still contain paint with up to 50% lead on exterior walls, fences, eves, doors and window frames.

The main risk of exposure arises when lead-based paint deteriorates or is removed improperly. Indeed, many home renovators unwittingly expose themselves and others due to a lack of knowledge of lead hazards.

Paints containing lead are no longer used in Australia, but remain on countless homes. Reducing exposure

The United States Environmental Protection Agency introduced legislation specifically targeting houses with lead paint to prevent contamination and to minimise avoidable lead exposures.

Unfortunately this regulatory gap has not been filled in Australia. Despite the widespread historic use of lead-based paints and the high proportion of exposure related to it, our data reveals a concerning legacy of soil lead contamination in older suburbs.

We recommend that people residing at or planning to purchase or renovate homes built before 1970 should get their soils and paint tested for lead. Using a qualified lead-abatement decorator in older homes would also help prevent exposure. Where parents and homeowners think they may have caused exposure, their GPs can provide a blood lead test.

Reducing even low-level exposures is critical, as demonstrated by Bruce Lanphear’s “prevention paradox” (see the image below). The graphic illustrates that the most IQ points across a population are lost from low-level lead exposures.

Bruce Lanphear’s prevention paradox. The majority of IQ points lost to lead exposure occurs in children who have low-to-moderate exposure to lead. Adapted from Reference (Lanphear 2015) What can gardeners do?

Where non-food-growing soils exceed the Australian soil metal guidelines, we recommend maintaining year-round cover of lawn or mulch to minimise dust generation.

Where metal guidelines are exceeded in food-growing soils, we recommend either replacing existing soil with new, uncontaminated soil, or relocating the food garden to an above-ground vegetable plot (again with new soil).

In this way, gardeners can exercise our motto, which is to carry on gardening knowing their soils are clean.

The VegeSafe program is ongoing for all Australians. Gardeners can send their soil samples to Macquarie University for free soil metal screening of their soil. We do, however, take donations to help sustain our program – so please support your citizen science.

Mark Patrick Taylor is affiliated with: Broken Hill Lead Reference Group. LEAD Group Inc. (Australia). NSW Government Lead Expert Working Group - Lead exposure management for suburbs around the former Boolaroo (NSW) Pasminco smelter site, Dec 2014–ongoing. Appointed by NSW Environment Minister to review NSW EPA’s management of contaminated sites, October 2015–ongoing. The VegeSafe project receives funding support via voluntary donations from the public. The VegeSafe study published in the journal Environmental Pollution was completed during a period of cash and in-kind support for a broader evaluation of the use and application of field portable XRFs for the assessment of environmental contamination. This funding support came from two sources: OIympus Australia Pty Ltd and the National Measurement Institute, North Ryde, Sydney.

Louise Kristensen, Marek Rouillon, Paul Harvey, and Steven G George do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Prince Charles has been signed up by the publishers to write an expert’s book. But maybe readers nowadays prefer spoofs

My twins are “studying” Jack and the Beanstalk, and I’ve just packed them off to school with my battered copy of Ladybird’s Well-Loved Tales.

I’ve collected a few old Ladybirds from car boot sales because they are beautiful and nostalgic, hailing from a time when truths were simpler and there was faith in the future. My favourite is The Story of Newspapers, a Ladybird Achievements Book that is testimony to the speed of terrifying technical obsolescence – and welcome progress. A drawing of a newsroom where all 14 journalists are men shows the past wasn’t always lovely.

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The incoming Trump administration accepts far more of the research on climate change than many of their political supporters, say British scientists.

The British Antarctic Survey is pulling all staff out of the space-age Halley base in March because of a big crack in nearby ice.

Norway’s two-day city centre ban angers motorists who were encouraged to buy diesel vehicles in 2006

Oslo will ban diesel cars from the road for at least two days this week to combat rising air pollution, angering some motorists after they were urged to buy diesel cars a few years ago.

The ban will go into effect on Tuesday on municipal roads but will not apply on the national motorways that criss-cross the Norwegian capital. Better atmospheric conditions are expected on Thursday. Motorists violating the ban will be fined 1,500 kroner (£174).

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ETI says technology is 10 times dearer than other low carbon power sources and UK should prioritise tidal stream

An embryonic industry trying to harness the UK’s waves to generate clean electricity has been dealt a significant blow by a warning that the technology is too costly.

Wave power devices being tested in Cornwall and at Orkney are 10 times more expensive than other sources of low carbon power and need a radical rethink, the Energy Technologies Institute (ETI) said.

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The remaining climate change uncertainties point toward higher risks and greater urgency for action

President-elect Donald Trump’s nominee for Secretary of State – and until recently the CEO of ExxonMobil – Rex Tillerson was given a confirmation hearing by the Senate Foreign Relations Committee last week. In his testimony, Tillerson accepted the reality of human-caused global warming and that “The risk of climate change does exist and the consequences of it could be serious enough that action should be taken.”

While he accepted the problem exists, Tillerson nevertheless proceeded to downplay its risks, saying:

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Sharp rise in discarded electronic goods is generating millions of tonnes of hazardous waste, putting pressure on valuable resources and the environment, study shows

Asia’s mountains of hazardous electronic trash, or e-waste, are growing rapidly, new research reveals, with China leading the way.

A record 16m tonnes of electronic trash, containing both toxic and valuable materials, were generated in a single year – up 63% in five years, new analysis looking at 12 countries in east and south-east Asia shows.

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Cardigan Bay, Ceredigion Made up of rounded cobbles graded in size, this ‘causeway’ looks beguilingly like the work of our ancestors

The amount of ice on the narrow footpath came as a surprise. Hidden from the sun on the south side of the valley, it had probably accumulated over a number of days – along with the layered, crusted frost on the nearby vegetation. Few people seemed to have walked this stretch of the Wales coast path recently; a fox crossing the track ahead and a briefly perched buzzard both seemed shocked to see me.

As I reached the footbridge above the beach at Wallog, I folded away my heavily used Ordnance Survey map and consulted its nautical equivalent. While OS maps provide only scant information about the space beyond the coast, admiralty charts give detailed data on the underwater landscape – in this case the geological oddity that is Sarn Wallog.

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Engie to invest in new large scale solar farms as it prepares to close Hazelwood, confirming the rapid shift from coal fired power to solar in Australia. Still, conservatives and fossil fuel lobbyists are continuing to attack renewables.

Tesla reveal how those without unlimited Supercharger access for the Model S and Model X electric vehicles will be charged.

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New York Governor Andrew Cuomo promises declining carbon emissions even as the state closes the Indian Point nuclear power plant.

Obama sees the world as at a tipping point and that a clean energy revolution is already underway.

This video taken from a drone shows travel blogger Isabelle Fabre’s close encounter with a great white shark while kitesurfing off the West Australian coast. Fabre explains that she initially thought the shadow under her board was from her kite, and then that it was a dolphin. ‘I heard Cyril shouting “Shark! Isabelle, get out!” He saw everything through the drone and he thought I was done’

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Environment minister says government ‘deeply disappointed’ after Sea Shepherd photos show minke whale killing in Antarctic sanctuary

The federal environment minister, Josh Frydenberg, has criticised Japan following the release of photographs allegedly showing the slaughtering of protected whales inside Australia’s Antarctic whale sanctuary.

Frydenberg’s statement came as conservationists called for tougher action from Australia.

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Afghan refugees are happy to call Shepparton home; training up the next generation of jackeroos and jillaroos; we cruise Wilson Inlet with fisherman George Ebbett; and give baby crocs a helping hand into the world.

In the past, extreme weather and disastrous harvests have proved socially divisive. We have been warned, say climate researchers

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Short of real temperature readings, descriptions of such incidents and records of rivers and lakes freezing over for months at a time, tree rings and ice cores are what climate scientists have to use to trace weather extremes of the past.

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