Dirty bomb: Mark Taylor and Damian Gore test the soil in the backyard of Tilly Boleyn and Rick Calder (in background with infant daughter Saskia) for lead levels.
Dirty bomb: Mark Taylor and Damian Gore test the soil in the backyard of Tilly Boleyn and Rick Calder (in background with infant daughter Saskia) for lead levels. Photo: Kate Geraghty

Inner-city families are unwittingly exposing their children to the risk of sickness and even brain damage from lead hidden in backyard soil and old paint, a study has found.

Lead experts fear the trend towards home vegetable patches and community and verge vegetable gardens is also putting children at risk. They say inner-city dwellers in suburbs such as Balmain, Marrickville and Surry Hills have no idea about the hidden contaminants lurking in their soil.

A study following five Sydney families over 15 months has discovered a direct link between lead contamination in soil and contaminated lead inside the house, with family members and pets likely walking it in. The study found summer is particularly dangerous, as dry weather creates more contaminated dust that easily moves around.

Mark Taylor, a professor of environmental science at Macquarie University and co-author of the study, said children were most at risk.

''Children absorb about 50 to 60 per cent of the lead they ingest, whereas adults only absorb about 10 per cent," he said.

Next weekend he will launch a trial program called Veggie Safe at the Macquarie University open day, which will allow people to bring in soil from their backyards to be tested.

''We want the public to be aware but not alarmed - this is about informing people of the potential risks and then educating them how to act,'' he said.

Mark Laidlaw, the leader of the study, which has been accepted for publication in the journal Environmental Pollution, said the contaminated soil could have come from the garden or surrounding streets. He said people who were concerned could take samples of their soil and vacuum dust for testing relatively cheaply, or could simply cover it with new soil.

''That prevents the soil from being tracked into the house, and the lead from being resuspended in the dust in the interior of the home,'' he said.

Elizabeth O'Brien, from community organisation the LEAD group said she was horrified at the trend in inner city areas for verge vegetable gardens and home-rainwater tanks, which in some cases can add lead to water. ''The lead is already in verge soil in particular and people could be eating it unaware,'' she said.

Some inner-city cafes also operate vegetable bartering systems, using home-grown vegetables from their customers.

Tilly Boleyn and her partner Rick Calder live in inner-city Glebe with their eight and a half-month-old daughter Saskia.

The Australian standard indicates soil should be no more than 300 parts per million lead. In their veggie garden, where lettuce and parsley were growing, Professor Taylor found the soil reached up to 1300 parts per million. In another, which is no longer used for food, it was nearly 1800 parts per million.

''I feel slightly sick,'' Ms Boleyn said. ''But it is better to know.''

She will cover the contaminated soil with mulch, and paint over peeling lead paint found on her front window.

A 2006 study of vegetables sampled from the Sydney Basin area found 32 per cent contained lead levels that exceeded the allowable limits for vegetables, with lettuce, parsley and leek the worst offenders.