Toxic Truth: Health risk disappearing without soil remediation

Hunter New England Health public health physician Craig Dalton
Hunter New England Health public health physician Craig Dalton

A DECADE after Pasminco’s lead and zinc smelter closed at Boolaroo and as the land is being prepared for redevelopment, the Newcastle Herald and Macquarie University collected more than 130 soil and  dust samples from homes and public spaces in surrounding suburbs. The analysis revealed alarming levels of contamination remained, despite a government-approved Lead Abatement Scheme.

REMEDIATING Boolaroo area properties to reduce lead levels in soil and dust may be of limited value considering resident blood lead levels have already fallen to historically low levels,  Hunter New England Health, public health physician Craig Dalton says.

But other lead experts say leaving residential properties ‘‘contaminated for decades’’ would be ‘‘ridiculous’’.

Hunter New England Health announced free blood lead level testing for all children under five years of age in Boolaroo, Argenton and Speers Point the same day the  Newcastle Herald launched its Toxic Truth campaign.

Dr Dalton, who has co-authored reports into the impact that the smelter’s closure had on blood lead levels of children, said readings had been falling since the Pasminco smelter shut in September 2003.

‘‘Blood lead levels have [already] been following a straight downwards trajectory since the closure of the smelter – without any significant remediation,’’ he said. ‘‘We are hopeful  the new survey will provide evidence that this trend is continuing.’’

When the  health service last tested children in June 2006 it found 4per cent of the children aged 12 and under and 7per cent of the children aged four and under had blood lead levels of 10 and above.

A critical finding, Dr Dalton said, was the expected peak in blood lead levels at two years old – when children become mobile and practise hand-to-mouth behaviour that increases their risk of ingesting lead in soil – had completely disappeared.

‘‘This was not what was expected going back years before the smelter shut, we thought the lead in soil would remain a problem forever but it didn’t,’’ he said. ‘‘This basically shows  the problem from the smelter basically went away with its closure.

‘‘People think that soil lead models blood lead – it may in some places – but it doesn’t model in Lake Macquarie.’’

Dr Dalton said that previously elevated blood lead levels in north Lake Macquarie would have been driven by inhaling   emissions  carrying chemically active lead particles that transformed over time. The lead that settled in household dust and soil, on the other hand, was not always indicative of a problem or a need to remediate, he said.

But international lead expert Professor Bruce Lanphear, of Simon Fraser University in Canada, said it was ‘‘ridiculous’’ not to abate soil and leave properties ‘‘contaminated for decades’’.

Professor Lanphear said the primary source of lead exposure for people living in old smelter towns was soil.

‘‘Any lead in soil will contribute to a child’s blood lead concentrations, especially if a child puts soil or dirt in their mouth,’’ he said.

‘‘Lead exposure has been linked with IQ deficits, diminished academic abilities and antisocial behaviours, like delinquency and crime.’’

Professor Lanphear said a lead in soil reading above 100parts per million was a hazard.

‘‘The impact of tobacco, physical activity and deaths from injuries is greater, but lead isn’t far behind these risks,’’ he said.

Macquarie University Professor of Environmental Science Damian Gore questioned if the downwards trajectory of blood lead levels to 2006 reflected the levels of every child in the area, or only the average level among the age group.

A report published in the American Journal of Public Health in 2011 criticised the ethics of using blood levels to measure the value of remediation and ongoing risk to people.

The report by Sue  Moodie and Emily Lorraine Evans cited concerns about public health efforts that were more reactive than preventive.

One child has been reported to Hunter New England Health since 2006 with a raised blood lead level – in 2009. The child also had an elevated blood lead level before the smelter closed.

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