RMIT researchers have led a critical study into lead levels in the soil at Flint, Michigan, a US city in the international spotlight over a lead contamination crisis in its drinking water supply.
Thousands of children in Flint have been exposed to drinking water with high levels of lead since the city changed its water supply to the Flint River in 2014.
The corrosive river water caused lead from ageing pipes to leach into the water supply, resulting in extremely elevated levels of the heavy metal.
But a new study led by RMIT’s Dr Mark Laidlaw and Professor Andrew Ball has revealed that Flint children showed elevated lead levels in their blood during drier months of the year, even before the water supply switch.
The findings suggest that lead contaminated dirt is most likely the culprit especially in the older, more industrial areas of the city.
“The seasonal resuspension and deposition of soil lead into homes is a major contributor to chronic lead exposure in the United States,” Laidlaw said.
“While soil lead is not a bigger issue in Flint than in any other older industrial city in the United States, the problem has been exacerbated there because of the water contamination crisis.”
Since 2010, lead blood levels were consistently higher in Flint during the months of July, August and September, specifically in children living within the city.
In 2014 and 2015, levels rose about 50 per cent higher. The city’s water supply was switched in 2014.
Laidlaw, a Postdoctoral Fellow in the Centre for Environmental Sustainability and Remediation (EnSuRe) in RMIT’s School of Science, said lead-based paint and lead leaching from water pipes were known to be important sources of exposure.
“But the constant background of soil-dust lead exposes millions to health harms, and cannot be ‘remediated away’ by repainting houses or changing water supply chemistry,” he said.
“A failure to isolate soils in urban inner city areas will result in the continued exposure of children during summer, due to direct contact with lead contaminated soil dust as well its resuspension in the air.
“Selective approaches to the isolation of lead -contaminated surface soils in high-risk urban areas must be implemented to rid people of the lead nuisance once and for all.”
Laidlaw, who has family living in Michigan and used to live in the Detroit area, has spent over a decade studying how the resuspension of lead contaminated urban soils in the United States causes peaks in children's blood lead levels in the summer and early autumn.
After publishing a paper on how the issue affected Detroit three years ago, he observed the same pattern in Flint and began working to investigate the problem in that city.
The research, conducted in collaboration with Michigan State University (MSU), Indiana University and the Tulane University School of Medicine, has been published in the International Journal of Environmental Research and Public Health.
Rick Sadler, a public health expert in MSU who has grown up in Flint and is helping the city combat the lead problem through his research, mapped out soil lead levels in and around the city for the study.
“Typically, wealthier populations are able to buffer themselves from these issues because they live outside the more urban areas, so the brunt of the problem falls on the disadvantaged,” Sadler said.
“It's important to note that nearly all Flint soils are well below the EPA threshold, but the locations that are problematic tend to be the lower income areas where people are already struggling to survive.”
Story: Gosia Kaszubska