Heavy metal head scratcher - 20% of urban garden soils contaminated with toxic levels of lead: Study
Updated: Aug 4
A new study of soil lead levels in urban vegetable gardens in Australia made headlines last week with its finding that a whopping fifth of all samples tested had dangerously high levels of the noxious heavy metal.
Why does this matter? Well, lead is toxic and can wreak havoc with our health - more on that shortly.
In the study, researchers at Macquarie University analysed more than 17,000 samples from some 3,600 homes around the country. What they found was astounding. And worrying with close to a third of those in Sydney, the country's largest city, deemed unsafe.
According to Professor of Environmental Science and Human Health Mark Patrick Taylor, who led the study, the biggest risk factors for lead contamination in soil were the home’s proximity to the city and whether it was painted with lead paint.
The picture in the UK is likely to be even murkier. Indeed, Safe Soil UK has written about the dangers of soil lead contaminated, particularly to children, in a post last year.
Many instances of lead poisoning are due to ongoing low-dose exposure. Because its symptoms are predominantly emotional and mental in nature, lead poisoning is not easily spotted. Children are at greatest risk because lead can delay physical and mental development in babies and the young. It’s also dangerous to adults with accumulations in the body resulting in kidney and nervous system damage, anaemia, stroke, Alzheimer's and cancer.
The following summary, courtesy of Penn State University, sums up the risks and makes for sobering reading:
“Serious human health risks, particularly for children under 6 years of age, are associated with lead poisoning… Low-level, chronic exposure to lead in contaminated residential soil can cause several developmental and behavioral problems in children. Among these are reduced IQ and attention span, hyperactivity, impaired growth, learning disabilities, hearing loss, and insomnia. Once absorbed by the human body, lead is extremely difficult, if not impossible to remove. Therefore, not only is prevention of lead poisoning the best cure, but it may be the only cure.”
All of which leads to the obvious question: What about UK gardens? Well, to our knowledge no definitive study on the scale of that carried out in Australia has been done. But considering the extent of our industrial heritage, it would be hard to imagine levels in our cities to be lower. Indeed, if anything, probably higher - perhaps considerably so.
Research in the UK points to at least one source of lead contamination in Britain that is certainly not shared with Australia - the Blitz. Seriously! British Geological Survey researchers found a connection between the mass bombing of cities in Britain during the Second World War and elevated levels of calcium, zinc and, yes, lead in soil.
After an extensive investigation, they concluded that elevated levels of all three elements in parts of London were caused by the distribution of dust and debris that was the result of the mass destruction of buildings during the war. All were widely used in paint, mortar and piping in construction during the previous century and were scattered during the widespread destruction of many city centres across the UK.
As such, it’s probably not all that surprising that many of our clients across the UK have also found worryingly high levels of lead in their soils.
While some choose to have a layer of the contaminated soil removed and replaced with clean soil, most tend to cover the ground with mulch or lawn and instal raised beds. Many instal a membrane at the bottom of these that effectively cuts off their beds from the soil beneath. The soil in these can also be tested to ensure the topsoil is up to scratch or the impact of airborne deposition of dust from contaminated soil in the area or nearby heavy-traffic areas.
Anyone wanting to test their soil for this heavy metal or others, or indeed other contaminants that can blight our growing spaces can do so by ordering one of the Safe Soil UK testing packages below:
- Standard Contamination Test (£150 plus VAT)
- Basic Metals Screen (£50 plus VAT)
- Comprehensive Contamination Suite (£750 plus VAT)
- Topsoil Investigation Screen (£300 plus VAT)
A full list of all our testing packages, including those measuring fertility, herbicide and pesticide residues and others, can be viewed here.
Safe Soil UK is Britain's premier convenience soil testing service, making the process quick, easy and affordable.