City offers soil-cleaning tips to promote urban gardening
Brandy Humes now enjoys a lush garden full of tomatoes, watermelon, peppers and raspberries, but it took replacing all the soil on her property to make her feel comfortable about growing food. Photo by Richard Lautens, Toronto Star.
Lead poisoning in children can cause neurological damage
By Theresa Boyle
Toronto Star
September 3, 2010
Excerpt:
“My neighbourhood has a long history of contamination,” Armstrong says of the south Junction Triangle, once a highly industrialized area. “We have a 2½-year-old and a 6-year-old and we don’t want them eating anything that is questionable.”
It is for residents like Armstrong that the city is developing a soil-contaminant protocol. To be released next year, the protocol will help urban gardeners determine if their soil is contaminant-free. If it’s not, the protocol will explain how they can still grow edible fruits and vegetable on their property. This might involve doing raised-bed gardening or having their soil remediated.
The main targets of the protocol are those who garden in community and allotment gardens and on vacant land. Backyard gardeners like Armstrong can also benefit.
“The objective is to put tools in the tool box of city staff and residents and empower them with the information they need to make informed choices about where and how they garden,” explains Josephine Archbold, a research consultant in the environmental protection office of Toronto Public Health.
1 comment
Hi
Here in Sandwell UK (birthplace of industrialised mining and metalworking) we have a serious legacy of industrial contamination. In our searches for land for community agriculture, very often we find complex cocktails of heavy metals, inorganic, and organic contaminants. This can make reclamation strategies difficult to identify – for example the strategy for amelioration of lead and cadmium by adjusting soil ph are the reverse of each other. The evidence base on the risks posed by such cocktails is pretty much non-existent. Contaminants can also move up and down the soil profile with the water table.
There are 3 key steps: the risk assessment, the options appraisal and then the remediation strategy – if such a thing is a viable option, sometimes you have to walk away as the risks, costs and other burdens are too great to bear. And you need to understand the different contamination pathways (dermal, inhalation, ingestion).
Also, official guidance on ‘acceptable’ levels of contaminants in soil is a movable feast: guideline levels are subject to change and for some contaminants there are none, which makes decision making difficult. Some contaminants present a risk to people, some to plant growth.
A very good guide from the UK is available on line at Health Protection Agency: An introduction to land contamination for health professionals http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1270616512522)
Another good source is http://www.contaminatedland.co.uk
Accurate soil testing at depth (we test down to 3 metres if there is any suspicion of landfill) is expensive if you want to test across the range of potential contaminants to include things like heavy metals, phenols, polyaromatic hydrocarbons and PCBs. In our experience even land designated as green space can be contaminated, as dumping (legal and illegal) has been widespread and is rarely adequately documented. Making those informed choices is sometimes very difficult!
It’s great that Toronto (where I am writing from, on my way to present in the Brownfields track of the Growing Power conference in Milwaukee) is to produce a guide and is to make available to people the expertise of the Toronto Public Health Dept, because deciding what to analyse for and how to interpret technical data (e.g. the results of analyses) has to be backed up with sometimes expert technical advice and interpretation of any soil investigations, and possibly with longer term environmental public health tracking.
We are lucky enough to have a specialist contaminated lands unit in our local authority, but the relationship has not always been an easy one – authorities can be very defensive about dealing with the public around such a sensitive issue as land contamination, which might land them with a very big cleanup bill, or get into the local press.
There is also an important environmental justice issue here: should individual households/families/community groups be responsible for the costs and other burdens of testing and cleaning up? Or should it be the responsibility of the polluter (often long gone) or the state?
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