Distribution and In Vitro Bioaccessibility of Potentially Toxic Metals in Soils at Select Urban Parks at Eastern Canadian Cities

This study investigated the human health risks associated with exposure to potentially toxic metals, including arsenic, barium, cadmium, chromium, cobalt, copper, lead, nickel, and zinc, at select parks in Eastern Canadian cities. Except for arsenic in Halifax, the mean metal concentrations in the cities, including Saint John, Fredericton, Ottawa, Toronto, London, Windsor, Woodstock, Kitchener, Guelph, Chatham, and Montreal, were below the Canadian Council of Ministers of Environment soil quality guideline for parkland use. Metal distribution reflected either the regional natural-occurring concentrations or anthropogenic sources such as industrial activities, historical land use, and heavy traffic corridors. In vitro bioaccessibility values were variable and in the order chromium < nickel < cobalt < arsenic < zinc < copper < lead < cadmium. The risk associated with incidental soil ingestion for children, incorporating bioaccessibility, indicated unacceptable levels of non-carcinogenic effects for 6 out of the 101 samples analyzed. For adults, unacceptable non-carcinogenic effects were noted for only one sample. Lead was the leading contributor to the non-carcinogenic risk. Carcinogenic risk for arsenic was limited to two samples. The overall risks associated with exposure to metals in soils in most of the parks studied were deemed low except for arsenic and lead at a few parks.