Environmental and potential human health legacies of non-industrial sources of lead in a Canadian urban landscape – the case study of St John's, Newfoundland

Abstract

Residential soil and house dust were collected in St John's to assess the levels of lead exposure and potential human health risk. Although St John's does not have an identified, major point source for lead, nor is it a heavily industrialized or populated city, 51% of all analysed soil samples (n = 1231) exceeded the Canadian Council of Ministers of the Environment (CCME) residential soil lead guideline of 140 ppm, 26% exceeded the 400 ppm United States Environmental Protection Agency (US EPA) guideline for soil in children's play areas, and 9% exceeded the 1200 ppm US EPA guideline for soil outside of play areas. High soil lead concentrations, particularly those above 1200 ppm, are clustered in the older downtown core. Samples located along exterior house walls (dripline) have the highest mean soil lead concentrations, followed by open spaces in yards (ambient) and then roadside sites. Lead in dripline soil samples from older housing stock is sourced to lead-bearing paint. Lead from both dripline and ambient samples on properties developed between the 1940s and 1980s have a mixture of sources including coal ash, paint, and leaded gasoline. Approximately 12% of analysed house dust samples (n = 96) exceeded the US EPA guidelines for lead in indoor dust, all from pre-1950s housing and all associated with dripline soil lead concentrations greater than 900 ppm. Human health risk predictions suggest that, although the wider St John's community may not be at risk of adverse health effects, children living in pre-1970s housing may be exposed to increased risk.