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

摘要

Residential soil and house dust were collected in St John's to assess the levels of leadexposure and potential human health risk. Although St John's does not have anidentified, major point source for lead, nor is it a heavily industrialized or populatedcity, 51% of all analysed soil samples (n = 1231) exceeded the Canadian Council ofMinisters 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 EPAguideline for soil outside of play areas. High soil lead concentrations, particularly thoseabove 1200 ppm, are clustered in the older downtown core. Samples located alongexterior house walls (dripline) have the highest mean soil lead concentrations,followed by open spaces in yards (ambient) and then roadside sites. Lead in driplinesoil samples from older housing stock is sourced to lead-bearing paint. Lead from bothdripline and ambient samples on properties developed between the 1940s and 1980shave a mixture of sources including coal ash, paint, and leaded gasoline. Approxi-mately 12% of analysed house dust samples (n = 96) exceeded the US EPA guidelinesfor lead in indoor dust, all from pre-1950s housing and all associated with dripline soillead 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.