Inorganic contaminants in Canadian First Nation community water systems.

While previous Canadian studies have examined microbiological water quality in First Nations, there is little published information on inorganic contaminants. In Atlantic Canada, the lead, manganese, and arsenic content of First Nations' drinking water has been measured for more than a decade, but the data have not been analyzed comprehensively. These contaminants are linked with health problems, and high levels in drinking water are a cause for concern. We examined 12 years of data from 47 First Nation community water systems to identify systems experiencing difficulties meeting sampling frequency or regulatory guidelines. While most contaminant concentrations were below guideline values, we identified elevated concentrations and issues with sampling frequency. No system met both sampling frequency requirements - a minimum of one sample per year per analyte - and regulatory guidelines. Exceedance rates for lead, manganese, and arsenic were high in some systems. Moreover, current sampling procedures for lead specify that taps be flushed prior to sampling, which is known to underestimate lead exposure. We find that a switch to random daytime sampling would at least sometimes yield higher estimates of lead at the tap. Our analysis demonstrates the need for increased monitoring and updated sampling procedures to better characterize inorganic contaminant occurrence in First Nations.