Survey for cadmium, cobalt, chromium, copper, nickel, lead, zinc, calcium, and magnesium in Canadian drinking water supplies.

A second national survey was done to ascertain the levels of Cd, Co, Cr, Cu, Ni, Pb, Zn, Ca, and Mg in Canadian drinking water supplies. Raw, treated, and distributed water samples collected from 71 municipalities across Canada were analyzed both by atomic absorption spectrophotometry using the direct method and by an APDC-MIBK extraction procedure. As in the first national survey, the amounts of trace metals found in the 3 types of water samples were essentially the same. Contamination of the water supplies with these metals except Cu and Zn was minimal during treatment and distribution. For Canadian drinking water, the median and extreme values expressed as ng metal/mL water were: Cd less than or equal to 0.02 (less than or equal to 0.02-0.07), Co less than or equal to 2.0 (less than or equal to 2.0-6.0), Cr less than or equal to 2.0 (less than or equal to 2.0-4.1), Cu less than 10 (less than or equal to 10-900), Ni less than or equal to 2.0 (less than or equal to 2.0-69.0), Pb less than or equal to 1.0 (less than or equal to 1.0-79.7), and Zn less than or equal to 10 (less than or equal to 10-750). Hardness values as mg CaCO3/L ranged from 6.7 in St. John's, Newfoundland, to 328.3 in Portage La Prairie, Manitoba. The median values for the Canadian drinking water supplies were well below the maximum permissible limits set by Health and Welfare Canada and the World Health Organization.