No abstract

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 ≤0.02 (≤0.02-0.07), Co ≤2.0 (≤2.0-6.0), Cr ≤2.0 (≤2.0-4.1), Cu ≤10 (≤10-900), Ni ≤2.0 (≤2.0-69.0), Pb ≤1.0 (≤1.0-79.7), and Zn ≤10 (≤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.

An exact knowledge of environmental particulate levels at their sources of production, geographic sites of dissemination and/or anatomic sites of deposition after they have been inhaled or ingested by the body is considered a main priority in the environmental health field. One must therefore recognize the need for rapid, accurate and sensitive means of sampling and analyzing these materials, often found in trace amounts, with little alteration from their original physical and chemical structure. A summary of the various theoretical approaches and methodologies investigated in our laboratory towards that goal are discussed with emphasis on X-ray techniques used, correction factors involved, and areas requiring further research.