Dietary intakes of lead, cadmium, arsenic and fluoride by Canadian adults: a 24-hour duplicate diet study.

Twenty-four hour duplicate diets, including drinking water and snacks, were collected from 24 adults living in five Canadian cities. Each diet was separated by the participants into 10 food categories, and each of the samples was analyzed in duplicate for lead, cadmium, arsenic and fluoride. Minimum detection limits for the respective elements in foods were about 0.1, 0.01, 0.3 and 5 ng/g. Mean dietary intakes were 53.8 micrograms/day or 0.80 micrograms/kg/day for lead, 13.8 micrograms/day or 0.21 micrograms/kg/day for cadmium, and 16.7 micrograms/day or 0.26 micrograms/kg/day for arsenic. The median intakes were 42.7 micrograms/day or 0.57 mu/kg/day for lead, 11.9 micrograms/day or 0.17 micrograms/kg/day for cadmium, and 9.79 micrograms/day or 0.139 micrograms/kg/day for arsenic. Half of the participants lived in communities with 1 microgram/g fluoride in the drinking water, and half lived in cities with less than 0.2 microgram/g fluoride in the water. The dietary intake of fluoride for the former was 2802 micrograms/day or 39.7 micrograms/kg/day; while that of the latter was 563 micrograms/day or 8.5 micrograms/kg/day. The respective median intakes of fluoride were 2090 micrograms/day or 30.3 micrograms/kg/day, and 414 micrograms/day or 7.0 micrograms/kg/day. Contribution of individual foods and food categories to the dietary intakes is discussed.