Secular Trends of environmental pollution as monitored by human intake of cadmium and lead

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In the years around 1990, 24-hour diet duplicate samples were collected from 274 subjects (55 men and 219 women) in Iwate, Miyagi, Mie, Yamaguchi and Okinawa prefectures. A portion (10 g) of the duplicates, after weighing, were wet-ashed by heating in the presence of mineral acids, and the digests were subjected to analysis for cadmium and lead by means of flameless atomic absorption spectrometry. Ammonium nitrate was added as a matrix modifier in the case of lead analysis. The daily cadmium intake thus obtained was 25.0 ug/day (1.90) and 17.5 ug/day (1.93) as GM (GSD) for men and women, respectively. The value for women was significantly (P<0.01) lower than the value for men. The values for lead were 12.1 ug/day (1.93) and 10.8 ug/day (2.25) for men and women, respectively, with no significant difference between two sexes. When the subjects were grouped by the study region and by sex, and the data base for 1980 measurements were retrieved, 9 pairs (4 pairs for men and 5 pairs for women) of 1980 GM and 1990 GM were available for comparison. Statistical analysis showed the 1990 GMs were significantly (P<0.05) lower than the counterpart 1990 GMs in 5 pairs (3 for men and 2 for women) in the case of daily cadmium intake, and it was so in 5 pairs (2 for men and 3 for women) in the case of lead. There was no case of increase both in cadmium and in lead. The grand GMs showed some 40% reduction in cadmium intake in the past 10 years, and the reduction was by ca. 45% in the case of lead.