This Tokyo study measured copper alongside zinc, lead and cadmium in hospital-diet composites, feces and autopsy liver and renal cortex. Liver copper was several times higher than renal-cortex copper in every age group and was highest in infants and young children. Fecal copper excretion was also tabulated for residents of a cadmium-polluted area, a control area and Tokyo. The food, feces and organ samples came from different people, so the paper describes matrix patterns rather than individual body burdens.
Key numbers
- Liver copper, geometric mean (geometric standard deviation factor), µg/g, wet basis per figure axes: age 0, 15.21 (2.85), n = 6; ages 1 to 9, 9.02 (2.30), n = 9; ages 20 to 29, 7.73 (1.46), n = 16; ages 70 and over, 5.51 (1.87), n = 11 (Table 1, p. 120).
- Renal-cortex copper, geometric mean, µg/g: 2.20 to 3.59 across the nine age groups (Table 1, p. 120).
- Correlation of copper with zinc: 0.340 in food (n = 20, not significant) and 0.454 in feces (n = 221, p < 0.01) (Tables 2 and 3, p. 122).
- Correlation of copper with cadmium in renal cortex: 0.522 (n = 85, p < 0.01); in liver, -0.137 (not significant) (Tables 4 and 5, p. 123).
- Daily fecal copper excretion, mean ± SD: cadmium-polluted area, 30 men over 50 years, 2.71 ± 1.82 mg/day (0.05 ± 0.02 mg/g dry feces); control area, 30 men over 50 years, 1.27 ± 0.73 mg/day; Tokyo, 19 men aged 21 to 24 sampled for 5 days, 1.32 ± 0.91 mg/day (Table 6, p. 123).
Methods (brief)
Liver and renal cortex from 85 sudden-death autopsy cases without chronic disease or poisoning were wet-ashed and analyzed by atomic absorption spectrophotometry after DDTC-MIBK extraction. Twenty daily composites of three hospital meals (including tea and milk) were freeze-dried, and 221 fecal samples were freeze-dried, ashed at 400 °C and analyzed by the same technique. Cross-checks on ten samples found no difference between the two pretreatment methods.
Evidence fitness
Supports historical reference values for copper in human liver and renal cortex by age, fecal copper excretion in men, and the observation that copper ratios to cadmium and zinc differ between food, feces and organs. It does not report diet copper concentrations, so it does not support a dietary intake estimate or a food concentration distribution.
Limitations
The diet samples came from one hospital kitchen over 20 days, and the food, feces and organ samples were not drawn from the same individuals. Table 1 does not restate the wet or dry basis; the figure axes give µg/g wet. Measurements date from the 1970s and use pre-ICP-MS methods with no reported reference material.
Related evidence
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