On a wet-weight basis, the silver levels in human soft tissues such as brains, kidneys, lymph nodes, lungs, muscles, testes and ovaries, ranged from 1 to 4 µg/kg. Hard tissues, such as rib bones, had 101 mg/kg (Klein 1978). On a dry-weight basis some values for normal tissues were spleen, 2.68 mg/kg, and kidney, 0.36 mg/kg. On an ash-weight basis levels were liver, 0.7 to 1.70 mg/kg, brain, 0.5 to 1.7 mg/kg and skin, 1.3 mg/kg (MRI-1975). Placental levels of 5 µg/kg and umbilical cord blood levels of 5 µg/L were measured; the maternal blood level was measured as 4 µg/L (Creason et al. 1976).
Molluscs have been found to contain 0.1 to 10 mg/kg dry-weight in their tissues and crustaceans 2 mg/kg dry-weight. Trout from Lake Cayuga, NY contained 0.48 to 0.68 mg/kg dry-weight (USEPA 1980a). Molluscs from coastal areas of the North Sea contained up to 2 mg/kg (Friberg et al. 1986).
Levels of heavy metals in oranges and avocados from Ghana, in gold mining and in control areas, were reported by Golow et al. in 1994. Soil levels of silver were not measured. Konongo and Obuasi soils were rich in gold but Kumasi soils did not contain gold. The data shown in Table 2.1 indicate slightly higher silver levels in the fruit from gold-rich soils than from the gold-poor soil, and slightly higher levels in the peels or rinds than in the flesh except for the avocados from Obuasi which had higher silver levels in the flesh.