Silicate nephrotoxicity in the experimental animal: the missing factor in analgesic nephropathy.

Three silicon-containing compounds (magnesium trisilicate BP, crushed quartz and crushed Arran granite) were added to the drinking water (250 mg/l) of three groups of male guinea pigs for four months. At autopsy all animals receiving magnesium trisilicate showed a focal tubulo-interstitial nephritis mainly affecting the distal nephron. Similar but less intense lesions were encountered in two animals receiving crushed quartz. No renal lesions were found in the control group or in animals receiving crushed Arran granite. The concentration of soluble silicates in drinking water, measured as elemental silicon (Si) by atomic absorption spectroscopy (AAS) was determined for twenty-eight locations in different regions of Britain. Following ingestion of magnesium trisilicate, significant increases in urinary excretion of Si were demonstrated in two healthy adults using atomic absorption spectroscopy.