Ti – Titanium is found in igneous rocks at 5,700 ppm, shale at 4,600 ppm; sandstone at 1,500 ppm; sea water at 0.00 1 ppm; soils at 5,000 ppm; marine plants at 12-80 ppm (accumulates in plankton); land plants at 1 ppm; marine animals at 0.2 to 20 ppm and land animals at 0.2ppm.
Titanium resembles aluminum in being abundant in the lithosphere and soils, and in being poorly absorbed and retained by plants and animals. The poor absorption and retention of titanium results in levels in the tissues of plants and animals being generally much lower than those in the environment to which the organisms are exposed. Bertrand and Voronca-Spirt examined a variety of plants for titanium and recorded levels ranging from 0.1 to 5 mcg/g, with a high proportion being close to I mcg/g Similar concentrations were reported by Mitchell in his subsequent study of the mineral composition of red clover and ryegrass grown on different soils. A mean of 1.8 mcg/g dry weight (range 0.7-3.8 mcg/g) was obtained for the former species and 2.0 mcg/g dry weight (range 0.9-4.6 mcg/g for the latter.
Very little is known of the titanium content of human foods. Furr and coworkers found that on a dry-weight basis, a variety of tree nuts, fruit kernels, and maple syrup contained 0.5-6.1 mcg titanium per gram; most values ranged between 2 and 3 mcg/g. This study indicated urinary excretion of titanium was high, thus suggesting either considerable absorption from the diet or loss from previously retained tissue titanium. Both individuals were in negative balance, with approximately equal excretion via the feces and urine. No evidence has appeared that suggests absorbed titanium performs any vital function in animals or that it is a dietary essential for any living organism.
Titanium is essentially nontoxic in the amounts and forms that are usually ingested. The findings of Schroeder and co-workers indicated that 5 mcg/ml titanium in the drinking water fed to mice for their lifetime did not consistently affect growth, longevity, and tumor incidence. A review of titanium toxicity questioned whether evidence of a specific oral toxicity had ever been found.