TITANIUM-DIOXIDE (RUTILE) PARTICLE UPTAKE FROM THE RAT GI TRACT AND TRANSLOCATION TO SYSTEMIC ORGANS AFTER ORAL-ADMINISTRATION

Titanium dioxide (rutile) particles of nominal size 500 nm were admini stered as a 0.1 ml dose of a 2.5% w/v suspension (12.5 mg kg-1) to fem ale Sprague Dawley rats, by oral gavage daily for 10 days. Organs and tissues such as Peyer's patches, small intestine, colon, mesentery net work and nodes, peritoneal tissue, liver, spleen, heart and kidney wer e removed for histology, scanning electron microscopy, and spectroscop ic analysis for titanium, using the technique of inductively coupled p lasma atomic emission spectroscopy. Histological and chemical analysis proved the presence of titanium dioxide particles in all the major ti ssues of the gut associated lymphoid tissue (GALT), and demonstrated t hat 500 nm tianium dioxide particles were translocated to systemic org ans such as the liver and the spleen. Titanium dioxide particles were also found in the lung and peritoneal tissues, but were not detected i n the heart or the kidney. The uptake of inert particulate matter, suc h as titanium dioxide, used in pharmaceuticals and food poses the ques tion whether insolubility and inertness necessarily guarantees their i nnocuous nature.