Pharmaceutical/food grade titanium dioxide particles are absorbed into the bloodstream of human volunteers
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Pharmaceutical/food grade titanium dioxide particles are absorbed into the bloodstream of human volunteers Laetitia C. Pele1, Vinay Thoree1, Sylvaine FA Bruggraber1, Dagmar Koller1, Richard PH Thompson1, Miranda C. Lomer2 and Jonathan J. Powell1*
Abstract Background: Exposure to persistent engineered nano and micro particles via the oral route is well established. Animal studies have demonstrated that, once ingested, a small proportion of such particles translocate from the gastrointestinal tract to other tissues. Exposure to titanium dioxide is widespread via the oral route, but only one study has provided indirect evidence (total titanium analyses) of absorption into the blood stream in humans. We sought to replicate these observations and to provide additional evidence for particulate uptake. Findings: Human volunteers with normal intestinal permeability were orally administered 100 mg pharmaceutical/food grade titanium dioxide. Blood samples were collected from 0.5 to 10 h post ingestion and analysed for the presence of reflectant bodies (particles) by dark field microscopy, and for total titanium by inductively coupled plasma mass spectrometry (ICP-MS). Blood film analyses implied early absorption of particles (2 h) with a peak maximum at 6 h following ingestion. The presence of these reflectant particles in blood roughly mirrored the levels of total titanium by ICP-MS, providing good evidence for the latter being a measure of whole particle (titanium dioxide) absorption. Conclusions: This study shows that a fraction of pharmaceutical/food grade titanium dioxide is absorbed systemically by humans following ingestion. It confirms that at least two routes of particle uptake may exist in the human gut- one proximal and one distal. Further work should quantify human exposure and uptake of such persistent particles. Keywords: Titanium dioxide, Particles, Absorption, Blood stream
Background Oral exposure to non-biological nano- and micro- particles from the diet, environment, and man-made health and hygiene products, is now well established [1]. Persistent particles, meaning those that are not broken down easily by the gastrointestinal tract or intracellularly, have been the subject of particular attention as animal studies indicate that they may migrate from the gut mucosa to draining lymph nodes and then become translocated to most tissues of the body [2]. However, there is much less evidence in man. Examination of surgical and post-mortem specimens has confirmed that there is retention of engineered particles in the human intestinal * Correspondence: [email protected] 1 Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK Full list of author information is available at the end of the article
mucosa, especially the Peyer’s patch lymphoid follicles [3–5]. Using large micron-sized biological particles (such as starch and pollen), Volkeimer has convincingly shown their appearance in the blood stream following
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