ISSX 2006 | Esther Brandon1 Human in vitro digestion models powerful tools to predict maximum oral (relative) bioavailability Esther F.A. Brandon Centre for Substances and Integrated Risk Assessment National Institute for Public Health and the Environment (RIVM)

ISSX 2006 | Esther Brandon2 consumer products work place environment air water soil oral dermal inhalatory food, medicines Humans are exposed to many compounds

ISSX 2006 | Esther Brandon3 Outline of presentation bioaccessibility and bioavailability in vitro digestion models examples –lead from paint in top –folic acid from dietary supplements validation conclusions

ISSX 2006 | Esther Brandon4 Oral exposure: bioaccessibility and bioavailability External exposure small intestine portal vein liver mouth oesophagus, stomach, small intestine systemic circulation Internal exposure Exposure to contaminant in a matrix Ingestion of matrix + contaminant F B = Fraction released from matrix = bioaccessible fraction F A = Fraction of F B absorbed by small intestine F H = Fraction of F A after the liver without being metabolised F = Fraction reaching systemic circulation = bioavailable fraction F = F B x F A x F H

ISSX 2006 | Esther Brandon5 Oral exposure release depends on type of oral contact release depends on type of matrix release from matrix  exposure release from matrix can be measured by sampling –one way to study release after oral exposure is using in vitro digestion models

ISSX 2006 | Esther Brandon6 In vitro digestion model principle  various compartments of the human gastrointestinal tract (mouth to small intestine) are simulated  digestive juices are prepared artificially based on human physiology  matrix is introduced in mouth compartment, then transferred to the stomach and finally to the small intestine  transit times depend on the input of the risk assessor and human physiology  sampling compartment based on site of absorption

ISSX 2006 | Esther Brandon7 In vitro digestion models

ISSX 2006 | Esther Brandon8 Developed in vitro digestion models for application of compounds in food and supplements fasted conditions fed conditions for application of consumer products sucking sucking and then swallowing direct swallowing under fasted conditions direct swallowing under fed conditions for application of soil fasted conditions fed conditions

ISSX 2006 | Esther Brandon9 Different products and compounds tested mycotoxins from food folic acid from dietary supplements and enriched food products folate from natural food sources azo dyes in textile lead in street chalk and paint scraped from tops benzoic acid in finger paint lead and arsenic from contaminated soils lead from house dust

ISSX 2006 | Esther Brandon10 example - lead in paint scraped from top paint: lead level mg/g situation simulated: ingestion of scraped of paint –bioaccessibility under fasted conditions ~9.5% –bioaccessibility under fed conditions ~4% large difference between external and internal exposure based on risk assessment this top is not safe for children (11 mg paint leads to exceeding the TDI)

ISSX 2006 | Esther Brandon11 Validation for lead and arsenic from soil (Oomen et al,. 2006) the mycotoxins aflatoxin B1 and ochratoxin A investigating different adsorbents (Versantvoort et al., 2004) Although relevant in vivo data are scarce, we succeeded to preliminary validate the model for some cases These cases showed good correlation and never underestimated the bioavailability

ISSX 2006 | Esther Brandon12 Scientific conclusions internal exposure can be considerably less than external exposure bioaccessibility/bioavailability is highly dependent on matrix and compound bioaccessibility can easily be measured experimentally the outcome should be interpreted as indicative

ISSX 2006 | Esther Brandon13 Relevancy for industry, policy makers and upholders more accurate risk assessment of ingested contaminants more accurate exposure assessment for other compounds, e.g. vitamins

ISSX 2006 | Esther Brandon14 Acknowledgment Agnes Oomen (Centre for Substances and Integrated Risk Assessment, RIVM) Adrienne Sips (Centre for Substances and Integrated Risk Assessment, RIVM) Carolien Versantvoort (Centre for Substances and Integrated Risk Assessment, RIVM) Cathy Rompelberg (Centre for Nutrition and Health, RIVM) Marco Blokland and co-workers (Laboratory for Food and Residue Analyses, RIVM) Peter Bragt and Martien Spanjer (Food and Consumer Product Safety Authority) Bülent Kabak (University of Cukurova, Turkey) Paula Alvito (Food Safety and Nutrition Centre, Portugal) Karin Ljung (Swedish University of Agricultural Sciences, Sweden) Rawad Massoud (Utrecht University, The Netherlands)

ISSX 2006 | Esther Brandon15 RIVM reports and articles Kabak B, Brandon EFA, Vara I, Sizoo EA, Blokland MH, van Egmond HP, Sips AJAM. Effects of probiotic bacteria on the bioaccessibility of aflatoxin B1 and ochratoxin A using an in vitro digestion model under fed conditions. In preparation. Oomen AG, Brandon EFA, Swartjes FA, Sips AJAM (2006). How can information on oral bioavailability improve human health risk assessment for lead-contaminated soils? Implementation and scientific basis. RIVM report , Bilthoven, the Netherlands. Available at Brandon EFA, Oomen AG, Rompelberg CJM, Versantvoort CHM, van Engelen JGM, Sips AJAM (2006). Consumer product in vitro digestion model: bioaccessibility of contaminants and its application in risk assessment. Reg Toxicol Pharmacol 44: Versantvoort CHM, Oomen AG, van de Kamp E, Rompelberg CJM, Sips AJAM (2005). Applicability of an in vitro digestion model in assessing the bioaccessibility of mycotoxins from food. Food Chem Toxicol 43: Versantvoort CHM, van de Kamp E, Rompelberg CJM. Development and applicability of an in vitro digestion model in assessing the bioaccessibility of contaminants from food (2004). RIVM report , Bilthoven, the Netherlands. Available at Oomen AG, Rompelberg CJM, Bruil MA, Dobbe CJG, Pereboom DPKH, Sips AJAM (2003). Development of an in vitro digestion model for estimating the bioaccessibility of soil contaminants. Arch Environ Contam Toxicol 44: