Development of novel in-vitro chemical tools to simulate gastro-intestinal and lung environments in order to assess bioaccessibility of contaminants

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Children are regularly exposed to toxic substances such as polycyclic aromatic hydrocarbons (PAHs) and metals via multiple pathways, including contaminated soil ingestion and inhalation of airborne particulate matter (PM). In risk assessment studies conducted on contaminated sites, assuming that 100% of a toxic substance in ingested or inhaled material enters the bloodstream (bioavailable) may lead to unrealistically high risk estimates. On the contrary, using the fraction of an inhaled or ingested pollutant which is soluble in simulated gastrointestinal conditions or simulated lung fluids (bioaccessible), measured via cost effective in-vitro tests, can help environmental engineers and risk assessors to obtain more accurate risk estimates. Such a chemical approach entails, at the same time, a reduction in the use of animal testing which involves strong ethical, technical, and financial issues. In spite of recent progress in chemical bioavailability research applied to metal contaminated soils, much work is needed to advance the scientific basis for incorporating PAH bioaccessibility testing into contaminated site-specific risk assessments. The objective of my research program is to develop novel and improved in-vitro tools for oral bioaccessibility assessment (ingestion and inhalation) of metals and PAHs in contaminated soils, airborne particulate matter and children's consumer products. More precisely, my work will aim at investigating and challenging recently developed PAH in-vitro bioaccessibility tests (FOREShT and IVG) and at assessing the influence of various food additives and of synthetic lipid sinks on in-vitro chemical bioavailability results using a wide array of industrial PAH-contaminated soils. In the case of PAH-contaminated sites, the success of this research program will allow for reduced land cleanup costs, following the formulation of more accurate site specific reclamation criteria. Moreover, this research program brings the prospect of implementing less intrusive and more sustainable remediation approaches. This innovative research program also aims at gaining knowledge on bioaccessibility in simulated lung fluids of PAHs and metals associated with airborne PMs. A novel Gamble's solution containing surfactant lipids specifically developed for PAH, and the existing synthetic interstitial fluids (pH 7.4) and artificial lysosomal fluids (pH 4.5) will be tested. Finally, building on our pioneer work on chemical bioavailability of metals in toys and low-cost jewelry, this research program will also focus on developing a much-needed, semi-continuous and food-containing version of the IVG bioaccessibility test, to simulate prolonged exposure to ingested metallic items.This program will enable the training of highly qualified environmental engineers (1 PDF, 3 PhD, 2 MSc, 6 undergraduates) with a strong knowledge in risk assessment.