Impact of reference geosorbents on oral bioaccessibility of PAH in a human in vitro digestive tract model

Abstract

Former studies on human oral bioaccessibility of polycyclic aromatic hydrocarbons (PAH) from natural soil samples using human in vitro digestive tract models (physiologically based extraction tests, PBET) show highly variable results (0-100% of mobilized PAH). Apart from other factors, the type and amount of present geosorbents are assumed to be significant for the degree of desorption/release of PAH into the digestive juice. Therefore, in this study, the reference geosorbents pure quartz sand, Na-montmorillonite clay, Pahokee peat, and charcoal "Sommerhit" were spiked with selected deuterated PAH and employed as single materials in a PBET. Lowest bioaccessibility was determined in charcoal, representing black carbon (0.1 ± 0.1 % for ∑10 PAH-d) in contrast to higher bioaccessibility in peat (6.4 ± 2.2%) and clay (4.8 ± 1.1%). Highest bioaccessibility was determined in sand (26.9 ± 7.5%). The results show a systematic impact of heterogeneous geosorbents on human oral bioaccessibility of PAH and particularly black carbon acting as a very strong geosorbent that reduces human health risk.

Predicting the Relative Bioavailability of DDT and Its Metabolites in Historically Contaminated Soils Using a Tenax-Improved Physiologically Based Extraction Test (TI-PBET)

“…For example, no significant correlation ( p = 0.61) was observed between PAH RBA using a swine model and soil TOC, while the relationship was significantly ( p < 0.01) negatively correlated with soil recalcitrant organic carbon . In another study, Meyer et al spiked deuterated PAHs onto sand, clay, peat, and charcoal (typical black carbon), after which PAH bioaccessibility was measured using the PBET. The lowest bioaccessibility was observed for PAHs spiked onto charcoal, indicating that black carbon acts as a strong sorbent in the simulated human digestion system, similar to its role in the water–soil system .…”

“…In another study, Meyer et al spiked deuterated PAHs onto sand, clay, peat, and charcoal (typical black carbon), after which PAH bioaccessibility was measured using the PBET. The lowest bioaccessibility was observed for PAHs spiked onto charcoal, indicating that black carbon acts as a strong sorbent in the simulated human digestion system, similar to its role in the water–soil system . However, the complex conditions in the simulated digestion system may influence the sorption properties of black carbon, which may partly explain why only a moderate correlation was observed between black carbon content and in vivo data/PBET results.…”

Oral Bioavailability, Bioaccessibility, and Dermal Absorption of PAHs from Soil—State of the Science

“…These were followed by studies of oral bioavailability in animal models and the development of physiologically based extraction tests (PBETs) to measure PAH bioaccessibility, with the latter topic yielding most of the publications in the last 10 years. To date, 67 publications or abstracts have been identified for review regarding the oral bioavailability, − bioaccessibility, ,,,,− and dermal absorption ,,− of PAHs in soil or PAH source materials (soot, char, coal, coke, coal tar, pitch, creosote, and petroleum products).…”

Health risk assessment of mixed contaminants: Interaction of metals on the uptake of polycyclic aromatic hydrocarbons in human liver cells

“…The sorption of PAH to soil is reported to be influenced by the soil organic matter (SOM), total organic carbon (TOC) and clay content (Müller et al, 2007;White et al, 1999). A decrease in extractability and bioavailability of PAHs was observed with increasing TOC, while soils with higher content of sand had comparatively higher BAC of PAHs (Meyer et al, 2015).…”

“…The use or absence of food component is referred to as the "fed" or the "fasted" state. Bioaccessibility of a PAHs can also be influenced by a number of soil properties such as total organic carbon (Hack and Selenka, 1996;Vasiluk et al, 2007), silt and clay (Meyer et al, 2015;Duan et al, 2014) and black carbon (Meyer et al, 2015). Further, the effect of ageing and weathering of soils is also reported to influence PAH absorption, hence bioaccessibility (Ruby et al, 2016).…”