Physiologically based extraction test PBET

Figure 5.25 The physiologically based extraction test (PBET) used to determine the bioaccessibility of metals from foodstuffs [30].

Bioaccessibility testing of metals using the physiologically based extraction test (PBET) or the simplified bioaccessibility extraction test (SBET) has gained popularity in recent years in the UK (Nathanail McCaffrey 2002). The aim of the tests is to simulate the extraction of metals into solution in the juices in the stomach, upper and lower intestine (PBET) and in the stomach (SBET). The empirical test results should only be applied to the ingestion of soil or dust pathways. The tests have been calibrated for lead, and to a lesser degree for arsenic. Risk assessors should be satisfied that the health criteria... 

Soils contaminated with Pb may also be remediated by iron-based nanoparticles. Iron phosphate (vivianite) nanoparticles stabilized with CMC have been reported to reduce the toxicity-characteristic leaching procedure (TCLP) and physiologically based extraction test (PBET) bioaccessibility in calcareous, neutral, and acidic soils (84). While phosphate addition has been known since at least 1993 to immobilize Pb(II) in soils, phosphate addition can cause its own problems in that it easily leaches into surface and groundwaters, where it causes problems related to excessive nutrient input. CMC-vivianite nanoparticles release 50% less phosphate into the environment than more traditional phosphate soil amendments, partly because of the insolubility of vivianite. Unlike the PdNPs/S mixture, the Pb-sequestering reactions take place at ambient temperatures. At acidic pH values, the reaction sequence is as shown in Equations (20.5a) and (20.5b). 

SBET, simple bioaccessibility extraction test PBET, physiologically based extraction test DIN, E DIN 19738 German method RIVM, in vitro digestion model, National Institute of Public Health and the Environment,... 

---