Factors affecting the bioaccessibility of polybrominated diphenylethers in an in vitro digestion model.

The factors affecting the bioaccessibility of polybrominated diphenyl ethers (PBDEs) in foodstuffs were investigated using a static in vitro model. The results showed that the gastrointestinal digestion increased the bioaccessibility of PBDEs in the intestinal solution. The incubation time significantly affected the bioaccessibility, which increased to about 25% in 4-6 h and reached equilibrium. The adsorption and release processes followed a Langmuir isotherm equation (R(2) > 0.99). The concentrations of PBDEs in foodstuffs did not affect the bioaccessibility, while the ratios of liquid to the mass of foodstuffs had a significant effect when the ratios were less than 90. The bioaccessibility of PBDEs increased with increasing pH, reached a maximum at a pH of 7.3 +/- 0.1, and then decreased in the intestine. To our knowledge, this is the first report demonstrating the digestive parameters playing such an important role for the bioaccessibility of PBDEs in foodstuffs. Even though in vitro tests are often conducted to study bioaccessibility, the extrapolation of such results to explain what is happening inside the highly dynamic environment of the human gastrointestinal tract is still sometimes uncertain and sometimes underestimated.