A human pregnancy PBBK model for lead , mercury and selenium

A human physiologically-based biokinetic (PBBK) model for the trio mixture of mercury, lead and selenium which was developed in an earlier study has been modified into a mixture model for a pregnant mother/fetus. The modified model was capable of simultaneously simulating the absorption, distribution, metabolism, and elimination (ADME) properties of these three elements in a pregnant mother and her fetus. This model consists of three pairs (a pair for each of the elements, lead, mercury and selenium) of maternal/fetal models which were integrated into a single model. This model was adapted and employed to investigate the health risk posed to a pregnant mother and her fetus due to simultaneous exposure of the pregnant mother to these elements. The health risk index (HRI) to three organs (brain, liver and kidney) of the mother and two organs (brain and liver) of the fetus were simulated. The simulated HRI were for a pregnant mother presumed to have consumed contaminated cereals from a contaminated mining village (Bagega in nothern Nigeria). Two scenarios were assumed namely; (a) adequate selenium intake (2.5 μmol /kg/day), and (b) high selenium intake (7.5 μmol /kg/day). Mercury and lead input doses were calculated as 1773.077 μmol /kg/day and 3361.534 μmol /kg/day, respectively. A continuous exposure, for the entire period of gestation was simulated. For the two scenarios simulated, the HRI for the brain, liver and kidney of the pregnant mother were all high throughout the gestation period. The liver and kidney of the pregnant mother appeared to be particularly at risk in the second trimester. The results also showed that even with adequate or high selenium intake by a pregnant mother, the consumption of these contaminated cereals from Bagega could put the brain and liver of the fetus at risk, particularly within the first two months of gestation.