Modeling of mercury distribution in human body under conditions of chronic exposure: Development of a Biologically Based Dynamic (BBD) model with application to the Italian adult population

The biologically based dynamic (BBD) model was used to study the concentration dynamics of methylmercury (MeHg) and its inorganic metabolites (IHg) in the human body. The study focused on the populations residing close to an industrial site characterized by mercury (Hg) pollution, with the main objective of supporting public health decision-making. The BBD model was modified to introduce some novelties compared to previous investigations. First, the BBD model considered the estimated weekly intake of methylmercury (EWI) and the body weight (BDW) as a function of age. Second, the calibration procedure of the BBD model parameters was based on the human biomonitoring data published in previous studies, and metabolism differences between the two genders was considered. Third, the theoretical Hg burdens in major organs and excreta were converted into Hg concentrations to compare the numerical results with the experimental data. The total mercury concentrations in biological matrices were theoretically reproduced for the Italian population, showing a reasonable agreement with values measured in blood (χ ̃^2=1.507 for men and for χ ̃^2=0.778 for women), urine (χ ̃^2=0.202 for men and for χ ̃^2=0.364 for women) and hair (χ ̃^2=0.425 for men and for χ ̃^2=0.067 for women) of the adult population residing in Augusta Bay between October 2012 and April 2013. Furthermore, the BBD model simulated the methylmercury and inorganic mercury concentrations in major organs, i.e. brain, kidney and liver, of local foodstuff consumers residing in highly polluted areas, showing an acceptable agreement with values measured in cadavers from Hyogo Prefecture (Japan) between November 1971 and May 1972. The model results depended strongly on the diet preferences of the investigated population and the mercury content in consumed foodstuffs. The BBD model can be improved by considering the variations of some biological parameters as a function of age, even if this would require a lot of experimental data on the main organs, which are difficult to obtain. By introducing these improvements, the BBD model could become a useful tool for assessing mercury chronic exposure risks near industrial areas and for improving policies aimed at preventing diseases associated with mercury pollution.