The distribution and total burden of microplastics in the human body

Now that it has become clear that nano- and microplastic particles (NMP) can enter the human body, there is a great need to assess the risks of these particles for adequate healthcare worldwide. Two approaches are used to determine external and internal exposure to NMP: (1) model approaches such as external exposure analysis and PBK biodistribution modelling, and (2) empirical approaches, such as measuring NMP in organs, tissues, and bodily fluids. However, data from studies worldwide in the latter category are incomparable and incomplete. They are incomparable because they have been obtained with different methods, and incomplete because none of those methods can fully quantify the toxicologically relevant metrics and fractions of the NMP continuum we are exposed to. This limits the ability to validate PBK models and to combine exposure data with in vitro and in vivo effects data for consistent risk characterization. Here, we introduce data alignment and read-across methods to bring all available NMP concentration data under one denominator to calculate a whole body burden. These methods utilize the 'habits' of NMP in a similar manner to what was previously applied in data alignment for ecological risk assessment. After alignment and based on mass fractions of organs, tissues, and bodily fluids, we calculate the total NMP body burden and the distribution of NMP fractions across these body compartments. The calculations were performed probabilistically to account for the uncertainty in the calculations and the diversity of NMP as it occurs in media relevant for human exposure. Also see: https://micro2024.sciencesconf.org/559101/document