Single particle ICP-MS detection of metal oxide nanoparticles in human samples, providing a powerful tool to assess the population exposure and risk assessment

Background: The evaluation of exposure to metal oxide nanoparticles (MONPs) through human biomonitoring (HBM) provides a crucial contribution to assess risk levels in populations potentially exposed to these substances. Currently, there is insufficient data available to assess the exposure and risks to human health from the growing use of MONPs, and the chemical-physical analysis methods currently used have not yet reached scientific consensus. To this end, an analytical method based on single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) was fully validated to characterize different MONPs (Al2O3, CeO2 Co3O4, Cr2O3, CuO, Mn3O4, NiO, TiO2, ZnO and ZrO2) in HBM matrices. Results: The validated method showed the ability to simultaneously detect MONPs composition, size and size distribution, and number-based concentration in human urine and blood. It requires only simple sample preparation, eliminates pre-concentration steps, and delivers outstanding sensitivity (LoD <10 nm – 40 nm and 0.01 μg/L to 0.60 μg/L), trueness (± 20%) and intermediate precision (<15%), all within an ultra-fast SP-ICP-MS analysis time (60 s). The validated method was then applied to a set of HBM samples of the general not-exposed population and native MONPs of Al2O3 in urine and Cr2O3 and TiO2 in blood were detected. The results achieved demonstrated the suitability of the method for biological matrices where MONPs typically occur at extremely low concentrations and small diameters, and for HBM studies where a high number of samples need to be characterized. Significance: The unparalleled advantages positioned the method as a powerful and indispensable tool for HBM programs of a broader range of MONPs, many of which have not previously been characterized in HBM matrices. Its standardization ensure reliable and consistent HBM results, enhancing public health through effective exposure monitoring and risk management to nanomaterials.