Exposure scenarios for human health risk assessment of nano- and microplastic particles

Evidence of nano- and microplastic particles being present in the human body has increased in recent years, yet there is no acceptable methodology to perform a human health risk assessment for these particles because of limitations in the exposure and hazard assessments. Exposure assessment can be improved by establishing comprehensive and justifiable exposure scenarios for a defined exposure demographic, thoroughly describing the relevant exposure pathways, and performing multidimensional data alignment, thereby facilitating probabilistic estimates of nano- and microplastic particle exposure. General considerations of exposure scenarios are outlined, along with specifics details on the complexity and prioritization for nine demographic groups: adults; women; the elderly; individuals with disease; individuals employed in high-hazard occupations; and children demographics, including early infants, toddlers, school children, and teenagers. Recommendations to advance exposure assessments and scenarios are also provided which suggest: i) the use of well-defined exposure scenarios for demographics that are prioritized according to their level of complexity and concern; ii) a thorough description of relevant activity factors (physiological parameters, behavioural traits) and exposure factors (duration, frequency, media characterization) for the chosen demographic; iii) thorough descriptions of exposure via ingestion and inhalation, and in the case of early infants, including exposure via maternal transfer; iv) multidimensional data alignment and probabilistic methods to enable credible comparisons of exposure data across studies and inform physiologically based toxicokinetic models to estimate internal exposure.

The online version contains supplementary material available at 10.1186/s43591-025-00134-9.