Particle size and morphology drive the kinetic parameters that govern how external exposure translates into internal dose — specifically airway and lung deposition fractions, as well as placental, gut and pulmonary translocation fractions. These fractions are retrieved from a size- and morphology‑based kinetic lookup table derived from published values (see documentation). Clearance kinetics are not currently modelled; the framework currently assumes that once MNPs enter the systemic circulation they are not cleared. Polymer and chemical toxicity scores [Christopher et al. 2024] combine with automatic size/morphology modifiers to produce the final hazard score.
Particle Size
Source: [van Boxel 2025; ICRP 66]Morphology
Source: [Sturm 2012; Zhou 1996]Polymer & Chemical Profile
Source: [Christopher et al. 2024]High EDI is expected for this life stage due to intense crawling and hand-to-mouth behaviours. Adjust dust concentrations to model a cleaner environment.
Body Weight (BW) [kg]
Source: [WHO Child Growth Standards]Active Crawling (Hrs_active) [hr/day]
Source: [EPA ExpoBox - Infant Activity]Normalisation Metric
Source: [Standard RA Practice vs. Particle-Specific]Using Body Weight is standard but may be less relevant for particle toxicology. 'Total Particle Load / day' provides the absolute particle flux.
Frequency (FQ_htm) [contacts/hr]
Source: [Xue et al. 2007 - Mouthing Frequencies]Hand Surface Area (SA_hand) [m²]
Source: [EPA Exposure Factors Handbook]Dust Adherence Factor (AF_hand) [mg/m²]
Source: [EPA Exposure Factors Handbook]Default reduced from 5,000 to 1,000 mg/m² (0.1 mg/cm²) per EPA standard for dry indoor hands. Higher values (up to 10,000) may be appropriate for sweaty/sticky hands or outdoor play.
Dust Concentration (C_dust) [p/mg]
Source: [Zhang et al. 2021; Jenner et al. 2022]Default revised from 500 to 50 p/mg following the Phase 0 audit. The previous 500 p/mg default (set when sizeWeight was removed) overshot the literature range. Jenner et al. (2022) report typical indoor settled dust MNP concentrations of 2–90 p/mg for inhalable fibres; 50 p/mg represents a conservative mid-range value.
Resuspended Dust Conc. (C_resus) [p/m³]
Source: [Wu et al. 2021 - Infant breathing zone]Active Breathing Rate (IR_breath) [m³/hr]
Source: [EPA - Infant short-term active]Exposure Thresholds
Source: [User Defined]Note on Thresholds
Exposure thresholds are currently arbitrary and user-definable. What constitutes Low, Medium and High in terms of daily particle exposures is to be resolved by scientific consensus.