PlastiWatch as a Standardized Multi-Parameter Framework for Microplastic Hazard Screening

Microplastic (MP) contamination is widely documented, yet comparisons among monitoring studies remain constrained by inconsistent units, analytical size cutoffs, and incomplete reporting of particle characteristics. This study introduces PlastiWatch as a screening-level hazard-prioritization framework, not a formal ecological risk model. It combines eight dimensions of MP contamination into a 0-100 score: particle size distribution (weight 3), concentration (weight 4), shape composition (weight 2), density classes (weight 1), hazardous chemical adsorption (weight 3), colour distribution (weight 1), degradation state (weight 2), and polymer identity (weight 4). The ordinal factors and weights express evidence-informed priorities; they are not probabilities, effect thresholds, or linear dose-response coefficients. The proof-of-concept used one selected site from each of seven published studies: four sites in India, two in Egypt, and one in China, spanning rivers, an alpine stream, a tidal distributary, coastal surface water, and a lake. Reported concentrations ranged from 1.53 to 98 particles/L. PlastiWatch scores ranged from 40 to 54, with six sites in the provisional moderate level and one in the high level. Despite heterogeneous reporting, PlastiWatch generated scores for all seven sites using four to six available parameters per site while transparently identifying recurrent data gaps, particularly for density, degradation state, and chemical adsorption. The application therefore demonstrates the operability of a partially observed framework rather than validation of all eight parameters or the upper score range. PlastiWatch supports transparent screening, identification of data gaps, and prioritization of confirmatory monitoring. Ecological risk conclusions require harmonized exposure data, dose metrics, and independent effect-based validation.