Control-point mismatch and cross-media transfer in a commercial-scale multiwalled carbon nanotube manufacturing archetype

Commercial-scale multiwalled carbon nanotube manufacturing requires controls that protect workers while preventing uncontrolled environmental releases. This study integrated task-resolved near-field/far-field exposure modeling, Monte Carlo analysis, annual release routing, and 10-year multimedia fate modeling within a source-to-boundary framework using K-nanoMFA. Seven tasks and six control configurations were compared against a reference compressed product. Routine conditioning and packaging presented the greatest risk of exceeding the National Institute for Occupational Safety and Health recommended exposure limit (REL), whereas filter replacement, reactor maintenance, and spill recovery generated the highest event-specific exposures. A control-point mismatch emerged: sealed transfer and automated packaging substantially reduced expected REL-exceedance events but provided a smaller reduction in the 10-year sediment predicted environmental concentration (PEC). Conversely, stack filtration and wastewater solids capture reduced environmental loading without altering upstream exposure. Wet spill recovery with high-efficiency particulate air-filtered vacuuming reduced total external release; however, under the reference routing assumptions, incomplete downstream solids capture increased water release and increased sediment PEC, illustrating a possible cross-media transfer. The integrated control train reduced expected REL-exceedance events, annual external release, and sediment PEC simultaneously. The control-point mismatch persisted when key archetype parameters and control multiplier sets were varied in robustness analyses. Effective control therefore requires exposure reduction, containment, and downstream residue management to protect both workers and the environment.