{"hq_id":"hq-c-mix-000028","name":"Nano polystyrene","context":"human_adult","risk_level":"low_to_moderate","schema":"legacy","note":"Synthesis unavailable: compound lacks vectorizable regulatory classifications. Raw safety data returned.","data":{"risk_level":"low_to_moderate","summary":"Nano polystyrene (nanoplastics, <1 μm) represents the smallest fraction of plastic particle pollution and is distinguished from microplastics (>1 μm; hq-c-mix-000003) by its potentially higher biological reactivity due to larger surface-area-to-volume ratio, greater colloidal stability in biological fluids, and increased ability to cross biological barriers. Human health data are very limited — the analytical challenges of detecting and quantifying nanoplastics in human tissues and biological fluids have only recently been partially overcome. Key human health concerns: (1) gut barrier translocation — nanoplastic particles of 100–500 nm have been shown in animal studies to cross the intestinal epithelium and distribute to lymph nodes, liver, and spleen; (2) placental transfer — nanoplastic particles have been detected in human placental tissue; (3) inflammatory response — nanoplastics trigger inflammatory cytokine responses in vitro and in animal models. EFSA published an emerging risk assessment for nanoplastics in 2016 and WHO's 2019 microplastics report noted that evidence for human health effects at environmental concentrations is insufficient to draw firm conclusions but called for further research. The chemical hazard of nanoplastics includes both the polymer matrix (which is generally chemically inert for polystyrene) and sorbed chemical contaminants (persistent organic pollutants, heavy metals, plasticizers) that concentrate on nanoplastic surfaces and may be released at gut mucosal surfaces. No regulatory limits or OELs exist specifically for nanoplastics.","source_refs":["efsa_nanoplastics_food","who_microplastics_water"]},"meta":{"synthesis_version":"n/a","timestamp":"2026-05-01T19:48:14.538Z"}}