In vitro inhalation bioaccessibility for PM₁₀-bound neonicotinoids: method development, effects of hydrophobicity,...

The concentrations of neonicotinoids in atmospheric inhalable particles (PM₁₀) and their inhalation bioaccessibility were examined in a coastal urban city in Eastern China. Seven neonicotinoids were analyzed using a QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction method in conjunction with a triple quadrupole mass spectrometer (HPLC-MS/MS) for PM₁₀ samples. Additionally, a dispersive liquid-liquid microextraction technique combined with HPLC-MS/MS detection was employed, offering a simple, rapid, sensitive, accurate, and cost-effective methodology for quantifying neonicotinoids in two simulated lung fluids: Gamble's Solution (GMB) and Artificial Lysosomal Fluid (ALF). The accuracy of the bioaccessibility study was evaluated using mass balance approaches with a PM₁₀ filter. Factors such as the solid-liquid ratio, extraction time, and oscillation rate were found to influence inhalation bioaccessibility. All samples contained neonicotinoids, with overall concentrations ranging from 23.3 to 140 pg/m³. The inhalation bioaccessibility of neonicotinoids under healthy conditions (GMB: 24.0-90.0%) was lower compared to that under inflammatory conditions (ALF: 33.7-91.1%). The bioaccessibility of organic components exhibited a negative correlation with both their hydrophobicity and molecular weight. The average bioaccessible concentrations of imidacloprid-equivalent total neonicotinoids (IMI_eq), determined using the relative potency factor method, was 114 ± 71.9 pg/m³ for GMB and 123 ± 71.6 pg/m³ for ALF. A health risk assessment of target PM₁₀-associated neonicotinoids via inhalation was conducted, taking into account bioaccessibility concentrations through the application of hazard quotient and IMI_eq methodologies. The results indicated an absence of carcinogenic risk for both children and adults in the area during the sampling period.