Objective To probe the exposure patterns of nano-calcium carbonate (CaCO3) in a manufacturer and analyze related health effects on workers.
Methods Three nano-particle concentrations (mass, surface area, and number concentrations) were measured in a CaCO3 manufacturer in Shanxi Province, and morphological analysis was also performed. Seventy-seven workers (exposure group, n=55; non-exposure group, n=22) were invited to physical examination to analyze the abnormal rates of indices in physical examination.
Results The nano-CaCO3 was calcite and polyhedral. The single particle size ranged from 50 to 70 nm, and the average size of agglomerates in air was about 200 nm. The mass concentration was in the range of 84.52-3264.69 μg/m3, with higher concentrations found in packaging workstation and fishing materials workstation. The surface area concentration was 78.3-2006.6 μm2/cm3 for alveolar (A) model and 25.6-411.8 μm2/cm3 for tracheo bronchial (TB) model, with higher concentrations found in packaging, drying, and pressure filtration workstations. Higher particle number concentrations were found in packaging (2.07& #215; 1011/m3), drying (1.64& #215;1011/m3), and pressure filtration (2.18& #215;1011/m3) workstations. The number concentrations and the surface area concentrations showed positive correlations (rA=0.864, rTB=0.805, both P < 0.01). However, the abnormal rates of physical examination indices of the workers presented no statistical differences between the workers with and without nano-CaCO3 exposure (P > 0.05).
Conclusion The nano-CaCO3 particles are emitted mainly in packaging, drying, and pressure filtration workstations. A strong correlation exists between the number concentration and the surface area concentration, but neither is associated with the mass concentration. The nano-CaCO3 particles have no significant health effects on the occupationally exposed workers in the study.
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