Dosimetry of Particles: Critical Factors Having Risk Assessment Implications.

Species differences in the handling of particles are topics of interest for setting ambient particulate matter standards as well as for studies involving the phenomenon of lung overload and the implications, if any, of such studies for workplace dust exposure standards. The dosimetry of inhaled particles differs among the three major regions of the respiratory tract (extrathoracic, tracheobronchial, and pulmonary). Particulate dosimetry includes both deposition, which is the process of removing particles from inhaled air to various locations in the respiratory tract during breathing, and clearance, which refers to the rates and routes by which deposited particles are removed from the respiratory tract.

Protein Carbonyls in Bronchoalveolar Lavage Fluid in Mice, Rats and Hamsters Following Inhalation of Pigmentary Titanium Dioxide Particles.

Elevation of protein carbonyls has been implicated in the clinical setting as a result of oxidant damage associated with a number of disease states in both humans and laboratory animals. Protein carbonyls, the product of oxidative modification of amino acid residues, may result from macrophage and neutrophil inflammatory responses to inhaled particles. We hypothesized that increased levels of protein carbonyl groups in the bronchoalveolar lavage fluid (BALF) may serve as a biomarker of oxidative stress in rodents exposed to extremely high airborne concentrations of poorly soluble particles (PSP) of low toxicity.

Comparison of Selected Pulmonary Responses of Rats, Mice, and Syrian Golden Hamsters to Inhaled Pigmentary Titanium Dioxide.

We present a preliminary report of a bioassay designed to compare and contrast selected pulmonary responses of female B6C3F1 mice, Fischer 344 rats, and Syrian golden hamsters to inhaled pigmentary titanium dioxide (TiO2). Animals were administered 10, 50, or 250 mg/m(3) TiO2 for 6 h/day and 5 days/wk, for 13 wk. Recovery groups were held for an additional 4-, 13-, or 26-wk period.