Using an ultrasonic nebulizer, cobalt aerosols (MMAD=0.76μm, σg=2.1) were generated from an aqueous suspension of ultrafine metallic cobalt particles (Uf-Co) with a primary diameter of 20 nm. Rats were exposed to Uf-Co aerosols at 2.72±0.44 mg/m3 for 5 hours (Exp. 1) or at 2.12±0.55 mg/m3 for 4 days at 5 hours/day (Exp. 2). Only minimum histopathological changes were observed in the lungs in Exp. 1. In Exp. 2, evidence of slight injury was noted, including focal hypertrophy or proliferation of the epithelium in the lower airways, damages of macrophages, intracellular edema of the type I alveolar epithelium, interstitial edema, and proliferation of the type II alveolar epithelium. A new finding in this study was the morphological transformaiton of some damaged type I cells to the juvenile form, which appeared to indicate the capability of self-repair of this cell type. The return to a juvenile form seemed to be a key response of type I cells during the early process of repair without cell division following non-lethal injury. Cobalt accumulated in the lungs after inhalation and was transferred rapidly to the blood. In conclusion, inhaled Uf-Co induced reversible pulmonary injury even after short-term exposure.
we devised a fluorometric HPLC method for determining δ-aminolevulinic acid (ALA) in the urine of lead-exposed workers. With this fluorometric HPLC method and the conventional colorimetric method, the concentrations of urinary ALA in 84 lead workers were determined and compared. In the measurement of urinary ALA at lower levels ( ?? 5 mg/ 1), the value of urinary ALA obtained by the fluorometric HPLC method was much lower than that obtained by the conventional colorimetric method, indicating that the colorimetric method also measures urinary ALA-like compounds such as aminoacetone. On the other hand, the measurement of urinary ALA at higher levels (> 5 mg/1) demonstrated that the ALA value obtained by the fluorometric HPLC method corresponded well with that of the conventional colorimetric method. A correlation coefficient between the fluorometric HPLC method and the colorimetric method was 0.856 for 60 urine samples with ALA ?? 5 mg/1, and 0.996 for 24 urine samples with ALA >5 mg/i.
ABSTRACT: Metallothionein (MT) is a low molecular weight metal-binding protein that is induced by a variety of heavy metals, and therefore is a candidate for an index in the biological monitoring of heavy metal exposure. As an approach to the establishment of a practical monitoring method, we estimated the MT levels in Cd-exposed cultures of human peripheral blood mononuclear cells as well as purified lymphocytes using a technique developed for the electrophoretic analysis of MTs. By this procedure, we could successfully detect the MTs induced by Cd in a dose-dependent manner. MTs were detectable even in cells exposed to as low as 0.5 μM Cd, which is close to the blood Cd levels of exposed workers. These results indicate the usefulness of this technique as a practical method for the monitoring of heavy metal exposure.