The potencial role of rare earths in the pathogenesis of interstitial lung disease: a case report of movie projectionist as investigated by neutron activation analysis.

A 60-year-old male subject who worked as a movie projectionist and who was exposed for 12 years to rare earths (RE) containing dusts from cored arc light carbon electrodes was investigated. Chest X-ray films and pulmonary function tests showed an interstitial lung disease, emphysema and a severe obstructive impairment with marked decrease of carbon monoxide diffusion capacity. The histological examination of a transbronchial biopsy confirmed the diffuse interstitial lung fibrosis. Neutron activation analysis (NAA) of the biopsy showed concentrations of cerium (Ce), lanthanum (La), neodimium (Nd), samarium (Sm), terbium (Tb) and ytterbium (Yb) which were high compared to the corresponding elements in the transbronchial biopsies of 5 unexposed subjects as a control group. Thorium (Th) (which is generally present as an impurity of the RE compounds) was also determined in order to estimate the radiation dose in the lung of the worker. On the basis of the clinical observations, of the analytical results by neutron activation analysis of RE and of the presence of Th in the transbronchial biopsy, as well as of the differential diagnosis, which tended to exclude other occupational or non-occupational lung diseases, a relation between the observed interstitial lung fibrosis and occupational exposure to RE is highly probable.

Pulmonary toxicity of stable and radioactive lanthanides.

The pulmonary toxicity of inhaled lanthanides has been the subject of debate. In question have been the relative contributions of radioactive vs. stable elements in the development of lanthanide-associated progressive pulmonary interstitial fibrosis. The central question of this debate is: Are lanthanide dusts that are devoid of radioactive contaminants capable of producing progressive pulmonary disease, or are lanthanide-induced lesions more appropriately termed "benign pneumoconioses"? This paper examines the epidemiologic and experimental record in order to answer the above question. It is clear from the available data that significant pathogenic potential of inhaled lanthanides exists and is related to the type and physicochemical form of the material inhaled and to the dose and duration of exposure. Contamination of the dust with radioactive materials may accelerate and enhance the pathologic response, depending on the form and dose of radioactivity encountered. Nevertheless, there is little evidence to suggest that the level of radioactive contamination of occupationally encountered lanthanide dusts is sufficient to be included as a risk factor for pulmonary disease. Thus, the pulmonary syndrome induced by stable rare earths includes progressive pulmonary fibrosis and should not be referred to as "benign pneumoconiosis."

Serum ornithine carbamoyltransferase (OCT) in rats poisoned with lanthanum, cerium and praseodymium.

Serum ornithine carbamoyltransferase (OCT) in rats poisoned with lanthanum, cerium and praseodymium. Acta Physiol. Pol., 1977, 28 (6): 589-594. The serum ornithine carbamoyltransferase in relation to doses of lanthanum, cerium and praseodymium, administered intravenously as chlorides, was investigated. A directly proportional relationship was found between the doses of these compounds and the serum enzyme level in rats. The lowest doses at which a rise in the serum OCT level occured were determined. They were: lanthanum - 0.75 mg/kg of body weight, cerium - 1.5 mg/kg, and praseodymium - 3 mh/kg. A decreasing toxicity of these elements with increasing value of atomic number was observed.