[Pneumoconiosis caused by "rare earths" (cer-pneumoconiosis)]

Slowly progressive restriction in respiratory function was observed in five reproduction photographers who had been exposed to fumes of carbon arc lamps for more than a decade. In all cases interstitial lung fibrosis had developed and accumulations of fine granular dust particles were found in the tissue. Combined analyses including X-ray diffraction, infrared spectroscopy, plasma analysis, X-ray microanalysis and electron diffraction revealed the presence of rare earth minerals (mainly cerium compounds) in all lungs. The rare earth minerals originating from the core of the burned carbon rods used in the arc lamps represent the etiological factors responsible for the development of so-called "cerium pneumoconiosis".