Occupational hypersensitivity pneumonitis caused by fossil-containing rocks

Aims: We present a hypersensitivity immune response to inhalation of antigens from fossil soils frequently used in tile manufacture. We found that the soil polished by a worker affected by pneumonitis was a paleosol containing bivalves from the cretaceous period called Hippurites. Methods: We made a diagnostic study for pneumonitis (analysis, microbiology, radiology, high-resolution CT, bronchoalveolar lavage, pulmonary biopsy. A biochemical study of the polishing materials used (magnesium hexafluorosilicate crystallizer), steel spoilage, washing liquid and Bilbao red limestone) after scraping of the same. Allergy study included skin tests with extracts from fossil soils, determination of IgG and IgE to mollusks, IgEimmunodetection with soil extracts with the patient's serum and non-atopic controls. Histology was made using scanning electron microscopy of the lung biopsy and the fossil soil to determine the presence of remains of mollusks, fungi, pollen or other fossil elements. Results: SDS-PAGE IgE Immunoblotting assay detecting IgE binding in soil extract between 66 and 35 kDa. Likewise, IgE-Immunblotting assay with extracts from bivalve mollusks (razor shell, mussel and scallop) and gastropod (sea snail), detecting IgE binding between 100 kDa -30 kDa, as well as in some bands with molecular mass between 20 and 14 kDa, proving sensitization to mollusks. Conclusions: Bivalve proteins preserved in fossil soils may produce an immune hypersensitivity response. This may impact on the precautions exposed workers, in this case fossil soil cutters and polishers, should take.