The spectrum of immunologic lung disease occurring in a population of 196 workers involved in the manufacture of trimellitic anhydride (TMA) was assessed from January 1976 through December 1987. Workers were evaluated clinically by history, blood counts and chemistries, chest x-ray, and pulmonary function studies. Immunologic tests included skin testing with trimellityl-human serum albumin (TM-HSA) and assay of total antibody (TA) and of IgE antibody binding of 125I-TM-HSA. Seventeen workers had IgE-mediated asthma/rhinitis with a positive prick test to TM-HSA and IgE antibody of 0.8-57 ng of TM-HSA bound/ml. Seven workers had a late respiratory systemic syndrome with TA from 760-56,000 ng of TM-HSA bound/ml. Four had both syndromes. Three had late onset asthma with TA of 3,700-10,000 and trace levels of IgE to TM-HSA. One had marked arthralgia and myalgia occurring hours after TMA exposure, without respiratory symptoms, with an elevated TA level of 24,000. Of 46 workers reporting no symptoms, 8% had low TA levels, while 16% of 113 with irritant symptoms had low TA levels. There was a reduction in the number of workers exhibiting an immunologic syndrome during 1982-1987-8% (7 of 85) compared to 23% (26 of 111) during 1976-1981--in spite of increased TMA production. This paralleled environmental control and worker education efforts. Cooperative research by an academic Allergy-Immunology program and industry has defined TMA clinical syndromes and provided methods of immunologic monitoring, resulting in a reduction in new cases in spite of increased production of TMA.