A clinical and immunologic study to assess risk of TMA-induced lung disease as related to exposure

The objective of this study was to determine whether there are trimellitic anhydride (TMA) exposure levels that are very unlikely to cause immunologically mediated respiratory disease. A 3-year clinical and immunologic survey study of 286 employees was conducted at a facility that manufactures TMA. Each employee was assigned an exposure classification from 1 (highest) to 5 (lowest). Of the 28 individuals in exposure class 1, 8 (29%) developed disease; of the 57 class 2 employees, 2 (4%) developed disease; of the 79 class 3 employees, 4 (5%) developed disease. Of the 98 class 4 employees and the 24 class 5 employees, none developed disease. Inasmuch as individuals in class 4 and 5 (TMA exposure < 0.002 mg/m3) are at low risk of developing disease due to TMA, it appears that they do not warrant routine inclusion in surveillance studies.