Trimellitic anhydride exposure in a 55‐gallon drum manufacturing plant: Clinical, immunologic, and industrial hygiene evaluation

Nine workers at a 55‐gallon drum manufacturing plant had history of exposure to a paint powder that contained trimellitic anhydride (TMA). Environmental monitoring revealed airborne levels of TMA to be over 100 times the OSHA permissible exposure limit of 0.04 mg/m³. The exposed workers were evaluated in a cross‐sectional study by questionnaire, physical examination, screening pulmonary function tests, serial peak expiratory flow rates (PEFR), and serum antibody levels. Four workers had symptoms consistent with TMA‐induced irritant effects. Three had symptoms and IgG levels consistent with TMA late respiratory systemic syndrome (LRSS). Two of these three had PEFR changes that showed significant drops (>20%) 12‐18 hours after the end of a work shift. The material safety data sheet for the paint powder failed to list TMA as an ingredient. Despite the well‐described toxic effects of TMA, the present study documents that TMA‐related illness may continue to be a problem in situations where workers and management are not properly notified of the potential hazards. The measurement of PEFR may be useful in identifying TMA‐exposed workers with LRSS.