The relationship of airborne trimellitic anhydride concentrations to trimellitic anhydride-induced symptoms and immune responses

Eighteen workers exposed to trimellitic anhydride (TMA) powder were evaluated in 1979. Twelve of these workers were available for longitudinal study until 1982. Annual clinical evaluations and serum radioimmunoassays for total antibody binding and specific IgE binding to ¹²⁵I-TM-HSA were performed. In 1979, five workers had antibody against TM-HSA. Of these, three workers were diagnosed with the late respiratory systemic syndrome (LRSS) and one worker with TMA-induced allergic rhinitis. The LRSS workers had significantly elevated total antibody binding of ¹²⁵I-TM-HSA and the worker with rhinitis had significantly elevated specific IgE binding of ¹²⁵I-TM-HSA per milliliter of serum. Although TMA handling was intermittent throughout the year, average airborne dust concentrations from 1974 to 1978 at job stations of the two heaviest TMA-exposed occupations, operator and assistant operator, were 2.1 and 0.82 mg/m³, respectively. After local exhaust ventilation had been improved, average airborne dust concentrations of TMA at the two latter job stations fell to levels of 0.03 and 0.01 mg/m³, respectively, in 1982. The decrease in TMA exposure coincided with a gradual fall in total antibody binding of ¹²⁵I-TM-HSA per milliliter in 1982 and symptomatic improvement in the three individuals with the LRSS. The continuous low-level exposure of the worker with TMA rhinitis was sufficient to elicit a rise in specific IgE against TM-HSA from 1.1 ng of ¹²⁵I-TM-HSA bound per milliliter in 1979 to 2.12 in 1982. The results demonstrate that after establishment of IgG anti-TM protein antibodies associated with occupational immunologic lung disease, environmental control resulted in a decline in the IgG antibodies and absence of one form of occupational immunologic lung disease.