The Relationship of Airborne Methyltetrahydrophthalic Anhydride Concentrations to Methyltetrahydrophthalic Anhydride‐Induced Symptoms

Japan Acid anhydrides such as methyltetrahydrophthalic anhydride (MTHPA) are widely used in the production of alkyd and polyester resins and as curing agents for epoxy resins. These substances are known as potent low molecular allergens and induce predominantly type I allergies'. Therefore, safe use in industry demands control of the levels of exposure causing allergic diseases, including asthma, in the workshop. In the field of sensitizing agents, recommendations or guidelines appear to be few; for example, the American Conference of Governmental Industrial Hygienists (ACGIH) has only recommended exposure limits for some acid anhydrides such as acetic anhydride, maleic anhydride (MA), phthalic anhydride (PA), and trimellitic anhydride (TMA)2). Moreover, these control limits apply to irritancy rather than to allergy, except TMA; accordingly, the level of exposure to acid anhydrides should be kept as low as possible below these values. In surveillance studies of subjects exposed to acid anhydrides, the most important risk factor for the development of antibody and immunologically mediated disease is the exposure level'-'). To date, information on exposure-response relations has been limited. The purpose of this study was therefore to examine the relation between exposure to MTHPA and the occurrence of work related eye and nasal symptoms in a condenser plant. In occupational medicine, this approach enables us to offer further protection from allergic disorders due to MTHPA.