- Adhesives industry
- Chemical industry
- Dyeing industry
- Electrical component manufacture
- Epoxy resin industry
- Food packer
- Pharmaceutical industry
- Plastics industry
- Hexahydrophthalic anhydride HHPA
- Himic anhydride
- Maleic anhydride
- Phthalic anhydride
- Pyromellitic anhydride
- Tetrachlorophtalic anhydride TCPA
- Trimethyl anhydride
Incidence: the incidence of sensitisation depends on the nature of the product concerned: TCPA 15%, TMA 20%, HHPA 69%. PA is widely used throughout the plastics and pharmaceutical industries. TCPA and HHPA are used as hardening agents in the polymers industry. Asthma caused by HA has been reported in the production of fire retardant materials and products. Atopy does not play an important role. There is sometimes an IgE type sensitisation, but in addition to any immunological mechanism the substances are toxic and cause irritation which may give rise to RADS (Reactive airways dysfunction syndrome or asthma caused by irritants- Brook´s Syndrome). The continuation of symptoms after allergen avoidance is due to auto antibodies. Sensitisation to anhydrides significantly increases the risk of developing bronchial hyperreactivity.
Acid anhydrides are used as hardening agents for resins. They are released when polyvinyls compounds are melted. Mixture of anhydride powders may be dangerous.
Haemorrhagic rhinitis like asthma appears after a long period of exposure to the risk (greater than 10 years). Eye and skin problems may also occur. An influenza-like syndrome is sometimes observed with myalgia, fever and arthralgia (TMA). During periods of exposure to high concentrations of TMA, serious dyspnoea with haemoptysis and an infiltrate may be observed (toxic reaction). A recent study has shown that despite allergen avoidance, respiratory function remains disturbed even after 12 years.
Skin prick test with the sodium salt of TMA-HSA (1:200) 3.4 mg/ml. In a cohort of 370 subjects, only 3% of skin tests were positive.
Immunological assay: PTRIA with TMA-HSA; RAST/CAP RAST for PA and TMA.
Bronchial provocation test (in hospital). Similarly for HHH-HSA, a positive skin prick test is a strong indicator of the likehood of the onset of asthma.