Browsing by Author "Keskinen, Helena"

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    The Nordic Expert Group for Criteria Documentation of Health Risks from Chemicals and The Dutch Expert Committee on Occupational Standards : 136. Cyclic acid anhydrides
    (Arbetslivsinstitutet, 2004) Keskinen, Helena
    Cyclic acid anhydrides are widely used in the manufacture of resins and a variety of chemicals. Since the introduction of phthalic anhydride (PA) several new derivatives of cyclic acid anhydrides have came into use. Exposure to anhydrides occurs either in powder form or as fumes when anhydrides are used at elevated temperatures or when they are released as thermal degradation products. The technical product of a cyclic acid anhydride may contain other related anhydrides as impurities. The critical effects of cyclic acid anhydrides are sensitisation, rhinoconjunctivitis and asthma. Occupational rhinoconjunctivitis and asthma due to cyclic acid anhydrides are usually IgE-mediated. Irritant work-related rhinoconjunctivitis is often found without sensitisation to anhydrides. Allergic contact dermatitis due to anhydrides is rare. The sensitising potency of cyclic acid anhydrides varies. According to limited data, trimellitic (TMA), hexahydrophthalic (HHPA), and methyl tetrahydrophthalic anhydride (MTHPA) are more sensitising than PA and tetrachlorophthalic anhydride (TCPA). Based on immunological cross-reactivity, the sensitising potency of methyl hexahydrophthalic anhydride (MHHPA) might be near that of HHPA and MTHPA. The level of exposure needed to cause specific IgE antibody production and work-related symptoms in mucous membranes and respiratory organs may be less than 10 µg/m3 for the more highly sensitising anhydrides.