Exposure to cyclic anhydrides in welding: a new allergen-chlorendic anhydride

Respiratory effects associated with welding fumes have been manifested in welders as occupational asthma. Previous studies have concerned mainly the effects of metal fume exposure, although it has also been suggested that asthma may develop as a result of exposure to contaminants generated from painted metals. To determine whether welding fumes contain irritating and sensitizing anhydrides, air samples were collected during the repair welding of forest harvesters, which were painted with chlorinated polyester paint. Samples were collected with an assembly of a spiral glass trap inserted between a filter holder with a Teflon filter and a Tenax sampling tube. Sample analyses were with GC-MS and GC-ECD. Sensitizing anhydrides released from the paint into the air were primarily chlorendic anhydride (<2-44 microg/m(3)) and phthalic anhydride (11-21 microg/m(3)). Hydrogen chloride (HCl) and hexachlorocyclopentadiene were also found. Airborne HCl was measured with Dräger tubes. Since paint films are electrical insulators, the film around the welding seam was removed before arc welding. Removal of paint with an abrasive wheel caused the least exposure to HCl (<0.5 ppm) in contrast to burning with a gas fuel torch, (HCl approximately 5 ppm). HCl exposure was the highest (<0.5-20 ppm) during welding. It is recommended that dry paint coating be removed from an area around the seam with an abrasive wheel, not by burning, before welding.