EMISSION OF POLYBROMINATED DIBENZO-P-DIOXINES (PBDD) AND DIBENZOFURANES (PBDF) DUE TO THERMALLY LOADED PRINTED CARDS

Plastics when used for the manufacture of certain electrotechnical pro ducts (e.g. printed cards) are impregnated with flame protection agent s. Under thermal load these agents may react to polybrominated dibenzo -p-diokines (PBDD) and dibenzofuranes (PBDF). In the event of failures occurring in soldering systems for printed cards, the latter may catc h fire. Material samples of such ''burned'' cards turned out to contai n PBDD and PBDF. To assess possible workplace exposure, pyrolysis test s should be carried out to check whether or not and in which concentra tions these substances are released in the workplace atmosphere. Basic materials of seven printed cards were investigated; although neither decabromobiphenyl nor decabromodiphenylether was found in the material s, brominated derivatives of bisphenol A as well as bromophenol and di bromophenol were detected in their decomposition products after treatm ent in an ordinary pyrolysis apparatus. These cards (four bare, three printed) were exposed to heat under defined test conditions in a speci ally conceived thermal chamber. Emission of PBDD and PBDF could be sho wn with the highest concentrations measured for the printed cards. Thi s is probably due to the basic materials and the plastic coverings of the electronic components which are also impregnated with bromine-cont aining flame protection agents. The test results can however not be us ed to assess the actual workplace exposure to PBDD and PBDF: compared to real failure situations in the field, the thermal load in the test chamber represents a very ''worst case''. In addition, soldering syste ms are generally equipped with suction devices and separators so that particular (personal) protective measures should not be necessary.