POLYFLUORINATED DIBENZODIOXINS AND DIBENZOFURANS SYNTHESIS, ANALYSIS,FORMATION AND TOXICOLOGY

The 75 congeners of the polyfluorinated dibenzodioxins (PFDDs) and abo ut half of the 135 polyfluorinated dibenzofurans (PFDFs) have been syn thesized by pyrolysis of fluorophenols and fluorobenzenes. The individ ual congeners were characterized by GC/MS. 2,3,7,8-TFDD was also chara cterized by H-1-, C-13- and F-19-NMR spectroscopy. The retention behav ior of PFDDs and PFDFs during gaschromatographic separation is entirel y different from that of PCDDs/PCDFs or PBDDs/PBDFs. The PFDDs/PFDFs e lute earlier than the PCDDs/PCDFs and the order of the elution is not governed by the degree of substituion, O8FDD eluting e.g. much earlier than the M(1)FDDs. A preliminary toxicological evaluation of 2,3,7,8- TFDD was carried out. The elimination of 2,3,7,8-TFDD from mice after a single i.p. injection is biphasic with a very rapid elimination half -live of 5 minutes and a slower phase of 165 minutes. This means a dra matically reduced half-live compared to 2,3,7,8-TCDD with 8.5 d. In li ver the TFDD level reaches a maximum 30 minutes after injection and al so declined in a biphasic manner. In rat hepatocytes a primary culture induction of CYP4501A1-catalyzed EROD activity could be demonstrated, indicating that 2,3,7,8-TFDD activates the dioxin receptor. In rat he patocyte cultures similar EC(50) values were found for 2,3,7,8-TCDD an d 2,3,7,8-TFDD. So far no de novo synthesis of PFDD/PFDF could be dete cted under conditions were PCDDs/PCDFs are formed Also, formation of P FDDs/PFDFs could not be detected during thermal treatment of fluorotri chloromethane or Teflon.