PolyChloro-DibenzoDioxins,

Ballschmiter K, Budhert H, Neimczyk R, et al. 1986. Automobile exhausts versus municipal-waste incineration as sources of the polychloro-dibenzodioxins (PCDD) and furans (PCDF) found in the environment. Chemosphere 15 901-915. 

Polychloro-dibenzodioxins and polychloro-dibenzofurans are basically contaminants which can be formed when chemicals containing the element chlorine are synthesized or subjected to heat. There are many of these substances (75 PCDDs and 135 PCDFs) which can have various numbers of chlorine atoms, when they are known as congeners. In some cases there can be compounds that have the same number of atoms but arranged differently, when they are called isomers. 

Kuehl, D.W., R.C. Dougherty, Y. Tondeur, D.L. Stalling and C. Rappe, Negative Chemical Ionization Studies of Polychloro-dibenzodioxins and Dibenzofurans in Environmental Samples, In Environmental Health Chemistry. The Chemistry of Environmental Agents As Potential Human Hazards, J.D. McKinney (ed.), Ann Arbor Science Publishing Co., Ann Arbor, Michigan, 1980, Chapter 12. 

Schafer W, Ballschmiter K. 1986. Monobromo-polychloro-derivatives of benzene, biphenyl, dibenzofiiran, and dibenzodioxin formed in chemical-waste burning. Chemosphere 15 755-763. 

Of the other pollutants, polychloro-dibenzodiox-ins have attracted special attention, where a crucial point is the differentiation between isomers, since some of them are extremely poisonous. Of these compounds the vapour-phase IR spectra of 22 tetra-chloro-dibenzodioxins (TCDDs) were taken to prove that the TCDD isomers have unique IR spectra. Indeed, spectra-structure correlations showed that each TCDD isomer has characteristic, individual asymmetric and symmetric COG stretching frequencies, on the basis of which they can be safely distinguished at low-microgram concentrations from other, less-toxic isomers. 

---