| Popis: |
This is one second report on the origin of PCDD/F contamination in the environment. In our previous paper1, we reported that most PCDD/Fs from tetra- to octa-congener groups were not detected in ancient Eskimo human tissue samples that were frozen for more than one hundred years. It could not be concluded, however, whether H7CDD and OCDD were present in the tissue samples because of trace amounts of contamination in the blank. In this study, the reanalysis of those ancient tissues shows a presence of low ppt levels of H7CDD and OCDD in the samples after the contamination was carefully eliminated. The levels of PCDD/F are well below those reported for modern persons. In addition, no PCDD/Fs were found in a charcoal sample from a redwood forest damaged by a natural fire prior to 1850. The data support the hypothesis that the main source of PCDD/Fs is anthropogenic. |
