PCDFs data reporting

A plethora of effects have been reported from multiple animal studies following exposure to PCDDs, PCDFs and PCBs. The most extensive data set on dose-response effects is available for 2,3,7,8-TCDD less information is available for the other dioxinlike compounds. Therefore, the focus of the evaluation of the animal data is on the effects of 2,3,7,8-TCDD. 

E. Fly ash. Olie et al. reported in 1977 on the occurrence of PCDDs and PCDFs in fly ash and flue gas samples from municipal incinerators in the Netherlands (UjO. No quantitative data were given in this report, but Buser and Bosshardt made a... 

Although there are many peer-reviewed publications about organo-chlorine pesticides, PCBs and PCDDs/PCDFs, on or in water, sediments and mussels, information about these compounds on or in waterbirds in China is limited. In the present review, most of the data that were presented from China were from limited peer-reviewed publications (Connell et al., 2003 De Luca-Abbott et al., 2001 Dong et al., 2004 Nakata et al., 2005 Wan et al., 2006). Furthermore, it should be noted that the concentrations of various POPs reported were measured in different tissues of separate species, and expressed in different units. Thus, caution should be taken when the information is used or interpreted. 

Schlatter C (1991), in Banbury Report 35 Biological Basis for Risk Assessment of Dioxins and Related Compounds, Data on kinetics of PCDDs and PCDFs as prerequisite for human risk assessment", p. 215-226, Eds. Gallo MA, Scheuplein R, van der Heijden K Cold Spring Harbor Laboratory Press, New York... 

The integrated ion current for each analyte ion listet in Table 5 must be at least 2.5 times background noise and must not have saturated the detector. The internal standard ions must be at least 10.0 times background noise and must not have saturated the detector. However, if the M-[COCl]+ ion does not meet the 2.5 times S/N requirement but meets all the other criteria listed in Section 11 and in the judgement of the GC/MS Interpretation Specialist die peak is a PCDD/PCDF, the peak may be reported as positive and the data flagged on Form I. 

If a concurrent PCDD/PCDF SDG is being processed, the native spike and duplicate from that SDG may be shared with the rerun samples if the total number of samples does not exceed 20. The native spike and duplicate data shall be reported in the data packages for both SDGs, but are only billable once, under the original SDG for which they were prepared. If the total number of samples exceeds 20, an additional native spike and duplicate must be analyzed. 

Sources From Combustion Processes. In 1977, PCDD and PCDF were detected in particulate emissions from municipal incinerators (5). Similar data were soon reported from around the world. In 1980, workers at Dow Chemical Company, using the most sensitive and specific analytical techniques of that time, detected a range of PCDD in residues from many combustion processes (6). These workers postulated that all combustion processes that contain chlorine sources produce PCDD. Although this postulate is not supported in all situations, dioxin emissions from combustion sources are major contributors to PCDD in the environment (7). 

Hazardous waste incinerators. Hazardous waste incinerators have also been the object of public concern. However, available data indicate the emissions from such incinerators operating under good conditions are of the same magnitude as emissions from MSW incinerators. The isomeric patterns of PCDDs and PCDFs are similar to those reported from MSW incinerators... 

Air and particulate. Due to sampling and analytical problems very few data are available on the levels of PCDDs and PCDFs in normal urban air. Samples of air particulates from Washington, D.C., and St. Louis, MO, USA have been analyzed by Crummett et al. ik) and Czuczwa and Hites (15). Crummett et al. ik) report on isomer specific analyses for tetra-CDDs and hexa-CDDs while Czuczwa and Hites (15) only report a congener profile and do not discuss any specific isomers. In both studies octa-CDD was found to be a major constituent, reported in levels of 150-200 ppb. The level of 2,3,T 8-tetra--CDD was 5 50 ppt and of 2,3,T,8-tetra-CDF was IOO-38O ppt (lU). 

Typically data as to levels of PCB s/PCDD s/PCDF s are reported in units per 100 cm2 These data can then be separated into area of high exposure opportunity and loss exposure opportunity. 

There have been few recent advances in the toxicological literature as to the hazards of 2,3,7,8- TCDD or its equivalents. At a recent European conference reported human pharmocokinetic studies indicate the biological half-life of 2,3,7,8- TCDD has been calculated to be on the order of five years. Such conclusions were interpreted as justifying the rethinking of the reduction of acceptable daily intake levels. TCDF data on the biological fate of PCDF s support the five year biological half-life theory. 

Data regarding the reaction of OH with PCDFs are very sparse. In fact, the only study is that of Brubaker and Hites (1998), who studied the 2,8-dichloro-dibenzofuran congener using a relative rate technique (table in-G-99). The study was conducted over the 355 05 K range, and the reported rate coefficients increase from about 3 x 10 to 4 X 10 cm molecule" s over this temperature range. Given the lack of confirming data, and the discrepancies just noted in the database for OH reactions with the PCDDs, no recommendations are made at this time. 

---