Dioxin cleanup

For monitoring to clc substances, such as dioxin cleanup, assume we have calculated an x and s for each unit area or rectangular panel potentially needing cleanup and have been given an action level of 1 ppb. The action level Is a constant and has no variance. The x and s are computed from a field triplicate of a composite of subsamples equally spaced from a uniform grid covering the panel. The null hypothesis says "no difference," and represents the status quo. Hopefully, nonpolluted or less than 1 ppb Is the status quo, and polluted or equal to or larger than 1 ppb Is the exception. 

It is my hope that this book can define a very complex problem and describe solutions. The examples of dioxin cleanup issues and procedures are offered to provide engineers, health scientists, regulators, lawyers, business people, and other concerned individuals with a methodology applicable to other hazardous chemicals. I believe that science can detect pollutants in the environment and estimate their potential health risk. Society as a whole, scientist and nonscientist, determines acceptable risk. Society also plays a major role in managing risk because we face many problems and have limited resources to deal with them all. 

Immunoaffinity chromatography (lAC) is one approach that has been investigated to simplify dioxin cleanup [44-46]. Immunoaffinity columns have been generated from anti-dioxin antibodies and shown to selectively bind dioxins from samples. A monoclonal antibody column showed acceptable re-... 

Uniformly labeled 2,4-dichlorophenol- C (purchased from New England Nuclear Corp, Boston, Mass.) was used in the tracer preparation. This provided a label at all carbon positions in the dibenzo-dioxin structure. 2,7-Dichlorodibenzo-p-dioxin- C after initial cleanup by fractional sublimation, contained approximately 5% of an impurity, detected by thin layer chromatography (TLC) which gave mass peaks at 288, 290, 292, and 294 in the mass spectrometer, consistent with a trichloro-hydroxydiphenyl oxide. This is probably the initial condensation product of the Ullman reaction and is most likely 2-(2,4-dichlorophenoxy)-4-chlorophenol. It was removed easily by extractions with aqueous... 

Bunce, N. J., Petrulis, J. R. (1999). Dioxin-like compounds screening assays. In Meyers R. A. (Ed.). Encyclopedia of Environmental Pollution and Cleanup, Wiley, NY, pp 440-449... 

Dioxin-contaminated sites, which pose a human health threat, have been the subject of recent analyses by the Centers for Disease Control (CDC) in Atlanta, GA. It has been determined by CDC that 1 ppb of dioxin is detrimental to public health and that people should be dissociated from the hazard. A level of 1 ppb of dioxin (2,3,7,8-TCDD) in soil is recommended as an action level. In cases where soil concentrations exceed 1 ppb, it is recommended by CDC that potential human exposure to the contamination be examined further. If there is human exposure to I ppb or higher on a regular basis, cleanup is indicated. A substance that may be more toxic and hazardous than dioxin is expected to be discovered in the near future. 

Phase 2. In the seeond phase of the study, the partieipants were asked to analyze three extraeted and cleaned sediment samples using the DR CALUX bioassay. Sediments used for extraetion and cleanup were freshwater sediments from the Western Seheldt, The Netherlands. The sediment extracts were prepared by the Royal Institute for Fishery Research (RIVODLO), IJmuiden, The Netherlands, aeeording to the protoeol given here. Dilutions of the supplied sediment extracts were prepared by the partieipants in DMSO and tested for dioxin and/or dioxinlike content. On each 96-well mierotiter plate, a 2,3,7,8-TCDD standard ealibration curve was analyzed. Raw data as well as eonverted data were used for statistieal evaluation. 

The interlaboratory results obtained from the analysis of defined standard solutions, but also from the analysis of sediment extracts prepared either by the coordinator of the study or by the participants themselves, also provide a measure of the variation between laboratories. The results show that the interlaboratory reproducibility ranges from 6.5% for the defined dioxin sample to 27.9% for the sediment sample extracted by the participants themselves. As was mentioned before, the reproducibility for this last sample is relatively high and most presumably due to the introduction of extra handlings (extraction and cleanup) to the total procedure. In addition, the fact that not all the participants had prior experience with the extraction protocol to be used could have added to the increase in variability of the process. Furthermore, the dilution factor was not dictated. This also introduces a certain degree of variation. For the reproducibility of the DR CALUX bioassay itself and not caused by differences in operating extraction conditions, the maximum variation between laboratories was observed to be 18.0%. The results for the sediment extract samples can also be used to estimate the method variability for extracts, that is, based on samples of unknown composition. Again, given the intra-as well as the interlaboratory variations observed in this study, it appears justified to conclude that the standard deviation of the means provides a reasonable estimate of the method variability, based on the overall aver-... 

The in vitro bioassay for dioxins with cleaned sediment extracts (DR-CALUX) proved to comply with the QA/QC criteria needed to guarantee the reliability of data in an inter- and intralaboratory study (Besselink et al., 2004). The chemical stability of dioxins makes it possible to apply destructive clean-up procedures which remove all matrix factors. Sample extraction and cleanup for other in vitro bioassays for specific mechanisms of toxicity require further development to make sure that the chemicals of interest are not lost or unwanted chemicals included in the sediment extract to be tested. Table 4 summarizes possible bioassays that could be performed in addition to chemical analyses with the dredged sediment in a licensing system. 

For example, in eel, high concentrations of polychlorinated biphenyls can be present and can interfere in the cleanup procedure. Fly ash is difficult to extract. Drastic concentration and cleanup procedures such as saponification can convert some isomers. Oc-tachlorodibenzo-p-dioxin can easily be broken down during the cleanup procedure. For each matrix a specific isolation technique is necessary. The method has to be validated for all the isomers of the analytical program (24). 

A method for the extraction and cleanup of chlorinated dioxins and furans from house dust was published by Saito et al. (2003) using accelerated solvent extrachon... 

Saito, K., Takekuma, M., Ogawa, M., Kobayashi, S., Sugawara, Y., Ishizuka, M., Nakazawa, H. and Matsuki, Y. (2003) Extraction and cleanup methods of dioxins in house dust from two cities in Japan using accelerated solvent extraction and a disposable multi-layer silica-gel cartridge. Che.mosphe.re, 53,... 

Chlorinated dioxins and dibenzofurans are best analyzed by GC/MS techniques, using both low- and high-resolution mass spectrometry. A measured amount of sample is extracted with a suitable solvent. The solvent extract containing the analytes is concentrated down to a small volume and then subjected to cleanup for the removal of interferences. The extract is injected onto the GC... 

The hexane extract is shaken with 1 1 H2S04 in a small separatory funnel for 1 min and the bottom H2S04 layer is discarded. Such acid wash may be repeated two or three times. The extract is then repeatedly washed with 20% KOH solution. Contact time must be minimized because KOH could degrade certain chlorinated dioxins and dibenzofurans. If acid-base washing is performed, the sample extract should be washed with 5% NaCl solution each time after acid and base washes, respectively. Acid-base partitioning cleanup may, however, be omitted completely if the sample is expected to be clean. 

PAUSTENBACH, D.J., WENNING, R.J., LAU, V., HARRINGTON, N.W., RENNIX, D.K. and PARSONS, A.H. (1992). Recent developments on the hazards posed by 2,3,7,8-tetrachlordibenzo-p-dioxin in soil Implications for setting risk-based cleanup levels at residential and industrial sites, J. Toxicol. Environ. Health 36, 103-148. 

Alexandrou N, Miao Z, Colquhoun M, et al. 1992. Supercritical fluid extraction and cleanup with capillary GC-ion trap mass spectrometry for determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in environemental samples. J Chromatogr Sci 30(9) 335-382. 

Chang RR, Jarman WM, Hennings JA. 1993. Sample cleanup by solid phase extraction for the ultratrace determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in biological samples. Anal Chem 65 (18) 2420-2427. 

ATSDR concludes that the action level of 1 ppb (TEQ) for dioxin and dioxin-like compounds, when coupled to a site-specific context of evaluation for the range > 50 ppt (0.05 ppb) to < 1 ppb TEQs in residential soil, is protective of public health and continues to represent a level at which consideration t health action to interdict exposure, including cleanup, should occur. This conclusion is based on ATSDR s review and evaluation of... 

SET , incineration and plasma arc are very effective at achieving regulatory cleanup standards. However, SET is a nonthermal process, whereas the other processes are thermal. Thermal processes have the potential to produce hazardous by-products such as dioxins. SET does not form dioxins because it is a reduction process. Furthermore, the SET process is a closed system without an exhaust stack. When the SET process is used in soils, residual ammonia remains in the soil. This is typically on the order of 1-3%. Ammonia is a fertilizer which farmers pump (anhydrous) into their fields, so this residue is usually not harmful. 

Samples are transferred to a separatory funnel, surrogates are added, and an immiscible solvent (dichloromethane, hexane, etc.) is added. The liquids are shaken vigorously for a few minutes and then allowed to rest until a separation between the two phases occurs. The solvent is removed and the extraction process is repeated twice more. The extracts are combined, dried over anhydrous sodium sulphate, and processed further (cleanup) as required. Some laboratories have automated this tedious procedure by performing extractions in bottles. In this case, solvent and water are placed in a bottle and rotated (windmill rotators) or shaken (platform shakers) for 1—2 h. The lack of vigorous shaking is replaced by an extended time for extraction. Liquiddiquid extraction is used for all semivolatile analysis (hydrocarbons >C12, PAH, pesticides, PCB, dioxins). By lowering the pH, extraction of phenols (pentachlorophenol) and acidic compounds (2,4-dichlorophenoxyacetic acid—2,4-D) will be enhanced. Increasing the pH will increase extractability of basic (aromatic amines) and neutral compounds (PAH). 

Nam KS, Kapila S, Yanders AF, Puri RK (1990), Chemosphere 20 873-880.. .Supercritical fluid extraction and cleanup procedures for determination of xenobiotics in biological samples" Onuska FI, Terry KA (1989), HRC CC12 357-361.. .Supercritical fluid extraction of 2,3,7,8-tetrachlorodibenzo-p-dioxin from sediment samples"... 

Cleaning the Times Beach site was a massive estimated 200 million effort that included installation of a temporary incinerator to burn the contaminated soil, and the erection of a 15 ft high barrier around the incinerator to protect that area from regular flooding by the Meramec River. Contaminated soils were dug up, burned, and the resulting waste ash was buried on site. Cleanup of the site was completed by the end of 1997 by the US EPA and Syntex Agribusiness, the company that assumed responsibility for the site s cleanup. More than 265 000 tons of dioxin-contaminated soil from the site and 27... 

In some applications, the waste material may directly contain dioxins and furans, or it may contain halogens that could lead to the formation of dioxins and furans. Many of the U.S. Superfund cleanup sites contain soil that has been contaminated with halogenated compounds. One common method to clean the soil is to process it through an incinerator which reduces the contaminants to trace levels (see Chapter 8). 

Flue gas from waste incinerators is composed of NO c, CO, HCl, HF, and SO2 Metals such as Cd, Hg, Zn, and Pb, and organic compounds such as dioxines and furanes are also observed. The flue gas cleanup system downstream a waste incinerator is comparable to that of a power plant. Again, a number of locations of SCR may be distinguished leading to flue gases with different compositions. These are sulfur, alkaline metals, HCl, HF, dioxines and furanes containing gases with no dust, flue gas without sulfur and dust, and clean flue gas. 

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