Question

1. What are sources of Dioxin? 2. Usually we can find Dioxin in what concertation level? 3. List the thermal treatment techniques for Dioxin!! 4. The worst and toxic chemical I the world is called Agun Orang x Vietnam war. 5. Explain what is “DRE"! has been used in

Answer 1

1. Sources of Dioxin:

Dioxins are pollutants that are everywhere in the environment.

Natural sources:

Volcanoes, Forest Fires etc.

Mankind sources:

• Manufacturing of some herbicides and pesticides
• Burning household trash
• Chlorine bleaching of pulp and paper
• Incineration of hospital wastes
• Dismantling and recycling electronic products
• Industrial combustion

2. Dioxin concentration level:

The mean body burden of polychlorodibenzo-para-dioxins (CDD), polychlorodibenzofurans (CDF), and polyclorinated biphenyls(PCB)s is 25.4 pg TEQ_DFP-WHO98/g of lipid. PCBs contribute 5.3 pg TEQ/g of this body burden.

3. Thermal treatment techniques for dioxin:

• Plasma arc pyrolysis
• Rotary kilns
• Supercritical water oxidation
• High-temperature fluid wall destruction (advanced electric reactor)
• Liquid injection
• Fluidized bed/circulating fluidized bed
• Infrared thermal destruction
• Plasma arc pyrolysis
• In situ vitrification

4. Agent Orange

5. DRE:

Dioxin Response Element

Dioxins are typical persistent organic pollutants. Toxic effects are mainly mediated by the activation of the aromatic hydrocarbon receptor (AhR), a basic helix-loop-helix-PAS (bHLH-PAS)-containing transcriptional factor.  In the nucleus, the AhR dimerizes with ARNT (aryl hydrocarbon receptor nuclear translocator). Then, the heterodimer recognizes and binds with high affinity to dioxin responsive elements (DREs) in the promoter regions of target genes. Since DREs are found in the upstream region of most dioxin-inducible genes, the mere presence of a DRE sequence can be used to judge whether a gene is by AhR.

The DRE consensus sequence is 5′-TNGCGTG-3′, where the “N” stands for any one of the four nucleotides . Sequences adjacent to the core consensus DRE are also very important, because a cloned DRE alone does not drive reporter gene expression  

When activated by dioxin, the cytosolic AhR protein complex translocates into the nucleus and dimerizes with the ARNT (Ah receptor nuclear translocator) protein. The heteromeric ligand:AhR/Arnt complex then recognizes and binds to its specific DNA recognition site, the dioxin response element (DRE).