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Discuss recent research regarding the role of dioxin as a possible causative agent in birth defects, cancer, liver and thymus damage, and immune system suppression in humans.

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Introduction

Discuss recent research regarding the role of dioxin as a possible causative agent in birth defects, cancer, liver and thymus damage, and immune system suppression in humans. The term 'dioxin' is given to a class of approximately 419 chemically related compounds, with 30 of these chemicals having a significant toxicity1 Dioxins are an unwanted by-product of many industrial processes including pesticide manufacturing, pulp and paper bleaching and burning plastics. The most potent and dangerous of these chemicals, 2,3,7,8-tetrachloro-dibenzo-para-dioxin (2,3,7,8-TCDD), is listed as a Class-1 carcinogen, which by definition is a known human carcinogen.2 2,3,7,8-TCDD has been found to be a major unwanted contaminant in the herbicide 'Agent Orange' which was used extensively in the Vietnam War. The effects of this is still being felt worldwide today. Wide ranges of varying effects have been observed with animals exposed to varying levels of dioxins, in particular the dioxin 2,3,7,8-TCDD. There has been extensive on-going research regarding the effects of dioxins on certain animals to ascertain the integral biochemical factors related to dioxins and their potency in the hope that these effects may be maintained and prevented. ...read more.

Middle

This complex of receptor and its conjugate ligand can then be translocated into the cell's nucleus and interact with the DNA within; thus controlling gene activity. The dioxin-specific receptor, which is present in most living organisms, is called the Ah receptor, or aryl hydrocarbon receptor (AhR). Most dioxins and their related compounds bind to this receptor with a high affinity, thus being able to be translocated into the cell's nucleus and bind to the DNA. The AhR receptor's main function is to attach to natural toxicants, attach to the DNA and induce the production of a group of enzymes, which work to catalyse the breakdown of the toxicant, thus rendering it harmless. Once the dioxin-receptor complex has entered the cell's nucleus, it binds to certain elements within the DNA strands called Dioxin Responsive Elements (DRE's), which are also named Xenobiotic Responsive Elements (XRE's).4 The main DRE interaction that occurs is the interaction between the dioxin-receptor complex and a gene CypIA1. CypIA1 is responsible for the synthesis of the cytochromes P450IA1 and P450IA2, groups of enzymes, which are used for the metabolism of the toxicants, and ligands that bind to the AhR. ...read more.

Conclusion

The above results suggest that perhaps the carcinogenicity of dioxins has been overestimated slightly, due to the number of real cases being below the number of expected cases. The results of a long-term study involving people directly affected by the disaster were presented at a symposium, 20 years after the accident, and they concluded that: * Chloracne was positively correlated to 2,3,7,8-TCDD exposure. * Miscarriages, perinatal mortality, and other birth defects rose slightly.7 In research not directly related to humans, rats are a common subject to dioxin research. As mentioned earlier, exposure to dioxins (2,3,7,8-TCDD in particular) can cause adverse effects to a number of organs, most notably the liver and thyroid. This was observed in experiments carried out in rats and mice exposed to 2,3,7,8-TCDD.8 Conclusion There is evidence to suggest that perhaps dioxins are the causative agents for these diseases, however, the results do not conclusively prove that this is the case. However, most of the results so far obtained by laboratory experiments have supported the hypothesis discussed earlier in this paper. The dioxin debate will continue to rage for years, and only through extensive laboratory research can the true measure of what dioxins are capable of be fully realised. ...read more.

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