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What are Organochlorines?

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Introduction

What are Organochlorines? The last two decades have witnessed growing scientific concerns and public debate over the potential adverse effects that may result from exposure to a group of chemicals known as organochlorines. Concerns regarding exposure to these chemicals are primarily due to observed effects on wildlife, fish, ecosystems and humans. Organochlorines are toxic substances that contain chemically combined chlorine and carbon. Around 11,000 organochlorines are produced and used commercially in products diverse as pesticides, plastics, solvents and refrigerants. As a result, these compounds are now spread throughout the global environment. The very properties that made organochlorines desirable to the chemical industry have led to widespread environmental problems. These chlorinated hydrocarbons are classified into four main groups based on their chemical structure and the way in which they are produced. Dichloro-diphenylethane derivatives e.g. DDT Hexachloro-cyclohexane derivatives e.g. HCB Cyclodiene derivatives e.g. Dieldrin Mirex and Chlorodecone Each of these organochlorines is a hydrophobic compound. This means that they do not dissolve in water, but will dissolve in some organic solvents, and also have the ability to enter cell membranes. ...read more.

Middle

The harmful nature of organochlorines is due to their persistence, toxicity and their ability to accumulate in living tissues. These properties make organochlorines a very dangerous group of chemicals to which natural systems may be exposed to. Most organochlorines are extremely stable. Their chlorine-carbon bond is generally very strong and resists being broken down by normal biochemical and physical processes. As the majority of organochlorines are foreign to nature, living organisms have not found many methods to detoxify them. As a result, organochlorines remain in the environment for a very long time. Some may take 100 years to fully break down into harmless chlorides, while some may not degrade at all to any significant extent. When organochlorines do break down, they often will produce other organochlorines because their chlorine-carbon bond remains intact as part of another compound. These are often more toxic and far more hazardous than the original substance. An example of this occurring in the environment is trichloroethane found in groundwater degrading to highly toxic vinyl chloride. Most organochlorines dissolve far more readily in fats than they do in water, therefore are inclined to build up in the fatty tissues of living organisms. ...read more.

Conclusion

Ways in which organochlorines are thought to affect organisms are the mimicking of natural hormones, interference with cell function and interference with enzyme activity, all which may lead to hormone imbalances. The toxicity of the individual organochlorine compounds depend not only on the particular chemical concerned, but also on the species, strain, age and condition of the animal involved. The effects of organochlorines on the endocrine, immune and reproductive systems of both animals and humans represent major interference on a large scale. Since both the contaminants and their toxic effects are passed on from one generation to the next, the impact of this interference may increase over the next century, even if the release of these chemicals were stopped immediately. The damage to both the environment and humans can not be attributed to one single compound; rather a whole range of organochlorines may be responsible. Organochlorines are most often released as diverse mixtures including many compounds which can not be identified. If we are to safeguard the health and survival of both humans and animals, action must be taken now to terminate the release of organochlorines and other toxic persistent chemicals into the environment. Otherwise, it may be too late. ...read more.

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