It is estimated that there are 37 billion kg of hazardous organopollutants produced annually in the USA alone, of which only 10% are disposed of in a safe manner.  Organopollutants are polluting carbon containing chemicals that are used in industry, technology and in the home.  For example we know about DDT (a pesticide that is now banned worldwide), TNT (an explosive that will be found at any military site, likely also in most war zones) and creosote (shortly to be banned in the UK).  But whilst these are household names, we do not know about the other everyday chemicals that contaminate our environment and endanger every organism within it.  The current regulatory system allows synthetic chemicals to be used unless they are proven beyond doubt to be dangerous.  Therefore until proven harmful, a chemical is deemed safe.
 

This has contributed to a persistent mistreatment of our environment and also has resulted in making many land areas toxic to organisms by the effluent and waste from industrial processes.  The consequences of these chemicals are as yet not fully known, but we are already seeing the effects of one of the most dangerous chemicals that has been in use - DDT (a.k.a. 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane).  Used to kill mosquitoes carrying the malarial virus, it had widespread use until the 70’s and was estimated to have saved 25 million lives (WHO).  However it cannot be metabolised easily, and as a result builds up in the fatty tissues of animals.   Of high toxicity to fish, it is also passed along the food chain up higher trophic levels, and consequently is of risk to humans. 

The picture shows where DDT can damage the body

The risks DDT poses are unpleasant (see picture): cancer-of all kinds, birth deformations, miscarriages, cardiovascular problems, interference with the central nervous system and many more.

All the organopollutants are xenobiotic compounds, meaning that they are artificially produced, and would never be seen naturally in the environment.

The next section is designed to be an overview of the organopollutants, not a comprehensive list by any means!

The major organopollutants are:

PAHs: Polycyclic aromatic hydrocarbons- these are the most common of the organopollutants, being formed from many different sources, such as fossil fuel burning, natural oil deposits, vegetation decomposition, transport, industrial processes.  Major constituents of creosote, they are usually formed from the burning of organic material. They are one of the constituents of tobacco smoke.  Some chemical names you might know: Benzopyrene, anthracene, phenanthrene and naphthalene.  They are all very toxic and persistent, they are carcinogenic and some metabolites can bind to DNA and form mutations, thus making them mutagenic. 

PCBs: Polychlorinated biphenyls – also used in pesticides, they have strong thermal and electrical properties that makes them ideal for use in industrial applications like flame retardants, solvents, and in the textile and printing industries.  Marketed under the names of Aroclor, Declor and more.

Pesticides-(herbicides/insecticides/fungicides)

These include the organochlorines: DDT, aldrin, lindane, PCP, endosulfan, and organophosphates.

• DDT: see above

• Aldrin: a chemical from a family that includes dieldrin and heptachlor, has strong persistence in soil.

• Lindane: (γ-isomer of 1,2,3,4,5,6-hexachlorocylohexane)-whilst its use in now being restricted, it is the foremost pesticide for cocoa plants.  The chocolate you eat could quite likely be contaminated with it.

• PCP: Pentachlorophenol, used in agriculture and as wood preservative amongst other uses, a priority pollutant according to the Environmental Protection Agency (EPA).  Strongly chlorinated.

• Endosulfan: Used extensively around the world as an efficient herbicide, it is still registered for use and is a common contaminant in the environment.

• Organophosphates: generally not as persistent in the environment like organochlorines, they still pose a significant risk.

Crops being sprayed with pesticide in Italy

[F.Y.I.:

Another use of these chemicals was in the manufacture of Agent Orange, the defoliant that was used extensively in the Vietnam War by the American government.  Not only has this caused pollution but it has had horrific repercussions for the people of Vietnam from the toxicity and quantity used.]

Other contributors of organopollution:

Munitions:  Munitions usage and waste is another cause of organopollution.  TNT (trinitrotoluene) world production is estimated at 900,000 kg annually.  It is used in the manufacture of explosives, and so consequently is has widespread use.  Military compounds are generally the worst affected, where there is prevalent pollution of local ground and water.

Bleach Plant Effluents:  From paper bleaching, which requires a chlorine-mediated process.  The effluent contain chlorophenols, already discussed.

Synthetic Dyes: E.g. Azo, Anthraquinone, Triarylmethane.  All used in textile dyeing, paper printing, colour photography and petroleum products, where it is estimated that between 10-15% of the dyes used end up in the effluent, and contaminate the local environment.  Azo is the predominant dye used, it is estimated that it is used in around half of all dyeing processes.  They are recalcitrant in water and hence are recalcitrant when absorbed into the local environment from the factory effluent.  They are also carcinogenic.

But surely there are some processes used that can get rid of some of these?

Of course there are many methods already in practice that attempt to rid the environment, or at least reduce the amount in the environment of these poisonous chemicals, but they are neither cost effective (estimated cost of $1 TRILLION to decontaminate toxic waste sites in USA using traditional methods) nor efficient.  Whilst some of these chemicals can be degraded by microorganism in soil like bacteria, the process is usually slow which results in persistence, and the metabolite products are often as toxic as the primary substance. 

What these organopollutants have in common, apart from being recalcitrant chemicals, is that they have strong similarities to lignin, by being aromatic compounds (containing a benzene ring).  And this is where the rotting fungi step into play.  Being the only microorganisms capable of lignin degradation, they have enormous potential in the degradation of these organopollutants.

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