The Organophosphate Pesticides in Agriculture

Chlorpyrifos Molecule, One of the Organophosphate Pesticides
Chlorpyrifos Molecule, One of the Organophosphate Pesticides

The Organophosphate Pesticides in agriculture compose a large group of plant protection products with – mainly – insecticidal and acaricidal activity.

These include some, whose active substances are among the most toxic have been used in the past and/or used up to date against almost every enemy, as the pests, of cultivated plants.

But sometimes they are also used against the enemy in general: in 1983 during the Iran-Iraq war, the regime of a well-known international criminal, Saddam Hussein – well-protected by some of the superpowers of that time – launched an attack for the first time in history with chemicals – organophosphates by Tabun, against Iran.

And apparently because he was not satisfy with the Tabun organophosphate activity, this bastard repeated himself in 1988 against civilians in Halabjeh, Kurdistan, with organophosphate Sarin this time – and admirable for subhumans results.

The Dirtbags of Organophosphates History

Since we began with references to historical events, let us continue our walk in the history of organophosphates, by giving the baton only to another one historical bastard, the Bayer’s scientist – chemist Dr. Gerhard Schrader.

And if someone wonders why we call bastard the Bayer’s scientist – chemist Dr. Gerhard Schrader, let us explain how must call the the Bayer’s scientist – chemist Dr. Gerhard Schrader, the inventor among others of Tabun or Ethyl dimethylphosphoramidocyanidate, who from 1934 up to fall of Berlin faithfully served the Nazi regime?

How should he be called the almost holy-biographied scientist of Bayer, a company who became IG Farben and which, among other things, produced the other admirable science achievement of the Nazis, ‘Κυκλώνα Β or Zyklon B, before became Bayer again, Dr. Gerhard Schrader?

But that’ll do! We’ve spent enough with the history of organophosphate dirtbags. Let’s go to these organophosphates themselves before the editorial team of ‘Kalliergeia‘ beats a stroke.

Praise for bastards, refuses to sign up.

The Organophosphate Pesticides

The Pharmaceutical Giant Bayer Bought Nazi Concentration Camp Prisoners To Experiment On
The Pharmaceutical Giant Bayer Bought Nazi Concentration Camp Prisoners To Experiment On

What are the Organophosphate Pesticides

The Organophosphate pesticides are organic compounds containing phosphorus. In the narrower (and more precise) sense, organophosphates are defined as those compounds containing at least one C-P bond, while in the broad sense in organophosphates includes all phosphorus-containing organic compounds, even if they do not forming C-P bonds, as for example it happens with the esters.

In the organophosphate compounds, the central phosphorus atom is linked to an oxygen or sulfur atom, two methoxy (-OCH3) or ethoxy (-OCH2CH3) groups, and a further R (-CH3) group linked to the phosphorus via oxygen or sulfur.

The Organophosphate Pesticides

Categories of Organophosphates

The Organophosphate pesticides, other than esters, include amides as well as thiol derivatives of phosphate, phosphonate, thiophosphate and/or triphosphoric acid.

At this point, it is worth mentioning that organophosphates are involved not only in insecticidal preparations but also in other classes of plant protection and pesticide products. These include defoliants, herbicides, insect chemosterilants, and even fungicides.

Chemical Classification

  1. Anhydride of phosphoric acid or esters of pyrophosphoric acid (Ethion or Diethion)
  2. Amides of phosphate or phosphonate acid (Dimethoate, Formothion, Vamidothion, Monocrotophos)
  3. Esters of dithiophosphoric or dithiophosphonic acid (Acephate, Thiometon, Trithion, Phorate, Disulfoton, Malathion, Azinphos Ethyl & Methyl, Phosalone, Phosmet)
  4. Thiol- and thio- compounds of phosphate or phosphonate acid (Demeton-S-Methyl, Malathion, Parathion, Parathion Methyl, Bromophos, Diazinon, Chlorpyrifos & Chlorpyrifos Methyl, Fenthion)
  5. Non sulfur compounds of phosphate or phosphonate acid (Glyphosate, Dichlorvos or DDVP, Trichlorfon, Phosphamidon, Tetrachlorvinphos)

Chemical Structure Classification

  1. Heterocyclic derivatives (Azinphos, Chlorpyrifos, Diazinon, Methidathion)
  2. Phenolic derivatives (Fenitrothion, Fenthion)
  3. Aliphatic derivatives (Demeton-S-Methyl, Dichlorvos or DDVP, Dimethoate, Malathion, Monocrotophos, Phorate, Phosphamidon)

Type of Activity Classification

  1. Systemic Organophosphate pesticides (Acephate, Demeton-S-Methyl, Dimethoate, Disulfoton (by the roots), Fenamiphos, Formothion, Heptenophos, Methamidophos, Monocrotophos, Omethoate, Phorate, Phosphamidon, Terbufos, Thiometon)
  2. Contact Organophosphate pesticides (Chlormephos, Chlorpyrifos, Chorpyrifos-Methyl, Diazinom, Dichlorvos, Ethion, Ethoprop, Fenitrothion, Fenthion, Malathion, Mecarbam, Methidathion, Parathion, Parathionmethyl, Phosalone, Phosmet, Pirimiphos-Methyl, Profenophos, Guinalphos, Triazophos)

The Organophosphate Pesticides

Aliens are Spraying (us) with Organophosphate Pesticides
Aliens are Spraying (us) with Organophosphate Pesticides

Organophosphate Pesticides Mode of Action

Between the nerve cells of both mammals and insects, in the chemical synaptic region, there is a distance. This distance, which is approximately 500 Ångstrom (20 nm) wide and is called synaptic cleft (or synaptic gap), prevents the direct transfer of any nerve stimulus from one presynaptic cell to another postsynaptic.

In order for the transfer, to ‘bridge’ the synaptic cleft and pass the information of the stimulus, the neurotransmitter acetylcholine is mediated. Acetylcholine is released from presynaptic nerve cell terminal vesicles, and when the signal is transfered, then the enzyme  acetylcholinesterase (or cholinesterase) converts acetylcholine into inactive metabolites.

In this way the acetylcholine receptors are released and the synapses are discharged so that they can transfer the next/following signal(s).

The biocidal activity of organophosphates consists of that: inhibiting the fulfillment of biochemical processes due precisely to the enzyme  acetylcholinesterase.

By basically acting as substrates of acetylcholinesterase, they react with it in a manner similar to that of acetylcholine, initially creating a complex with the enzyme. Then they phosphorylate and then – at extremely slow rates, which may last for months – dephosphorylation occurs.

The consequence of this, namely, the binding to the substance of acetylcholinesterase, is the non-completion of the vital process of discharging and transferring the neural signals by the synapses. Acetylcholinesterase accumulates in the areas of neural synapses, the messages transfer ceases, and disrupted nervous system stops working.

As a consequence of this, is the nervous overstimulation and death, which for mammals follow the paralysis of their respiratory system, and the insects are caused by paralysis of their nervous center.

The Organophosphate Pesticides

Organophosphate Pesticides Characteristics

In most cases, the organophosphate pesticides action is obvious either instantaneously – especially when it comes from insecticides – or within a few hours of applying the formulation. The majority of them are not characterized by their selectivity as for the target organisms, but their effects on a broad biocidal spectrum.

Some of them are insecticides that are also capable of attacking mites, and others are nematicides or molluscicides – sometimes both.

Due to the high toxicity they exhibit in warm-blooded organisms, some organophosphates are also used as rodenticides.

The persistence of organophosphate pesticides depends on the specific active substance at a time, and may be from short to a relatively long.

The Organophosphate Pesticides

Farm Labor Spraying Organophosphate Pesticide
Farm Labor Spraying Organophosphate Pesticide

Financial Data Regarding Organophosphate Pesticides

In 2017, the global sales volume of organophosphate formulations touched the $ 7 billion – not at all worthwhile. And of these, over $ 1 billion was related to the United States market and almost 800 million to the European market.

The estimated average scenario for the organophosphate pesticides perspective says that the end of the five-year period 2018-2023 will see the global organophosphate market rise by 5.5%, with the volume approaching only 9.5 billion dollars.

Protagonists in terms of these cute biocides are expected to continue to be Parathion, Malathion, Chorpyrifos, Diazinon, Dimethoate, Glyphosate and Methamidophos.

The Organophosphate Pesticides

Toxicity & Ecotoxicity of Organophosphate Pesticides

A preferential and inexhaustible research and writing field is what concerns the toxicity of the active substances involved in the synthesis of plant protection and pesticide products and formulations.

The same is true of organophosphate pesticides. The impact of their use and misuse, both in living organisms (albeit less) in the environment, is sometimes undeniably large, and the literature on this issue is extremely versatile and extensive.

For all of this, must be sure the always patient reader of ‘Kalliergeia’, that there will be special tributes (again when pigs fly), in the foreseeable future.

What can be said briefly in this article is that besides the harm they can cause to humans and the numerous studies and epidemiological investigations that have been made on this issue, organophosphates have been studied in depth in terms of their ecotoxicological dimension.

Thus, it is known that in vertebrates, their toxic activity is not limited only to the biochemical level, namely the binding of the enzyme acetylcholinesterase and the effects that this event brings, but also to the toxicity of the respective organophosphate on a critical organ of them.

But, as mentioned above, more information on this issue will be coming very soon.

The Organophosphate Pesticides

References

And because we were hitted right between the eyes by all these honorable bastards, the References of another epic dimensional article of ‘Kalliergeia’, with another historical title such as The Organophosphate Pesticides, will be presented by the colossal Fela Anikulapo Kuti with the first part of his International Thief Thief (I.T.T.) historical song.

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Fela Anikulapo Kuti & Afrika 70 - International Thief Thief (I.T.T.), Part 1
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  1. Fest, C., & Schmidt, K. (2012). The Chemistry of Organophosphorus Pesticides. Berlin, Germany: Springer Science & Business Media.
  2. Hayes, P. (2000). Industry and Ideology: I. G. Farben in the Nazi Era. Cambridge, England: Cambridge University Press.
  3. Satoh, T., & Gupta, R. (2011). Anticholinesterase Pesticides: Metabolism, Neurotoxicity, and Epidemiology. John Wiley & Sons, Inc.
  4. Δημόπουλος, Β. (2010). Φυτοπροστατευτικά προϊόντα – Τρόπος Δράσης και Εφαρμογές στην Ελλάδα [Plant Protection Products]. Αθήνα: Εκδόσεις Έμβρυο.
  5. Ζιώγας, Β., & Μαρκόγλου, Α. (2010). Γεωργική Φαρμακολογία [Agricultural Pharmacology]. Αθήνα: Εκδόσεις Έμβρυο.

The Organophosphate Pesticides

One More Idyllic Scene from the Battle Of Rural Life
One More Idyllic Scene from the Battle Of Rural Life

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