HISTORY OF THE DEVELOPMENT OF ORGANOPHOSPHATE POISONS

from
"The Best Control (2nd Edition)"
by Stephen Tvedten

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J. E. DuBois Jr. in The Devil's Chemists noted that the organophosphate pesticide poisons (OPO4) were developed in Hitler's Germany during World War II. These toxic poisons included TEPP (tetraethyl pyrophosphate, developed as a nicotine substitute), followed by Tabun (dimethyl phosphoroamidocyanidate) and Sarin (isopropyl methylphosphono fluoridate) - the chemical "nerve agents" that have been employed as nerve gases in warfare. The developer I. G. Farben, not content with tests on monkeys, confirmed lethality by testing Tabun on prisoners at Aushwitz. Thus, the OPO4 poisons such as chlorpyrifos and Diazinon became direct descendants of these nerve gas agents.

The Leading Edge International Research Journal, No. 104 noted in part: In 1939 the Drug Trust was formed by an alliance of the world's two greatest cartels in world history - the Rockefeller Empire and the German chemical company, I. G. Farbenindustrie (I. G. Farben). Drug profits from that onwards curved upwards into gigantic proportions and by 1948 it became a 10 billion dollar year industry. I. G. Farben's unsavory past is highlighted by the fact that during the Second World War it built and operated a massive chemical plant at Auschwitz using slave labour. Approximately 300,000 concentration-camp workers passed through I. G. Farben's facilities at Auschwitz and at least 25,000 of them were worked to death. Others were brutally killed in I. G. Farben's drug testing programs. Twelve of I. G. Farben's top executives were sentenced to terms of imprisonment for slavery and mistreatment offences at the Nuremberg war crime trials. Hoescht and Bayer, the largest and third largest companies in world pharmaceutical sales respectively, are descended from I. G. Farben. In September 1955, Hoechst appointed Friedrich Jaehne, a convicted war criminal from the Nuremberg trials, as chairman of its supervisory board. Also, a year later, Bayer appointed Fitz ter Meer, another convicted war criminal, as Chairman of its board.

In "Pesticides and Neurological Diseases" it was noted that in 1932, Lange in Berlin synthesized some compounds containing a phosphorus-fluoride bond (esters of monofluorophosphoric acid from silver salts and alkyl halides). During the synthesis of dimethyl- and diethylphosphorofluoridate, Lange and his graduate student, Gerda von Krueger, noted toxic effects of the vapors on themselves, the pertinent observations being included in a published chemical paper. Lange was unable to convince the chemical industry and I. G. Farbenindustrie, in particular, that the alkyl esters synthesized might be useful insecticides. In 1934, Gerhard Schrader was appointed by Otto Bayer to pursue the development of synthetic insecticides for I. G. Farbenindustrie, but it was not until 1936 that Schrader began working on phosphorus and sulfur acid fluorides in search of aphicidal and acaricidal compounds, initially discovering methane sulfonyl fluoride which was used as a fumigant. From 1938 to 1944, Schrader developed a series of fluorine-containing esters including DFP (di-isopropylfluorophosphate) and Sarin (l-methylethyl methylphosphonofluoridate), pyrophosphate esters including TEPP and OMPA (octamethylpyrophosphortetramide) and thio- and thionophosphorus esters including parathion and its oxygen analog paraxon. He was aware of the toxic signs produced by these esters and, while the potency of some of these chemicals prevented their development and use as "insecticides", they were of immediate interest to the German Ministry of Defense which recognized their value as chemical warfare agents. Production of stocks of Tabun and Sarin were carried out in a factory outside of Duhernfurt, near Breslau. Soman (1,2,2-trimethylpropyl methylphosphonofluoridate), another nerve gas was also synthesized at this factory. The pharmacological and toxicological studies of these compounds were carried out in a number of industrial and military laboratories.

British scientists had taken note of the comments of Lange and Krueger concerning the toxicity of acylphosphorofluoridates, and during World War II they were paying particular attention to fluorine-containing compounds. With this lead, it is interesting to note that studies conducted by these two protagonists were almost parallel, DFP and other alkyl phosphorofluoridates being the prime test chemicals. A similar line of investigation was being followed at Edgewood Arsenal in the U. S., again DFP being a compound of choice in such studies. Scientists on both sides of the Atlantic were well aware of the potent, irreversible, anticholinesterase properties of these esters. When the structures and properties of the German nerve gases Tabun and Sarin became known, it was realized that they were more potent than DFP by an order of two of magnitude.

With the cessation of hostilities and the exchange of information in the post-war period, the chemistry of organophosphorus insecticide poisons developed at a rapid rate. The decade from 1950 to 1960 can well be said to have been the era of the organophosphate poisons. Malathion [diethyl(dimethoxyphosphinothioyl) thiobutanedioate] was introduced by the American Cyanamid Company in 1950; this ester contains carboxy ester groups. In 1951, G. Schrader continued developing new insecticide poisons including Systox (demeton or mercaptophos, a mixture of the thiono- and thioloisomers of O,O-diethyl-2-ethylmercaptoethyl phosphorothioate), thereby introducing a new class of insecticide poisons having a thioether group. In 1952, the Perkow reaction was first described in which alpha-halogen carbonyl compounds were reacted with triethyl phosphite, resulting in the synthesis of a number of new dialkylvinyl phosphate esters such as dichlorvos (2,2-dichlorovinyl dimethyl phosphate) and trichlorfon (O,O-dimethyl [2,2,2-trichloro-1-hydroxyethyl] phosphate. The thio- and thionophosphorus esters arising from parathion and containing substituted aryl and heterocyclic groups have also been synthesized. Today, a wide range of organophosphorus esters having a variety of biological properties are available for such equally diversified range of uses as various "registered" poisons, e.g., insecticides, nematocides, acaricides, fungicides, etc.

Taken from the latest version of THE BEST CONTROL by Stephen L. Tvedten


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