History of POPs Discovery, Use and Ban

• History of POPs awareness
• History of DDT

History of POPs Awareness

The first discoveries

• 1774 - The Swedish apothecary Karl Eilhelm Scheele discovered the element chlorine. Chlorine substituents provide POPs molecules with properties of both persistence and lipophilicity.
• 1825 - Michael Faraday reported to the Royal Society of London the formation of "benzene hexachloride". Unknown to Faraday at the time, this reaction product actually

  (Photograph by UPI/Bettmann, National Geographic, 1945. Text in the picture: D.D.T. Powerful Insecticide Harmless to Humans applied by TODD...)

  consisted of a mixture of various isomers of hexachlorocyclohexane (HCH). In 1943, Van Linden gave the name lindane to the pesticide made with the active isomers of the mixture.
• 1873 - Othmar Zeidler who was working in the laboratory of Adolph von Bayer at the university of Strasbourg synthesised DDT.
• 1929 - PCBs were produced in some commercial mixtures called Aroclor. PCBs were manufactured in United States, Austria, France, Germany, Italy, Spain, United Kingdom, Russian Federation, China, Japan and exported to virtually every country.
• 1933 - Hexachlorobenzene (HCB) is introduced commercially as a fungicide for wheat. It also had industrial uses in organic syntheses as a raw material for synthetic rubber.
• 1939 - Paul Mueller, working for Geigy in Switzerland, discovered the insecticidal properties of DDT, far after the discovery of its synthesis in 1873.
• 1944 - Khanenia and Zhiravlev demonstrated that the chlorination of terpenes found in turpentine led to products with increased toxicity to lice. Some years later the Hercules Powder Company marketed the insecticide under the trade name of toxaphene.
• 1949 - Toxicological effects ultimately linked to TCDD are observed in workers following an industrial accident during the production of an herbicide at a Monsanto plant in Nitro, West Virginia.
• 1957 - Sanderman et al. report the first synthesis of 2,3,7,8-tetrachloro-p-dibenzodioxin (TCDD), and for the first time determined its structure. The preparation of the first chlorinated-p-dibenzodioxin was, however, realised in 1872, by Merts and Weits in Germany.

Rising awareness and beginning of bans

• 1962 - Rachel Carson published Silent Spring.
• 1966 - Soeren Jensen discovered PCBs as environmental contaminants in Baltic fish.
• 1970s - a debate initiated by the Carson's book "Silent Spring" led to the restriction in use and the ban of several pesticides. This after the discovery of their effects on species such as the peregrine falcon and eagles.
• 1970s - The use of hexachlorobenzene as fungicide was banned in the U.S., Canada and some European countries. HCB is still present as an impurity in the pesticides pentachlorophenol, dacthal, atrazine, picloram, pentachloronitrobenzene, chlorthalonil, and lindane. The major global sources HCB contamination are combustion processes and pesticide use.
• 1973 - 13 February, the Council of the OECD decided to restrict the production and use of some chemicals such as polychlorinated biphenyls (PCB).
• 1976 - European Directive 76/769/EEC on the restrictions on the marketing and use of certain dangerous substances and preparations such as PCBs.
  
• 1976 - an industrial accident in Seveso, Italy, resulted in the release of a large quantity of TCDD because of an uncontrolled chemical reaction.
• 1976 - USA banned the manufacturing, processing, distribution and use of PCBs, except in a "totally enclosed manner". Similar action was taken in Japan, Canada and western European countries.
• 1978 - (21 December), European Directive 79/117/EEC prohibiting the placing on the market and use of plant protection products containing certain active substances with the exception of some uses (aldrin, chlordane, dieldrin, DDT, endrin, HCH, heptachlor, hexachlorobenzene).
• 1985 - European Directive 85/467/EEC amending for the sixth time Directive 76/769/EEC. This law prohibited production, marketing and use of PCBs.
• 1986 - Toxaphene is banned in the USA toxaphene was still produced until the 1990s in Nicaragua and West Germany.

More adverse effects in top food chain predators and humans

• 1985 Reproductive impairment in seals is reported in the Baltic Sea. (Bergman and Olsson, 1985), and in Beluga whales in the St. Lawrence seaway, Canada (Beland et al., 1993). Both effects linked to PCBs.
• 1994 Immune system damages (Safe, 1994) and behavioural impairment (De Swart et al., 1994) shown in top predator species as correlated with some POPs.

• 1995 Endocrine disruption in humans and wild life was linked to some POPs. (Harrison et al., 1995).

Beginning of international action to regulate and phase out POPs

• 1995 - An international working group was convened by UNEP Governing Council to develop assessments for 12 POPs. This working group determined that the data were adequate for these 12 POPs to justify the eliminate or reduce emissions and even, in some cases, halt production and use.
• 1997 - IARC (International Agency for Research on Cancer) published the monograph on the evaluations of carcinogenic risks to humans regarding polychlorinated dibenzo-para-dioxins and polychlorinated dibenzofurans.
• 1998 - WHO consultation revisited the TDI (Tolerable Daily Intake) for dioxins and related compounds.
• 1998 - United Nations Economic Commission for Europe (UNECE), consisting of European countries, Russia, Canada and the United States, agreed on a Protocol which bans the production and use of some POPs, and scheduled some other, (DDT, heptachlor, hexachlorobenzene and PCBs for elimination at a later stage.
• 2001 - Signed the Stockholm Convention on UNEP 12 POPs.

History of DDT

DDT seemed at first to be the ideal insecticide: it was not acutely toxic to humans but highly toxic to insects; the fact that it was persistent represented a further advantage. DDT was discovered to be an insecticide in 1939 by Paul Mueller, a chemist working for the Swiss firm Geigy on the development of various chemicals to fight agricultural insects. Mueller was awarded the Nobel Prize for medicine and physiology in 1948 in recognition of many civilian lives DDT saved after the war. Products containing DDT were marketed within Switzerland beginning in 1941.

By the end of World War I, more than five million deaths had been caused by typhus. To avoid a repetition of such disasters during World War II, an incipient epidemic of typhus in Naples, Italy was thwarted by spraying all the civilians and the occupying allied troops with DDT. DDT was also used to combat mosquitoes that carried malaria in various parts of Europe, both during and after the war. (Photograph by UPI/Bettmann, National Geographic, 1945)

Once World War II ended, DDT began to be used not only for public health purposes in hot climates but also extensively in developed countries to control insect pests attacking agricultural crops. Initially it was used on fruit trees and on vegetable crops, and subsequently in the growing of cotton. Eventually some insect populations became resistant to DDT, and its effectiveness decreased. This phenomenon led farmers to apply greater and greater amounts of insecticide, particularly on cotton fields.

Within the scientific community, reservations about DDT as the "perfect insecticide" began to be heard almost as soon as it first went into use. In particular, it was known that DDT in soil persisted for several years and could become magnified in a food chain. The general public became aware of environmental problems associated with DDT upon the publication in 1962 of Rachel Carson's book Silent Spring. In it, she discussed the decline in certain regions of the United States of the America robin, due to its consumption of earthworms that were laden with the DDT used in massive amounts to combat Dutch elm disease. Carson's book stimulated widespread public concern about DDT and other pesticides. Through a series of legal hearings in the United States instigated by lawyers and scientists working with the Environmental Defense Fund, DDT was eventually banned or severely restricted in most states. In 1972, the U.S. Environmental Protection Agency banned all DDT uses except those essential to public health. Similar bans were instituted by Sweden in 1969 and later in most of the developed countries. DDT is still being used in developing countries to control disease, in particular for control of malaria carrying mosquitoes. (Baird, 1998). Unfortunately in some countries the regulatory system does not prevent DDT form being deviated form the public health to the agricultural sector.

Read More About the History of POPs Awareness

Persistent, Bioaccumulative, and Toxic Chemicals I, fate and exposure. R.L. Lipnick, J.L.M. Hermens, K.C. Jones and D.C.G. Muir. American Chemical Society, Washington, DC, 2000.

Persistent Organic Pollutants (POPs): state of the science. K.C. Jones, P. de Voogt. Environmental Pollution 100, 209-221, 1999.

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