History of POPs Discovery, Use and Ban
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
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
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
- 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
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
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.