Chemical Warfare - Organic Pollutants: An Ecotoxicological Perspective - page 14

Chemical warfare agents came to be used on the battlefield during the 1914-1918
war. These included mustard gas (yperite) and lewisite. More toxic compounds, the
organophosphorous nerve gases, were produced later, during the Second World War
(1939-1945), although they were not actually used in combat. Organophosphorous
anticholinesterases were synthesized under the direction of G. Schrader at the I.G.
Farbenindustrie in Germany from the mid-1930s, and some of these, for example,
tetraethylpyrophosphate (TEPP) and parathion, came to be used as insecticides.
Others were taken over by the government for development as potential chemical
warfare agents (Holmstedt 1963; Maynard and Beswick 1992; Marrs, Maynard, and
Sidell 2007).
From 1942-1944 the OP chemical warfare agents tabun (ethyl N,N- dimethyl
phosphoroamido cyanidate) and sarin (isopropyl methylphosphonylfluoridate) were
synthesized on a large scale at a factory at Duhernfurt near Breslau (now Wroclaw,
Poland). In Great Britain, the related compounds dimethyl and diethyl phosphofluo-
ridate and diisopropyl phosphofluoridate (DFP) were synthesized during 1940-1941.
Subsequent to the war, further work was done on the development of chemical
weapons of this type, the United States and Great Britain being active in this field.
Fortunately, there has not yet been any large-scale use of these weapons, although it
is alleged that Saddam Hussein used a nerve gas against Kurdish villagers in Iraq.
By contrast, many organic pesticides have been developed and widely used since
the Second World War. Insecticides, herbicides, rodenticides, fungicides, nematicides,
acaricides, and molluscicides have all been employed in the war against crop pests,
diseases, and weeds, often with considerable success, but not without longer-term
problems. In particular, their regular and intensive use has led to the development
of resistance in target species. Similarly, insecticides have been widely employed
in vector control, for example, the malaria mosquito and tsetse fly, and rodenticides
have been used to control rats and mice, and again there have been problems of resis-
tance. Pesticides of different kinds feature prominently among the organic pollutants
mentioned in the this topic. In the ensuing account, particular attention is given to
the effects of pesticides on populations—both in terms of changes in population
numbers and changes in population genetics (the development of resistance).
The pollutants to be described in this topic are predominantly the products of
human activity, although a few, such as PAHs and methyl mercury, are also naturally
occurring. The harmful effects of these pollutants on individual organisms, on the
numbers and genetic composition of populations, and on the structure and function
of communities and ecosystems represent the basic material of this topic. The main
purpose of this introductory chapter is to put the matter into perspective. The effects
to be described should always be seen against the background of the long and con-
tinuing history of chemical warfare on earth. Following from this, effects on popu-
lations may be caused not only by anthropogenic chemicals but by natural ones as
well. Indeed, some population changes may be the consequence of the simultaneous
action of chemicals originating from both sources; for example, effects of PAHs and
organomercury on populations may be due to chemicals coming from both human
and natural sources at the same time; natural estrogens may enhance the endocrine
disruption caused by artificial estrogens. In the end, it is vital to adopt a holistic
approach when attempting to understand the effects of chemicals in the field.