Uses and Environmental Pollution of Biocides - Pesticides: Evaluation of Environmental Pollution - page 5

of Clear Lake, Dutch elm disease, are landmarks in that undesirable history, let alone the
little known sad stories of those innumerable victims of pesticide intoxication in develop-
ing countries.
The history of pesticide use dates back many centuries, certainly before 1000 BC, when
it was mentioned by Homer, but the real landmark in terms of modern agriculture is the
spread of the Colorado beetle ( Leptinotarsa decemlineata ) across the United States in the
second half of the nineteenth century. The knowledge and skills for protecting crops
against pests and diseases have greatly improved over the centuries. Since an old era,
people have used pesticides to prevent damage to their crops. The first known pesticide
to be used was sulfur. By the fifteenth century, toxic chemicals such as arsenic, mercury,
and lead were being applied to crops to kill pests. In the seventeenth century, nicotine
sulfate was extracted from tobacco leaves for use as an insecticide. The nineteenth century
saw the introduction of two more natural pesticides, pyrethrum and rotenone. A dramatic
breakthrough in insect pest control was achieved in 1939 with the discovery of the insect-
killing properties of DDT, which led to the development of chlorinated hydrocarbon and
organophosphate pesticides during the Second World War (1940-1945). It quickly became
the most widely used pesticide in the world. However, in the 1960s, it was discovered that
DDT was preventing many fish-eating birds from reproducing, causing birth defects in
animals and humans, which was a huge threat to biodiversity. DDT is now banned in
many countries, but is still used in some developing nations to prevent malaria and other
tropical diseases. Pesticide use has increased 50-fold since 1950, and 2.5 million tons of
industrial pesticides are now used each year. Table 1.1 shows the chronology of pesticide
development in the world.

TABLE 1.1
Chronology of Pesticide Development

Period Example Source Characteristics

1800s-1920s Early organics, nitrophenols,

chlorophenols, creosote,
naphthalene, petroleum oils

Organic chemistry,
by-products of coal gas
production, etc.

Often lacked specificity and
were toxic to user or
nontarget organisms

1945-1955 Chlorinated organics, DDT,

hexachlorocyclohexane
(HCCH), chlorinated
cyclodienes

Organic synthesis Persistent, good selectivity,

good agricultural properties,
good public health
performance, resistance,
harmful ecological effects

1945-1970 Cholinesterase inhibitors,

organophosphorus
compounds, carbamates

Organic synthesis, good use
of structure-activity
relationships

Lower persistence, some user
toxicity, some environmental
problems

1970-1985 Synthetic pyrethroids,

avermectins, juvenile
hormone mimics, biological
pesticides

Refinement of structure
activity relationships, new
target systems

Some lack of selectivity,
resistance, costs, and variable
persistence

1985- Genetically engineered

organisms

Transfer of genes from
biological pesticides to
other organisms and into
beneficial plants and
animals. Genetic alteration
of plants to resist nontarget
effects of pesticides

Possible problems with
mutations and escapes,
disruption of microbiological
ecology, monopoly

Source: From Stephenson, G. A. and Solomon, K. R. 1993. Pesticides and the Environment. Department of Environmental

Biology, University of Guelph, Guelph, ON. www.fao.org/docrep/w2598e/w2598e07.htm .