PESTICIDES 957
An estimate for 1982 indicated that 113 million hectares
of cropland were treated with 337 million kilograms of
pesticides, with herbicides applied to 59%, insecticides to
18%, and fungicides to 3% of cropland. It was estimated
that 16% of the total area of the United States received
some direct application of pesticide annually (Pimentel
and Levitan, 1986).
Major changes have occurred in the types of pes-
ticides applied in the United States during the last half
of the 20th Century. Available data for the farm use
of major pesticides during the last two decades is pre-
sented in Table 2. The organochlorine insecticides
DDT, BHC, toxaphene, aldrin, dieldrin, endrin, hepta-
chlor, and chlordane dominated the market for about 25
years following their introduction after World War II.
These persistent and broad-spectrum insecticides proved
to be environmentally uncontrollable, and legal restric-
tion of the use of DDT in 1973 was followed by restric-
tions on the use of aldrin and dieldrin in 1974, chlordane
and heptachlor in 1976, and toxaphene in 1983. As a result
the use of these organochlorines, which comprised 46% of
all farm insecticides in 1971, declined to 29% in 1976 and
was nearly phased out by 1984 (Table 2). Similar regula-
tion of use has occurred in Western Europe, USSR, China,
and Japan, although extensive use of these insecticides still
occurs in developing countries of Asia, Africa, and South
America. The organochlorine insecticides were almost
entirely replaced during the last decade with biodegradable
organophosphate insecticides such as parathion, methyl
parathion, diazinon, malathion, and chlorpyrifos; and with
the carbamate insecticides carbaryl, carbofuran, methomyl,
and aldicarb. During the past decade a new group of insec-
ticides, the synthetic pyrethroids permethrin, deltamethrin,cypermethrin, fenvalerate, and flucythrinate have become
used extensively.
The use of herbicides has increased four-fold since 1960 as
the preplanting technology of weed control developed. There
has been a decrease in the use of the chlorinated phenoxyace-
tic acids and chlorinated benzoic acid herbicides. Presently
the market is dominated by the triazines such as atrazine and
cyanazine, the acetamides such as alachlor, the nitroanilines
such as trifluralin and pendimethalin, the carbamate butylate,
and the urea linuron.
There are approximately 600 individual chemical com-
pounds registered as pesticides in the United States includ-
ing 80 fungicides, 200 insecticides and 300 herbicides. These
are available in about 50,000 formulations. On a world basis
more than 900 chemicals are in commercial use as pesticides
and the number of different formulations is estimated to
exceed 100,000 (Melnikov, 1971, Büchel, 1983). However,
as shown in Table 2, about 10 individual pesticides comprise
50% of the total farm use in the United States and the herbi-
cides alachlor and atrazine comprise about 36% of the total
herbicide use.
The chemical properties, biological behavior, and envi-
ronmental fate of this large array of pesticides are exceed-
ingly complex and are beyond the scope of this discussion
(Melnikov, 1971, White-Stevens, 1971, Büchel, 1983). The
role of these chemicals in pest control and crop production
has been studied intensively and their use has become virtu-
ally indispensable to modern agriculture. Nevertheless, for
the majority of the individual pesticides thee is only super-
ficial knowledge of the effects of their long term use on the
quality of the environment (Brown, 1978, McEwen and
Stevenson, 1979).
During the 1980s the introduction of several groups
of pesticides with 10- to 100-fold greater activity thanTABLE 1
Production of synthetic organic pesticides in the United StatesaYearMillions of kilogramsFungicides Herbicides Insecticides Total1962 70 85 216 370
1964 70 118 208 396
1966 76 124 256 455
1968 87 183 265 534
1970 64 184 223 410
1972 65 205 256 526
1974 74 275 295 644
1976 65 298 257 620
1978 67 302 275 644
1980 71 366 230 667
1982 50 285 172 506
1984 56 325 159 540
1986 51 330 155 536
a Data from International Trade Commission.TABLE 2
Estimated farm use of pesticides in the United StatesaPesticideMillions of kilograms1966 1971 1976 1982Alachlor — 6.7 40.2 37.7
Atrazine 10.7 26.1 41.0 34.1
2,4-D 18.2 15.2 17.5 9.5
Trifluralin 2.4 5.2 12.9 15.9
Toxaphene 15.7 16.8 14.0 1.4
DDT 12.3 6.5 — —
Aldrin 7.1 3.6 0.4 —
Carbaryl 5.6 8.1 4.2 —
Carbofuran — 1.3 5.3 3.2
Methyl parathion 3.6 12.5 10.4 4.1
Parathion 3.8 4.3 3.0 —
a Data from USDA Agr. Econ. Repts. 254 (1974), 418 (1979), Council
Environ. Qual. Rept. 15 (1984).C016_004_r03.indd 957C016_004_r03.indd 957 11/18/2005 11:00:06 AM11/18/2005 11:00:06 AM