Environmental Engineering Reference
In-Depth Information
11.1 History of Pesticide
Synthetic pesticides were first introduced in the twentieth century. Organochlorine
pesticides (OCPs), organophosphate pesticides (OPPs), carbamates (CMs), and
pyrethroids have been used to control insects around the world since the 1940s.
Dichlorodiphenyltrichloroethane (DDT), the first OCP, was developed in 1939 by Paul
Muller and was used to control malaria during World War II. The development of DDT
prompted the search for other OCPs such as hexachlorocyclohexane (HCH), chlordane,
and aldrin. At that time, these became the most widely used pesticides for agricultural
and public health purposes due to their broad spectrum, high persistence, and low cost
(Perry et al. 1998). OCPs were heavily used worldwide from 1940 to 1970. Starting in the
1950s, there were increasing reports of the adverse health effects due to OCPs, including
effects on the reproductive system of nontarget organisms. The chemical properties of
OCPs (hydrophobic, lipophilic, and low biodegradation potential) help facilitate the bio-
accumulation in organisms, which can lead to adverse health effects. Accordingly, OCPs
were banned in many countries including the United States, Japan, and Sweden since the
1970s (Keithmaleesatti et al. 2009).
OPPs were discovered and synthesized by German scientists in the 1930s. Parathion was
one of the earliest OP insecticides used. OP compounds were used as warfare agents by
Nazi Germany in World War II. After World War II, many OPPs, such as malathion, were
produced and used on a worldwide scale. Today, more than 100 OPPs are used in countries
such as Thailand, Vietnam, and India for public health purposes (Raghavendra et al. 2010)
and to protect crops (Gupta 2006).
CMs, derivatives of carbamic acid, are most commonly used for gardening and agricul-
ture. The first successful CM produced was carbaryl, which was developed in the 1950s.
The mode of action of CMs and OPPs is similar; however, CM is lower in toxicity than
OPPs (Gupta 2006).
The last group of pesticides, the pyrethroids, is currently the most widely used group of
pesticides. Pyrethroids are synthetic chemicals, which were developed to enhance the insecti-
cidal properties of natural pyrethrins. The active component of natural pyrethrin is extracted
from the East African chrysanthemum flower, which was long known to have insecticidal
properties. Natural pyrethrin products pose far less risks to mammals than OPPs and CM
insecticides but have no residual or long-term control qualities as they are rapidly degraded
by sunlight. However, they are extremely toxic to insects and fish. Examples of common pyre-
throids include permethrin, cypermethrin, deltamethrin, allethrin, and fenvalerate. Synthetic
pyrethroids are classified into two types: type I and type II. Type I pyrethroid is a non-α-
cyanopyrethroid including natural pyrethrins, allethrin, tetramethrin, permethrin, kade-
thrin, etc. Type II pyrethroid is α-cyanopyrethroid including cypermethrin, deltamethrin,
and fenvalerate (Perry et al. 1998). Modes of Action of pesticides are summarized in Table 11.1 .
11.1.1  Pesticide Exposure in the Aquatic Invertebrate Food Web
Pesticide exposure can occur directly or indirectly. Direct exposure is the deliberate applica-
tion of pesticides to control weeds and pests or the vectors of disease-causing organisms.
Indirect exposure is the result of pesticide runoff from riparian land or spray-drift deposi-
tion. Some banned pesticides, such as DDT and its derivatives, persist in the sediment where
aquatic invertebrates at the base of the food web feed. The food web is a network of consumer-
resource interactions among a group of organisms, populations, or aggregate trophic units
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