Pesticide Residues in Man - Pesticides: Evaluation of Environmental Pollution - page 513

Pesticide Application Technologies : All users of pesticides are confronted with several
potential hazards. Those who mix, load, apply, and handle pesticides have a risk of expo-
sure. Misapplication, spills, and drift are all major sources of human and environmental
contamination. Because pesticides are likely to be a part of the pest management system
for the foreseeable future, ways to reduce risks in the use of pesticides must be prac-
ticed. Subsequently, marked improvements in the application technologies of pesticides
have been developed. Variable rate applications, prescription rates of crop protection
products, direct injection, closed handling systems, on-board dry and liquid applica-
tion systems, control systems, spot sprayers, shielded sprayers, air assist systems, new
nozzle designs, and tank-rinsing devices are examples of the technological developments
that have affected the pesticide application industry. There has also been a major effort to
reduce the amount of chemicals used. Chemical companies are developing new products
that are effective at very low rates and designed for targeted applications with equipment
that can apply precisely the correct amount when and where it is needed (Wolf 2002).
Organic Food : Chemophobia is the most common reason for the public to choose organic
food on the assumption that such food is free of synthetic pesticides. Organic farms are
distinguished from all other forms of farming by a rejection of soluble minerals as fertil-
izers and synthetic pesticides in favor of natural ones (Trewavas 2004). Subsequently, this
has resulted in increasing demand for organic produce of different varieties of vegetables,
fruits, milk products, and cereals in many parts of the world. While organic food accounts
for 1%-2% of the total food sales worldwide, the organic food market is growing rap-
idly, far ahead of the rest of the food industry, in both developed and developing nations.
World organic food sales jumped from US $23 billion in 2002 (Organic Monitor 2002) to
US $52 billion in 2008 (Datamonitor 2009). The world organic market has been growing by
20% a year since the early 1990s, with future growth estimates ranging from 10% to 50%
annually, depending on the country. It is supposed that organically produced vegetables
and fruits contain less (or nil) pesticide residues as compared with that in conventionally
produced ones. In recent studies, organically farmed cucumber fruits and potato tubers
were found to contain total pesticide residues and heavy metals much lower than those
found in conventionally farmed products (Mansour et al. 2009a,b).
Genetically Modified Crops (e.g., Transgenic Bt Crops) : These are pesticidal substances pro-
duced by plants from the genetic material that has been added to the plants. For example,
the gene for the Bacillus thuringiensis (Bt) pesticidal protein can be isolated and introduced
into the plant's own genetic material. Then the plant, instead of the Bt bacterium, manu-
factures the substance that destroys the pest. So, there will be no need to use chemical
pesticides to combat the pests attacking such genetically modified plants. Since 1996, a
wide range of crop plants have been genetically engineered to contain the δ-endotoxin
gene from Bt. These “Bt crops” are now available commercially in the United States and in
many other countries. Some developing countries, such as Egypt, have been dealing with
this technology since 1990 (Mansour 2009). EPA regulates both the protein and its genetic
material; the plant itself is not regulated. Using this technology, scientists have modified
corn, cotton, and potatoes to produce a pesticidal protein that is toxic when ingested
by specific insect pests. Such GM crops are known as “plant-incorporated protectants
(PIPs).” Since March 1995, EPA has registered 12 PIPs. Also, scientists have applied bio-
technology to produce crops that are resistant to certain herbicides. The most common
herbicide-tolerant crops (HTC or HRC) are those resistant to glyphosate herbicide (e.g.,
cotton, corn, soybean, and canola) (EPA and SEG 2003; EPA 2004). Benefits versus risks of
Bt transgenic plants, however, still face a big debate between the supporters and the chal-
lengers (IUPAC 2004; EPA 2004).