Decades ago, agrochemicals were introduced aiming at enhancing crop yields and at
protecting crops from pests. Due to adaptation and resistance developed by pests to
chemicals, every year higher amounts and new chemical compounds are used to protect
crops, causing undesired side effects and raising the costs of food production. Eventually,
new techniques, including genetically modified organisms (GMOs) resistant to pests, could
halt the massive spread of agrochemicals in agriculture fields. Biological chemical-free
agriculture is gaining also more and more support but it is still not able to respond to the
need for producing massive amounts of food. The use of agrochemicals, including pesticides, remains a common practice especially in tropical regions and South countries. Cheap compounds, such as DDT, HCH and lindane, that are environmentally persistent, are today banned from agriculture use in developed countries, but remain popular in developing countries. As a consequence, persistent residues of these chemicals contaminate food and disperse in the environment. Coordinated efforts are needed to increase the production of food but with a view to enhanced food quality and safety as well as to controlling residues of persistent pesticides in the environment.
3. Current trends in the use of agrochemicals
and food safety
Agrochemicals are an obvious part of current agriculture
production systems. Regarding their use, in the present, there
are two opposite trends each one related to a geographic
region. Developed countries, including European Union, USA
and Canada, approved new laws restraining the use of
agrochemicals. This legislation aims at protecting consumers
through a more thorough toxicological testing of compounds
and enforcement of lower concentration limits for the
residues tolerated in food and water (Harris, 2002). For
example, the maximum permitted concentration of pesticides
in drinking water set by the EU is 0.1mg/l (Directive 80/778/
EEC), challenging even the detection limits of current
analytical methods (Barcelo´ and Hennion, 1997).
This move is driven by health concerns of the public and
consumer associations that perceive the presence of pesticide
residues in the environment as detrimental to life quality.
Results of scientific research support this point of view.
Actually, it has been shown that even in low concentrations,
the combined effect of xenobiotic chemicals causes suppression of immune response and hypersensitivity to chemical agents. In many cases, a relationship between organochlorine
residues and breast cancer, and between PCBs and reduced
sperm count and male sterility has been documented (Uri,
1997; Rivas et al., 1997; Sharpe, 1999; EEA, 2005).
Developed countries go, therefore, in the direction of fewer
chemicals and more ‘‘green products’’. Furthermore, new
pesticides are less persistent in the environment (more
environmentally friendly) than classic pesticides. These new
pesticides, however, are more costly when compared with old
chemicals, and generally cannot be afforded by developing
countries.
Developing countries go in a different direction in these
matters. They need to increase the agriculture production and
the use of crop protection chemicals seems a simple way for
obtaining better crop yields. Therefore, either they use
chemicals that are cheap, such as DDT, HCH, BCH, because
either their patents have expired and are easy to synthesize or
they are even offered by developed countries. In this path the
contamination of environment, exposure of the public, and
residues in food are higher. Risks to public health are higher
too.
Countries in the tropical belt and with industrial capability
to produce pesticides, such as India, invest in cheap pesticides
as DDT and HCHs. The sales of these pesticides to Bangladesh,
Philippines and Latin America, are the route for a massive use
of organochlorine compounds in the tropics. However,
compound volatilization causes the spread of residues that
are transported by atmospheric processes to higher latitudes.
Trans-boundary contamination arrives to countries in temperate zones and even to polar regions by this process (Chernyak et al., 1996; Carvalho, 2005).
The ban on the use of these persistent organic pollutants
(POPs), that are bio accumulative and toxic, have been the goal
of an international agreement recently achieved (UNEP, 2005).
However, residues of persistent organic chemicals will remain
in the biosphere still for years to come and, at least some of
them, with toxic activity (Pelley, 2006; Young et al., in press).
Full PDF File: https://www.uni-hohenheim.de/fileadmin/einrichtungen/agnas/Documents/Carvalho__2006.pdf
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