Uses and Environmental Pollution of Biocides - Pesticides: Evaluation of Environmental Pollution - page 6

Due to the tough competition and large demand, many farmers resort to the extensive
and irrational use of pesticides to increase yield. A rapid increase in synthetic pesticide
use occurred during the second half of the twentieth century, bringing enormous ben-
efits including improved food security and disease vector control. However, a number of
drawbacks became apparent. Organochlorine pesticides (aldrin, chlordane, DDT, dieldrin,
endrin, heptachlor, mirex, toxaphene, hexachlorobenzene (HCB)) constitute nine of the
twelve chemical substances/groups currently defined under the Stockholm Convention
on POPs. While use of these chemicals had been either banned or restricted in many devel-
oped countries during the 1970s and 1980s, they are still used in developing countries and
continue to linger in the environment because of their chemical stability. A global surveil-
lance of DDT levels in human tissues discovered higher levels in Africa, Asia, and Latin
America than in Europe and the United States (Jaga and Dharmani 2003).
Many environmental contaminants that are produced and released into the environ-
ment at low latitudes tend to accumulate in the polar regions. POPs, for example, are stable,
fat-soluble, carbon-based compounds that volatilize at warm temperatures and are trans-
ported poleward by wind, water, and wildlife. Atmospheric transport is the most rapid
pathway by which POPs, especially volatile or semivolatile compounds, reach the poles.
Once in the polar regions, POPs are deposited on particles or exchanged with water, both
processes that are enhanced by low temperature. Oceanic transport occurs more slowly
but is an equally or more important pathway for compounds such as hexachlorocyclohex-
ane that partition strongly into water (MacDonald et al. 2002). Organochlorine pesticides,
which have been classified by the US Environmental Protection Agency (EPA) as POPs,
have the ability to bioaccumulate and biomagnify and can bioconcentrate (i.e., become
more concentrated) up to 70,000 times their original concentrations. These compounds do
not break down in the environment and are classified as probable or possible carcinogens.
For POPs and other kinds of pesticides, there is a need to monitor levels and trends now
and into the future in order to assess compliance with the regulations or standards within
each country as well as on a regional and global basis and a need for a useful tool for fol-
lowing the impacts on health and environment. In this respect, most developed countries
have a regular and routine monitoring program for such contaminants, covering all envi-
ronmental segments such as air, water, food, soil, and biota (EC 2000, SCOOP, and EC 2001),
but this is not the case for most developed countries specially in the Mediterranean region,
where the lack of analysis facilities and resources is common. In Egypt, for example, less
data exist on POPs in food or environmental samples (e.g., Loutfy et al. 2007, 2008, 2010).
1.2.2 Biocides and Pesticides
Biocidal products are necessary for the control of organisms that are harmful to human or
animal health and that cause damage to natural or manufactured products. According to
the Directive 98/8/EC of the European Parliament and Council of 16 February 1998, biocide
products are defined as active substances and preparations containing one or more active
substances, put in the form in which they are supplied to the user, intended to destroy, ren-
der harmless, prevent the action of, or otherwise exert a controlling effect on any harmful
organism by chemical or biological means. Most biocidal substances are highly reactive. If
they are not used under controlled terms, their use can bring risks to human health and the
environment in a variety of ways due to their intrinsic properties and associated use pat-
terns. Particularly vulnerable groups like children or pregnant women are threatened by
the wide and improper use of hazardous biocides. The Biocidal Products Directive 98/8/
EC classified biocides into 4 main groups and 23 product types (i.e., application categories),