Pesticide Residues in Man - Pesticides: Evaluation of Environmental Pollution - page 470

Approximately 85%-90% of the applied agricultural pesticides never reach the target organ-
isms, but disperse through the air, soil, and water (Moses et al. 1993). Persistent pesticides
can remain for decades; the half-life of toxaphene in soil, for example, is up to 29 years (PAN
1993). Pesticides that are not bound in soils or taken up into plants and animals can run
off into rivers and lakes and move into the aquatic food chain, inducing severe damage to
aquatic life. Such environmental mobility can cause contamination of several environmen-
tal compartments. Pesticides, thereby, augment other sources of environmental pollution,
which include manufacturing processes such as the pulp and paper industry, textile and
leather dying, and thermal processes in the metallurgical, cement, motor vehicle, and steel
industries (Barakat 2003).
Organochlorine pesticides (OCPs) are a class of chemicals that came into widespread
use in the late 1940s. Despite being banned in industrialized countries since the 1970s,
or subjected to restrictions in use in many others, they persist to this day in the environ-
ment. Distribution and accumulation of these chemicals in different environmental com-
ponents had been long recognized. Mansour (2004) reviewed this issue in detail, focusing
on the situation in Egypt and in Africa (Mansour 2008). In the same issue, Gupta (2004) has
published an extensive report on the status in India. From these reports, it can clearly be
deduced that the OCP residues are present in all environmental components, however, in
varying concentration levels, according to the lipophilic character of the analyzed sample.
15.2.1 Principal Sources of Pesticide Residues in Man
The main source of nonoccupational exposure to pesticides is through the diet. With the
exception of occupational exposure to pesticides, most exposure to these chemicals occurs
via dietary intake (DeVoto et al. 1998), especially food of animal origin, but also through
water, ambient and indoor air, dust, and soil (Dua et al. 2001; Manirakiza et al. 2002). In
a nonoccupational pesticide exposure study (NOPES) carried out by US EPA, it was con-
cluded that for 14 of the 25 pesticides tested, food appears to be the major contributor to
total exposure, whereas air appears to be the dominant one for six of the other eleven
compounds (EPA 1990). Food contamination by pesticides originates from normal use of
agricultural pesticides before and/or after crop harvesting, misuse of these chemicals, and
unintended environmental contamination (Eilrich 1991). OCPs are lipophilic compounds
that accumulate and even biomagnify their concentration along the food chain, especially
in fatty foods (Manirakiza et al. 2002). However, pesticide residues in food reported from
most surveys are sufficiently below MRLs for the respective compounds. But much of the
concern over residue levels is whether the current levels are safe rather than whether they
are under the legal tolerance level (Gots 1992).
Some published reports (DeVoto et al. 1998; Hanaoka et al. 2002; Manirakiza et al. 2002)
suggest that the serum levels of organochlorines (OCs) are related to the consumption
of various foods. Thus, biological monitoring of the exposure can be carried out by the
determination of intact compounds or their metabolites in the blood, serum, plasma, and
urine. Such biological materials can be conveniently obtained for the study of body burden
following chronic exposure to pesticides (Waliszewski et al. 1999a).
15.2.2 Outdoor Pesticide Contamination
A great number of pesticide compounds have been found to contaminate water resources,
ambient air, fog, rain, and soils, in numerous studies (Glotfelty et al. 1987; Coupe et al. 2000;
Sanusi et al. 2000). Professional uses of pesticides include crop, greenhouse, cattle, and pet