Environmental Engineering Reference
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more than 20% of the air samples. On the other hand, indoor air concentrations were often
low, but could reach 200-300 ng/m 3 in residences for atrazine and propoxur. Propoxur
levels significantly differed between the air in veterinary places and that in other places, so
did the dieldrin levels between residences and workplaces. There were a greater number of
pesticides on the hands than in air, and the most frequently detected were malathion, lin-
dane, and trifluralin, in more than 60% of the subjects. Maximum levels (up to 1000-3000
ng/hands) were observed either in the general population or in workers, depending on
the pesticides. However, no significant difference was observed between the workers' and
general population's hand-wipe pesticide levels. As expected, gardeners were exposed to
pesticides sprayed in greenhouses. Florists and veterinary workers, whose pesticide expo-
sure had not been described until now, were also indirectly exposed to pesticides used for
former pest control operations. Overall, the general population was exposed to more vari-
ous pesticides and at levels sometimes higher than in occupational places (Bouvier et al.
2006). According to Bouvier et al. (2006), the most frequently found pesticides in residences
were not the same as those in the US studies but the levels were similar.
Tan et al. (2007) measured OCPs and PCBs in house-dust samples collected from 31 homes
across the island-state of Singapore. OCPs such as HCHs, chlordanes, and dichlorodiphe-
nyltrichloroethanes (DDTs) were tested, with a range of <LOD to 240 ng/g dust, <LOD to
110 ng/g dust, and <LOD to 770 ng/g dust, respectively. Of 41 target PCB congeners mea-
sured, 28 were detected, and the median level of PCBs was 5.6 ng/g dust. The prevalence of
these pesticides and industrial chemicals, which have been banned many years ago, sug-
gests limited indoor degradation and ongoing environmental accumulation. Weak nega-
tive correlations between an increased elevation of the residence and the concentration of
DDTs and some low-chlorinated PCB congeners were noted, most likely due to increased
ventilation and distance from ground-based sources at higher floors. The authors con-
cluded that levels detected in several studies conducted in the United States were several
orders of magnitude higher than the concentrations observed in Singapore. Values of daily
human intake of OCPs and PCBs via house dust were low compared with dietary data
from overseas. Ingestion of dust is indeed an exposure pathway for these OCs, but may not
be the predominant one (Tan et al. 2007).
15.3 Pesticide Residues in Human Body
Pesticides entering the human body through various routes are preferentially distrib-
uted among different body fluids and tissues. Such distribution is influenced by many
factors related to the physicochemical and biological characteristics of the pesticides
and the physiological conditions of the exposed individuals. In this respect, we will
present research data on pesticide residues in the human blood, urine, seminal fluid,
and adipose tissues.
15.3.1 Pesticide Residues in Human Blood
Stehr-Green et al. (1988) measured the levels of 11 pesticide residues and metabolites in the
serum samples collected from 85 rural-dwelling white Americans in 1986. This group had
a mean age of 36.9 ± 17.3 years and a male:female ratio of approximately 3:2. The average
number of years spent living in rural areas was 33 ± 16 years, and 75% of the participants
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