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the theory that the total body load of organochlorines is shed via the breast milk with each
successive pregnancy and lactation. Rahman (2010) found in a study conducted in Egypt
that there was no significant difference between the levels of OCPs and the mother's age,
while there was a significant difference and correlation between the levels of OCPs and the
number of times the mother had breast-fed (primiparous and multiparous).
Although it cannot be clearly explained why no significant correlation was observed
between the levels of OCs in human breast milk and the age or parity, the narrow range of
mothers' age and the low number of samples analyzed in the present study might be the
plausible explanations.
17.7 Trends in Mother's Milk Residues
In general, the levels of organochlorine pesticides in countries where these chemicals have
been banned have dropped well below all current benchmark levels (Solomon and Weiss
2002). The levels of these chemicals in milk of the general population have been decreasing
over time, after the periods of their peak production and use. Relatively higher concentra-
tions of DDTs were detected in mother's milk from Asian developing countries than in
samples from other countries (Sudaryanto et al. 2005; Tanabe and Kunisue 2007).
The more recent surveys of pesticides in human milk have demonstrated that the con-
centrations are lower than those observed in previous surveys. Despite this decrease in
concentrations, more effort is needed to characterize the potential adverse effects of the
low concentrations of chlorinated pesticides found in human milk. Differences in the
accumulation patterns of OCs indicate region-specific usage of chemicals in India. DDT
levels were lower than those in the same locations observed previously, indicating that
the concentration of DDT has been declining in the Indian environment. For example, the
concentration of DDT in human breast milk samples from New Delhi collected in 1989
was 3700 ng/g lipid weight and has declined to 1500 ng/g lipid weight; the DDT levels
in Mumbai have declined from 8000 ng/g lipid weight in 1984 to 450 ng/g lipid weight;
in Kolkata, there was a decline from 4800 ng/g lipid weight in 1984 to 1100 ng/g lipid
weight (Devanathan et al. 2009). Except in Chennai, levels of DDT and HCH were lower
when compared to previous observations, indicating the effects of bans and restrictions
imposed. The general declining trends found in the present study confirm the positive
effects of governmental and voluntary restrictions and prohibitions on the usage of DDT
and other measures taken to minimize the pollution. Comprehensive studies on the OC
contamination in India are therefore necessary to understand the source and evaluation of
possible long-term impacts of OCs (Devanathan et al. 2009).
The present comprehensive study on OCP residues in breast milk showed that DDT was
the most abundant pesticide, followed by HCH and HCB. These concentrations of DDT
and HCH dramatically declined with time compared with data from regional breast milk
surveys in China in the past 20 years (Zhou et al. 2011).
The DDT levels in breast milk indicate a marked decline in DDT human body load in
Hong Kong in the past 30 years, assuming reasonable comparability of assay results in
different previous surveys (Hui et al. 2008). The sum of DDT levels was also slightly lower
than those in more recent breast milk samples (Wong et al. 2002). Both p,p′-DDT and p,p′-
DDE concentrations in breast milk in Hong Kong decreased over time (Hui et al. 2008).
This observation is consistent with a worldwide downward trend in DDT body load (Smith
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