Threats to Human Health: Use of Chlorine, an Obsolete Treatment Technology - Global Drinking Water Management and Conservation - page 198

findings: they found that showering for 10 min
and bathing for 20 min consistently resulted in at least a twofold increase in median
THM in blood. They also state that

Nuckols et al. con rmed these

It is well established that THM concentrations
in water in residential water heaters are generally much higher than in tap water
from the utility distribution system.

“

” (Nuckols et al. 2005 , p. 869).

9.2.4 Contribution of DBPs to the Estrogenic Effects
in Drinking Water

The potential health risks of endocrine disrupting chemicals (EDCs) have been of
great concern since the mid-1990s (Itoh et al. 2011 ). Many epidemiological studies
have been conducted to assess the relationship between “ adverse reproductive and

developmental outcomes (Itoh et al.

2011 ). Some reviews of these studies (Zavaleta et al. 1999 , IPCS (International
Programme on Chemical Safety) 2000 , Nieuwenhuijsen et al. 2000 and USEPA
2006 ) pointed out that THMs and other chlorinated DBPs can lead to adverse
outcomes, such as spontaneous abortion, stillbirth, low birth weight, neurotoxicity,
and birth defects. Currently, hundreds of compounds have been identi

” and “ exposure to chlorinated drinking water ”

ed as sus-
pected EDCs (Endocrine Disruptor Screening and Testing Advisory Committee
(EDSTAC 1998 ), and

“ most research on EDCs focuses on these individual micro-

pollutants (Itoh et al. 2011 ). Since epidemiological studies have discovered the

relationship between exposure to DBPs formed from NOMs and reproductive and
developmental toxicity, in addition to suspected EDCs, it is important to measure
the effects of chlorinated DBPs in drinking water and of raw water containing both
micro-pollutants and NOMs on reproductive and developmental outcomes (Itoh
et al. 2011 ). Moreover, the Endocrine Disruptor Screening and Testing Advisory
Committee (EDSTAC) ( 1998 ) established by the USEPA also recommended that a
mixture of DBPs be evaluated for their potential to cause endocrine disruption.
Figure 9.1 a illustrates the components of water that induce estrogenic effects and
how they are changed by chlorination (Itoh et al. 2009 ). First, NOMs have a weak
estrogenic effect that increases after chlorination, and then the effect increases
gradually over time, even in the absence of residual chlorine (Itoh et al. 2009 ). The

”

findings from Fig. 9.1 a, b illustrate the components of the estrogenic effect that
comes from NOMs. The estrogenic substances formed after chlorination as part of
the chlorinated DBPs and the change into estro-

genic substances over time, and hence the estrogenic effect increases over time after
chlorination. Itoh et al. ( 2011 ) further suggested that

“ estrogenic effect intermediates ”

to decrease the estrogenic
effects in drinking water, NOMs in addition to suspected EDCs should be removed
before chlorination. Furthermore, it is important to assess the reproductive and
developmental toxicity of mixtures of DBPs that originated from NOMs.

“

”