Environmental Engineering Reference
In-Depth Information
Table 9.7 Odds Ratios and 95 percent Con
dence Intervals (CI) for risk of cancers of the colon
and rectum according to exposure to water factors, by sex (King et al.
2000
)
Colon cancer
Rectal cancer
Water factor level
Men OR (CI)
Women OR
(CI)
Men OR (CI)
Women OR
(CI)
Chlorinated (year)
0
-
9
1.00
1.00
1.00
1.00
10
19
1.70
(1.07
0.55
(0.32
1.10
(0.69
0.71
(0.40
-
2.68)
0.94)
1.76)
1.27)
-
-
-
-
20
34
1.33
(0.96
0.85
(0.58
0.98
(0.71
0.89
(0.58
-
1.86)
1.24)
1.36)
1.37)
-
-
-
-
>34
1.53
(1.13
-
2.09)
0.74
(0.52
-
1.05)
0.97
(0.72
-
1.32)
1.04
(0.71
-
1.53)
THM > 75
g/L
μ
(year)
0
9
1.00
1.00
1.00
1.00
-
10
-
19
1.12
(0.85
-
1.46)
0.91
(0.66
-
1.25)
0.89
(0.67
-
1.18)
1.00
(0.71
-
1.40)
20
-
34
1.49
(0.99
-
2.26)
0.92
(0.54
-
1.56)
1.08
(0.70
-
1.68)
0.81
(0.44
-
1.47)
>34
2.10
(1.21
1.20
(0.60
0.96
(0.49
0.89
(0.39
3.66)
2.42)
1.89)
2.02)
-
-
-
-
THMs. The odds ratios for bromoform, DBCM, DCBM, and Chloroform were
1.85, 1.78, 1.15, and 1, respectively, indicating that the
rst three THM compounds
lead to an increased risk of rectal cancer. In particular, exposure to bromoform in
drinking water may be associated with the highest risk for rectal cancer.
9.2.2 Effects on Preterm Births and Health Defects
in the Unborn Child
Exposures and risks affect vulnerable populations such as pregnant women and the
unborn child, to which we now turn. In an important study, Lewis et al. (
2007
)
focused on a single water utility during 1999
-
2001. Vital record data were obtained
for a large, racially diverse population residing in 27 Massachusetts communities
that received drinking water from a single public utility. This water system was
monitored weekly for total THMs, and it maintained geographically stable total
THMs levels system-wide during the study period. They employed proportional
hazards regression to examine the effects of trimester-speci
c and shorter-term peak
exposures to total THMs in drinking water late in pregnancy on preterm births in
37,498 singletons. They found that for all women, there was an increase in risk for
delivering a preterm baby when exposed to
60
g/L total THMs during the
≥
μ
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