Geoscience Reference
In-Depth Information
Table 3.1
Results of various correlation studies between nitrate intake and cancer in humans
Induced cancer effect
No effect
Protective
effect
Brain cancer
Barrett et al. (
1998
)
Steindorf et al. (
1994
),
Muelleret al. (
2001
)
Central nervous system
tumors
Barrett et al. (
1998
)
Gastric cancer
Barrett et al. (
1998
),
van Loon et al. (
1998
)
Esophageal cancer
Barrett et al. (
1998
)
Non-Hodgkin's lymphoma
Weisenburger (
1993
),
Ward et al. (
1996
)
Lymphatic cancer
Jensen (
1982
)
Hematopoietic (blood or
bone marrow) cancer
Jensen (
1982
)
Uterine cancer
Jensen (
1982
), Thouez
et al. (
1981
)
Weyer et al.
(
2001
)
Ovarian cancer
Jensen (
1982
), Thouez
et al. (
1981
)
Bladder cancer
Weyer et al. (
2001
)
Ward et al.
(
2003
)
Rectal cancer
Weyer et al.
(
2001
)
phosphoribosyltransferase gene (HPRT) variant frequencies and by endogenous
formation of carcinogenic NOCs from nitrate-derived nitrite (van Maanen et al.
1996
).
NOCs are known carcinogens (Odashima
1980
; Lijinsky and Epstein
1970
;
Magee and Barnes
1967
; Tricker and Preussmann
1991
) and have been found to
induce cancer in a variety of organs in more than 40 animal species, including
higher primates (Bogovski and Bogovski
1981
). However, and despite the fact that
NOCs are produced from nitrate in the human body, only mixed results linking
nitrates and their derivatives to various cancers are reported in ecological studies.
For example, stomach, esophagus, nasopharynx, urinary bladder, and prostate
cancer have been reported to be linked to nitrate intake (e.g., Cantor
1997
; Ei-
cholzer and Gutzwiller
1990
). However, other ecological studies comparing
populations that were exposed to varying nitrate concentrations in drinking water
did not find any correlation to gastric and esophageal cancer rates (Barrett et al.
1998
) but found increased incidence of adult brain and central nervous system
tumors in regions with high nitrate concentrations; this latter effect was not
observed by others (Steindorf et al.
1994
; Mueller et al.
2001
). Table
3.1
sum-
marizes several examples of the mixed results that correlate nitrate intake to
cancer.
