Title
Epidemiologic approaches to assessing human cancer risk from
consuming aquatic food
resources from chemically contaminated water.
Author
Ozonoff D; Longnecker MP
Address
Boston University School of Public Health, MA 02118.
Source
Environ Health Perspect, 1991 Jan, 90:, 141-6
Abstract
Epidemiologic approaches to assessing human cancer risk from
consuming fish from
contaminated waters must confront the problems of long latency
and rarity of the end point
(cancer). The latency problem makes determination of diet history
more difficult, while the
low frequency of cancer as an end point reduces the statistical
power of the study. These
factors are discussed in relation to the study designs most commonly
employed in
epidemiology. It is suggested that the use of biomarkers for
persistent chemicals may be
useful to mitigate the difficulty of determining exposure, while
the use of more prevalent
and timely end points, such as carcinogen-DNA adducts or oncogene
proteins, may make
the latency and rarity problems more tractable.
Title
Arsenic risk assessment [comment] [see comments]
Author
Carlson Lynch H; Beck BD; Boardman PD
Address
ChemRisk Division, McLaren/Hart Environmental Engineering Corporation,
Portland, ME
04102.
Source
Environ Health Perspect, 1994 Apr, 102:4, 354-6
Abstract
We review recent publications by Hopenhayn-Rich et al. and Smith
et al. regarding two
critical issues in arsenic risk assessment: the role of methylation
in the dose-response
relationship and the role of internal cancers. Hopenhayn-Rich
et al. applied simple linear
regression to data from several studies to determine whether
the percentage of inorganic
arsenic in urine increases with increasing dose. Although their
results failed to show a
correlation between percent inorganic arsenic and urinary arsenic
concentration, their
evaluation does not demonstrate the absence of a methylation
threshold because of the
relatively low level of arsenic in urine and the use of grab
samples in evaluating methylating
capacity. Using data from an epidemiological study in Taiwan,
Smith et al. have indicated
that arsenic could be an important risk factor not only for skin
cancer (the basis of the
current EPA cancer slope factor), but also for several internal
cancers including lung, liver,
bladder, and kidney. We note the following deficiencies in the
analysis of Smith et al: 1) the
likely underestimated exposure estimate due to lack of consideration
on nonwater sources of
arsenic and the underestimate of water consumption, 2) lack of
consideration of
detoxification in estimating potential risks from low-level exposures
typical of the U.S.
population, and 3) lack of consideration of key differences,
particularly nutritional
differences, between the Taiwanese and U.S. populations that
could affect potential risks.
Title
An examination of the relationship between fluoridation of water
and cancer mortality in 20
large US cities.
Author
Smith AH
Address
Source
N Z Med J, 1980 Jun, 91:661, 413-6
Abstract
A comparison of mortality of 10 US cities with fluoridated water
supplies compared with
10 non-fluoridated cities has been used as evidence that artificial
fluoridation of drinking
water causes cancer and has been widely publicised in New Zealand.
Several deficiencies
are noted in the analysis used by the investigators in this study
and it is shown that
appropriate analysis of the data from these cities yields additional
evidence for the safety of
fluoridation. This finding agrees with that from previous examinations
of the same data in
spite of the fact that they included an error in the mortality
report from one city.
Title
Risk assessment for carcinogens under California's Proposition
65.
Author
Pease WS; Zeise L; Kelter A
Address
University of California, School of Public Health, Berkeley 94720.
Source
Risk Anal, 1990 Jun, 10:2, 255-71
Abstract
Risk assessments for carcinogens are being developed through
an accelerated process in
California as a part of the state's implementation of Proposition
65, the Safe Drinking Water
and Toxic Enforcement Act. Estimates of carcinogenic potency
made by the California
Department of Health Services (CDHS) are generally similar to
estimates made by the U.S.
Environmental Protection Agency (EPA). The largest differences
are due to EPA's use of
the maximum likelihood estimate instead of CDHS' use of the upper
95% confidence
bounds on potencies derived from human data and to procedures
used to correct for studies
of short duration or with early mortality. Numerical limits derived
from these potency
estimates constitute "no significant risk" levels,
which govern exemption from Proposition
65's discharge prohibition and warning requirements. Under Proposition
65 regulations,
lifetime cancer risks less than 10(-5) are not significant and
cumulative intake is not
considered. Following these regulations, numerical limits for
a number of Proposition 65
carcinogens that are applicable to the control of toxic discharges
are less stringent than limits
under existing federal water pollution control laws. Thus, existing
federal limits will become
the Proposition 65 levels for discharge. Chemicals currently
not covered by federal and state
controls will eventually be subject to discharge limitations
under Proposition 65. "No
significant risk" levels (expressed in terms of daily intake
of carcinogens) also trigger
warning requirements under Proposition 65 that are more extensive
than existing state or
federal requirements. A variety of chemical exposures from multiple
sources are identified
that exceed Proposition 65's "no significant risk"
levels.
Title
Mutagenic activity associated with by-products of drinking water
disinfection by chlorine,
chlorine dioxide, ozone and UV-irradiation.
Author
Zoeteman BC; Hrubec J; de Greef E; Kool HJ
Address
Source
Environ Health Perspect, 1982 Dec, 46:, 197-205
Abstract
A retrospective epidemiological study in The Netherlands showed
a statistical association
between chlorination by-products in drinking water and cancer
of the esophagus and
stomach for males. A pilot-plant study with alternative disinfectants
was carried out with
stored water of the Rivers Rhine and Meuse. It was demonstrated
that the increase of direct
acting mutagens after treatment with chlorine dioxide is similar
to the effect of chlorination.
Ozonation of Rhine water reduced the mutagenic activity for Salmonella
typhimurium TA
98 both with and without metabolic activation. UV alone hardly
affects the mutagenicity of
the stored river water for S. typh. TA 98. In all studies, practically
no mutagenic activity for
S. typh. TA 100 was found. Although remarkable changes in the
concentration of individual
organic compounds are reported, the identity of the mutagens
detected is yet unclear.
Compounds of possible interest due to their removal by ozonation
are
1,3,3-trimethyloxindole, dicyclopentadiene and several alkylquinolines.
Compounds which
might be responsible for the increased mutagenicity after chlorination
are two brominated
acetonitriles and tri(2-chlorethyl) phosphate. Furthermore, the
concentration procedure with
adsorption on XAD resin and the subsequent elution step may have
affected the results. It is
proposed to focus further research more on the less volatile
by-products of disinfection than
on the trihalomethanes.
Title
Drinking water and cancer.
Author
Morris RD
Address
Department of Family and Community Medicine, Medical College
of Wisconsin,
Milwaukee, USA. morris@post.its.mcw.edu
Source
Environ Health Perspect, 1995 Nov, 103 Suppl 8:, 225-31
Abstract
Any and all chemicals generated by human activity can and will
find their way into water
supplies. The types and quantities of carcinogens present in
drinking water at the point of
consumption will differ depending on whether they result from
contamination of the source
water, arise as a consequence of treatment processes, or enter
as the water is conveyed to the
user. Source-water contaminants of concern include arsenic,
asbestos, radon, agricultural
chemicals, and hazardous waste. Of these, the strongest evidence
for a cancer risk involves
arsenic, which is linked to cancers of the liver, lung, bladder,
and kidney. The use of
chlorine for water treatment to reduce the risk of infectious
disease may account for a
substantial portion of the cancer risk associated with drinking
water. The by-products of
chlorination are associated with increased risk of bladder and
rectal cancer, possibly
accounting for 5000 cases of bladder cancer and 8000 cases of
rectal cancer per year in the
United States. Fluoridation of water has received great scrutiny
but appears to pose little or
no cancer risk. Further research is needed to identify and quantify
risks posed by
contaminants from drinking-water distribution pipes, linings,
joints, and fixtures and by
biologically active micropollutants, such as microbial agents.
We need more cost-effective
methods for monitoring drinking-water quality and further research
on interventions to
minimize cancer risks from drinking water.
Title
Dose-response relation between arsenic concentration in well
water and mortality from
cancers and vascular diseases.
Author
Wu MM; Kuo TL; Hwang YH; Chen CJ
Address
Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan,
Republic of China.
Source
Am J Epidemiol, 1989 Dec, 130:6, 1123-32
Abstract
Age-adjusted mortality rates were analyzed to examine the dose-response
relation between
ingested arsenic levels and risk of cancers and vascular diseases
among residents in the
endemic area of blackfoot disease, a unique peripheral vascular
disease associated with
long-term exposure to high-arsenic artesian well water and confined
to the southwestern
coast of Taiwan. The arsenic levels in well water determined
in 1964-1966 were available in
42 villages of the study area, while mortality and population
data during 1973-1986 were
obtained from the local household registration offices and Taiwan
Provincial Department of
Health. Age-adjusted mortality rates from various cancers and
vascular diseases by sex
were calculated using the 1976 world population as the standard
population. A significant
dose-response relation was observed between arsenic levels in
well water and cancers of the
bladder, kidney, skin, and lung in both males and females, and
cancers of the prostate and
liver in males. However, there was no association for cancers
of the nasopharynx,
esophagus, stomach, colon, and uterine cervix, and for leukemia.
Arsenic levels in well
water were also associated with peripheral vascular diseases
and cardiovascular diseases in a
dose-response pattern, but not with cerebrovascular accidents.
The dual effect of arsenic on
carcinogenesis and arteriosclerosis and the interrelation between
these two pathogenic
mechanisms deserve more intensive study.
Title
Pancreatic cancer mortality and total hardness levels in Taiwan's
drinking water.
Author
Yang CY; Chiu HF; Cheng MF; Tsai SS; Hung CF; Tseng YT
Address
School of Public Health, Kaohsiung Medical College, Taiwan, Republic
of China.
chunyuh@cc.kmc.edu.tw
Source
J Toxicol Environ Health, 1999 Mar, 56:5, 361-9
Abstract
The possible association between the risk of pancreatic cancer
mortality and hardness levels
in drinking water from municipal supplies was investigated in
a matched case-control study
in Taiwan. All eligible pancreatic cancer deaths (883 cases)
of Taiwan residents from 1990
through 1994 were compared with deaths from other causes (883
controls), and the
hardness levels of the drinking water used by these residents
were determined. Data on
water hardness throughout Taiwan was collected from Taiwan Water
Supply Corporation
(TWSC). The control group consisted of people who died from other
causes and were pair
matched to the cancer cases by sex, year of birth, and year of
death. The results show that
there is a 39 % excess risk of mortality from pancreatic cancer
in relation to the use of soft
water. Trend analyses showed an increasing odds ratio for pancreatic
cancer with decreasing
levels of hardness in drinking water. This is an important finding
for the Taiwan water
industry and human health.
Title
The relationship between gastric mucosal changes and nitrate
intake via drinking water in a
high-risk population for gastric cancer in Moping county, China.
Author
Xu G; Song P; Reed PI
Address
Department of Nutrition and Food Hygiene, Beijing Medical University,
Peoples Republic
of China.
Source
Eur J Cancer Prev, 1992 Oct, 1:6, 437-43
Abstract
There are conflicting reports on whether nitrate intake is related
to gastric carcinogenesis. In
this laboratory/field study from a high-risk area for gastric
cancer, we analysed 178 samples
of drinking water for nitrate and nitrite, and examined the relationship
between gastric
mucosal lesions (including gastric cancer) and quality of different
types of drinking water
and nitrate intake via water. The results showed that the nitrate
content in the local drinking
water was generally very high, with a mean of 109.6 mg/l (range
4.4-497.2 mg/l). There
were significant differences in the nitrate content in drinking
water from different wells in
qualitatively different types of water. The histological changes
were closely related to the
quality of drinking water and its nitrate content. The results
suggest that nitrate in drinking
water probably plays an important role in gastric carcinogenesis
and that in future
aetiological studies of gastric cancer should include more information
on well depth, the
presence of public or private wells and nitrate content of water.
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