American Journal of Public Health | November 2004, Vol 94, No. 11 1936 | Research and Practice | Peer Reviewed | Zierold et al.
RESEARCH AND PRACTICE
Prevalence of Chronic
Diseases in Adults
| Kristina M. Zierold, PhD, Lynda Knobeloch, PhD,
and Henry Anderson, MD
Inorganic arsenic is naturally oc-
curring in groundwaters through-
out the United States. This study
investigated arsenic exposure and
self-report of 9 chronic diseases.
We received private well-water
samples and questionnaires from
1185 people who reported drink-
ing their water for 20 or more
years. Respondents with arsenic
levels of 2 µg/L or greater were
statistically more likely to report
a history of depression, high blood
pressure, circulatory problems,
and bypass surgery than were re-
spondents with arsenic concentra-
tions less than 2 µg/L. (Am J Pub-
lic Health. 2004;94:1936–1937)
Inorganic arsenic is commonly found in
groundwaters throughout the United States.
In October 2001, the US Environmental
Protection Agency reduced the maximum
contaminant level drinking water standard
for arsenic from 50 µg/L to 10 µg/L. By
2006, all public drinking water supplies in
the United States are required to comply
with the new standard. This new standard is
based on existing epidemiological evidence
documenting the association between ar-
senic exposure and cancers of the lung and
bladder. The health effects associated with
inorganic arsenic exposure are numerous
and include basal cell cancer of the skin; tu-
mors of the bladder, kidney, liver, and
lung1–4; blood vessel damage5; peripheral
vascular and cardiovascular disease4,6–8;
numbness in the hands and feet9,10; and dia-
Many studies have documented associa-
tions between arsenic exposure and chronic
illness; however, most have focused on high
exposures and cancers.2,4,5,13–15Less studied
have been the effects of low-level arsenic
In 1987, a groundwater study conducted
by the Wisconsin Department of Natural
Resources identified arsenic in groundwater
above the maximum contaminant level co-
incident with a bedrock layer at the inter-
face of the St. Peter Sandstone and Sin-
nippee Dolomite. The geologic formation
exists beneath more than 20000 private
water supply wells throughout several Wis-
consin counties. Water samples collected
from 1943 private wells between 1992 and
1993 contained arsenic concentrations that
ranged from less than 2 µg/L to 12000
µg/L. Nearly 20% of the water samples
contained concentrations that exceeded the
new federal drinking water standard of
The principal objective of this research
was to evaluate the prevalence of 9 differ-
ent chronic diseases in adults who drink
water from privately owned wells in the
Between July 2000 and January 2002,
19 townships in the arsenic-contaminated
area sponsored well-water testing programs
to promote arsenic awareness and remedia-
tion options. All township homeowners were
eligible and encouraged to obtain a well-
water sample kit from the local town hall.
A survey, which contained questions about
lifetime residential history, usual drinking
water consumption, use of water-treatment
systems, and family health status, was in-
cluded in the kit. The homeowners’ col-
lected water sample and completed surveys
were returned to the town hall for analysis.
All the surveys were returned before the
homeowners received the results of their
At the completion of the awareness cam-
paign (approximately 1 month after all sam-
ples were returned), homeowners were in-
vited to an informational meeting at the local
town hall. During this meeting, they received
the results of their well-water tests and were
given the opportunity to ask state experts
Data from the surveys were analyzed
with SAS, Version 8.2 (SAS Institute Inc,
Cary, NC). Arsenic water concentrations
were grouped into 3 strata (<2 µg/L,
2–10 µg/L, >10 µg/L). Analysis was lim-
ited to those aged 35 years or older who
reported drinking their well water for 20 or
more years. To evaluate the magnitude of
any association between arsenic water con-
centrations and chronic disease status, mul-
tivariate logistic regression was used to cal-
culate adjusted odds ratios (ORs) and 95%
confidence intervals (CIs).
The mean age of the 1185 respondents
who met our inclusion criteria was 62
years (SD=12 years). The respondents re-
ported drinking their well water for 20 to
83 years (mean=30 years; SD=10 years).
The arsenic water concentrations ranged
from 0 µg/L to 2389 µg/L, with a median
of 2 µg/L. Most (84%) of the water sam-
ples had arsenic concentrations of 10 µg/L
The results of the logistic regression anal-
ysis are shown in Table 1. Individuals with
wells in the mid strata of arsenic concentra-
tions (between 2 µg/L and 10 µg/L) were
significantly more likely to report having
depression than were respondents in the
lowest strata (arsenic concentrations <2
µg/L) (adjusted OR=2.74; 95% CI=1.14,
6.63). Additionally, respondents with well-
water arsenic concentrations greater than
10 µg/L were significantly more likely to
report having had cardiac bypass surgery,
high blood pressure, and circulatory prob-
lems than were respondents whose well
water had arsenic concentrations less than
Our study is consistent with other studies
that have found an association between ar-
senic exposure and cardiac disease,4,6–8,17
but the association between arsenic water
concentration and depression is novel and
November 2004, Vol 94, No. 11 | American Journal of Public Health Zierold et al. | Peer Reviewed | Research and Practice | 1937 Download full-text
RESEARCH AND PRACTICE
TABLE 1—Associations Between Reported Chronic Illness and Arsenic (As) Exposure
2 µg/L≤As≤10 µg/L
Reported Chronic Illness
High blood pressure
Type 2 diabetes mellitus
Note.OR=odds ratio; CI=confidence interval.
aReferent group=As<2 µg/L.
bAdjusted for gender,age,smoking status,and body mass index.
*Significant at P≤.05.
merits further investigation. Only a few
studies have evaluated the effect of arsenic
exposure on brain function.18–20Calderon et
al.18found that arsenic exposure is associ-
ated with lower verbal IQ and poorer long-
term memory in children. The Agency for
Toxic Substances and Disease Registry17has
stated that acute toxic exposures to inor-
ganic arsenic have been shown to lead to
emotional lability and memory loss. A
mechanism of action has not been identi-
fied, but perhaps long-term exposure to ar-
senic may interfere with the neurotransmit-
ters associated with depression. Mechanistic
research into effects on the brain and men-
tal development is needed to understand
the role arsenic may play in the develop-
ment of neurological disease.
Caution in interpretation of our results is
warranted because the health data are self-
reported and not verified by medical record
review. Also, we did not know the arsenic
levels in the homeowner’s drinking water
over the entire period of more than 20 years
or how much arsenic was actually ingested.
We assumed that our arsenic water concen-
tration strata assignment was a reasonable
surrogate for exposure and would have re-
mained constant over the period. The possi-
bility of other co-minerals and metals in the
water samples contributing to health out-
comes was not evaluated.
About the Authors
Kristina M. Zierold is with the Department of Environ-
mental Health Sciences, Arnold School of Public Health,
University of South Carolina, Columbia. Lynda Knobe-
loch and Henry Anderson are with the Wisconsin Divi-
sion of Public Health, Bureau of Environmental Health,
Requests for reprints should be sent to Kristina M.
Zierold, PhD, Department of Environmental Health Sci-
ences, Arnold School of Public Health, 800 Sumter St,
University of South Carolina, Columbia, SC 29208
This brief was accepted November 11, 2003.
K.M. Zierold conducted the analyses and led the writ-
ing of the brief. L. Knobeloch conceived the study and
supervised its implementation. H. Anderson assisted
with the study and the analysis. All authors helped to
conceptualize ideas, interpret findings, and review and
edit drafts of the brief.
Human Participant Protection
No protocol approval was needed for this study.
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