Primary Drinking Water Source and Acute
Gastrointestinal Illness: New Mexico, 2007
Shawna J. Feinman, P. Barry Ryan,
Barbara Toth, Wayne A. Honey & Julia
W. Gargano
Water Quality, Exposure and Health
ISSN 1876-1658
Water Qual Expo Health
DOI 10.1007/s12403-014-0148-0
1 23
Your article is protected by copyright and
all rights are held exclusively by Springer
Science+Business Media Dordrecht 2014
(outside the USA). This e-offprint is for
personal use only and shall not be selfarchived in electronic repositories. If you wish
to self-archive your article, please use the
accepted manuscript version for posting on
your own website. You may further deposit
the accepted manuscript version in any
repository, provided it is only made publicly
available 12 months after official publication
or later and provided acknowledgement is
given to the original source of publication
and a link is inserted to the published article
on Springer's website. The link must be
accompanied by the following text: "The final
publication is available at link.springer.com”.
1 23
Author's personal copy
Water Qual Expo Health
DOI 10.1007/s12403-014-0148-0
ORIGINAL PAPER
Primary Drinking Water Source and Acute Gastrointestinal
Illness: New Mexico, 2007
Shawna J. Feinman · P. Barry Ryan · Barbara Toth ·
Wayne A. Honey · Julia W. Gargano
Received: 3 June 2014 / Revised: 3 October 2014 / Accepted: 6 October 2014
© Springer Science+Business Media Dordrecht (outside the USA) 2014
Abstract The objectives of this study are to characterize
New Mexico residents’ primary drinking water sources, consumption, and filter use by demographic characteristics, and
to compare the 30-day prevalence of self-reported acute gastrointestinal illness (AGI) by water sources. We analyzed data
on 6,600 adults surveyed in the 2007 New Mexico Behavioral Risk Factor Surveillance System. We estimated population frequencies and evaluated associations using chi-square
tests and weighted multivariable logistic regression modeling. Over half (55 %) of individuals used public water as their
primary drinking water source, 18 % used private wells, and
27 % used bottled water. Overall, 43 % of residents said they
filtered their home tap water, which did not differ significantly by source. Compared to public water users, private
well users had key demographic differences, including age,
marital status, race, and education. The overall 30-day prevalence of AGI was 15 %. In models adjusted for demographic
characteristics and health status indicators, individuals using
well water had a non-significantly decreased odds of reporting AGI and seeking medical attention for AGI (odds ratio
(OR) 0.83, 95 % CI 0.65–1.06 and OR 0.85, 95 % CI 0.41–
1.80). This baseline measure suggests private well users are
not uniformly distributed throughout the New Mexico popS. J. Feinman · P. B. Ryan
Rollins School of Public Health, Emory University, Atlanta,
GA, USA
S. J. Feinman · J. W. Gargano (B)
Waterborne Disease Prevention Branch, Centers for Disease
Control and Prevention, 1600 Clifton Rd. NE, MS C-09, Atlanta,
GA 30329, USA
e-mail: igc5@cdc.gov
B. Toth · W. A. Honey
Epidemiology & Response Division, New Mexico
Department of Health, Santa Fe, NM, USA
ulation. This information is useful when planning educational outreach to targeted populations. Our cross-sectional
analyses did not reveal significant associations between primary drinking water source and AGI. Future epidemiologic
studies including children and measuring the duration of
exposure and water quality are needed to fully understand
the health impacts of drinking untreated or undertreated
water.
Keywords Groundwater · Drinking water · Behavioral
surveillance · Acute gastrointestinal illness · Surveys
Introduction
American Housing Surveys from 1997 to 2007 indicate 12.9
million to 15.6 million households used private well water as
their primary source of drinking water (U.S. Census Bureau
2000, 2008). While the Safe Drinking Water Act (SDWA)
empowers the Environmental Protection Agency (EPA) to
regulate public water supplies, private water sources are not
regulated under federal law. Instead, the responsibility to
maintain and periodically test private well water quality falls
upon well owners, who are not legally obligated by any federal regulations to perform such tests. Although no national
data are available, a few studies have indicated that many well
owners do not properly test or maintain their wells (Jones
et al. 2005; Laflamme and Van Derslice 2004). The large
number of individuals affected emphasizes the importance
of understanding health risks associated with drinking from
such sources and providing a more current assessment of the
population at risk.
Groundwater supplies, including those that supply private wells, are susceptible to pathogen contamination. A US
Geological Survey study, which was conducted across the
123
Author's personal copy
S. J. Feinman et al.
US from 1991 to 2004, examined contamination of domestic
well raw source water samples (i.e., sampled from the point
of extraction). The study found that coliform bacteria were
present in 34 % and E. coli were present in 8 % of sampled
wells
(DeSimone 2008). Multiple studies have found viral
(Borchardt et al. 2003, 2012), bacterial (Zimmerman et al.
2001), and other indicators of fecal contamination (Strauss et
al. 2001) in private water sources. Contaminated water supplies can result in illness when individuals ingest pathogens
that might be in the water. Waterborne disease outbreak surveillance conducted in the United States between the years of
1971–2006 indicated that 31 % of drinking water-related outbreaks occurred as a result of using contaminated untreated
groundwater. Among outbreaks involving public water systems, 26 % were due to using untreated or improperly treated
groundwater that was contaminated at the source. Among
outbreaks involving individual water systems (primarily
private wells), the most common deficiency (83 %) was
untreated or improperly treated contaminated groundwater
(Craun et al. 2010).
The millions of U.S. residents who depend on private
wells might periodically or routinely be exposed to waterborne pathogens while assuming their water is safe (Jones
et al. 2005). In addition, certain populations, such as the
elderly and young children, are more susceptible to getting
ill and therefore require special precautions (Committee on
Envrionmental Health and Committee on Infectious Diseases
2009; U.S. Environmental Protection Agency 2003). Promoting private well testing and maintenance is a worthwhile
public health goal, but few studies have published populationbased information on the demographic characteristics of private well users to inform health promotion efforts. Such
information would be especially important in a state such
as New Mexico, where 20 % of the population receives their
water from a private well and the population demographics
are diverse (State of New Mexico 2014; U.S. Census Bureau
2012). This information could be useful in planning for specific public health interventions and increasing awareness of
well maintenance guidelines. The objectives of our analysis
were to characterize New Mexico residents’ primary drinking
water sources by demographic characteristics, and to compare the 30-day prevalence of self-reported acute gastrointestinal illness (AGI) by residents’ primary drinking water
sources.
Methods
We used data from the New Mexico 2007 Behavioral Risk
Factor Surveillance System (BRFSS) survey regarding water
consumption, AGI episodes, health status indicators, and
demographic characteristics. A detailed description of the
123
BRFSS survey design and random sampling procedures is
available elsewhere (Centers For Disease Control and Prevention 2008). All analyses used survey procedures in SAS
version 9.3 (SAS Institute Inc., Cary, NC) to account for
the BRFSS complex survey design. The analyses appropriately weighted survey responses to represent the noninstitutionalized (i.e. not residing in institutional group quarters or facilities such as correctional institutions, juvenile
facilities, skilled nursing facilities, and other long-term
care living arrangements) adult population of New Mexico
(Behavioral Risk Factor Surveillance System 2006).
Respondents were asked whether they had experienced
diarrhea (defined as 3 or more loose stools in a 24-h period)
in the 30 days prior to the interview, and if so, whether they
had sought medical attention; positive responses to these
questions were defined as “AGI” and “AGI requiring medical attention,” respectively. Respondents were asked three
questions about water: (1) their primary source of drinking water (public, private, or commercially produced), (2)
whether they filter their home drinking water in any way,
and (3) how many cups of home tap water they drink per
day, which included water used in making hot beverages or
juice. Demographic characteristics and health status indicators were both analyzed with respect to primary drinking water source and reported AGI. Health indicators were
selected to take into account the overall health of respondents
and to identify any underlying health conditions that might
affect health behaviors. Sample frequencies were tabulated,
and population percentages and 95 % confidence intervals
(CI) were estimated using PROC SURVEYFREQ. Differences in proportions were assessed using the Rao-Scott chisquare test (SAS Institute Inc. 2008).
The association between AGI and primary water source
was investigated using logistic regression models. To address
the complex survey design, logistic regression was carried
out using the SAS procedure SURVEYLOGISTIC. Water
source was retained in all models because this was the
primary exposure of interest. Separate models of demographic and health status indicators associated with AGI were
developed using manual backward selection (P < 0.05 to
remain in the model); the variables selected in these models were combined into one model, and non-significant variables were removed. In addition, confounding was assessed
by evaluating whether each variable changed the odds ratio
for water source by ≥10 % and any demographic characteristic or health status indicator that met these criteria
were added back into the final model. Modeling procedures were repeated for the outcome AGI requiring medical
attention.
Statistical significance was based on a P value of <0.05
or a 95 % confidence interval around an odds ratio that
did not include 1. Cells with a minimum denominator cell
size less than 50 were suppressed. All percentages were
Author's personal copy
Primary Drinking Water Source and AGI
weighted to reflect the New Mexico non-institutionalized
population.
Results
Out of an estimated total population of 1.3 million, a total
of 6,606 non-institutionalized New Mexico adults residing
in private residences with a landline telephone responded to
the survey after being randomly selected for inclusion. The
survey, before applying population weights, captured 2,457
males and 4,149 females aged 18–99 years, with a median
age of 53. All questions used in this analysis had response
rates between 90–100 %. However, only individuals who
provided information regarding their primary drinking water
source were included in this analysis (n = 5,963).
With the exception of sex, and presence of children in
the home, all respondent demographic characteristics tested
were significantly different among primary drinking water
sources (Table 1). Homes with children had a marginally significant lower proportion reliant on private well water than
homes without children (15.8 vs. 19.5 %, P = 0.05). An estimated 40.4 % (95 % CI 38.5–42.2) of all households included
children and 35.4 % (95 % CI 31.1–39.7) of homes relying
on private wells included children (not shown). Income was
also analyzed with primary drinking water sources, though
there was no significant finding.
The 30-day prevalence of AGI was 15.0 % (95 % CI
13.8–16.3) (Table 2). Of the residents with AGI, 11.2 %
sought medical attention for their diarrhea and about half
of those individuals provided a stool sample to their health
care provider (not shown). In bivariate analyses, AGI did
not differ significantly by sex, education, income, or number
of children in household. AGI was significantly associated
with age and marital status. The age groups with the highest
AGI 30-day prevalence were 25–44 and 45–64 years (17.4
and 16.4 %, respectively), and the age group with the lowest
AGI 30-day prevalence was 18–24 years (8.3 %). Respondents who were divorced or separated reported the highest
30-day prevalence of AGI (20.2 %), and respondents who
were never married reported the lowest 30-day prevalence of
AGI (12.2 %). High blood pressure and previously having a
heart attack were not significantly associated with AGI 30day prevalence; having arthritis and being a current smoker
were significantly associated with AGI.
Overall, nearly 43 % of residents filtered their water;
residents who used private sources as their primary water
source were the most likely to filter their tap water (45.9 %)
and residents whose primary water source was from commercial sources were the least likely to filter their tap
water (39.7 %), but these differences were not statistically
significant (not shown). The prevalence of AGI was nonsignificantly lower for people using private well sources
(12.9 %) than for people using public water (15.7 %) or
commercial water (16.3 %) (Table 3). AGI prevalence was
similar among those who did and did not filter their tap
water.
The unadjusted odds ratio of reporting an AGI episode
was 0.80 (95 % CI 0.63–1.02) for those who primarily used
private well water and 1.05 (95 % CI 0.82–1.34) for those
who primarily use commercial water compared to those who
primarily use public water sources (Table 4). In the fully
adjusted model, age, arthritis, and smoking remained significantly associated with AGI. Residents aged 25–44 had a
significantly higher odds of AGI than residents aged 18–24
[OR 2.03 (95 % CI 1.10–3.75)]. Persons with arthritis had
an increased odds of AGI (OR 1.90, 95 % CI 1.55–2.33)
compared to persons without arthritis. Current smokers had
higher odds of AGI than non-smokers (OR 1.61, 95 % CI
1.28–2.03). Adjusting for these variables did not meaningfully alter the magnitude of the association between primary
water sources and AGI.
Water source was not significantly associated with seeking
attention for AGI in unadjusted or adjusted models (Table 5).
In the unadjusted model, the odds ratio for AGI episode was
0.74
(95 % CI 0.36–1.52) for those who primarily used private
well water and 0.84 (95 % CI 0.49–1.44) for those who primarily use commercial water, compared to those who primarily used public water sources. After adjusting for household
income, history of heart attack, arthritis, or hypertension,
and age, the magnitudes of the odds ratios for primary water
source were attenuated and remained non-significant.
Discussion
AGI prevalence did not vary significantly by primary water
supply in this cross-sectional survey, although well-water
users had non-significantly lower odds of AGI than did public water users. To our knowledge, this study is the first
that uses BRFSS data to quantify AGI burden associated
with private well use within a population. Anticipating that
the lack of regulation on private wells would result in low
frequency of water quality monitoring and poor maintenance of wells, we had hypothesized that AGI would be
more common among private well users. This hypothesis
was informed by results of surveys and focus groups exploring well-owners’ management tendencies (Jones et al. 2005;
Laflamme and Van Derslice 2004), as well as studies that
linked AGI outbreaks to contaminated groundwater sources
(Brunkard et al. 2011; Craun et al. 2010; Fong et al. 2007;
Gallay et al. 2006; Kvitsand and Fiksdal 2010; Richards
2005; Said et al. 2003; Schuster et al. 2005), detected
pathogens or indicators of fecal contamination in well water
used for drinking (Borchardt et al. 2003, 2012; Lambertini
123
Author's personal copy
S. J. Feinman et al.
Table 1 Percentage of residents relying on different primary sources of drinking water by demographic characteristics and primary health indicators,
New Mexico, 2007
Variables
Total
P valueb
Public water
Private well water
Commercial water
Na
Na
% (95 % CI)a
Na
% (95 % CI)a
18.1 (16.7–19.4)
1,500
26.7 (25.1–28.4)
–
0.19
% (95 % CI)a
3,321
55.2 (53.4–57.0) 1,142
Male
1,264
56.0 (53.1–58.9)
460
18.8 (16.5–21.1)
Female
2,057
54.4 (52.2–56.7)
682
17.4 (15.7–19.02)
Sex
475
25.2 (22.5–27.9)
1,025
28.2 (26.2–30.2)
Age (in years)
18–24
119
45.5 (37.6–53.3)
37
18.1 (11.4–24.8)
101
36.5 (29.0–44.0)
25–44
842
55.4 (52.3–58.5)
258
14.8 (12.7–16.9)
472
29.7 (26.8–32.6)
45–64
1,362
54.6 (52.2–57.1)
540
20.7 (18.8–22.6)
649
24.7 (22.6–26.8)
998
63.8 (60.9–66.7)
307
19.0 (16.6–21.3)
278
17.2 (14.9–19.6)
1,893
57.1 (55.0–59.2)
712
18.8 (17.3–20.3)
817
24.1 (22.3–26.0)
594
55.5 (51.4–59.6)
179
15.3 (12.6–18.1)
306
29.2 (25.3–33.0)
65+
<0.0001
Marital status
Married/living together
Separated/divorced
Widowed
466
62.0 (57.2–66.8)
123
15.4 (12.3–18.5)
147
22.6 (18.0–27.2)
Never married
362
46.6 (40.8–52.4)
123
18.0 (13.0–23.0)
225
35.5 (29.8–41.1)
<High school diploma
375
52.7 (47.5–58.0)
114
12.7 (9.8–15.6)
264
34.6 (29.6–39.5)
High school diploma/GED
887
52.8 (49.1–56.4)
330
20.0 (17.2–22.9)
403
27.2 (23.8–30.6)
Some college
865
52.4 (48.8–56.1)
301
19.4 (16.2–22.5)
399
28.2 (24.9–31.5)
1,190
60.7 (57.9–63.5)
396
17.3 (15.4–19.3)
433
22.0 (19.5–24.4)
<0.0001
Education
College graduate
<0.0001
Children in household
None
1 or more
2265
54.3 (52.1–56.6)
837
19.5 (17.8–21.3)
963
26.1 (24.0–28.2)
1,056
56.5 (53.4–59.5)
305
15.8 (13.6–18.1)
537
27.7 (24.9–30.4)
0.05
Race/ethnicityc
176
46.6 (39.4–53.7)
83
18.5 (13.5–23.4)
160
35.0 (28.4–41.6)
Hispanic
American Indian or Alaska Native
1,026
54.9 (51.8–58.1)
310
14.2 (12.1–16.3)
572
30.8 (27.9–33.8)
White
2,038
56.6 (54.3–58.9)
728
21.1 (19.1–23.1)
709
22.3 (20.2–24.3)
Yes
1,095
57.3 (54.2–60.4)
373
19.5 (16.8–22.2)
448
23.2 (20.5–25.8)
No
2,220
54.4 (52.2–56.6)
767
17.5 (15.9–19.2)
1,052
28.1 (26.0–30.1)
Yes
202
66.8 (60.3–73.2)
52
15.8 (10.9–20.7)
55
17.4 (12.2–22.5)
No
3,098
54.7 (52.9–56.6) 1,076
18.0 (16.6–19.5)
1,442
27.2 (25.5–29.0)
Yes
1,226
59.3 (56.5–62.1)
397
18.8 (16.4–21.2)
486
21.9 (19.6–24.1)
No
2,091
53.7 (51.4–56.0)
741
17.7 (16.0–19.4)
1,009
28.6 (26.4–30.7)
Yes
645
57.7 (53.6–61.8)
212
16.1 (13.1–19.2)
298
26.2 (22.6–29.9)
No
2,666
54.6 (52.6–56.6)
927
18.5 (17.0–20.1)
1,197
26.8 (25.0–28.7)
<0.0001
High blood pressure
0.02
Heart attack
<0.01
Arthritis
<0.001
Current smoker
0.32
Percentages might not add up to 100 % due to rounding
a N represents the sample frequencies. Row percentages and 95 % confidence intervals (CI) are weighted to account for sampling design and adjust
the sample demographics to the age, gender, and region of residence of the adult population; see text for details
b P value from Rao-Scott chi-square test. Null hypothesis is no association between primary water source and row variable
c Race/ethnicities of Asian or Pacific Islander and Black or African American were removed from the analysis due to small sample size
123
Author's personal copy
Primary Drinking Water Source and AGI
Table 2 30-day prevalence of
acute gastrointestinal illness by
respondent demographic
characterization and primary
health status indicators, New
Mexico, 2007
Variables
Na
% (95 % CI)a
P valueb
Total
993
15.0 (13.8–16.3)
–
Male
367
15.1 (13.1–17.2)
0.91
Female
626
15.0 (13.5–16.4)
Sex
Age (in years)
18–24
26
25–44
279
17.4 (15.0–19.8)
8.3 (4.0–12.7)
45–64
454
16.4 (14.6–18.1)
65+
234
13.1 (11.2–15.1)
Married/living together
542
15.1 (13.6–16.6)
Separated/divorced
231
20.2 (16.8–23.5)
Widowed
106
13.1 (10.1–16.1)
Never married
110
12.2 (8.5–15.9)
<0.001
Marital status
<0.01
Education
<High school diploma
103
12.9 (9.5–16.3)
High school diploma/GED
254
14.2 (11.7–16.8)
Some college
303
17.0 (14.4–19.6)
College graduate
332
15.0 (13.1–16.9)
0
677
15.6 (14.0–17.1)
1 or more
316
14.3 (12.2–16.4)
77
13.9 (10.1–17.7)
Hispanic
304
13.5 (11.5–15.6)
White
591
16.3 (14.6–18.0)
Yes
353
16.7 (14.4–19.1)
No
636
14.4 (12.9–15.8)
Yes
66
19.7 (14.1–25.4)
No
916
14.8 (13.5–16.1)
0.23
Children in household
0.35
Race/ethnicityc
American Indian or Alaska Native
a N represents the sample
frequencies, and percentages
and 95 % confidence intervals
(CI) are weighted to account for
sampling design and adjust the
sample demographics to the age,
gender, and region of residence
of the adult population; see text
for details
b P value from Rao-Scott
chi-square test for differences in
proportion with AGI across
categories
c Race/Ethnicities of Asian or
Pacific Islander and Black or
African American were
removed from the analysis due
to small sample size
0.03
High blood pressure
0.08
Heart attack
0.06
Arthritis
Yes
455
20.9 (18.6–23.3)
No
537
12.8 (11.3–14.3)
<0.0001
Current smoker
Yes
258
20.0 (16.9–23.2)
No
731
13.7 (12.4–15.1)
et al. 2012; Strauss et al. 2001; Zimmerman et al. 2001), and
associated land parcels served by private wells with mapped
cases of parasitic and bacterial gastrointestinal infections
(Uhlmann et al. 2009).
Although we considered primary water source, amount of
water consumed, and water filtration habits, and evaluated
two definitions of AGI, we did not identify any significant
association between water source and AGI. Residents who
habitually drink contaminated water might be less likely to
<0.0001
develop symptoms of illness than visitors who consume the
same water because frequent exposure to pathogens confers some level of immunity or reduced likelihood of symptomatic infections (Blumberg et al. 2011; Frost et al. 1998;
Isaac-Renton et al. 1994; Macler and Merkle 2000; Simmons
et al. 2013). The BRFSS survey did not include short-term
visitors or children (who by definition have had a shorter
duration of exposure to their home water supply), so our
study population might not have included individuals most
123
Author's personal copy
S. J. Feinman et al.
Table 3 30-day prevalence of AGI according to primary drinking water source, filtration, and consumption, New Mexico, 2007
Variables
Total
Residents with AGI
Na
% (95 % CI)a
Na
AGI Prevalence % (95 % CI)a
Public
3,321
55.2 (53.4–57.1)
540
15.7 (14.0–17.4)
Well
1,142
18.1 (16.7–19.4)
176
12.9 (10.6–15.3)
Commercial
1,500
26.7 (25.1–28.4)
246
16.3 (13.4–19.2)
Yes
2,408
42.8 (41.0–44.6)
396
15.6 (13.7–17.5)
No
3,553
57.2 (55.4–59.0)
569
15.4 (13.6–17.2)
0–4 cups/day
2,081
37.2 (35.4–39.0)
362
15.2 (13.3–17.2)
5+ cups/day
3,882
62.9 (61.0–64.6)
600
15.6 (13.9–17.2)
P valueb
Primary water source
0.19
Water filter
0.88
Water consumption
0.78
Filtered by source
Public, filtered
1,401
24.0 (22.5–25.5)
229
15.6 (13.2–18.0)
Public, unfiltered
1,905
31.4 (29.7–33.1)
311
15.8 (13.5–18.2)
8.3 (7.2–9.4)
71
12.7 (9.1–16.2)
Well, filtered
465
Well, unfiltered
670
9.8 (8.7–10.8)
105
13.3 (10.2–16.4)
Commercial, filtered
530
10.5 (9.4–11.7)
93
17.2 (12.7–21.8)
Commercial, unfiltered
952
16.0 (14.6–17.4)
151
16.0 (12.2–19.8)
0.59
Water consumption by source
Public, 0–4 cups
856
15.5 (14.2–16.9)
151
15.5 (12.4–18.6)
Public 5+ cups
2,452
39.9 (38.0–41.5)
387
15.7 (13.7–17.8)
Well, 0–4 cups
278
4.9 (4.1–5.7)
46
13.5 (8.9–18.2)
Well 5+ cups
856
13.1 (11.9–14.3)
130
12.8 (12.0–15.5)
Commercial, 0–4 cups
938
16.8 (15.4–18.2)
163
15.2 (12.6–18.3)
Commercial 5+ cups
545
9.9 (8.6–11.0)
80
18.3 (12.6–24.0)
0.48
Water consumption by filtration
0–4 cups, filtered
747
14.6 (13.3–16.0)
125
15.1 (11.6–18.5)
1,318
22.6 (21.0–24.1)
236
15.4 (12.9–17.9)
5+ cups, filtered
1,653
28.3 (26.6–29.8)
270
15.9 (13.6–18.2)
5+ cups, unfiltered
2,205
34.6 (32.8–36.3)
329
15.4 (13.0–17.9)
0–4 cups, unfiltered
0.98
aN
represents the sample frequencies, and percentages and 95 % confidence intervals (CI) are weighted to account for sampling design and adjust
the sample demographics to the age, gender, and region of residence of the adult population; see text for details
b P value from Rao-Scott chi-square test for differences in proportions with illness across exposure categories
at risk of waterborne illnesses. No information was gathered on duration of residence, so it was not possible to
test whether residents who moved into the area recently
had a higher prevalence of illness than long-term residents.
The age group most likely to report AGI was 25–44 year olds.
This was somewhat surprising in light of research indicating
that the very young and the very old are most susceptible to
AGI (Committee on Envrionmental Health and Committee
on Infectious Diseases 2009; Jones et al. 2007).
Most demographic characteristics investigated differed
significantly by primary drinking water source, indicating
that primary drinking water sources are not uniformly distributed throughout the population. This might be explained
by highly variable population density between different areas
123
of the state (i.e. those who dwell in the city are demographically different from those who reside in rural areas), and typically areas of greater population density use public water,
while areas less densely populated use private well sources.
The analysis of income indicated that income was not significantly related to AGI or source of drinking water. Demographic information should be considered when developing
and distributing educational materials for well owners. For
example, the survey found that 40 % of well-water users (not
shown) either had only a high school diploma/GED or less
than high school diploma, 69 % were between the ages of
25–64, and 65 % had no children living in the household.
Therefore, educational materials should aim to reduce technical wording and highlight potential health risks for all ages,
Author's personal copy
Primary Drinking Water Source and AGI
Table 4 Unadjusted and
adjusted odds of reporting AGI
by primary drinking water
source, demographic
characteristics, and health status
indicators, New Mexico, 2007
Variables
Unadjusted n = 5,937
Adjusted n = 5,906
OR
OR
95 % CI
95 % CI
Primary water source
Public
1.00
1.00
Well
0.80
0.63
1.02
0.83
0.65
1.06
Commercial
1.05
0.82
1.34
1.11
0.86
1.42
Age (years)
18–24
1.00
25–44
2.03
1.10
3.75
45–64
1.62
0.89
2.95
65+
1.16
0.62
2.16
1.55
2.33
1.28
2.03
Arthritis
No
1.00
Yes
1.90
Current smoker
Table 5 Unadjusted and
adjusted model odds of seeking
medical attention for AGI by
primary drinking water source,
demographic characteristics,
and health status indicators,
New Mexico, 2007
No
1.00
Yes
1.61
Variables
Unadjusted n = 5,937
Adjusted n = 5,307
OR
OR
95 % CI
95 % CI
Primary water source
Public
1.00
Well
0.74
0.36
1.52
0.85
1.00
0.41
1.80
Commercial
0.84
0.49
1.44
0.97
0.54
1.74
Less than $20,000
0.99
0.41
2.38
$20,000–$35,000
0.41
0.16
1.03
$35,000–$50,000
1.00
$50,000–$75,000
0.63
0.23
1.77
$75,000 or more
0.22
0.08
0.62
1.49
6.32
3.27
12.31
0.70
3.16
15.28
Household income
Heart attack
No
1.00
Yes
3.07
Arthritis
No
1.00
Yes
6.34
Hypertension
No
1.00
Yes
1.49
Age (years)
18–24
1.00
25–44
3.01
0.59
45–64
1.32
0.26
6.57
65+
0.91
0.17
4.98
123
Author's personal copy
S. J. Feinman et al.
not just the very young or elderly. On the other hand, 35 % of
households on private well water did have children living in
the household. The American Academy of Pediatrics warns
that children on private water sources, especially those that
are not properly maintained or monitored, have an increased
risk of developing AGI symptoms, and are more vulnerable than adults to some water contaminants (Committee on
Envrionmental Health and Committee on Infectious Diseases
2009). Households with children and on private water sources
might need additional, targeted educational information. In
addition, discovering that some health indicators differ by
primary water source does not necessarily suggest that the
water source is responsible for the measured health problems. Rather, these findings might highlight the health and
demographic differences between city and rural dwellers.
Water filtration devices might provide a false sense of
security in terms of the microbiological safety of water. In this
survey, water filtration devices had no significant association
with AGI prevalence. The survey prompted respondents to
recall any filter type, including pitcher-type filters that likely
impact taste and odor but not microbiological quality of the
water and reverse osmosis systems that would be expected to
remove many microbial contaminants. While it is not clear
which residents were drinking water that was effectively filtering out pathogens, it is important to note that nearly half
of respondents reported using some sort of filter at home for
their home tap water. This presents another opportunity for
consumer education, as many consumers might not be aware
of the limitations of their home filtration systems.
The 30-day prevalence of AGI in this study, 15 % (95 %
CL = 13.8–16.3), was high compared to that found in other
population surveys in North America. A similar survey conducted in British Columbia, Canada found a 30-day AGI incidence of 10 % (Jones et al. 2007). A report of the Foodborne
Diseases Active Surveillance Network (FoodNet) described
a 7.7 % average monthly prevalence of diarrhea from 1996
to 2003 among FoodNet states (Jones et al. 2006). To further explore this varied prevalence of diarrhea we conducted
an additional regression analysis with the outcome restricted
to cases who sought medical attention for their illness, and
results with respect to water source were similar.
In our multivariable models, multiple health status indicators were included in order to adjust for the confounding effects of individuals’ overall health on the association
between water source and AGI. These analyses revealed the
incidental finding that both arthritis and smoking were significantly associated with reporting AGI and seeking medical
attention, which might be the result of certain drugs prescribed for arthritis (Bhatt et al. 2008), differences in hand
hygiene behavior, or the result of the stomach pH being more
favorable for bacteria in smokers (Bagaitkar et al. 2008).
The BRFSS survey was not created for the purpose of
investigating the association between household primary
123
drinking water source and reported AGI; therefore, the questions were not designed to be analyzed in this context. The
survey elicited data on primary source of drinking water,
which is likely a subset of all the water people consume. For
example, a person might use a public water supply at home,
drink commercially bottled water at work, and visit people or
businesses that use private well sources. In this instance, multiple exposure sources could complicate the ability to accurately determine associated risks. In addition, we did not have
information on the source waters (i.e., groundwater or surface water) or treatments used (e.g., filtration, disinfection)
by public water systems serving the respondents, and analyzing all public water systems as one category might have
masked meaningful heterogeneity in water supplies. Most
of New Mexico’s public water systems obtain water from
groundwater sources (United States Environmental Protection Agency 2013). Although the BRFSS expanded to include
cell phones in later years, the 2007 survey only included
households with landlines, which excluded 17.2 % of the
New Mexico population and might have resulted in sampling
bias if this population differed significantly and in some consistent or systematic fashion from households with landlines.
For example, the age of the population captured may have
been skewed because recent trends indicate younger individuals are less likely to have household telephone lines (Blumberg et al. 2011). The self-reported exposure and outcome
data could result in differential or non-differential misclassification, which could either increase or decrease the likelihood of finding an association between water source and
AGI. In addition, the 2007 NM BRFSS did not gather any
data that might have helped to identify or rule out possible
foodborne, zoonotic, person-to-person, or recreational waterassociated transmission of AGI. We are not aware of any data
that compares groundwater quality in New Mexico to that in
other states, and results of similar studies in other geographic
locations might identify associations that this study did not.
Finally, cross-sectional surveys, such as the BRFSS survey,
cannot be used to establish causation of illnesses by chronic
exposures, such as primary home drinking water source,
because the temporal relationship between exposure and outcome cannot be established from a one-time survey of the
population (Gordis 2009). The BRFSS is a population-based
survey producing results representative of the New Mexico
adult population. Therefore, the study results should be considered representative of the non-institutionalized adult population of New Mexico and cannot be generalized to other
areas of the United States. However, these results suggest
that similar data collection and analyses in other states may
be important to the evaluation of the relationship between
prevalence of self-reported AGI and use of unregulated private wells as a primary source of drinking water.
While this analysis neither supports nor refutes the
hypothesis that 30-day prevalence of AGI might be associ-
Author's personal copy
Primary Drinking Water Source and AGI
ated with primary drinking water source in New Mexico, the
results do provide valuable information regarding susceptible
persons and water filtration habits within a population. This
information might serve as a baseline measure and to direct
educational efforts to selected vulnerable populations. Future
epidemiologic studies that include children and measure the
duration of exposure and water quality are needed to understand the health impacts of drinking untreated or undertreated
water.
Acknowledgments The authors would like to thank Dr. Gordana
Derado for methodological input and constructive comments on an
earlier draft of the manuscript. The authors would also like to thank
Sarah Collier and Heidi Krapfl for constructive comments on manuscript drafts. This publication was supported in part by Cooperative
Agreements (CA) 5U38EH000949 and 5U38EH00097 from the Centers for Disease Control and Prevention (CDC); the New Mexico BRFSS
“Drinking Water Module” was supported by CA 1U38EH000183 from
CDC. Its contents are solely the responsibility of the authors and do
not necessarily represent the official views of the CDC. The manuscript
does not contain clinical studies or patient data.
References
Bagaitkar J, Demuth DR, Scott DA (2008) Tobacco use increases
susceptibility to bacterial infection. Tob Induc Dis. doi:10.1186/
1617-9625-4-12
Behavioral Risk Factor Surveillance System (2006) Behavioral Risk
Factor Surveillance System Operational and User’s Guide Version
3.0. ftp://ftp.cdc.gov/pub/data/brfss/userguide.pdf. Accessed 01
Oct 2014
Bhatt DL, Scheiman J, Abraham NS, Antman EM, Chan FKL,
Furberg CD, Johnson DA, Mahaffey KW, Quigley EM (2008)
ACCF/ACG/AHA 2008 Expert consensus document on reducing
the gastrointestinal risks of antiplatelet therapy and NSAID use: a
report of the american college of cardiology foundation task force
on clinical expert consensus documents. J Am Heart Assoc. doi:10.
1161/CIRCULATIONAHA.108.191087
Blumberg SJ, Luke JV, Ganesh N, Davern ME, Boudreaux MH, Soderberg K (2011) Wireless substitution: state-level estimates from the
National Health Interview Survey, January 2007–June 2010. Natl
Health Stat Rep 39:1–26 28
Borchardt MA, Bertz PD, Spencer SK, Battigelli DA (2003) Incidence
of enteric viruses in groundwater from household wells in Wisconsin. Appl Environ Microbiol 69:1172–1180. doi:10.1128/AEM.
69.2.1172
Borchardt MA, Spencer SK, Kieke BA Jr, Lambertini E, Loge FJ (2012)
Viruses in nondisinfected drinking water from municipal wells
and community incidence of acute gastrointestinal illness. Environ
Health Perspect 120:1272–1279. doi:10.1289/ehp.1104499
Brunkard JM, Ailes E, Roberts VA, Hill V, Hilborn ED, Craun GF,
Rajasingham A, Kahler A, Garrison L, Hicks L, Carpenter J, Wade
TJ, Beach MJ, Yoder J (2011) Surveillance for waterborne disease
outbreaks associated with drinking water—United States, 2007–
2008. MMWR Surveill Summ 60(12):38–68
Centers For Disease Control and Prevention (2008) About the BRFSS.
http://www.cdc.gov/brfss/about.htm. Accessed 30 Dec 2012
Committee on Envrionmental Health and Committee on Infectious Diseases (2009) Drinking water from private wells and risks to children. Pediatrics 123:1599–1605. doi:10.1542/peds.2009-0751
Craun GF, Brunkard JM, Yoder JS, Roberts VA, Carpenter J, Wade T,
Calderon RL, Roberts JM, Beach MJ, Roy SL (2010) Causes of
outbreaks associated with drinking water in the United States from
1971 to 2006. Clin Microbiol Rev 23:507–528. doi:10.1128/CMR.
00077-09
DeSimone LA (2008) Quality of water from domestic wells in principal aquifers of the United States, 1991–2004: Overview of major
findings. U.S. Geol. Survey Sci Investigations http://pubs.usgs.
gov/circ/circ1332/includes/circ1332.pdf. Accessed 01 Oct 2014
Fong TT, Mansfield LS, Wilson DL, Schwab DJ, Molloy SL, Rose
JB (2007) Massive microbiological groundwater contamination
associated with a waterborne outbreak in lake Erie, South Bass
Island. Ohio Environ Health Perspect 115:856–864. doi:10.1289/
ehp.9430
Frost FJ, Calderon RL, Muller TB, Curry M, Rodman JS, Moss DM, De
La Cruz AA (1998) A two-year follow-up survey of antibody to
cr yptosporidium in Jackson County, Oregon following an outbreak of waterborne disease. Epidemiol Infect 121:213–217
Gallay A, De Valk H, Cournot M, Ladeul B, Hemery C, Castor C, Bon
F, Mègraud F, Le Cann P, Desenclos JC (2006) A large multipathogen waterborne community outbreak linked to faecal contamination of a groundwater system, France, 2000. Clin Microbiol
Infect 12(6):561–570. doi:10.1111/j.1469-0691.2006.01441.x
Gordis L (2009) Epidemiology. Saunders, Philadelphia
Isaac-Renton JL, Lewis LF, Ong CS, Nulsen MF (1994) A second community outbreak of waterborne giardiasis in Canada and serological investigation of patients. Trans R Soc Trop Med Hyg
88(4):395–399
Jones AQ, Dewey CE, Doré K, Majowicz SE, McEwan SA, WaltnerToews D, Henson SJ, Mathews E (2005) Public perception of
drinking water from private water supplies: focus group analyses.
BMC public health 5:129–141. doi:10.1186/1471-2458-5-129
Jones AQ, Majowicz SE, Edge VL, Thomas MK, MacDougall L, Fyfe
M, Atashband S, Kovacs SJ (2007) Drinking water consumption
patterns in British Columbia: an investigation of associations with
demographic factors and acute gastrointestinal illness. Sci Total
Environ 388:54–65. doi:10.1016/j.scitotenv.2007.08.028
Jones TF, McMillian MB, Scallan E, Frenzen PD, Cronquist AB,
Thomas S, Angulo FJ (2006) A population-based estimate of the
substantial burden of diarrhoeal disease in the United States; FoodNet, 1996–2003. Epidemiol Infect 135:293–301
Kvitsand HML, Fiksdal L (2010) Waterborne disease in Norway:
emphasizing outbreaks in groundwater systems. Water Sci Technol
61:563–571. doi:10.2166/wst.2010.863
Laflamme DM, Van Derslice JA (2004) Using the Behavioral Risk Factor Surveillance System (BRFSS) for exposure tracking: experiences from Washington state. Environ Health Perspect 112:1428–
1433
Lambertini E, Borchardt MA, Kieke BA Jr, Spencer SK, Loge FJ
(2012) Risk of viral acute gastrointestinal illness from nondisinfected drinking water distribution systems. Environ Sci Technol
46(17):9299–9307. doi:10.1021/es3015925
Macler BA, Merkle JC (2000) Current knowledge on groundwater
microbial pathogens and their control. Hydrogeol J 8:29–40
Richards A (2005) The Walkerton health study. Can Nurse 101(5):16–
21
Said B, Wright F, Nichols GL, Reacher M, Rutter M (2003) Outbreaks of
infectious disease associated with private drinking water supplies
in England and Wales 1970–2000. Epidemiol Infect 130(3):469–
479
SAS Institute Inc. (2008) SAS/STAT ® 9.2 User’s Guide. In SAS Institute Inc., Cary
Schuster CJ, Ellis AG, Robertson WJ, Charron DF, Aramini JJ, Marshall BJ, Medeiros DT (2005) Infectious disease outbreaks related
to drinking water in Canada, 1974–2001. Can J Public Health
96(4):254–258
123
Author's personal copy
S. J. Feinman et al.
Simmons K, Gambhir M, Leon J, Lopman B (2013) Duration of immunity to norovirus gastroenteritis. Gastroenteritis Emerg Infect Dis
19(8):1260–1267. doi:10.3201/eid1908.130472
State of New Mexico (2014) NM EPHT environmental exposure:
drinking water quality. https://nmtracking.org/environ_exposure/
water-qual/. Accessed 24 Feb 2014
Strauss B, King W, Ley A, Hoey JR (2001) A prospective study of
rural drinking water quality and acute gastrointestinal illness. BMC
Public Health 1:8
U.S. Census Bureau (2000) American Housing Survey for the United
States: 1997. http://www.census.gov/prod/99pubs/h150-97.pdf.
Accessed 4 Mar 2014
U.S. Census Bureau (2008) American Housing Survey for the
United States: 2007. http://www.census.gov/housing/ahs/files/
ahs07/h150-07.pdf. Accessed 4 Mar 2014
U.S. Census Bureau (2012) New Mexico. http://quickfacts.census.gov/
qfd/states/35000.html. Accessed 21 Sept 2012
U.S. Environmental Protection Agency (2003) Water on tap: what
you need to know. http://water.epa.gov/drink/guide/upload/book_
waterontap_full.pdf. Accessed 4 Mar 2014
123
Uhlmann S, Galanis E, Takaro T, Mak S, Gustafson L, Embree G,
Bellack N, Corbett K, Isaac-Renton J (2009) Where’s the pump?
Associating sporadic enteric disease with drinking water using
a geographic information system, in British Columbia, Canada,
1996–2005. J Water Health 7(4):692–698. doi:10.2166/wh.2009.
108
United States Environmental Protection Agency (2013) Safe drinking water information system. http://www.epa.gov/enviro/facts/
sdwis/search.html. Accessed 4 Mar 2014
Zimmerman TM, Zimmerman ML, Lindsey BD (2001) Relation between selected well-construction characteristics and
occurrence of bacteria in private household-supply wells,
south-central and southeastern Pennsylvania. U.S. Geol Survey http://www.wilkes.edu/include/WaterResearch/PDFs/3676/
Bacteria%20Well%20Water.pdf. Accessed 4 Mar 2014