Groundwater in the Great Lakes Basin

discharged with the wastewater into rivers, streams
or the nearshore environment of lakes. Some can be
broken down by newer technologies (Christen, 2007).
They are present in biosolids that are spread on land.
They sometimes have direct access to groundwater in
situations like abandoned wells that provide direct
access into groundwater for chemicals leaching out of
the manures and biosolids.
The USGS has done extensive surveys of their presence
in surface and groundwater. They have been detected
primarily in surface waters. The most common chemicals
found in surface water have been coprostanol (a
fecal steroid), caffeine, cholesterol, DEET, tri(2-chloroethyl)
phosphate (a fire retardant), 4-nonylphenol
and triclosan (USGS, 2002). Triclosan, an antimicrobial
disinfectant, is used in many consumer products under
a variety of trade names. Concern has been raised that
it may be a threat to human health because of trace
amounts of dioxin it contains as an impurity and
because it can be converted to dioxins when exposed
to sunlight. The most serious concern, however, is its
potential to promote the development of antibioticresistant
bacteria (Glaser, 2004). Antibiotic-resistant
bacteria, including pathogenic ones, are frequently
found downstream of wastewater treatment plants
(Ash, 2004).
Schwab et al. (2005) carried out health risk assessments
for 26 active pharmaceuticals and/or their
metabolites that have been found in U.S. surface and
groundwater. Fourteen different drug classes were
covered. ADIs that took into consideration sensitive
subpopulations were calculated from the toxicological
information available on the active pharmaceutical
ingredients. Predicted no-effect concentrations were
then calculated for drinking water and fish consumption.
No appreciable risk to human health associated
with the trace amounts in water and fish was found for
any of the 26 compounds.
Summary
Table 1 summarizes the MACs and MCLs for the
contaminants discussed above. The health effects
listed are those upon which the MACs and MCLs
were established and/or other effects likely to occur at
concentrations in the range of the MACs and MCLs.
These chemicals have a number of other serious health
effects at higher concentrations.
GREAT LAKES-ST. LAWRENCE RIVER BASIN
HUMAN HEALTH EFFECT STUDIES
A literature search on MEDLINE for groundwater/
ground water limited by the keyword “water pollutants/chemical”
and a separate search limited by the
keyword “adverse effects” and searches for well water
with the same limiters found 11 epidemiological studies
in which all or part of 9 study populations residing in
the Great Lakes-St. Lawrence River basin were exposed
to specific contaminants in groundwater. Of these,
four looked at arsenic, one at atrazine, two at aldicarb
and two at nitrate exposure. One study each looked
at exposure to fungicides/herbicides and manganese.
Seven of the studies were done in Wisconsin. Only one
was done in Canada.
Arsenic
Knobeloch, Zierold and Anderson. (2006) conducted
a survey of residents in 19 rural townships in the
Fox River valley in Wisconsin. Study participants
provided well water samples and completed a questionnaire
regarding their residential history, well water
consumption and family health. The study collected
information from 6,669 residents. The study examined
samples from 2,233 household wells. Well water arsenic
ranged from less than 1.0 to 3,100 µg/L. The median level
was 2.0 µg/L. 11% of the wells had arsenic levels above
20 µg/L; 80% were below the U.S. EPA drinking water
standard of 10 µg/L. In residents over 35 years of age
who had consumed water with elevated arsenic levels
for at least 10 years, there was a significant increase in
a history of skin cancer. For those with arsenic levels
between 1.0 and 9.9 µg/L compared to those less than
1.0 µg/L there was a significant 80% increase in skin
cancer risk. For those with arsenic concentrations
equal to or greater than 10 µg/L compared to those less
than 1.0 µg/L, the risk for skin cancer was 90% higher.
Haupert, Wiersma and Golring. (1996) reported in
a 1992-1993 study that Wisconsin residents with an
estimated intake of arsenic equal to or greater than 50
µg/day were significantly more likely to report a diagnosis
of skin cancer.
Zierold, Knobeloch and Anderson (2004) reported
on the rates of 9 chronic diseases in a survey of 1,185
Wisconsin residents who provided private well water
samples and were part of the larger study population in
the Fox River Valley by Knobeloch et al. (2006). They
had been drinking their well water for at least 20 years.
Respondents whose well water arsenic level was equal
to or greater than 2 µg/L had statistically significant
elevated rates of depression, high blood pressure, circulatory
problems and bypass surgery.
48
Meliker, Wahl, Cameron and Nriagu (2007) studied
residents in southeastern Michigan looking for elevated