Groundwater in the Great Lakes Basin

50
gastric cancer from 1982-1985 compared with deaths
from other causes. The level of nitrates in the drinking
water of the study participants was determined. Private
water sources were tested. Levels in municipal water
were determined from the historical record. Matched-pair
analysis was conducted using 0.0-0.5, 0.6-2.5, 2.6-5.0, 5.6-
10.0 and >10.0 mg/L nitrate concentrations as the exposure
levels. No association between nitrate in drinking water
and gastric cancer was found at any of these levels. Most
of the exposure levels were below the United States and
Canadian 10 mg/L drinking water standard.
Manganese
Bouchard et al. (2007) studied 24 boys and 22 girls 6-15
years of age. Drinking water for 28 of the children living
in a small Quebec community came from a well with
a mean concentration of 500 µg/L manganese (W1);
drinking water for the remaining 18 children came from
a well with a mean manganese concentration of 160 µg/
L (W2). The children were assessed for hyperactivity,
oppositional behaviour, cognitive problems/inattention
and ADHD using the four subscales of the Revised
Conners’ Rating Scale (RCRS) tool. The RCRS has
separate questionnaires for parents and teachers. The
children who drank from W1 had significantly higher
hair manganese levels than those who drank from W2.
Hair manganese concentration was significantly associated
with oppositional behavior and with hyperactivity
as seen in the classroom, but not observed by parents in
non-school situations. The hypothesis of an association
between manganese exposure and neurobehavioral
effects in children warrants further study.
Summary
This report reviews the epidemiological studies that
have been done on health effects related to chemicals in
groundwater in specific Great Lakes-St. Lawrence River
Basin populations. These studies support an increased
risk of skin cancer and some chronic diseases for Great
Lakes basin residents with exposure to elevated levels of
arsenic in their drinking water. There was also evidence
of a possible effect of exposure to pesticides in well
water on fertility and immune function as well as an
effect of manganese on children’s behaviour. Monitoring
for the presence of chemicals in groundwater has
increased in recent years. Further studies of human
populations exposed to the hazardous chemicals in
groundwater as identified in these studies are needed to
assess and address any health implications.
There are few studies available to review for this report.
They represent only a small portion of the likely individual
exposure to chemicals in groundwater for Great
Lakes basin residents. While public drinking groundwater
supplies are routinely tested for chemical contaminants,
many individuals do not have their wells checked
for chemical contamination. Such testing is more expensive
than more routine testing for microbial contamination.
Detailed monitoring and epidemiologic studies are
needed to determine the full extent of individuals who
have been made sick by chemicals in their well water.
OUTBREAKS AND CASE REPORTS OF ILLNESS
Since 1971 the Centers for Disease Control and
Prevention (CDC), the U.S. EPA and the Council of
State and Territorial Epidemiologists have maintained
a collaborative Waterborne Disease and Outbreak
Surveillance System that tracks outbreaks of waterborne
disease related to drinking water (WBDOs).
The data from this surveillance system is published
in The Mortality and Morbidity Weekly Report (MMWR).
This report focuses primarily on communicable disease
outbreaks including those that are waterborne through
drinking water, but it also gathers information on a
voluntary basis from the states on outbreaks of illness
caused by chemicals in drinking water. As such the
information is not complete, since the outbreak has to
be recognized, reported to state authorities and then
reported to CDC before it is included in the MMWR
record. The MMWR also sometimes publishes reports
of individual cases of illness related to chemical
exposure. Canada Communicable Diseases Report is a similar
publication in Canada but, as its name implies, its
scope is limited to communicable disease.
In 2003-2004 MMWR reported eight outbreaks related
to chemicals in drinking water affecting 27 persons.
Three outbreaks were related to copper in drink mix/
soda machines; three involved contamination of bottled
water by bromate and other disinfection by-products,
cleaning products or gasoline by-products; and two
were related to discharges of sodium hydroxide into
community water supplies. Two were in Minnesota,
one in New York (MMWR, 2006).
In 2001-2002 there were five outbreaks affecting 39
persons. One was related to copper in a church’s well
water in Minnesota; one to copper and other metals
in school well water in Minnesota; one to industrial
copper contamination in river/stream water in Ohio;
one to ethylene glycol contamination of a school’s
well water supply in Florida; and one to ethylbenzene,
toluene and xylene in bottled spring water in Florida.
Reported outbreaks of disease related to contamination
in raw groundwater itself are very few (MMWR, 2004).
Figure 1 shows the record of various kinds of waterborne
outbreaks reported in MMWR since 1971 (MMWR,
2006). Very few of these have related to chemical
contamination, fewer still to groundwater and few
occurred in the Great Lakes Basin. The United States-