Water & Health Newsletter
March 1, 1995
And Public Health
by Kathleen Blair, MS
Research on Chlorine and Cryptosporidium
Congress = New Approaches
Future of Water
And Public Health
Kathleen Blair, MS
Epidemiologist, City of Milwaukee Health Department
In the spring of 1993, the largest documented waterborne disease outbreak
in U.S. history occurred in Milwaukee, Wisconsin. Cryptosporidium was
identified as the cause, and more than 400,000 residents were infected
with the parasite. Cost estimates of the outbreak exceeded $54 million
and will probably go higher.
Cryptosporidium was first identified in humans in 1976, and for most of
the following decade it was seen almost exclusively among AIDS patients.
The species responsible for most infections in both domestic and wild
animals and humans is Cryptosporidium parvum Isolates from animals are
able to cause illness in humans and vice versa. Like many other waterborne
pathogens, Cryptosporidium completes its life cycle in the gastrointestinal
(GI) tract. The cycle begins with ingestion of the oocyst, which breaks
open and releases sporozoites. The sporozoites invade and feed off the
epithelial cells of the GI tract. The most common clinical characteristic
of the resulting infection in both healthy and immunocompromised individuals
is watery diarrhea. In immunocompetent persons, the illness is self-limited.
In immunocompromised persons, however, infection can be unrelenting and
fatal. Over 100 persons in the Milwaukee area with compromised immune
systems are believed to have died prematurely after being infected with
Milwaukee has always prided itself in the quality of its water. But on
the morning of Monday, April 5, 1993, the Milwaukee Health Department
became aware of widespread gastrointestinal illness in the community through
phone calls from citizens and the media. There was increased absenteeism
from schools and businesses, and groceries and pharmacies reported depletion
of anti-diarrheal medications.
Due to the widespread distribution of illness, water became an early suspect.
Milwaukee receives its water supply from Lake Michigan and is served by
two water treatment plants, located in the north and south sides of the
city. Telephone logs from the Water Department indicated widespread consumer
complaints from the area served by the south treatment plant, and increased
turbidity readings at the plant in recent weeks. Increases in plant effluent
turbidity can indicate microbial contamination and have been associated
with other documented waterborne disease outbreaks. (All applicable water
quality standards were met by the city's treatment plants throughout the
By Wednesday, April 7, Cryptosporidium had been isolated in eight stool
specimens, enough evidence for Mayor John 0. Norquist to issue a boil-water
advisory to all 880,000 customers served by the Milwaukee Water Works.
The next day the south water treatment plant was shut down. The boil advisory
was effective in stemming the outbreak. After a week (the average incubation
period for Cryptosporidium), the incidence of illness dropped precipitously
as indicated by active disease surveillance among nursing home residents
and the daily review of hospital emergency room logs and stool specimen
data from clinical laboratories.
Within two weeks, a team of water industry professionals had completed
an engineering review of both water treatment plants, focusing on modifications
to improve plant performance, and cleaning and disinfection procedures
to safely bring the south treatment plant back into operation.
Since chlorine in concentrations practical for drinking water treatment
is ineffective in eradicating Cryptosporidium optimizing the filtration
process becomes critical. Both treatment plants have installed continuous
on-line turbidimeters and particle counters to monitor the effluent of
each of the 40 filter beds. In addition, monitoring occurs on raw water
and in the clearwell. The new equipment enables staff to receive significantly
more information with which to rapidly respond to changing lake conditions
and monitor finished water quality.
The Milwaukee Health Department has opened a new "Crypto Lab," and regular
testing for Cryptosporidium and Giardia is done on raw, backwash and finished
water. These tests will provide valuable information over the long term
about the presence of this organism in our environment and are used in
conjunction with particle and turbidity readings to monitor plant efficiency.
Regular testing for Cryptosporidium will not prevent contaminated water
from reaching the consumer. Even in the best of situations the sampled
water has long been in the distribution system by the time testing is
completed. Milwaukee has placed its emphasis on using particle and turbidity
readings, thereby reducing the number of Cryptosporidium-sized particles
that pass through the plant. These monitoring tools are a true reflection
of current water quality and allow immediate plant operation decisions
to be made before water moves into the distribution system. Should turbidity
or particle counts rise, there are written protocols for assembling a
team of Water and Public Health officials at the plant to provide guidance
Milwaukee discovered that passive, laboratory-based surveillance for Cryptosporidium
was inadequate for detecting the outbreak. Few people sought medical care
for their illness, and those who did were not tested for Cryptosporidium.
Since the outbreak, the city has put in place alternative surveillance
systems that are more sensitive in detecting diarrheal disease in the
community. Pharmacies now report over-the-counter anti-diarrheal sales,
and diarrheal disease among nursing home residents is routinely monitored.
Many of the clinical laboratories in Milwaukee report weekly the number
of stool specimens submitted for Cryptosporidium testing and report any
positives. One hospital has tested every stool specimen received in the
facility for Cryptosporidium as part of a yearlong surveillance project.
Two studies are under way to elucidate the possible sources of Cryptosporidium
in the Milwaukee watershed. In a coordinated effort between the City of
Milwaukee and the Department of Natural Resources, multiple sites throughout
the entire watershed are being tested for Giardia and Cryptosporidium.
Testing sites include both urban and rural locations. Information obtained
will help determine whether the presence of Cryptosporidium is related
to land use, season, weather conditions or geographic locations.
The University of Wisconsin recently completed an analysis of the southern
plant intake, and has recommended relocation of the intake crib to reduce
the effect of pollutants from the rivers and the sewage treatment plant
that feed into the lake.
At this point there is no single, clear source of contamination of the
Milwaukee watershed, and we may never know exactly what happened in April
1993. Possible sources include cattle along the two rivers that flow into
the Milwaukee harbor above the southern treatment plant, local slaughterhouses
and human sewage. Rivers swelled by significant rain and snow runoff may
have transported oocysts great distances into the lake and from there
to the intake of the southern plant.
High Price Tag
In August the City of Milwaukee received a final report from CH2M Hill,
an environmental and engineering consulting firm hired to study Milwaukee's
water system. Their recommendations, which could easily apply to hundreds
of utilities across the country, point to the need for long-term investment
in the infrastructure and technology that supply the city's and the nation's
water. In November, the Milwaukee Common Council voted in support of Mayor
Norquist' s budget proposal to upgrade the water treatment system. The
price tag is high. In Milwaukee, the cost of moving the southern plant
intake crib alone is estimated to be $11 million; it will cost $27 million
to upgrade both treatment plants and replace filter beds, and another
$51 million to provide an enhanced disinfection system using ozone as
a primary disinfectant. Chlorine is still used in reduced amounts so that
residual levels are maintained.
Milwaukee's outbreak was a wake-up call to the nation, pointing out the
inadequacies in watershed protection programs, public health surveillance
and drinking water standards. It has prompted the formation of new partnerships
between water utilities and public health agencies. Communities throughout
the country have begun to question the safety of their water supplies
and have put pressure on federal and state governments to develop more
stringent water quality standards and to increase the resources currently
allocated for water quality monitoring and plant modernization.
The outbreak clearly points out the need for a strong and flexible public
health infrastructure, and for testing for Cryptosporidium in patients
with diarrhea so that the prevalence of this illness can be assessed.
This can be accomplished in part by making it a reportable condition.
Milwaukee's experience has also made clear the need to utilize timely
surrogate markers, such as particle counts and turbidity, until such time
as a rapid and sensitive means of detecting and quantifying Cryptosporidium
in treated water are available.
Additionally, we must develop a national, enforceable and adequately funded
watershed protection program so that the mw water is never again as contaminated
as it was in Milwaukee in April 1993 when even one glass of water consumed
at the airport while passing through the city was enough to cause illness.
Given our experience, we urge other communities and the federal government
to take the proactive steps necessary to prevent similar outbreaks of
Cryptosporidium or other emerging pathogens.
with permission from Health & Environment De a publication of the Freshwater
Foundation For subscription information, contact Health & Environment
Digest 725 Country Road 6, Wayzeta, Minnesota 55391 Copyright 1995.
a waterborne pathogen, has been identified as the cause of a major outbreak
of gastrointestinal disease that struck Milwaukee in 1993, infecting 400,000
and causing the death of more than 100. Other cities also have experienced
problems with Cryptosporidium in their drinking water supplies.
Does Cryptosporidium Affect Public Health?
is a microscopic parasite contained in an oocyst that breaks open
and releases sporozoites once it enters the gastrointestinal tract.
These sporozoites invade the GI tract lining, causing a disease known
as Cryptosporidiosis, the chief symptom of which is acute watery diarrhea.
There is no known cure other than treatment of the symptoms.
of the primary sources of Cryptosporidium is drinking water or contact
with recreational waters contaminated by domestic and wild animal
feces or human wastewater. Contact with infected animals or individuals
is another possible pathway. It can infiltrate drinking water systems
from source water contaminated by sewer overflows, wastewater plants
and agricultural operations, as well as treatment plant breakdowns.
more severely affects those with depressed immune systems, such as
AIDS and cancer patients, the very young or the elderly. However,
in instances where drinking water supplies become contaminated, widespread
effects may occur in the general population.
Are Water Systems Kept Free of Cryptosporidium?
of its ubiquity in animals, the presence of Cryptosporidium oocysts
is widespread in surface water sources as well as in some groundwater
this parasite is resistant to the traditional disinfection methods
alone. Filtration in conjunction with ozonation and chlorine, plus
chloramines, is generally effective in removing or destroying it if
such treatment occurs before the water is released for distribution.
in watershed areas can detect the presence of Cryptosporidium and
alert water treatment authorities to take necessary preventive measures.
Particle and turbidity readings can be used to evaluate filtration.
the water supply becomes contaminated, boil-water advisories are required
to prevent or minimize infection among the population.
Is the Public Being Protected from Cryptosporidium Infection?
approaches in monitoring do not guarantee protection from Cryptosporidium
in drinking water. Health professional s, water treatment specialists,
environmental experts and government regulators have been examining
methods to improve the prevention, detection and treatment of Cryptosporidium
in water sources. Cooperative efforts among these entities will enhance
their ability to contain future outbreaks of Cryptosporidium related
research is proceeding on the health effects of Cryptosporidium, which
are still incompletely understood.
Environmental Protection Agency has proposed new regulations for water
disinfectants and disinfectant by-products as well as for surface
water treatment, in an attempt to improve monitoring, testing and
treatment for both chemical and microbial contaminants. More research
and regulatory flexibility is being sought to balance the relative
risks between these two threats to drinking water supplies.
water suppliers are attempting to develop and implement the most effective
detection and treatment methods for dealing with Cryptosporidium.
Multi-barrier techniques, including source water protection, followed
by filtration and disinfection in the treatment plant, plus a distribution
system disinfectant residual, are considered the best approach.
RESEARCH ON CHLORINE AND CRYPTOSPORIDIUM
New research results indicate that chlorine and chlorine-based disinfectants
may be more effective against Cryptosporidium than previously recognized.
Dr. Gordon Finch at the University of Alberta reported his preliminary
findings at the November 1994 American Water Works Association Water Quality
It appears that combinations of disinfectants, including chlorine followed
by chloramine, inactivate Cryptosporidium oocysts more effectively than
demonstrated by past studies with single disinfectants. In particular,
chlorine followed by chloramine, at concentrations and contact times typical
of those used in practice (chlorine (1 mg/ L, 60 min.), monochloramine
(2 mg/L, 240 min.), achieved substantial inactivations of this troublesome
parasitic organism. Assuming continuing studies confirm these results,
then water utilities would be able to adopt this inexpensive method for
both waterborne disease protection and reduction of disinfection byproducts.
Dr. Finch has received additional funding to continue his work from the
U.S. Environmental Protection Agency, the American Water Works Association
and the Chlorine Chemistry Division of the American Chemistry Council.
CONGRESS = NEW APPROACHES
The new Republican majority in Congress promises changes in the regulation
of water quality and other environmental issues, which raises many questions
about the future of the Clean Water and Safe Drinking Water Acts that
did not get through the reauthorization process last year.
The shift in leadership and members of jurisdictional committees, along
with the Republican commitment to reexamine many regulations, suggests
a new approach to the federal government's role in the protection of public
health and the environment. Drinking water issues will be at the top of
the agenda to be addressed in four major legislative vehicles: Risk Assessment,
Safe Drinking Water Act, Clean Water Act and the Farm Bill. Other topics
for review include unfunded mandates and property takings.
Clouded by Regulatory Reform Fever.
While both Chairmen Bliley and Chafee sponsored compromise legislation
reauthorizing the Safe Drinking Water Act in the last Congress and have
promised to bring up similar bills this year, the current focus is on
limiting further regulation. Those governing the environment - the Clean
Air Act, Clean Water Act, Safe Drinking Water Act, Superfund - will be
closely examined. Efforts to incorporate risk assessment and cost-benefit
analysis into environmental protection measures can be expected. Intense
opposition from advocacy groups to any perceived weakening of air and
water quality standards also can be anticipated.
Realignment of House committees presents the most changes: Rep. Thomas
Bliley (R-VA) takes over as chairman of the Committee on Energy and Commerce
and Rep. Michael Bilirikis (R-FL) chairs the Health and Environment Subcommittee,
replacing Rep. John Dingell (D-MI) and Rep. Henry Waxman (D-CA), respectively.
Rep. Bud Shuster (RPA) now chairs the Transportation and Infrastructure
Committee, formerly Public Works, replacing Rep. Norman Mineta (D-CA).
Sen. John Chafee (R-RI) moves into the chair of the Senate Environment
and Public Works Committee.
Following is a rundown of the major bills affecting drinking water programs:
Title III of HR 9, the Job Creation and Wage Enhancement Act, is the
principal vehicle of the Republican "Contract with America" that mandates
risk assessment and cost-benefit analysis of new regulations. Principles
of risk assessments, risk characterization and risk communication
would apply prospectively to "major rules," defined as those having
a total economic impact of more than $25 million a year. The bill
would also require an analysis of risk reduction costs and benefits,
and require peer review for rules with an annual economic impact of$l00
million. Before a new rule could go into effect, agencies would have
to go through a 23-step process, including possible judicial review,
to perform the required analyses.
In March, the House passed HR 1022, which incorporated the central
features of HR 9. The Senate Energy and Natural Resources Committee,
chaired by Sen. Frank Murkowski (R-AK), is considering a number of
risk reform bills at the subcommittee level. Senate floor action is
anticipated in May.
The Clinton Administration and environmental advocacy groups spent
some time defining their positions, but now have joined the debate
in an effort to maintain present environmental protections while still
streamlining the regulatory process.
Drinking Water Act
Reauthorization of the Act is expected to be a priority this spring,
with Senate hearings to be held by the new Drinking Water, Fisheries
and Wildlife subcommittee, chaired by Sen. Dirk Kempthorne (R-ID).
On the House side, Rep. John Dingell (D-MI) has reintroduced a reauthorization
bill (HR 226) identical to the one that passed the House last year.
However, with Republicans in control of the Commerce Committee, this
bill cannot be considered the main legislative vehicle in the House.
Instead, the committee has indicated it will have a different perspective
that reorders priorities on drinking water regulation. The approach
is likely to include a new standard setting process, based on scientific
risk assessment and cost-benefit analysis. Chairman Bliley sponsored
similar legislation in the 103rd Congress, although he has commented
that he does not intend to submit a bill that is too far to the right.
Not surprisingly, environmental groups find this new approach to safe
drinking water quite controversial, although their ability now to
significantly affect the outcome is probably limited.
House Transportation and Infrastructure Committee Chairman Bud Shuster
has moved forward with hearings on reauthorization of the Clean Water
Act. In the 103rd Congress, subcommittee action foundered on the unresolved
issues of unfunded mandates, state flexibility, cost-benefit analysis
and risk assessment, and compensation for property takings by the
federal government. These issues, which form the basis of Republican
regulatory reform initiatives described above, remain central to amending
the Clean Water Act.
How the Senate intends to proceed is unknown at this time.
Congress is due to consider reauthorization of agriculture programs,
last enacted in 1990. Whenever such legislation is introduced, the
primary focus will be on farm subsidy issues, particularly as they
affect efforts to scale back the federal budget, a priority for both
the Congress and the Administration. However, drinking water protection
in relation to the run-off of pesticides and other crop protection
chemicals also will be included.
A central feature of the current debate over the extent and cost of regulation
concerns unfunded mandates, where federal requirements are imposed on
the states without matching funds to pay the cost of their implementation.
Long a target of the nation's governors and local governments, whose shrinking
budgets must bear the brunt of these costs, banning unfunded mandates
has been drawn into the bull's eye of congressional budget cutters as
well. Legislation to help remedy the burden of federal regulation on states
and localities has passed the Congress and been signed into law by the
With majorities in state houses and the Congress, Republicans are likely
to accomplish much of their goal of replacing complicated, detailed federal
requirements with block grants that will allow the states more flexibility
in carrying out programs for public health and welfare and environmental
protection, including water quality programs.
It is unclear, however, whether Republican goals can sustain a presidential
FUTURE OF WATER
Balancing burgeoning public needs for safe drinking water with dwindling
supplies will be a major challenge for public works managers and regulators
in the years to come. So asserts a draft report prepared by the EPA Science
Advisory Board's Drinking Water Committee after a yearlong study.
The draft report, entitled Safe Drinking Water: Future Trends and Challenges,
cites numerous trends that will affect the potable water supply over the
next 10-20 years, and recommends steps EPA should take to ensure adequate
safe water resources. The report is expected to be made final early this
In reviewing drinking water resources, the study evaluates population
growth and its impact on groundwater and surface water availability and
contamination. The continuing decline in groundwater tables, which account
for half of the nation's residential consumption, is a major concern.
The situation is further complicated by agricultural and industrial uses
that both deplete water supplies and cause contamination from runoff and
Citing an increased demand for clean water, the committee addressed several
areas of concern:
public awareness of water environment issues and expectations for
regulatory and management policies that protect water resources;
scientific knowledge about health effects and lower detection levels
demand for protection of virgin resources along with stricter standards;
changing profile of chemical and microbiological contaminants that
endanger many water resource systems.
Drinking Water Committee report includes several recommended steps
that should be taken in response to the trends noted above. These
trends indicate a need to fundamentally change the way drinking water
is produced and managed. To that end, the Committee draft report recommends
source water protection and implement water recycling and conservation
changes in treatment technologies to reduce disinfection byproducts
while maintaining protection from microbial contaminants;
accelerate research to spur advances in risk assessment methodologies
for both chemical and microbial contaminants of water;
the consolidation of small distribution systems as a means of upgrading
aging infrastructure and assuring adequate supplies on a regional
basis for less populated areas.
a surveillance or alert system for emerging waterborne pathogens.
Water & Health Newsletter is a Publication of the Public Health Advisory
Board to the Chlorine Chemistry Council
Public Health Advisory Board
M. Brown, Jr.
School of Health and Social Work,
California State University, Fresno
K. Bernard, PH.D.
National Consumer League
Joint Commission on Accreditation of Health Care
Oakbrook Terrace, Illinois
Galveston County (Texas)
Pan American Health Organization
Chemistry Division of the American Chemistry Council