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U.S. EPA Office of Research
and Development's Science
To Achieve Results (STAR)
Research in Progress
Vol.2 Issue 3 April 1998 A product of the National Center for Environmental Research and Quality Assurance
DRINKING WATER RESEARCH
The challenge in delivering safe drinking
water is one of balance. In protecting the public
from health effects caused by microbial patho-
gens, public water supplies must achieve levels
of disinfection that destroy the greatest number
of pathogens while minimizing levels of disinfec-
tion byproducts that might themselves cause
health effects. Providing safe drinking water in-
volves meeting this challenge and simultaneously
complying with federal and state standards that
ensure protection from chemical contaminants.
Tap water that meets all EPA and state stan-
dards is considered safe to drink for the general
public. However, there are occasional, rare inci-
dents of disease outbreaks in U.S. populations
served by Public Water Systems (PWSs), in some
cases because standards have not been met, and in
other cases apparently because the standards did
not protect all exposed individuals. In particular, it
has been found that some contaminants in even
low concentrations pose special health risks to
particular groups of people. These groups include
infants, young children and the elderly. They also
include people with compromised immune systems
due to certain illnesses, or because they are under-
going chemotherapy. Drinking water standards are
being strengthened to reduce the risk of outbreaks.
However, some scientific uncertainty remains about
the degree to which current standards and monitor-
ing requirements protect all individuals from all
possible effects of microbial pathogens or chemical
pollutants.
While typi-
cally only very
small numbers, if
any, of U.S.
residents served by
PWSs experience
waterborne
diseases in any
given year, an
unprecedented
situation occured
in 1993, in which
over 400,000
people in Mil-
waukee became
ill, and there
were 104 deaths of highly susceptible individuals due
to a single outbreak of disease caused by the microor-
ganism Cryptosporidium. At that time, over the course
of one year, approximately 2000 additional U.S
residents experienced a total of sixteen other out-
breaks otCryptosporidium or other microorganisms
(Ciardia, Campylobacter, Salmonella and organisms
that cause shigellosis and cholera).
The United States enjoys one of the best supplies of drinking water in the world.
Ninety percent of Americans receive their tap water from public water systems (PWSs)
regulated by EPA and the states or tribes.
&EPA
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Chemical contaminants are
typically associated with fewer than
a handful of nationally reported
acute illnesses in any given year, and
these typically involve contamination
of private water supplies. (Nitrates,
which can cause illness in young
infants at levels that don't harm
other people, may be the most
common cause of chemically-
induced illness associated with
private wells.) However, there is
concern among scientists that the
potential for longer-term effects of
all chemical pollutants that may
occur in water supplies is not yet
fully understood. To address these
concerns, and based on require-
ments of the 1996 amendments to
the Safe Drinking Water Act, EPA has
developed a "Contaminant Candi-
date List" (CCL) of chemicals not
presently subject to regulation that
may occur in drinking water
supplies, and that have been
identified as priorities for research,
monitoring, guidance development,
and for determining which contami-
nants need to be selected for
drinking water regulation.
EPA's Overall Research
Strategy for Drinking
Water
This report summarizes
research grants funded in 1996 and
1997 through EPA's principal
external research program, the
Science to Achieve Results (STAR)
program. To address microbial
contaminant and DBP issues, EPA has
developed a comprehensive Micro-
bial Contaminants and Disinfection
Byproducts (M/DBP) study plan to
support future regulations for
microbial disinfectants and disinfec-
tion byproducts. In addition, EPA
has identified priority research
questions concerning possible
sources of risk from chemicals on the
CCL. Together, these questions form
an overall "Drinking Water Research
Strategy" on which EPA has con-
sulted with other federal agencies,
states, tribes, PWSs and the aca-
demic community. Studies summa-
rized in this report support each of
the microbial, DBP and chemical
contaminant components of the
overall drinking water research
strategy.
In addition to the STAR
research described here, EPA, the
National Institutes of Health, the
Centers for Disease Control and
Prevention, other federal agencies
and members of the American Water
Works Association Research Founda-
tion are conducting components of
the M/DBP study plan and CCL
research. More information on EPA's
drinking water research strategy and
related work by other groups is
available from Internet Websites
listed at the end of this report.
EPA's STAR grants are typically
awarded for three-year time periods.
On-going research is described in
this report; results will be presented
in future reports as findings are
completed and peer reviewed.
General Information
STAR Research Addressing
Drinking Water Issues
Cryptosporidium Research
Cryptosporidium parvum is the
pathogen that caused illness in over
400,000 people in Milwaukee in
1993. Contamination of the city's
water supply occurred because of
treatment plant failures that let
Cryptosporidium oocysts pass
through filters and into the distribu-
tion system. The disinfectant added
did not provide an additional
protective barrier because chlorine
cannot effectively inactivate
Cryptosporidium. Ingestion of a small
number of oocysts may cause illness
in otherwise healthy individuals. The
resulting disease outbreak was
detected because of an increase in
anti-diarrheal drug sales.
Cryptosporidium may be present in
fifty percent or more of the surface
waters in the U.S. at levels that
require careful operation of treat-
ment facilities and for some possibly
a change to a more effective
disinfectant such as ozone. How-
ever, data collected on the occur-
rence of the microorganism is
difficult to interpret because of
current uncertainties concerning
analytical methodology problems.
Four research projects supported by
STAR grants are attempting to
reduce these uncertainties concern-
ing Cryptosporidium monitoring and
disinfection.
Grants described in this report are part of EPA's Science to Achieve Results (STAR)
program, a major research initiative designed to improve the quality of scientific
information available to support environmental decision making. The STAR pro-
gram is managed by EPA's National Center for Environmental Research and Quality
Assurance in the Office of Research and Development (ORD). The program funds
approximately 200 new grants every year, with the typical grant lasting three years.
Funding levels vary from $50,000 to over $500,000 per year, withFY 1998 funding
level at about $80 million for grants to individual principal investigators or groups
of investigators. Additional STAR funds are provided for a number of Research
Centers specializing in scientific areas of particular concern to EPA, and for a fel-
lowship program supporting graduate students conducting environmental research.
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The Metropolitan Water
District of Southern California is
developing an assay to identify live
and infectious C. parvum oocysts
from environmental samples. This
may be useful in developing a
species-specific analytical method for
environmental samples. A method
to monitor oocyst survival will help
to ensure that disinfection processes
have been effective. The genetic
information can be used by other
researchers to refine methods for
studying the growth and infectivity
of C. parvum and other
Cryptosporidium species in laboratory
and field situations. Investigators
hope to increase understanding of
differences between species, and
among individuals of the same
species, which affect how likely the
pathogens are to infect people or
other host organisms. An investiga-
tor from Kansas State University is
going to construct DMA libraries for
various species and subgroups of
Cryptosporidium. This
Cryptosporidium genetic information
will support research across the
country, helping others to develop
and verify new analytic methods for
a wide variety of purposes.
St. Luke's Hospital and the
University of Texas are studying
whether different strains of
Cryptosporidium parvum differ in
virulence (affecting how many
people become ill and the severity of
the illness). Mice and human
volunteers are being evaluated to
determine the typical infectious
dose, and to evaluate individual
responses. In addition to assessing
the clinical response in healthy,
previously unexposed humans to
different strains of C. parvum, the
research examines the immune
response and a number of biological
"markers" that may be useful to
diagnose exposed and infected
individuals. This will also be useful in
assessing the prevalence of
cryptosporidosis in human popula-
tions. In work on related issues,
Ohio State University is using pigs
as test animals to study the virulence
of C. parvum isolates. Pigs of
different immonological status
(normal and immunologically
compromised) will be tested to
improve understanding of how this
affects susceptibility to
Cryptosporidium.
Other Microbial
Contamination Studies.
Researchers at the University
of North Carolina at Chapel Hill
are working with human volunteers
to study infectivity of two viruses,
Norwalk virus and Snow Mountain
Agent. They will examine immune
responses of individuals most
susceptible to infection, and evaluate
models of dose infectivity. Results
will help to refine risk assessments.
The 1996 Amendments to the
Safe Drinking Water Act require
disinfection of groundwater used for
drinking water unless "natural
disinfection" can be demonstrated
to occur. Researchers at the
University of California and the
Baylor College of Medicine are
using recombinant Norwalk virus
particles to evaluate their survival in
groundwater. Preliminary data
suggest pH may be the most
important factor. Results of this
research will be relevant to establish-
ing suitable set-back distances
between potential contaminant
sources and intake points.
Enhancing natural bacterial
activity may aid in situ (in-place)
bioremediation of contaminated
ground water. The New York State
Department of Health and the U.S.
Geological Survey are evaluating
field methods to measure bacterial
activity by monitoring oxygen
consumption. Preliminary results
indicate low bacterial respiration
rates in the aquifer, indicating that
introducing oxygen is probably an
effective way to speed up natural
bioremediation. Early results from a
study being done by El Paso
Community College and Texas
A&M indicates that viruses can exist
in groundwater in a "reversibly
inactivated" state, unable to cause
infection until reactivated. This may
explain contradictory results in
testing effectiveness of disinfection
procedures. This study will investi-
gate inactivation mechanisms and
environmental factors that could
promote or retard reactivation.
Monitoring microbial patho-
gens is often costly and time
consuming. Low sample volume
methods are needed that identify
only live viruses. The University of
Arizona is developing a combined
cell culture/PCR technique for
enteroviruses from sewage. This
technique, combining advantages of
the two approaches, is expected to
be sensitive and cost-effective. (In
addition to drinking water, this is
applicable to marine recreational
waters.)
Fecal coliform contamination
of drinking water sources is moni-
tored with standard tests that do not
distinguish human from animal and
other sources of coliform bacteria.
Human fecal wastes have a much
higher likelihood of containing
human pathogens than livestock and
other animal wastes. In preliminary
studies, researchers at the University
of North Carolina have developed
techniques by which human fecal
contamination can be distinguished
from that of animals or other
wildlife, with the exception of waste
from pigs. These investigators have
received a STAR grant to refine their
methodology. Methods that could
accurately distinguish fecal sources
would help in assesing potential
public health risk.
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Socio-Economic Study of
Protecting Upstream
Water Sources
Cornell University is assessing
public opinion on watershed
protection issues, based on inter-
views with upstate New York
watershed residents and New York
City residents whose drinking water
comes from the watershed. Results
will provide information useful in the
on-going public process by which
the City, other local governments,
the State and the U.S. EPA are
assessing options for protecting
water quality in the watershed, in an
effort to avoid the need for a new
filtration plant with a projected cost
of $5 billion.
Research Concerning
Disinfection By-products
(DBFs)
Health Effects Studies: The
potential for cancer-causing
effects of trihalomethanes is being
evaluated through rodent studies at
the Medical College of Ohio.
Results should decrease uncertainties
of estimates of the human health
hazards of these DBPs. Investigators
from the University of Illinois at
Urbana-Champaign are evaluating
the use of mammalian cell cultures
rather than bacterial genotoxicity
tests to predict DBP risks. The cell
cultures may be more representative
of potential human impacts.
Investigators at Pacific
Northwest National Laboratories
theorize that the human system can
detoxify small amounts of
haloacetate DBPs from drinking
water, but that ingestion beyond a
threshhold amount results in partial
or complete inactivation of the
enzymes needed for such detoxifica-
tion. Rodents and human liver cell
cultures will be used to study
whether enzyme inactivation occurs,
where haloacetates are distributed
after ingestion, and how they are
eliminated. Results will allow more
accurate risk assessment for
haloacetate.
Exposure Studies: Exposure
to DBPs in tap water can be
from drinking the water, inhaling
volatile DBPs (for example in
showers and baths) and dermal
exposure. The University of
Medicine and Dentistry of New
Jersey is investigating human
exposure to haloacetic acid DBPs
from dermal absorption and
inhalation, to assess the relative
importance of each exposure route.
Halogenated acetonitriles are
DBPs that are both toxic and
carcinogenic. Investigators from the
University of Texas Medical Branch
are attempting to identify haloge-
nated acetonitrile "biomarkers",
molecular-level changes in living
tissues that demonstrate they have
been exposed to these specific
chemicals. These could be used to
assess exposure and identify particu-
lar affected tissues. The University
of North Carolina at Chapel Hill is
also investigating the chemical
nature and metabolite formation of
haloacetic acid DBPs with an eye to
identifying biomarkers. In particular,
haloacetic acids may form macromo-
lecular adducts that could serve as
biomarkers.
Detection Methods: A new
drinking water standard for the
carcinogen bromate is being
proposed at a level for which good
detection methods are not widely
available. The University of North
Carolina at Chapel Hill is evaluating
a cost-effective ion chromatographic
system for detection of all oxyhalides
(bromate, iodate and chlorite) using
UV spectrophotometry.
Precise, low-cost methods to
measure DBPs called haloacetic acids
are being developed at Pennsylva-
nia State University, using a
technique called "surface enhanced
Raman scattering". The method
requires a minimum of
expertise to perform and
thus would be practical for
regular on-site monitoring
at treatment plants. The
University of Massachu-
setts is developing and
refining analytical methods
for DBPs of ozonation
disinfection processes.
Improved Disinfection
Processes: The University of
Washington and University of
Colorado are investigating a method
to reduce the quantity of metal
coagulant necessary for satisfactory
removal of natural organic matter
and particles from drinking water. A
graduate student at Michigan State
University has received a STAR
fellowship award to investigate
methods for reducing DBPs in water
containing natural humic
substances, using ozonation and
biological treatment. This study will
include examining how humic
substances are modified during
ozonation, and the biodegradability
of the ozonation by products, and
will track formation of toxic
organochlorine compounds during
chlorine disinfection.
The University of Michigan
and the Hebrew University are
analyzing the DBPs resulting from a
secondary disinfectant formulation
using hydrogen peroxide and silver.
They are evaluating the method for
use in long-term residual disinfec-
tion. The University of Colorado at
Boulder is studying the use of
softening and coagulation treat-
ments to remove DBP precursors as
well as arsenic from drinking water.
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Other Toxic Chemical
Risks
Rodent studies are being used
at the University of Kentucky and
Purdue University to evaluate brain
accumulation of aluminum from
drinking water. Oral bioavailability,
influence of water hardness, alumi-
num circulation and elimination
from the brain will be studied.
Princeton University is
studying the role of microorganisms
in arsenic cycling in contaminated
freshwater. Investigators propose
that bacteria convert one form of
arsenic into another, more mobile
form, and also catalyze precipitation
of arsenic sulfides. Results will help
to refine assessments of actual
human exposure and hazard from
arsenic contamination of water
supplies.
Drinking Water Research
in EPA's Small Business
Innovative Research
Program
EPA conducts a Small Business
Innovative Research Program (SBIR)
to take advantage of the talents of
small businesses to find solutions to
priority environmental problems. A
number of proposals funded
through EPA's SBIR program are
directly related to and supportive of
EPA's overall drinking water research
strategy. Subject areas on which
drinking water SBIR projects focus
include developing sensors and
other monitoring equipment for
microbial pathogens, and refining or
developing new removal technolo-
gies for contaminants including
DBPs, nitrates and toxic chemicals.
More information about SBIR
research projects is available at EPA's
website, www.epa.gov/ncerqa/sbir
Future Directions for
Drinking Water Research
A top priority for future STAR
drinking water research is to
complete studies of emerging
contaminants from the currently
drafted CCL. Work funded in 1998
and anticipated for 1999 will
emphasize filling information gaps
with respect to potential health risks
of these contaminants at levels that
are likely to occur in drinking water,
and of the mechanisms ("modes of
action") by which they might cause
adverse effects.
In addition, future work will
build on the findings of earlier work
concerning microbial pathogens,
moving into establishing approaches
for determining the general impact
of susceptibility factors (e.g., age,
pregnancy, nutrition, protective
immunity, pre-existing diseases, and
behavioral patterns) on infectious
disease incidence associated with
exposure to primary waterborne
pathogens and to emerging patho-
gens. At present little is known
about the occurrence of some
emerging pathogens in U.S. source
waters. It is possible that some of
these poorly understood pathogens
may have caused some disease
outbreaks for which no explanation
has yet been found. Analytical
Find Out More About the STAR Research Program
General information on EPA's STAR research program is available from
the following sources:
ORD's National Center for Environmental Research and Quality Assurance
(NCERQA): Internet website: http://www.epa.gov/ncerqa
Mailing Address:
Office of Research and Development
National Center for Environmental Research and Quality Assurance
Office of the Director (8701 R)
401 M Street, SW
Washington, DC 20460
methods to detect emerging
pathogens will be a principle focus
of this future research. In another
area of microbial research, methods
for counteracting the action of
"biofilms" that can form in treat-
ment systems and protect patho-
genic microorganisms from disinfec-
tants will be also be a subject of
future study.
In the area of DBPs, much of
the research work already completed
or now underway is paving the way
for improved and more cost-effective
techniques for treatment by large
and small PWSs. But additional
research is still needed relative to
some disinfection processes. The
technique of ozonation followed by
a secondary disinfectant is a poten-
tial treatment alternative for water
utilities to avoid chlorinated
byproduct formation. However, the
reaction of ozone with natural
organic matter is not entirely
understood, so research will be
supported to identify and quantify
byproducts of ozonation and
secondary disinfection as a function
of source water quality.
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STAR Research Projects Described in this Report
Development of a Quantitative Cell
Culture-Based Infectivity Assay for
Cryptosporidium parvum in Source and
Finished Water. Metropolitan Water
District of Southern California.
Cenomic Database for Cryptosporidium
spp., Kansas State University.
Virulence Factors in Cryptosporidium and
Infective Dose in Humans. University of
Texas.
Understanding Risk Factors to
Cryptosporidium parvum: Studies in
Gnotobiotic Pigs. The Ohio State
University.
PCR Based Detection of cytopathogenic
and Non-Cytopathogenic Viruses in
Water. University of Arizona.
Nomalk Virus-Like-Particles (VLPs) for
Studying Natural Groundwater
Disinfection. University of California
Irvine; Baylor College of Medicine.
Studies of the Infectivity of Nomalk and
Norwalk-Like Viruses. University of
North Carolina at Chapel Hill.
In Situ Assessment of the Transport and
Microbial Consumption of Oxygen in
Groundwater. New York State
Department of Health.
Reversible Inactivation of Viruses in
Groundwater. El Paso Community
College; Texas A&M
Direct Quantitation of Haloacetic Acids
by Surface Enhanced Raman Scattering.
Pennsylvania State University.
Combined donation and Biological
Treatment for the Removal ofHumic
Substances from Drinking Waters.
Michigan State University.
Investigation and Optimization of Dual
Coagulation Processes., University of
Washington.
Evaluation of the Efficacy of a New
Secondary Disinfectant Formulation
Using Hydrogen Peroxide and Silver and
the Formulation of Disinfection By-
Products Resulting from Interactions
with Conventional Disinfectants.
University of Michigan.
Health Risk of the Trihalomethanes
Found in Drinking Water: Carcinogenic
Activity and Interactions. Medical
College of Ohio.
Analysis of Organic By-Products from
the Use of Ozone / Chlorine and Ozone
/ Chloramines in Drinking Water
Treatment. University of Massachu-
setts.
Development of a New, Simple,
Innovative Procedure for the Analysis of
Bromate and Other Oxy-Halides at Sub
ppb Levels in Drinking Water.
University of North Carolina at
Chapel Hill.
Inhalation and Dermal Exposure to
Disinfection By-Products of Chlorinated
Drinking Water. University of
Medicine and Dentistry of New
Jersey.
Evaluate the Disposition, Toxicokinetics
and Metabolism of Selected Haloacids
on Fischer 344 Rats and B63F1 Mice
and Investigate the Effect of Chronic
Exposure and co-Administration of
Haloacids on Toxicokinetics. Pacific
Northwest National Laboratories.
Development ofBiomarkers for
Haloacetonitriles: Induced Cell Injury in
Peripheral Blood. The University of
Texas Medical Branch.
Genotoxicity and Occurrence
Assessment of disinfection By-Product
(DBP) Mixtures in Drinking Water.
University of Illinois at Urbana.
Metabolic Fate of Halogenated
disinfection By-Products In-Vivo, and
Relation to Biological Activity.
University of North Carolina at
Chapel Hill.
The Microbial Transformations of
Arsenic in Anoxic Waters. Princeton
University.
Arsenic removal by Softening and
Coagulation. University of Colorado-
Boulder.
Detecting Fecal Contamination and Its
Sources in Water and Watersheds.
University of North Carolina.
Public Opinion on Environment and
Water Quality Management in the New
York City Watershed. Cornell
University.
Aluminum Toxicokinetics: Oral
Absorption from Drinking Water and
Brain Retention. University of
Kentucky Research Foundation.
&ERA
United States
Environmental Protection Agency
Mail Code 8701R
Washington, D.C. 20460
Offical Business
Penalty for Private Use
$300
EPA/600/F-98/010
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