| Introduction:
Contaminants in Children’s Drinking Water |
Exceedances of Drinking Water Standards |
Monitoring and Reporting
Contaminants in Children’s Drinking
Water
The contaminants in drinking water are quite varied and may cause
a range of diseases in children, including acute diseases such as
gastrointestinal illness, developmental effects such as learning
disorders, and cancer.56
Children are particularly sensitive to microbial contaminants because
their immune systems are less developed than those of most adults.56
Children are sensitive to lead, which affects brain development,58-65
and to nitrates and nitrites, which can cause methemoglobinemia
(blue baby syndrome).66-68
Fertilizer, livestock manures, and human sewage are significant
contributors of nitrates and nitrites in groundwater sources used
for drinking water.69-71
EPA sets drinking water standards for public water systems, referred
to as Maximum Contaminant Levels (MCLs).72
These standards are designed to protect people against adverse health
effects from contaminants in drinking water while taking into account
the technical feasibility of meeting the standard and balancing
costs and benefits. EPA has set MCLs for more than 80 microbial
contaminants, chemicals, and radionuclides. EPA also has developed
regulations to protect drinking water sources and to require treatment
of drinking water. An important treatment-related regulation, the
Surface Water Treatment Rule, requires treatment of surface waters
used for drinking water by filtration to remove microbial contaminants.
Drinking water rules often are added or modified. For example,
EPA established more stringent filter performance requirements in
1998 to further strengthen protection against microbial contaminants.
In the same year, EPA also established new drinking water standards
for disinfection byproducts, exposure to which has been associated
with bladder cancer73
and possible reproductive effects.74
In 2000, EPA finalized standards protecting against radionuclides
in drinking water.75
In addition, EPA strengthened the existing standard for arsenic
in 2001. Changes in regulatory requirements may affect the outcome
of the measures presented in this report, as the resulting trends
sometimes may be related to changes in standards rather than changes
in exposures.
Measure E6: Exceedances of Drinking Water
Standards
One way to measure children’s risk of exposure to contaminated
drinking water is to identify public water systems that contain
contaminants at levels greater than those allowed by the drinking
water standards. Ideally, concentrations for all chemical and microbial
contaminants in all drinking water systems would be available for
analysis to identify areas of risk for children. Currently this
is not possible. The Safe Drinking Water Information System (SDWIS)
does not track concentrations of contaminants in drinking water,
but instead tracks the frequency with which standards are exceeded.
Public water systems are required to monitor individual contaminants
at specific time intervals to assess whether they have achieved
compliance with drinking water standards. When a violation of a
drinking water standard is detected, the public water system is
required to report the violation to state and federal governments.
Information about exceedances can be used as a surrogate for exposure
to unacceptably high levels of drinking water contaminants.
The reported violations received by the federal government are
highly accurate, but violations may be under-reported in some cases
because some public water systems fail to fully monitor contaminants
or report their monitoring results. Data identifying public water
systems that do not monitor or report their results are available.
A review of the federal SDWIS database published in October 2000
found that 68 percent of the microbial contaminant violations, 19
percent of violations for other contaminants, and 11 percent of
treatment and filtration violations that should be included in the
SDWIS database are reported.76
As a result of these findings, many states have taken corrective
steps to improve their SDWIS data quality.
It also is important to consider information about water sources
that are not included in the SDWIS database. Because data are only
available for public water systems, this measure does not include
children served by private water sources, such as wells or bottled
water. Approximately 42 million people are served by private water
systems that are not required to monitor and report the quality
of drinking water.77
Many people served by private water supplies live in rural and agricultural
areas, which may be at increased risk for nitrate and nitrite contamination.
Conversely, many children served by public water systems may not
drink the tap water or may use a water filtration device to further
purify the water. Thus, the measure may overestimate the percentage
of children exposed to contaminated drinking water.
A violation of “treatment and filtration” is defined
as any failure in the treatment process, or in operation and maintenance
activities, or both, that may affect water quality.78
The Surface Water Treatment Rule specifies the type of treatment
and maintenance activities that systems must use to prevent microbial
contamination of drinking water.
Data table for this graph
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- The percentage of children served by public water systems that
reported exceeding a Maximum Contaminant Level or violated a treatment
standard decreased from 20 percent in 1993 to 8 percent in 1999.
- Every category of reported violation decreased between 1993
and 1999 except for nitrates and nitrites, which remained steady.
The largest decline was for violations of the treatment and filtration
standards.
- From 1993-1999, approximately 0.2 percent of the children served
by public water systems were served by systems that reported violations
of the nitrate or nitrite standard.
- Between 1993 and 1999, fewer than 0.2 percent of all children
served by public water systems were served by systems that had
violations of the Total Trihalomethane (TTHM) standard. Four recent
epidemiological studies have found significant associations between
elevated TTHM exposure and stillbirth or miscarriages, but more
study is necessary before any definitive conclusion can be made.79-86
Related Measures:
Healthy People 2010:
Objective 8-05 of Healthy
People 2010 
seeks to increase the number of people served by community water
systems that meet the regulations of the Safe Drinking Water Act.
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