关键词：水质 标准 水质标准 健康
Why are the Elderly More Susceptible
to Contaminants in Drinking Water?
Aging is associated with physiological, functional, and
behavioral changes that can result in increased vulnerability
to biological and chemical contaminants in drinking water.
As a group, the elderly are at increased risk of infection and
disease from microbial contamination due to many factors,
such as reduced immunity, frailty from malnutrition, or
existing chronic illness. In addition, decreased liver and
kidney function associated with aging affects how the body
processes chemicals, and irregularities of the thirst mechanism
alter fluid balance ( 1,2). Exposure patterns for the
institutionalized elderly may also differ in important ways
from patterns in other populations. As a group, the elderly
can suffer more severe consequences from infections such
as Salmonella and E. coli O157:H7, and are at greater risk
of dying from waterborne infections ( 3,4).
The Elderly are Particularly
Susceptible to Microbial Contaminants
The functioning of various immune system cells declines
with age, and immunity can be compromised by chronic
diseases, malnutrition, and treatment with pharmaceuticals—
all common in the elderly ( 5). Aging also leads to hypochlorhydria,
thought to result from chronic atrophic gastritis,
degenerative systemic illness, or the use of potent medications
that inhibit acid secretion. The resulting increased stomach
pH inhibits the defense against enteric pathogens like
Salmonella (6). Decreased intestinal motility associated with
medications, other coexistent gastrointestinal diseases, and
more frequent use of antibiotics ( 7) and diuretics, may also
put older patients at greater risk.
Diarrhea, often a trivial illness in younger adults, can be
catastrophic in the aged population, resulting in hospitalization
or death ( 8). Fluid losses are normally mediated by
urinary concentration and an increased thirst response. With
age, some of these mechanisms are less effective. The rapid
dehydration that can result from diarrhea in the elderly may
have severe consequences, including decreased blood flow
in vital organs, infarction, and arrhythmias ( 8).
Common microbial agents responsible for acute diarrhea
in the elderly include Salmonella, Shigella, Campylobacter
jejuni , E. coli O157:H7, Giardia, and Norwalk virus (8),
which can all be waterborne. The elderly may also be more
susceptible to the effects of cryptosporidiosis ( 9,10).
Long-term Res
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