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Drinking-water
quality,
sanitation,
and
breast-
feeding:
their
interactive
effects
on
infant
health
J.
VanDerslice,1
B.
Popkin,2
&
J.
Briscoe3
The
promotion
of
proper
infant
feeding
practices
and
the
improvement
of
environmental
sanitation
have
been
two
important
strategies
in
the
effort
to
reduce
diarrhoeal
morbidity
among
infants.
Breast-feeding
protects
infants
by
decreasing
their
exposure
to
water-
and
foodborne
pathogens
and
by
improving
their
resistance
to
infection;
good
sanitation
isolates
faecal
material
from
the
human
environment,
reducing
exposures
to
enteric
pathogens.
Taken
together,
breast-feeding
and
good
sanitation
form
a
set
of
sequential
barriers
that
protect
infants
from
diarrhoeal
pathogens.
As
a
result,
breast-feeding
may
be
most
important
if
the
sanitation
barrier
is
not
in
place.
This
issue
is
explored
using
data
from
a
prospec-
tive
study
of
2355
urban
Filipino
infants
during
the
first
6
months
of
life.
Longitudinal
multivariate
analy-
ses
are
used
to
estimate
the
effects
of
full
breast-feeding
and
mixed
feeding
on
diarrhoeal
disease
at
different
levels
of
sanitation.
Breast-feeding
provides
significant
protection
against
diarrhoeal
disease
for
infants
in
all
environments.
Administration
of
even
small
portions
of
contaminated
water
supplements
to
fully
breast-fed
infants
nearly
doubles
their
risk
of
diarrhoea.
Mixed-fed
and
weaned
infants
consume
much
greater
quantities
of
supplemental
liquids,
and
as
a
result,
the
protective
effect
of
full
breast-feed-
ing
is
greatest
when
drinking-water
is
contaminated.
Similarly,
full
breast-feeding
has
stronger
protective
effects
among
infants
living
in
crowded,
highly
contaminated
settings.
Introduction
Breast-feeding
is
an
extremely
effective
means
of
protecting
young
infants
from
diarrhoeal
disease.
Infants
who
are
not
breast-fed
have
a
two-to-three
times
greater
risk
of
diarrhoea
than
breast-fed
infants
and
a
three-to-five
times
greater
risk
than
those
who
are
exclusively
breast-fed
(1-7).
Other
studies
have
documented
even
stronger
protective
effects
(8-11).
There
are
two
mechanisms
through
which
breast-feeding
protects
infants
from
enteric
infec-
tions.
First,
it
reduces
or
eliminates
exposure
to
food-
and
waterbome
pathogens.
Weaning
foods
and
breast-
milk
substitutes
pose
a
particular
risk
since
bacterial
pathogens
can
readily
multiply
in
these
foods
if
they
are
stored
at
ambient
temperatures
after
preparation
(12-19).
Second,
mature
breast
milk
contains
several
compounds,
e.g.,
secretory
IgA,
which
can
improve
the
infant's
ability
to
resist
infection
(20-23).
A
num-
I
Assistant
Professor,
University
of
Texas-Houston,
School
of
Public
Health,
MPH
Program
at
El
Paso,
901
Education
Bldg,
U.T.E.P.,
El
Paso,
Texas
79968-0642,
USA.
Requests
for
reprints
should
be
sent
to
this
author.
2
Professor,
Department
of
Nutrition,
and
Fellow,
Carolina
Popu-
lation
Center,
University
of
North
Carolina
at
Chapel
Hill,
Chapel
Hill,
NC,
USA.
3
Chief,
Water
and
Sanitation
Division,
World
Bank,
Washington,
DC,
USA.
Reprint
No.
5506
ber
of
studies
have
found
significant
associations
between
pathogen-specific
antibody
levels
in
breast
milk
and
the
risk
or
severity
of
diarrhoea
caused
by
that
pathogen
(24-26).
Reducing
the
level
of
environmental
contamina-
tion
similarly
reduces
the
risk
of
diarrhoea.
Good
sanitation
protects
infants
by
creating
a
series
of
bar-
riers
to
keep
enteric
pathogens
out
of
their
environ-
ment;
excreta
disposal
facilities
isolate
human
wastes;
improved
water
supplies
protect
drinking-water
from
faecal
contamination;
and
handwashing
and
personal
hygiene
reduce
the
transmission
of
enteric
pathogens
in
the
home.
As
a
result,
poor
sanitation
may
pose
more
of
a
risk
to
those
who
are
particularly
vulnerable,
i.e.,
non-breast-fed
infants.
Weaning
foods
and
breast-
milk
substitutes
are
more
likely
to
be
contaminated
in
areas
where
water
supply,
sanitation,
and
hygiene
are
lacking.
Furthermore,
families
living
under
these
conditions
often
have
fewer
economic
resources
and
thus
are
less
apt
to
prepare
foods
freshly
for
each
meal,
adequately
reheat
previously
prepared
foods,
or
store
foods
under
refrigeration.
Consequently,
mixed-fed
and
weaned
infants
living
in
poor
sanitary
conditions
probably
face
considerably
higher
expo-
sures
to
foodbome
pathogens
than
similarly
fed
infants
in
less
contaminated
environments.
Thus,
exclusive
breast-feeding
may
provide
greater
protec-
tion
to
infants
living
in
highly
contaminated
environ-
ments.
Bulletin
of
the
World
Health
Organization,
1994,
72
(4):
589-601
©
World
Health
Organization
1994
589
J.
VanDerslice
et
al.
Put
simply,
breast-feeding
and
sanitation
can
be
thought
of
as
a
set
of
sequential
"barriers"
protecting
the
infant
from
enteric
pathogens.
Accordingly,
the
breast-feeding
barrier
is
most
important
when
the
sanitation
barrier
is
not
in
place.
Also,
the
sanitation
barrier
is
most
important
when
the
breast-feeding
barrier
is
absent.
The
hypotheses
that
are
explored
in
this
article
follow
from
this
simple
model:
-
Hypothesis
1:
The
protective
effect
of
breast-
feeding
is
greatest
where
sanitary
conditions
are
poor.
-
Hypothesis
2:
The
protective
effect
of
good
sani-
tary
conditions
is
greatest
among
those
not
breast-fed.
Only
two
published
studies
have
addressed
this
issue.
Using
retrospective
data
gathered
from
1262
women
in
the
Malaysian
Family
Life
Survey,
Habicht
et
al.
found
that
any
breast-feeding
was
associated
with
lower
infant
mortality
and
that
this
protective
effect
was
significantly
stronger
among
households
lacking
toilet
facilities
or
piped
water
(27).
In
a
similar
analysis
of
the
same
data,
Butz
et
al.
assessed
the
effect
of
the
duration
of
breast-
feeding
on
infant
mortality
at
various
levels
of
sani-
tation
(28).
Exclusive
and
supplemented
breast-feed-
ing
had
the
strongest
protective
effects
when
toilets
and
piped
water
were
absent,
and
somewhat
smaller
effects
in
households
that
had
either
of
these
facil-
ities.
Breast-feeding
had
the
smallest
protective
effect
against
infant
mortality
in
households
that
had
both
piped
water
and
a
toilet.
These
results
support
hypothesis
1.
In
a
related
study,
Clemens
et
al.
examined
the
relationship
between
breast-feeding
and
the
risk
of
severe
cholera
among
Bangladeshi
children
under
3
years
of
age
(4).
The
protective
effect
of
any
breast-
feeding
against
severe
cholera
infection
was
stronger
for
infants
living
near
(presumably
contaminated)
rivers,
compared
with
those
who
did
not.
Similarly,
a
stronger
association
was
observed
among
infants
whose
families
did
not
have
a
latrine.
These
results
also
concur
with
hypothesis
1,
with
breast-feeding
having
a
stronger
protective
effect
in
poor
sanitary
conditions;
however,
the
protective
effect
also
appeared
to
be
greater
for
families
who
had
a
tube-
well
in
their
compound.
The
effects
of
breast-feeding
under
good
or
poor
sanitary
conditions
were
not
sta-
tistically
different.
In
the
present
study
we
have
used
prospective
(rather
than
retrospective)
data
from
a
large,
repre-
sentative
sample
of
infants,
with
detailed
information
on
feeding
pattems,
environmental
sanitation
condi-
tions,
and
diarrhoeal
morbidity
to
address
the
follow-
ing
questions:
-
Is
the
protective
effect
of
breast-feeding
against
diarrhoeal
morbidity
greatest
where
water
quality
and
sanitary
conditions
are
poor?
-
Is
the
protective
effect
of
improved
water
quality
and
sanitary
conditions
greatest
when
breast-
feeding
is
not
practised?
-
What
specific
aspects
of
environmental
sanitation
are
particularly
important
in
protecting children
who
are
not
breast-fed?
The
answers
to
these
questions
have
profound
implications
for
resource
allocation
decisions
in
infant
health
and
environmental
sanitation
pro-
grammes.
Methods
Data
collection
Study
design
and
sample.
The
investigation
used
data
collected
by
the
Cebu
Longitudinal
Health
and
Nutrition
Survey
(CLHNS)
in
a
prospective
study
of
3080
children
living
in
urban,
periurban,
and
rural
areas
of
metropolitan
Cebu
city,
Philippines.
The
survey
consisted
of
14
interviews
of
mothers
conducted
during
the
third
trimester
of
pregnancy,
soon
after
birth,
and
every
2
months
thereafter
until
the
child
was
2
years
of
age.
The
sample used
in
the
present
analysis
comes
from
a
12-month
cohort
of
all
births
in
17
randomly
selected
urban
and
periurban
barangays
(communities).
All
the
women
were
informed
of
the
purpose
of
the
study,
the
types
of
questions
they
would
be
asked,
and
that
participation
in
the
study
was
completely
voluntary.
Of
the
2555
women
recruited,
2355
had
single,
live
births
be-
tween
April
1983
and
May
1984
and
agreed
to
parti-
cipate
in
the
study.
Data
for
the
first
6
months
of
life
were
used
since
during
this
time
the
infant's
immune
system
is
developing
and
full
breast-feeding
is
prevalent.
Attri-
tion,
because
of
migration
out
of
the
area,
death,
and
refusal
to
participate
reduced
the
sample
size
to
1963
at
the
end
of
6
months.
This
loss
to
follow-up
did
not
appear
to
result
in
a
selectivity
bias
(29,
30).
More
information
on
the
survey
design
and
content
have
been
published
previously
(30).
Diarrhoeal
disease.
At
each
bimonthly
interview
the
infant's
mother
or
care-giver
was
asked
whether
the
infant
had
experienced
any
episode
of
diarrhoea
in
the
7
days
prior
to
the
interview
day.
The
local
term
for
diarrhoea
used
in
the
questionnaire
(kalibang)
de-
notes
frequent,
watery
stools.
In
a
separate
study
on
the
validity
of
retrospective
morbidity
data
conducted
in
the
study
area,
mothers'
reports
of
diarrhoea,
based
on
frequent
or
loose
stools,
had
a
sensitivity
of
WHO
Bulletin
OMS.
Vol
72 1994
590
Drinking-water,
sanitation,
and
breast-feeding:
effects
on
infant
health
95-97%
and
a
speciflcity
of
80%
compared
with
diagnoses
made
at
health
clinics
and
hospitals
(31).
Feeding
practices.
Infant
feeding
encompasses
a
complex
set
of
behaviours,
and
apparently
small
dif-
ferences
in
behaviour
can
have
a
large
impact
on
an
infant's
exposure
to
pathogenic
organisms
and
sus-
ceptibility
to
infection.
A
complete
24-hour
dietary
recall
was
taken
at
each
interview,
including
the
amounts
of
all
foods
consumed
by
the
child,
method
of
preparation
for
broad
categories
of
foods,
and
whether
the
infant
was
suckled.
For
the
descriptive
statistics,
infants
were
classified
at
each
time
period
as
either
exclusively
breast-fed,
breast-fed
and
given
only
non-nutritive
liquids
(NNL),
mixed-fed,
or
completely
weaned,
based
on
the
24-hour
recall.
Exclusively
breast-fed
infants
received
only
breast
milk.
The
breast-fed
+
NNL
infants
were
primarily
breast-fed,
but
also
given
liquids
lacking
caloric
con-
tent,
such
as
teas,
brews,
and
plain
water.
Mixed-fed
infants
were
those
receiving
nutritive
foods
and/or
liquids
in
addition
to
breast
milk.
Completely
wean-
ed
infants
did
not
breast-feed
at
all.
These
definitions
are
generally
consistent
with
other
recommendations
that
have
appeared
(32).a
For
the
bivariate
and
multivariate
analyses,
the
exclusively
breast-fed
and
breast-fed
+
NNL
infants
were
combined
into
a
"fully
breast-fed"
category,
indicating
that
the
infants
received
all
nutrition
through
breast-feeding,
and
that
they
were
not
exposed
to
potentially
contaminated
weaning
foods.
These
categories
were
based
on
the
reported
feeding
practices
8
days
prior
to
the
interview,
minimizing
the
possibility
that
the
reported
practice
was
a
result
of,
rather
than
a
determinant
of,
diarrhoea
in
the
week
before
the
interview.
In
view
of
the
large
number
of
infants
in
this
study,
the
variety
of
foods
consumed,
and
the
con-
siderable
variation
in
food
contamination
levels
due
to
microbial
multiplication,
it
was
not
feasible
to
test
weaning
foods
directly
for
bacterial
contamination.
The
effect
of
consuming
contaminated
weaning
foods
is
captured
primarily
by
the
infant
feeding
var-
iables:
fully
breast-fed
infants
were
not
exposed
to
potentially
contaminated
foods,
while
the
mixed-fed
and
non-breast-fed
infants
were
exposed.
In
addition,
a
variable
representing
poor
food
storage
practices
was
constructed,
indicating
that
the
child
consumed
either
a
breast-milk
substitute
or
a
semisolid
food
that
had
been
stored
without
refrigeration
for
more
than
an
hour
after
preparation.
Exposure
to
water-
a
Indicators
for
assessing
breast-feeding
practices:
report
of
an
informal
meeting,
11-21
June
1991,
Geneva,
Switzerland.
Unpublished
document
WHO/CDD/SER/91.14,
1991.
borne
pathogens
in
non-nutritive
liquids
was
cap-
tured
by
a
water
quality
variable
(see
below).
Environmental
sanitation.
The
study
infants
faced
a
variety
of
environmental
conditions.
To
capture
this
complex
array
of
sanitation-related
exposure,
the
following
environmental
factors
were
considered:
drinking-water
quality;
access
to
water;
type
of
excreta
disposal
facility;
presence
of
excreta
in
the
household's
yard;
and
the
sanitation
conditions
in
the
household's
neighbourhood.
The
water
sources
used
by
the
household
were
identified
during
the
baseline
survey
and
verified
at
each
bimonthly
survey.
Between
two
and
five
water
samples
were
collected
from
each
drinking-water
source
over
the
course
of
a
year;
water
sources
with
more
variable
quality
(such
as
open
dug
wells)
were
sampled
more
frequently.
The
samples
were
analys-
ed