Drinking
Water
Criteria
Document
for
Haloacetonitriles
EPA/
OW/
OST/
HECD
VI­
1
Final
Draft
Chapter
VI.
Health
Effects
in
Humans
Human
epidemiology
data
on
the
toxicity
of
the
HANs
are
lacking.
Most
of
the
human
health
data
for
HANs
are
as
components
of
complex
mixtures
of
water
disinfection
byproducts.

These
complex
mixtures
of
disinfection
byproducts
have
been
associated
with
increased
potential
for
adverse
effects
on
reproduction
(
reviewed
by
Nieuwenhuijsen
et
al.,
2000).

Although
most
studies
of
human
health
effects
following
exposure
to
water
disinfectant
byproducts
have
used
total
trihalomethanes
as
the
exposure
metric,
Klotz
and
Pyrch
(
1999),

conducted
a
case­
control
study
on
the
relationship
between
neural
tube
defects
and
drinking
water
exposure
to
trihalomethanes,
HANs,
and
haloacetic
acids.
The
study
included
112
eligible
cases
of
neural
tube
defects
in
1993
and
1994
that
were
identified
through
the
New
Jersey
Birth
Defect
and
Fetal
Death
Registries.
A
total
of
248
controls
were
selected
randomly
from
all
New
Jersey
births
with
approximately
ten
controls
selected
for
each
month
over
24
months.
While
a
statistically
significant
prevalence
odds
ratio
(
POR)
was
reported
for
the
highest
tertile
(
third)
of
trihalomethane
exposure,
only
a
slight
non­
statistically
significant
excess
risk
(
POR
1.3:
95%

confidence
interval
0.6­
2.8
for
the
mid
tertile,
and
POR
1.3:
95%
confidence
interval
0.6­
2.5
for
the
upper
tertile)
was
found
for
cases
when
analyzed
based
on
total
HAN
tertiles.
The
specific
compounds
that
were
measured
as
part
of
the
total
HAN
exposure
estimate
were
not
identified.

Based
on
the
results
of
the
study,
the
authors
concluded
that
the
HANs
did
not
exhibit
a
clear
association
with
neural
tube
defects.
Drinking
Water
Criteria
Document
for
Haloacetonitriles
EPA/
OW/
OST/
HECD
VI­
2
Final
Draft
No
epidemiological
studies
have
evaluated
directly
the
carcinogenic
potential
of
HANs
in
humans.
Rather,
studies
have
evaluated
the
carcinogenic
potential
of
chlorinated
versus
unchlorinated
drinking
water
or
the
presence
of
trihalomethanes
as
a
marker
of
chlorination
byproducts
(
IARC,
1999;
Mills
et
al.,
1998).
Many
of
these
studies
have
shown
an
association
between
chronic
exposure
to
chlorinated
water
and
increased
risks
of
bladder,
rectal,
or
colon
cancers
(
Mills
et
al.,
1998;
WHO,
2000).
