UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.
20460
OFFICE
OF
PREVENTION,
PESTICIDES
AND
TOXIC
SUBSTANCES
9/
26/
03
MEMORANDUM
SUBJECT:
Triethylene
Glycol
Estimated
Drinking
Water
Concentrations
TO:
Jack
Housenger,
Associate
Division
Director
Antimicrobial
Division
(
7510C)

FROM:
Sid
Abel,
Chief
Environmental
Risk
Branch
I
Environmental
Fate
and
Effects
Division
(
7507C)

Summary
This
memorandum
transmits
an
assessment
of
the
estimated
environmental
concentrations
of
triethylene
glycol
from
use
as
an
active
ingredient
(
indoor
use)
and
from
agricultural
and
nonagricultural
(
outdoor)
uses.
Based
on
a
series
of
"
what
if"
approaches,
the
estimated
environmental
concentrations
of
triethylene
glycol
in
surface
water
would
not
likely
exceed
a
peak
(
24­
hour
time
averaged)
concentration
of
885
ppb
or
an
annual
average
(
single
year)
concentration
of
29
ppb.
Estimated
concentrations
in
ground
water
would
not
likely
exceed
106
ppb.

Approach
to
the
Assessment
The
environmental
fate
information,
which
formed
the
bases
of
the
inputs
to
the
modeling,
were
obtained
from
readily
available
open
literature
data.
Based
on
a
review
of
the
information,
triethylene
glycol
(
TEG)
is
miscible
in
water,
mobile
in
soils
and
stable
to
abiotic
degradation
hydrolysis
and
soil
and
aquatic
photolysis.
Biodegradation
is
expected
to
proceed
rapidly
in
surface
waters
based
on
a
number
of
River
Dye­
away
tests
(
complete
mineralization
between
7
and
11
days)
and
will
degrade
in
soils
in
days
(
primary
degradation)
to
weeks
(
complete
mineralization)
based
sludge
innoculum
studies
and
predictions
of
ready
biodegradability.
The
use
of
sludge
innoculum
data
as
a
surrogate
for
terrestrial
soil
metabolism
is
subject
to
considerable
uncertainty
because
sludge
innoculums
tend
to
be
acclimated
to
the
introduction
of
organic
substances
more
so
than
soils
and
the
biomass
on
a
per
volume
basis
tends
to
be
greater.
In
light
2
of
these
uncertainties,
data
reported
for
the
mineralization
of
TEG
in
sludge
innoculums
were
assigned
an
uncertainty
factor
of
3
time
the
estimated
value
to
account
for
media
differences.
This
adjustment
factor
in
conjunction
with
the
use
of
a
mineralization
time
rather
than
a
half­
life
is
likely
to
bound
the
upper­
end
of
the
potential
soil
half­
life,
thus,
maintain
a
reasonble
yet
conservative
assessment.

Application
rates
were
not
available
for
indoor
or
outdoor
uses,
although
percentages
of
formulations
were.
To
assess
the
potential
concentrations
of
TEG
in
surface
and
ground
water,
application
rates
of
1
lb/
acre
and
10
lbs/
acre
were
assessed.
Through
experience,
the
Lower
Toxicity
Pesticide
Chemical
FOCUS
Group
(
formerly
the
Inerts
FOCUS
Group)
has
concluded
that
with
rare
exceptions,
inert
compounds
are
not
applied
at
rates
greater
than
10
pound
per
acre.
Therefore,
assessing
TEG
at
a
maximum
of
10
lbs/
acre
is
considered
a
reasonable
high­
end
exposure
scenario.
Aerial
application
of
TEG
is
assumed
although
it
is
unlikely
to
be
used
in
spray
applications
where
a
ultra
fine
droplet
size
is
used
due
to
its
vapor
pressure.

The
FQPA
Index
Reservoir
Screening
Tool
(
FIRST)
was
used
to
estimate
concentrations
of
TEG
at
the
intake
of
a
community
water
system.
SCI­
GROW
was
used
to
estimate
concentrations
of
TEG
in
shallow
ground
water
drinking
water
sources.
The
environmental
fate
inputs
for
TEG
are
presented
in
Table
1.
The
half­
life
of
TEG
on
soils
was
assumed
to
be
equal
to
the
highest
observed
time
for
mineralization
(
95
%
of
total
applied)
of
approximately
28
days.
In
addition,
an
uncertainty
factor
of
3
times
the
mineralization
time
was
applied
to
account
for
the
differences
in
media
(
soils
vs.
sludge).
The
aerobic
aquatic
metabolism
half
life
was
modeled
at
7
and
11
days.
These
time
are
equivalent
to
the
time
to
complete
mineralization
rather
than
a
true
half­
life
which
will
introduce
additional
conservatism
in
the
assessment.
Raw
data
were
not
available
to
determine
an
actual
half­
life
from
the
River
Dye­
away
studies.

Table
1.
FIRST
Input
Parameters
for
Triethylene
Glycol
Parameter
Scenario
1
Scenario
2
Scenario
3
Scenario
4
Application
Rate/
Number
1/
1
1/
1
10/
1
10/
1
Soil
Koc
10
10
10
10
Water
Solubility
(
mg/
L)
100,000
100,000
100,000
100,000
Hydrolysis
Half­
life
(
days)
stable
stable
stable
stable
Photolysis
half­
life
(
days)
stable
stable
stable
stable
Soil
Metabolism
Half­
life
(
days)
84
84
84
84
Aerobic
Aquatic
Metabolism
Half­
life
(
days)
11
7
11
7
Table
2
provides
the
estimated
environmental
concentrations
from
the
outdoor
uses
of
TEG.
Estimated
exposures
from
indoor
use
of
TEG
as
the
active
ingredient
and/
or
as
an
inert
ingredient
are
unlikely
to
result
in
surface
water
concentrations
greater
those
from
outdoor
uses.
Releases
to
wastewater
treatment
plants
are
expected
to
be
minimally
removed
because
of
the
3
lack
of
residence
time
(
hours).
Predicted
removal
efficiencies
do
not
exceed
10
percent
of
the
amount
released.
Estimated
groundwater
concentrations
are
provided
in
Table
2
as
well.

Table
2.
FIRST
and
SCI­
GROW
Estimated
Environmental
Concentrations
(
ppb)

Model
Scenario
1
Scenario
2
Scenario
3
Scenario
4
FIRST
Peak
88.5
88
885
880
Annual
Average
2.9
1.9
29
19
SCI­
GROW
10.6
10.6
106
106
