THE
WEINBERG
GROUP
INC.

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WASHINGTON
NEW
YORK
SAN
FRANCISCO
BRUSSELS
PARIS
HEALTH
RISK
EVALUATION
OF
SELECT
METALS
IN
INORGANIC
FERTILIZERS
POST
APPLICATION
Prepared
for:

The
Fertilizer
Institute
(
TFI)

January
16,
2000
i
DRAFT
TABLE
OF
CONTENTS
EXECUTIVE
SUMMARY...................................................................................................
vi
INTRODUCTION.................................................................................................................
1
SECTION
1.0
¾
DEFINING
THE
SCOPE
OF
THIS
EVALUATION..............................
5
Selection
of
Representative
Fertilizer
Products
............................................
5
Selection
of
Metals
of
Potential
Concern
(
MOPC).......................................
7
Selection
of
Health
Protective
Exposure
Scenarios
......................................
9
Summary
of
Scope
........................................................................................
14
SECTION
2.0
¾
DERIVATION
OF
RISK
BASED
CONCENTRATIONS
(
RBCs).........
17
Risk
Based
Concentration
(
RBC)
Equation
..................................................
17
Acceptable
Target
Risk
(
TR)
or
Hazard
Index
(
THI)
...................................
19
Summary
Intake
Factor
(
SIF)
Parameters
.....................................................
19
Application
Rate
(
AR)
and
Fraction
of
Nutrient
(
FON)
...............................
24
Soil
Accumulation
Factor
(
SACF)
................................................................
25
Plant
Uptake
Factors
(
PUFs).........................................................................
28
Toxicity
Assessment......................................................................................
31
SECTION
3.0
¾
PRESENTATION
OF
RISK
BASED
CONCENTRATIONS
(
RBCs)

FOR
METALS
OF
POTENTIAL
CONCERN
(
MOPC)..............................
33
SECTION
4.0
¾
SCREENING
HEALTH
EVALUATION:
COMPARISON
OF
THE
RISK
BASED
CONCENTRATIONS
(
RBC)
WITH
THE
CONCENTRATION
OF
THE
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
IN
FERTILIZER
PRODUCTS
......................................................
34
Results
...........................................................................................................
35
SECTION
5.0
¾
DERIVATION
OF
THE
RISK
BASED
CONCENTRATION
(
RBC)

FOR
RADIONUCLUDE
(
RADIUM226)
AND
SCREENING
LEVEL
HEALTH
EVALUATION:
COMPARISON
OF
THE
RBC
WITH
PRODUCT
DATA........................................................................................
36
Relative
Toxicity...........................................................................................
36
Relative
Concentration
in
Product
................................................................
36
Evaluation
Precedence
..................................................................................
36
Derivation
of
the
Risk
Based
Concentration
(
RBC)
.....................................
37
ii
DRAFT
SECTION
6.0
¾
DISCUSSION
OF
UNCERTAINTY.......................................................
39
Scope
of
the
Evaluation.................................................................................
39
Derivation
of
the
Risk
Based
Concentration
(
RBC)
.....................................
40
Overall
Assessment
of
Uncertainty
on
the
RBC
and
Health
Risk
Screening
Evaluation.....................................................................................
42
SECTION
7.0
¾
CONCLUSIONS
OF
EVALUATION.....................................................
43
SECTION
8.0
¾
COMPARISON
to
other
EVALUATIONS
.............................................
44
Purpose
and
General
Approach.....................................................................
44
Scope
.............................................................................................................
45
Key
Parameters..............................................................................................
45
Conclusion
Regarding
Determination
of
Risk
..............................................
48
REFERENCES
..................................................................................................................
49
GLOSSARY
..................................................................................................................
53
LIST
OF
APPENDICES
Appendix
A
DEVELOPMENT
OF
RELATIVE
ABSORPTION
FACTORS
(
RAF)
AND
DERMAL
ABSORPTION
FACTORS
(
ABS)

Appendix
B
APPLICATION
RATE
DATABASE
COMPILED
FROM
USEPA
(
1999)
AND
CALCULATION
OF
APPLICATION
RATES
(
ARs)
FOR
PHOSPHATE
AND
ZINC
FERTILIZERS
Appendix
C
COLLECTION
OF
DATA
AND
SUMMARY
STATISTICS
FOR
PLANT
UPTAKE
FACTORS
(
PUFs)
iii
DRAFT
LIST
OF
TABLES
Table
1
SELECTION
OF
REPRESENTATIVE
FERTILIZER
PRODUCTS:
CONSIDERATION
OF
AMOUNT
USED
IN
THE
UNITED
STATES
(
U.
S.),
APPLICATION
RATE,
PERCENT
NUTRIENT
IN
PRODUCT,
AND
MOPC
CONCENTRATION
Table
2
SELECTION
OF
METALS
OF
POTENTIAL
CONCERN
(
MOPC):
CONSIDERATION
OF
RELATIVE
TOXICITY,
RELATIVE
PRODUCT
CONCENTRATION,
AND
EVALUATION
PRECEDENCE
Table
3
SELECTION
OF
REPRESENTATIVE
AND
HEALTH
PROTECTIVE
EXPOSURE
SCENARIO
Table
4
SELECTION
OF
REPRESENTATIVE
AND
HEALTH
PROTECTIVE
CROP
GROUPINGS
Table
5
VALUES,
DESCRIPTIONS,
AND
REFERENCES
FOR
BIOLOGICAL
EXPOSURE
PARAMETERS
Table
6
APPLICATION
RATES
(
ARs)
FOR
PHOSPHATE
FERTILIZERS
AND
ZINC
MICRONUTRIENT
FERTILIZERS
Table
7
PARAMETERS
USED
TO
CALCULATE
SOIL
ACCUMULATION
FACTORS
(
SACFs)

Table
8
SOIL
ACCUMULATION
FACTORS
(
SACFs)

Table
9
PLANT
UPTAKE
FACTORS
(
PUFs)
FOR
EACH
CROP
GROUP
Table
10
ORAL
AND
DERMAL
TOXICITY
VALUES
Table
11
SUMMARY
OF
ALL
OF
THE
PARAMETERS
AND
ASSUMPTIONS
USED
TO
CALCULATE
THE
SUMMARY
INTAKE
FACTORS
(
SIFs)

Table
12
SUMMARY
INTAKE
FACTORS
(
SIFs)

Table
13
PARAMETERS
(
SACF,
AR,
PUF,
FOL,
AND
TOXICITY
VALUES)
USED
TO
CALCULATE
THE
RISK
BASED
CONCENTRATIONS
(
RBCs)

Table
14
UNIT
RISK
BASED
CONCENTRATIONS
(
RBCs)
FOR
ALL
SCENARIOS
Table
15
PERCENT
FRACTION
OF
NUTRIENT
(
FON)
ESTIMATES
FOR
PHOSPHATE
FERTILIZER
PRODUCT
CATEGORIES
iv
DRAFT
Table
16
PERCENT
FRACTION
OF
NUTRIENT
(
FON)
ESTIMATES
FOR
MICRONUTRIENT
FERTILIZER
PRODUCT
CATEGORIES
Table
17
SCREENING
LEVEL
EVALUATION:
COMPARISON
OF
THE
CONCENTRATION
OF
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
IN
PHOSPHATE
FERTILIZERS
TO
THE
ADJUSTED
RISK
BASED
CONCENTRATION
(
RBC)

Table
18
SCREENING
LEVEL
EVALUATION:
COMPARISON
OF
THE
CONCENTRATION
OF
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
IN
MICRONUTRIENT
FERTILIZERS
TO
THE
ADJUSTED
RISK
BASED
CONCENTRATION
(
RBC)

Table
19
MAJOR
ASSUMPTIONS
AND
UNCERTAINTIES
ASSOCIATED
WITH
THE
RISK
BASED
CONCENTRATIONS
(
RBCs)
AND
THE
SCREENING
LEVEL
HEALTH
RISK
EVALUATION
Table
20
MAGNITUTE
OF
RELATIVE
IMPACT
ASSOCIATED
WITH
EACH
PARAMETER
IN
THE
RISK
EQUATION
Table
21
COMPARISON
OF
THE
PURPOSE,
GENERAL
APPROACH,
AND
SCOPE
OF
THIS
EVALUATION
TO
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
AND
CDFA
(
1998)
DEVELOPMENT
OF
RISK
BASED
CONCENTRATIONS
(
RBCs)
FOR
ARSENIC,
CADMIUM,
AND
LEAD
Table
22
COMPARISON
OF
KEY
PARAMETERS
USED
IN
THIS
EVALUATION
TO
THESE
PARAMETERS
IN
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
AND
CDFA
(
1998)
DEVELOPMENT
OF
RISK
BASED
CONCENTRATIONS
(
RBCs)
FOR
ARSENIC,
CADMIUM,
AND
LEAD
Table
23
COMPARISON
OF
PLANT
UPTAKE
FACTORS
(
PUFs)
USED
IN
THIS
EVALUATION
TO
THE
PUFs
DEVELOPED
IN
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
AND
CDFA
(
1998)
DEVELOPMENT
OF
RISK
BASED
CONCENTRATIONS
(
RBCs)
FOR
ARSENIC,
CADMIUM,
AND
LEAD
Table
24
COMPARISON
OF
THE
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
CONCENTRATIONS
IN
PHOSPHATE
FERTILIZER
PRODUCTS
USED
IN
THIS
EVALUATION
TO
THE
MOPC
CONCENTRATIONS
USED
IN
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
Table
25
COMPARISON
OF
THE
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
CONCENTRATIONS
IN
MICRONUTRIENT
FERTILIZER
PRODUCTS
USED
IN
THIS
EVALUATION
TO
THE
MOPC
CONCENTRATIONS
USED
IN
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
v
DRAFT
LIST
OF
FIGURES
Figure
1
RISK
EVALUATION
FOR
THE
LIFE
CYCLE
OF
AN
INORGANIC
FERTILZER
Figure
2
NARROWING
THE
SCOPE
OF
THIS
SCREENING
LEVEL
EVALUATION
 
FOCUSING
ON
THE
FERTILIZERS
PRODUCTS,
METALS,
AND
EXPOSURE
SCENARIO
OF
HIGHEST
CONCERN
Figure
3
POTENTIAL
EXPOSURE
PATHWAYS
OF
METALS
OF
POTENTIAL
CONCERN
(
MOPC)
IN
INORGANIC
FERTILIZER
POST
APPLICATION
INCLUDES:
TRANSPORT
PATHWAYS,
MEDIA
OF
POTENTIAL
CONCERN,
AND
ASSOCIATED
EXPOSURE
ROUTES
LIST
OF
EQUATIONS
Equation
1
RBC
FOR
THE
SINGLE
CROP
FARM
Equation
2
RBC
FOR
THE
MULTI­
CROP
FARM
Equation
3
ACCUMULATED
SOIL
CONCENTRATION
Equation
4
SOIL
ACCUMULATION
FACTOR
(
SACF)

Equation
5
METAL
LOSS
DUE
TO
LEACHING
FROM
SOIL
vi
DRAFT
EXECUTIVE
SUMMARY
An
evaluation
of
the
potential
human
health
risks
from
exposure
to
metals
(
primarily
nonnutritive
elements)
found
in
inorganic
fertilizers
following
their
application
to
agricultural
soil
is
presented
in
this
report.
This
evaluation
comprises
one
component
of
a
program
developed
and
funded
by
The
Fertilizer
Institute
(
TFI)
that
is
intended
to
answer
the
question:
are
fertilizers
safe?
The
overall
program
is
viewed
in
the
context
of
the
life
cycle
of
an
inorganic
fertilizer.
Two
additional
components
of
the
program
include:
(
1)
an
assessment
of
risks
to
fertilizer
applicators
from
exposure
to
metals
in
products1,
and
(
2)
a
whole
product
toxicity
and
occupational
exposure
evaluation.
There
are
also
two
other
recent
reports,
one
by
the
United
States
Environmental
Protection
Agency
(
USEPA)
and
another
by
the
California
Department
of
Food
and
Agriculture
(
CDFA),
that
provide
information
to
address
the
same
questions
of
post
application
fertilizer
safety.
Their
scopes,
methodologies
and
conclusions
are
also
summarized
in
this
report.

Metals
are
generally
present
in
inorganic
fertilizers
as
byproducts
or
contaminants.
There
are
however
some
metals,
for
example
zinc,
iron
and
copper,
that
are
plant
nutrients
and
are
intentionally
included
in
fertilizer
formulations.
It
is
acknowledged
a
priori
that
exposure
to
high
enough
levels
of
metals
(
nutrient
or
otherwise)
could
pose
a
health
risk.
This
evaluation
establishes
safe
limits
of
metals,
referred
to
as
risk
based
concentrations
(
RBCs),
in
inorganic
fertilizers
that
are
applicable
under
any
foreseeable
set
of
local
conditions.

The
methodology
used
to
develop
the
RBCs
is
a
back­
calculation
of
health
risks
and
is
standard
for
a
screening
level
risk
evaluation.
This
approach
provides
the
basis
to
screen
specific
fertilizers,
either
as
groups
(
e.
g.,
DAP,
phosphate
blends,
or
zinc
micronutrients)
or
individually
(
e.
g.,
a
10­
30­
5
blend
or
a
50%
zinc
oxide).
There
are
three
basic
steps
in
the
screening
level
evaluation:
(
1)
narrow
the
scope
to
focus
on
the
highest
possible
risks;
(
2)
derive
the
health
protective
RBC
values
for
each
metal
of
concern;
and
(
3)
compare
the
RBC
value
for
each
metal
to
the
measured
concentration
of
that
metal
in
fertilizer
products.
If
the
measured
concentrations
are
below
the
RBC
values,
then
there
are
negligible
health
risks.
If
the
measured
concentrations
exceed
the
RBC
values,
then
there
may
or
may
not
be
a
health
risk,
and,
a
further,
more
in­
depth
evaluation
is
warranted.

The
first
step
of
the
evaluation,
narrowing
the
scope,
involves
choosing
those
fertilizer
products,
metals,
and
exposure
scenarios
that
are
associated
with
the
highest
potential
health
risks.
Those
that
are
not
directly
evaluated
are
still
represented
because
their
associated
risks
are
even
less
than
those
that
are
evaluated
directly.
Based
on
the
available
data,
on
analyses
from
existing
reports
on
fertilizer
health
risks,
and
consistent
with
accepted
health
risk
assessment
methodology,
this
evaluation
focuses
on:

1
Evaluation
completed
for
metals
and
applicators;
it
was
determined
that
risks
to
fertilizer
applicators
from
metals
are
negligible
(
THE
WEINBERG
GROUP
INC.
(
TWG).
1999a,
Health
Risk
Based
Concentrations
for
Fertilizer
Products
and
Fertilizer
Applicators.
And
TWG
1999b,
Fertilizer
Applicator
Health
Risk
Evaluation
for
Nonnutritive
Elements
in
Inorganic
Fertilizers).
vii
DRAFT
·
phosphate
fertilizers
and
micronutrient
fertilizers;
·
12
metals
(
referred
to
as
metals
of
potential
concern
[
MOPC])
including:
arsenic,
cadmium,
chromium,
cobalt,
copper,
lead,
mercury,
molybdenum,
nickel,
selenium,
vanadium,
zinc,
and
one
radionuclide,
radium
226;
·
exposure
to
the
farm
family
(
including
adults
and
children);
·
ingestion
of
crops,
unintentional
ingestion
of
fertilized
soil,
and
dermal
contact
with
fertilized
soil;
and
·
single
and
multi­
crop
farming
scenarios.

The
second
step
of
the
evaluation,
deriving
the
health
protective
RBCs
for
each
metal,
involves
estimating
reasonable
maximum
exposures
(
RME)
to
the
metals.
The
metals
are
evaluated
for
non­
cancer
and/
or
cancer
hazards,
as
applicable,
and
the
RBCs
are
established
at
accepted
risk
levels
(
i.
e.,
a
1x10­
5
cancer
risk,
and
a
non­
cancer
hazard
index
of
1.0).
In
general,
USEPA
standard
approaches,
assumptions
and
default
high­
end
exposure
values
are
used
in
developing
the
RBCs.
Overall,
the
RBCs
for
metals
are
derived
to
be
health
protective
to
ensure
that
health
risks
are
not
underestimated.
There
are
separate
RBCs
for
phosphate
fertilizers
and
for
micronutrient
fertilizers.

The
third
and
final
step
of
the
evaluation
involves
comparing
the
RBC
for
each
metal
to
the
maximum
measured
level
of
that
metal
in
fertilizer
products.
Using
the
maximum
metal
concentration
provides
the
most
health
protective
determination
of
a
health
risk.
The
concentration
data
are
obtained
from
the
published
literature,
from
a
survey
of
fertilizer
manufacturers,
and
from
monitoring
programs
being
conducted
by
a
number
of
states.
The
database
is
compiled
by
THE
WEINBERG
GROUP
and
is
updated
as
new
data
become
available.
To
date,
there
are
approximately
925
individual
phosphate
fertilizer
samples
in
15
categories
of
products2,
and
approximately
140
individual
micronutrient
fertilizer
samples
in
four
categories
of
products.
3
The
screening
comparison
indicates
there
are
no
exceedances
for
any
of
the
phosphate
fertilizer
RBCs,
and
therefore,
no
post­
application
health
risks
from
exposure
to
metals
in
NPK
types
of
fertilizers.
This
same
conclusion
is
reached
by
USEPA
in
their
recent
(
1999b)
fertilizer
risk
assessment.
4
The
CDFA
(
1998)
issued
its
own
report
of
RBCs
for
arsenic,
cadmium
and
lead
in
inorganic
fertilizers.
5
While
the
report
did
not
compare
RBCs
to
measured
levels
in
products,
the
RBCs
are
very
similar
to
those
in
this
evaluation,
and
therefore,
would
support
the
same
conclusion
of
negligible
risk
for
NPK
type
fertilizers
if
a
screening
comparison
were
conducted.

2
The
phosphate
fertilizer
categories
include:
NPK
blends,
ammonium
phosphate
sulfate,
ammonium
polyphosphate,
diammonium
phosphate
(
DAP),
monoammonium
phosphate
(
MAP),
nitrophosphate,
orthophosphate,
phosphate,
phosphoric
acid,
superphosphate,
superphosphoric
acid,
triple
superphosphate,
urea­
ammonium
phosphate,
ureaammonium
polyphosphate,
and
urea­
diammonium
phosphate.
3
The
micronutrient
fertilizer
categories
include:
boron,
iron,
manganese
and
zinc
micronutrients
(
no
mixes).
4
In
addition
to
evaluating
health
risks,
USEPA
conducted
a
screening­
level
ecological
risk
evaluation
of
metals
in
fertilizer
runoff
into
streams,
and
concludes
that
no
exceedances
of
water
quality
criteria
are
projected.
USEPA
1999b,
Estimating
Risks
from
Contaminants
Contained
in
Agricultural
Fertilizers.
5
CDFA
1998,
Development
of
Risk
Based
Concentrations
for
Arsenic,
Cadmium,
and
Lead
in
Inorganic
Commercial
Fertilizer.
viii
DRAFT
With
regard
to
micronutrient
fertilizers,
there
are
exceedances
of
arsenic
and
lead
RBCs
for
several
micronutrient
fertilizer
products.
These
products
contain
relatively
high
levels
of
arsenic
and
lead
in
some
samples.
The
USEPA
(
1999b)
reached
a
similar
conclusion
indicating
that
a
few
micronutrient
fertilizer
products
exceeded
the
acceptable
risk
levels
for
arsenic.
Because
of
the
health
protective
methodology
employed
in
screening
level
evaluations,
and
because
exceedances
occur
only
at
the
maximum
arsenic
and
lead
concentrations,
a
firm
conclusion
regarding
health
risks
from
the
micronutrient
products
in
question
requires
a
closer
evaluation.
This
refined
evaluation
would
take
into
account
product
specific
information
on
crop
uses,
application
rates,
fraction
of
nutrients
in
the
product,
and
metal
concentrations
from
multiple
samples
of
the
same
product.
This
product­
specific
information
would
replace
the
default,
highend
exposure
values
used
in
the
screening
risk
evaluation
equation.

As
with
all
risk
assessments
there
is
some
level
of
uncertainty
associated
with
this
evaluation.
The
major
uncertainties
are
identified
and
described
in
the
report.
The
uncertainty
is
more
likely
to
err
on
the
side
of
overestimating
the
potential
for
risk
rather
than
underestimating
the
potential
risk
for
both
the
NPK
and
micronutrient
fertilizer
products.

In
conclusion,
this
report,
along
with
the
recent
USEPA
(
1999b)
and
CDFA
(
1998)
evaluations,
provide
considerable
and
definitive
information
to
answer
the
question:
do
metals
in
fertilizers
pose
a
health
risk
following
application?
The
answer
is:
these
evaluations
indicate
that
metals
in
inorganic
fertilizers
do
not
pose
post­
application
harm
to
human
health.
It
is
clear
that
the
risks
are
negligible
for
metals
in
NPK
type
fertilizers.
For
the
majority
of
micronutrient
fertilizer
products
for
which
we
have
data,
the
risks
are
also
clearly
negligible.
A
few
samples
for
a
few
micronutrient
products
have
concentrations
of
arsenic
or
lead
that
exceed
the
corresponding
RBCs.
However,
no
definitive
conclusion
regarding
health
risk
can
be
made
until
these
materials
are
further
evaluated
in
a
specific
case­
by­
case
manner.
Screening
risk
evaluations
are
designed
to
identify
if,
and
where,
additional
attention
may
be
warranted.
Actual
risks
may
well
be
overestimated,
but
they
are
not
underestimated,
by
the
RBC
values.

So
where
do
things
stand
in
the
life
cycle
evaluation:
are
inorganic
fertilizers
safe?
This
report
and
the
CDFA
(
1998)
report
address
post
application
health
risks;
the
recent
USEPA
(
1999b)
report
addresses
post
application
health
and
environmental
risks;
and
the
TWG
(
1999a,
b)
reports
address
applicator
risks
from
metals
in
fertilizers.
In
total,
these
evaluations
support
the
conclusion
that
these
fertilizers
are
safe.
The
remaining
aspect
of
this
life
cycle
evaluation
is
an
evaluation
of
whole
product
toxicity
and
occupational
risks.
This
evaluation
is
underway
at
TFI.
It
is
both
prudent
and
responsible
to
conduct
such
an
evaluation.
However,
the
fact
that
there
are
industry
and
government
standards
in
place
to
protect
workers
and
the
environment,
and
given
the
long
history
of
the
fertilizer
industry,
the
answer
seems
obvious.
The
information
that
is
being
assembled
is
the
proof.
1
DRAFT
INTRODUCTION
This
document
presents
an
evaluation
of
the
potential
human
health
risks
from
exposure
to
metals
(
primarily
non­
nutritive
elements)
found
in
inorganic
fertilizers
following
their
application
to
agricultural
soil.
This
evaluation
comprises
one
component
of
a
program
developed
and
funded
by
The
Fertilizer
Institute
(
TFI)
that
is
intended
to
answer
the
question:
are
fertilizers
safe?
The
overall
program
is
viewed
in
the
context
of
the
entire
life
cycle
of
an
inorganic
fertilizer,
as
diagrammed
in
Figure
1.
As
seen
in
Figure
1,
this
human
health
risk
evaluation
focuses
on
the
latter
part
of
the
life
cycle,
that
is,
post
application.
6
Metals
are
generally
present
in
inorganic
fertilizer
as
byproducts
or
contaminants.
These
nonnutritive
elements
are
not
purposely
present
in
the
fertilizer
and
are
not
needed
by
the
plant
for
growth.
Some
metals,
for
example
zinc,
iron,
and
copper,
are
plant
nutrients
and
their
presence
in
fertilizers
is
essential
for
plant
growth.
This
human
health
risk
evaluation
includes
a
dozen
metals,
both
non­
nutritive
and
nutritive,
as
well
as
radioactive
elements.
7
In
this
report,
all
of
the
metals
under
evaluation
are
referred
to
as
`
metals
of
potential
concern'
or
MOPC.

The
information
presented
in
this
document
is
intended
to
be
easy
to
use
by
fertilizer
manufacturers,
regulators,
and
the
public.
There
are
many
fertilizer
products,
many
uses
(
varying
by
local
conditions),
many
metals
(
and
at
varying
concentrations),
and
a
number
of
possible
scenarios
where
a
person
could
be
exposed
to
MOPC
following
the
application
of
fertilizers
to
agricultural
soils.
The
intention
of
this
document
is
to
derive
safe
exposure
levels
for
these
metals
that
would
be
applicable
under
any
foreseeable
set
of
local
conditions,
rather
than
to
determine
if
a
given
product
and
local
conditions
pose
an
unacceptable
health
risk.
In
the
language
of
`
risk
assessment',
the
former
is
called
a
back
calculation
of
risk
and
the
latter
is
called
a
forward
calculation
of
risk.
Both
approaches
use
the
same
fundamental
risk
assessment
science.
The
forward
calculation
allows
a
determination
of
whether
`
fertilizer
product
A'
used
under
`
conditions
B'
poses
a
health
risk.
The
back
calculation
allows
extrapolation
to
a
much
wider
set
of
product
and
local
condition
combinations
now
and
in
the
future.
In
the
back
calculation,
the
results
are
presented
as
concentrations
of
metals
that
are
considered
"
safe"
under
reasonable
worst
case
conditions.
These
concentrations
are
called
`
risk
based
concentrations'
or
RBCs.
By
the
nature
of
their
derivation,
RBCs
are
also
typically
called
`
screening
level
values'
and
are
intended
for
screening
level
evaluations.
In
a
screening
level
evaluation,
RBCs
are
used
to
determine
if
a
given
fertilizer
product
is
safe
by
comparing
the
RBC
with
the
metal
concentration
in
the
product.

6
The
Weinberg
Group
Inc.
(
TWG)
prepared
two
previous
reports
that
evaluate
the
health
risks
to
applicators
of
fertilizers
for
TFI.
They
are:
TWG.
1999a.
Health
Risk
Based
Concentrations
for
Fertilizer
Products
and
Fertilizer
Applicators.
and
TWG.
1999b.
Fertilizer
Applicator
Health
Risk
Evaluation
for
Non­
nutritive
Elements
in
Inorganic
Fertilizers:
Risk
Based
Concentrations
(
RBCs)
Compared
to
Measured
Levels
of
Non­
nutritive
Elements
in
Products.
These
reports
concluded
there
is
no
significant
health
risk
for
fertilizer
applicators.

7
Due
to
the
major
difference
regarding
the
toxic
nature
of
radionuclides
compared
to
metals,
and
thus
the
significant
difference
in
evaluating
risk
from
exposure,
radionuclides
are
evaluated
separately.
The
evaluation
of
radionuclides
can
be
found
in
Section
5.0.
2
DRAFT
Since
RBCs
are
used
primarily
for
screening
level
evaluations,
they
are
based
on
the
exposure
scenario
that
reflects
the
reasonable
maximum
exposure
(
RME),
and
are
intended
to
be
health
protective
of
all
other
scenarios.
In
this
way,
RBCs
are
derived
to
ensure
that
health
risks
are
not
underestimated.
In
general,
United
States
Environmental
Protection
Agency
(
USEPA)
standard
approaches
and
values
are
used
in
developing
the
RBCs
in
this
evaluation
of
metals
in
fertilizers.

In
addition
to
the
development
and
presentation
of
RBCs,
this
report
also
presents
a
screening
level
health
risk
evaluation
where
the
RBC
for
each
metal
is
compared
to
the
available
database
of
measured
levels
of
the
metals
in
fertilizer
products.
Measurements
of
metal
concentrations
in
fertilizer
products
conducted
in
the
future
could
also
be
compared
to
the
RBCs
in
order
to
screen
for
potential
human
health
risks.

Finally,
this
evaluation
builds
upon
existing
reports
and
information
on
potential
health
risks
from
exposure
to
metals
in
fertilizers
to
answer
the
question:
are
fertilizers
safe?
Considerable
data
and
analyses
have
been
reported
in
recent
months
by
the
USEPA
and
by
the
California
Department
of
Food
and
Agriculture.
8
This
report
is
organized
as
follows:

SECTION
1.0
 
DEFINING
THE
SCOPE
OF
THIS
EVALUATION.
The
logic
and
rationale
that
was
used
to
define
the
scope
of
this
evaluation
is
presented.
Specifically,
this
section
identifies
the
fertilizer
product
categories
that
are
evaluated,
the
metals
for
which
RBCs
are
developed,
and
the
human
exposure
scenarios
and
the
crop
groups
that
the
RBCs
are
based
upon.

SECTION
2.0
 
DERIVATION
OF
RISK
BASED
CONCENTRATIONS
(
RBCs).
In
this
section,
the
RBC
equation
and
the
following
parameters
and
factors
are
described.

SECTION
3.0
 
PRESENTATION
OF
THE
RISK
BASED
CONCENTRATIONS
(
RBCs)
FOR
METALS
OF
POTENTIAL
CONCERN
(
MOPC).
In
this
section,
the
screening
level
RBCs
are
selected
and
described
for
each
MOPC.

SECTION
4.0
 
SCREENING
LEVEL
HEALTH
EVALUATION:
COMPARISON
OF
RBCs
WITH
CONCENTRATIONS
OF
MOPC
IN
FERTILIZER
PRODUCTS.
In
this
section,
the
RBCs
for
each
MOPC
are
compared
to
metal
concentration
data
for
each
of
the
product
categories.

8
The
following
resources
provided
critical
information
in
streamlining
and
focusing
the
scope
of
this
evaluation:

·
California
Department
of
Food
and
Agriculture
(
CDFA)
and
the
Heavy
Metal
Task
Force.
1998.
Development
of
Risk­
Based
Concentrations
for
Arsenic,
Cadmium,
and
Lead
in
Inorganic
Commercial
Fertilizer.
Foster
Wheeler
Environmental
Corporation,
Sacramento,
CA.
·
United
States
Environmental
Protection
Agency
(
USEPA).
1999a.
Background
Report
on
Fertilizer
Use,
Contaminants
and
Regulations.
Columbus,
OH:
Battelle
Memorial
Institute.
·
United
States
Environmental
Protection
Agency
(
USEPA).
1999b.
Estimating
Risk
from
Contaminants
Contained
in
Agricultural
Fertilizers.
Draft.
Washington,
D.
C.:
Office
of
Solid
Waste
and
Center
for
Environmental
Analysis.
3
DRAFT
SECTION
5.0
 
DERIVATION
OF
THE
RISK
BASED
CONCENTRATION
FOR
RADIONUCLUDE
(
RADIUM226)
AND
SCREENING
LEVEL
HEALTH
EVALUATION:
COMPARISON
OF
THE
RADIUM226
RBC
WITH
PRODUCT
DATA.
In
this
section,
a
RBC
for
radium
226
is
derived
and
the
RBC
is
compared
to
radium226
product
data.

SECTION
6.0
 
DISCUSSION
OF
UNCERTAINTY.
In
this
section,
uncertainties
related
to
the
scope
of
this
health
risk
evaluation
and
the
derivation
of
RBCs
are
presented.

SECTION
7.0
 
CONCLUSIONS
OF
EVALUATION.
In
this
section,
conclusions
are
drawn
from
the
screening­
level
health
risk
evaluation
for
NPK
and
micronutrient
fertilizers.

SECTION
8.0
 
COMPARISON
TO
OTHER
EVALUATIONS.
In
this
section,
the
outcome
of
this
evaluation
is
compared
to
other
health
risk
evaluations
for
fertilizers,
including
USEPA
(
1999b)
and
CDFA
(
1998).
FIGURES
manufacture
transport
blending
storage
focus
on
products
and
application
(
a)

occupational
risks
(
b)
environment
this
evaluation
focus
on
metals
and
crop
ingestion
/
soil
contact
risks
(
a)
Occupational
exposure
to
metals
during
application
was
determined
to
be
safe
in
previous
evaluation
(
TWG
1999a,
b).

(
b)
Whole
product
toxicity
and
occupational
exposure
are
being
evaluated
in
another
program.

FIGURE
1.
RISK
EVALUATION
FOR
THE
LIFE
CYCLE
OF
INORGANIC
FERTILIZERS
DRAFT
5
DRAFT
SECTION
1.0
¾
DEFINING
THE
SCOPE
OF
THIS
EVALUATION
Consistent
with
a
screening
level
risk
evaluation9,
the
scope
of
this
evaluation
is
narrowed
to
focus
on
the
fertilizer
product
categories,
metals,
and
exposure
scenarios
that
have
the
highest
potential
for
health
risks.
10
Developing
RBCs
that
are
based
on
"
high­
end"
exposures
results
in
RBCs
that
are
protective
of
other
less
risky
scenarios
and
results
in
health
risks
that
are
not
underestimated.
Figure
2
entitled
`
Narrowing
the
Scope
of
the
Evaluation
­
Focusing
on
the
Fertilizer
Products,
Elements,
and
Exposure
Scenario
of
Highest
Concern'
presents
a
summary
of
how
each
of
these
key
components
was
narrowed.
In
addition,
the
narrowing
of
each
of
these
components
is
discussed
in
the
following
sections.

Selection
of
Representative
Fertilizer
Products
As
stated
previously,
the
purpose
of
this
assessment
is
to
evaluate
potential
health
risks
from
metals
in
inorganic
fertilizers
following
their
application
to
agricultural
soils.
The
fertilizer
products
that
result
in
the
greatest
addition
of
metals
to
soil
are
the
products
of
highest
concern.
The
magnitude
of
MOPC
addition
to
soil
is
dependent
on
several
factors
including
(
1)
the
composition
of
the
fertilizer,
(
2)
the
concentration
of
the
metal
in
the
fertilizer,
and
(
3)
the
amount
of
fertilizer
that
is
applied.
By
evaluating
the
health
risks
from
those
products
whose
use
results
in
the
greatest
addition
of
metals
to
soil,
the
wide
array
of
inorganic
fertilizers
is
covered
as
well.
That
is,
`
all'
fertilizers
can
be
evaluated
by
screening
for
health
risks
based
on
those
products
posing
the
highest
potential
risks.
Therefore,
a
critical
component
of
this
evaluation
is
the
characterization
of
inorganic
fertilizer
products
and
the
selection
of
the
products
that
will
be
representative
of
all
other
inorganic
fertilizer
products.

Table
1
presents
a
summary
of
each
of
the
factors
determining
the
magnitude
of
metal
addition
to
soil
and
identifies
the
representative
products
that
are
selected
for
health
risk
evaluation.
11
Each
of
the
factors
is
also
discussed
below.

Types
of
Inorganic
Fertilizers
and
Use
There
are
three
general
categories
of
inorganic
fertilizers:
macronutrient
(
or
primary)
fertilizers,
secondary
fertilizers,
and
micronutrient
fertilizers.
Each
of
the
general
categories
of
inorganic
fertilizers
supplies
plants
with
different
nutrients.
Macronutrient
fertilizers
supply
primary
nutrients,
which
include
nitrogen
(
N),
available
phosphate
(
P),
and
soluble
potash
or
potassium
(
K).
There
are
products
that
supply
each
of
the
nutrients
separately,
as
well
as
blends;
for
example
NPK.
Also,
there
are
numerous
phosphate
fertilizers,
such
as,
diammonium
phosphate
(
DAP),
triple
super
phosphate
(
TSP),
and
monoammonium
phosphate
(
MAP).
There
are
also
many
different
types
of
macronutrient
nitrogen
fertilizer
products
(
e.
g.,
ammonium
nitrate,

9
Narrowing
the
scope
of
a
screening
level
evaluation
to
focus
on
the
scenario
that
is
health
protective
and
representative
of
all
other
scenarios
is
standard
USEPA
practice
[
as
indicated
in
USEPA
guidance
(
1995),
and
used
to
assess
health
and
environmental
risks
from
fertilizers
in
USEPA
(
1999b)
and
CDFA
(
1998)].
10
Based
on
a
screening
level
ecological
risk
evaluation
of
metals
in
fertilizer
runoff
into
streams,
USEPA
(
1999b)
concluded
that
no
exceedances
of
water
quality
criteria
are
projected.
11
Information
used
in
this
section
was
obtained
primarily
from
USEPA
(
1999a)
and
TWG
(
1999b).
6
DRAFT
ammonium
polysulfide,
sodium
nitrate,
and
urea).
Macronutrient
fertilizers
are
used
the
most
in
the
US,
accounting
for
91%
of
the
total
inorganic
fertilizer;
specifically,
38%,
12%,
10%,
and
31%
of
N,
P,
K,
and
NPK
are
used,
respectively
(
USEPA
1999a).

Secondary
fertilizers
supply
secondary
nutrients
to
plants
including
calcium,
magnesium,
and
sulfur.
Examples
of
secondary
fertilizer
products
include
calcium
chloride,
calcium
chelate,
and
magnesium
chelate.
Secondary
and
micronutrient
fertilizers
(
discussed
below)
account
for
only
4.5%
of
the
total
inorganic
fertilizer
use
in
US
agriculture
(
USEPA
1999a).

Micronutrient
fertilizers
supply
plants
with
boron,
chlorine,
cobalt,
copper,
iron,
manganese,
molybdenum,
sodium,
and/
or
zinc.
For
example,
zinc
micronutrient
fertilizers
supply
zinc,
iron
micronutrient
fertilizers
supply
iron,
and
mixes
supply
one
or
more
of
the
micronutrients.
Examples
of
micronutrient
products
include
manganese
oxide,
cobalt
sulfate,
and
zinc
sulfate.
Among
the
various
micronutrient
fertilizers
(
e.
g.,
boron,
iron,
manganese,
and
zinc),
zinc
is
used
the
most
throughout
the
US
(
Hignett
and
McClellan
1985).

Product
Composition
/
Percent
Nutrient
In
addition
to
the
nutrient
composition
(
i.
e.,
N,
P,
K
and
secondary
and
micronutrient
described
above),
the
percent
of
each
nutrient
(
e.
g.,
P2O5
or
zinc)
in
a
product
varies.
For
example,
as
can
be
seen
in
Table
1,
percent
nutrient
of
P2O5
ranges
from
2­
70%
(
USEPA
1999a).

Application
Rates
The
application
rate
(
AR)
of
any
given
fertilizer
can
vary
depending
on
the
nutrient
needs
of
the
plant
and
the
local
soil
conditions.
The
AR
is
also
influenced
by
the
composition
of
the
product
and
the
percent
nutrient
content.
The
lower
the
percentage
of
nutrient
in
a
product,
the
higher
the
AR
required
to
meet
the
plant's
nutrient
needs.
The
ARs
presented
in
Table
1
are
high­
end
estimates
(
95th
percentile)
and
are
based
on
the
nutrient
needs
of
high
acreage
US
crops
(
USEPA
1999a).
As
can
be
seen
in
Table
1,
nitrogen
(
N)
has
the
highest
AR
of
each
of
the
primary
nutrients
and
phosphate
(
P)
has
the
second
highest
AR.
The
ARs
for
secondary
and
micronutrients
are
generally
much
lower
than
the
ARs
for
the
primary
nutrients.

Concentration
of
Metal
in
Products
Metals
occur
in
fertilizers
because
of
the
sources
of
the
nutrients.
As
a
category,
phosphate
fertilizers
have
the
highest
levels
of
metals
among
the
primary
and
secondary
nutrients,
thus,
the
"
high"
relative
concentration
rating.
Nitrogen
fertilizers
(
and
NPK
applied
for
N)
have
lower
concentrations
of
MOPC
compared
to
phosphate
fertilizers
(
and
NPK
applied
for
P)
and
potash
fertilizers
generally
have
much
lower
concentrations
of
MOPC
than
nitrogen
fertilizers
(
USEPA
1999a,
b).
Phosphorous
is
mined
from
phosphorous
rock,
and
phosphorous
ores
naturally
contain
metals.
12
Depending
upon
their
source
of
nutrients,
micronutrient
fertilizers
can
also
have
relatively
high
levels
of
metals.
As
presented
in
Table
1,
iron
and
zinc
micronutrients
have
12
As
reported
in
Raven
and
Loeppert
(
1997),
Potash
&
Phosphate
Institute
(
PPI)
(
1998),
CDFA
(
1998),
TWG
(
1999c),
and
USEPA
(
1999a).
7
DRAFT
the
highest
relative
concentrations
of
MOPC
(
especially
when
considering
arsenic
in
iron
micronutrients)
(
USEPA
1999a,
b).
Micronutrient
mixes
can
also
have
relatively
high
concentrations
of
select
MOPC.
Since
the
metals
exist
in
the
nutrient
part
of
the
fertilizer,
the
percent
nutrient
of
the
product
has
a
direct
bearing
on
the
concentration
of
metal
in
the
final
product.
Table
1
lists
`
concentration
relative
ratings'
for
the
metals
evaluated
in
this
assessment.
The
actual
measured
concentrations
of
metals
in
numerous
products
have
been
compiled
in
a
database
from
industry,
state
and
literature
sources
(
TWG
1999c).

Representative
Fertilizer
Products
Considering
all
of
the
factors
discussed
above
and
the
information
presented
in
Table
1,
phosphate
fertilizers
are
selected
to
represent
the
macronutrient
(
primary
and
secondary)
fertilizers
in
developing
the
health
protective
RBCs
and
comparing
them
to
measured
levels
in
products.
The
application
of
phosphate
fertilizers
is
expected
to
result
in
the
greatest
addition
of
metals
to
soil,
and
therefore,
the
highest
potential
for
exposure
among
the
macronutrient
fertilizers.
13
The
RBCs
are
developed
for
a
generic
phosphate
fertilizer
but
are
then
modified
to
account
for
different
percent
nutrient
content
in
specific
phosphate
fertilizers
(
e.
g.,
DAP,
TSP)
or
phosphate
blends
(
e.
g.,
NPK
of
various
percent
nutrient
combinations).
14
Zinc,
manganese,
iron,
and
boron
micronutrient
fertilizers
are
selected
to
represent
micronutrient
fertilizers.
Micronutrient
mixes
are
not
specifically
evaluated,
however,
the
evaluation
of
the
other
micronutrients
will
be
health
protective
of
potential
risk
from
the
application
of
micronutrient
mixes
because
the
concentrations
of
MOPC
in
micronutrient
mixes
is
represented
by
the
other
micronutrient
fertilizers.
While
the
ARs
can
vary
among
micronutrient
products,
the
initial
screening
RBCs
are
based
on
the
AR
for
zinc
products.
The
ARs
for
different
micronutrient
fertilizers
are
similar.
In
the
health
risk
evaluation,
the
RBCs
are
modified
to
account
for
the
different
percent
nutrient
content
in
specific
micronutrient
fertilizers.

Other
commercial
fertilizer
products,
for
example,
nitrogen
only,
potassium
only,
secondary
nutrient
fertilizers,
and
the
remaining
micronutrient
fertilizers
and
mixes
are
not
specifically
evaluated
because
the
evaluation
of
phosphate
fertilizers,
and
select
micronutrients
(
as
discussed
above)
is
considered
health
protective
of
these
fertilizers.

Selection
of
Metals
of
Potential
Concern
(
MOPC)

As
can
be
seen
in
Table
2,
this
health
risk
assessment
begins
with
a
list
of
23
metals
that
are
potentially
found
in
inorganic
fertilizers.
15
For
similar
reasons
that
the
products
of
highest
potential
concern
are
selected
for
a
screening
risk
evaluation,
the
metals
selected
for
this
assessment
are
also
narrowed.
These
metals
are
called
MOPC.
MOPC
selected
for
evaluation
13
The
selection
of
phosphate
fertilizers
for
this
evaluation
is
further
supported
by
estimates
of
MOPC
loading
in
soil
from
macronutrient
fertilizer
application
in
both
the
USEPA
(
1999a)
and
CDFA
(
1998)
risk
assessments.
14
This
evaluation
focuses
on
granular
fertilizers.
Liquid
fertilizers
are
not
considered
separately
in
this
evaluation
because
liquid
fertilizers
are
generally
applied
at
a
much
lower
rate
then
granular
fertilizers.
Therefore,
the
evaluation
of
granular
fertilizers
will
be
health
protective
of
liquid
fertilizers
(
USEPA
1999a).
15
While
not
exhaustive,
this
list
is
considered
comprehensive.
It
was
developed
from
a
search
of
industry
and
published
literature
records
(
TWG
1999c).
Three
radionuclides
(
radium,
thorium
and
uranium)
were
also
considered
in
the
starting
list.
8
DRAFT
are
intended
to
be
representative
and
health
protective
of
all
the
metals
in
inorganic
fertilizer
products.
The
factors
that
are
considered
in
selecting
the
MOPC
include
(
1)
their
relative
toxicity,
(
2)
their
relative
concentration
in
products,
and
(
3)
whether
there
is
an
evaluation
precedence
(
e.
g.,
a
regulation
or
high
priority)
for
human
health
concerns.
Both
toxicity
and
concentration
in
products
are
considered
because
they
are
determinants
that
relate
directly
to
risk.
All
three
factors
are
detailed
in
Table
2,
along
with
the
list
of
MOPC
that
are
selected.

Relative
Toxicity
Relative
toxicity
is
determined
by
comparing
the
oral
reference
dose
(
RfD)
for
each
metal
as
established
by
USEPA
and
presented
in
USEPA's
Integrated
Risk
Information
System
(
IRIS).
16
The
oral
RfD
is
particularly
relevant
in
this
evaluation
because
oral
exposure
is
expected
to
contribute
the
greatest
potential
for
health
risk
from
metals
in
agricultural
soil.

Relative
Product
Concentration
The
data
describing
the
concentration
of
metals
in
products
comes
from
an
industry
and
published
literature
survey
conducted
for
TFI
(
TWG
1999c)
and
from
the
USEPA
publication
on
fertilizers
(
USEPA
1999a).
The
MOPC
concentration
in
the
fertilizer
products
is
rated
by
a
qualitative
evaluation
of
MOPC
concentrations
in
each
of
the
phosphate
fertilizer
and
micronutrient
fertilizer
product
categories
relative
to
each
other.
The
concentration
for
each
MOPC
is
compared
across
product
categories
and
rated
accordingly.
Products
with
obviously
high
MOPC
concentrations
are
rated
high;
product
categories
with
generally
low
MOPC
concentrations
are
rated
low.
The
relative
MOPC
concentrations
are
low
(
phosphate
fertilizer
<
10
ppm,
micronutrient
fertilizer
<
50ppm);
medium
(
phosphate
fertilizer,
10
ppm
 
100
ppm,
micronutrient
fertilizer,
50
ppm
 
1,000
ppm);
and
high
(
phosphate
fertilizer
>
100
ppm,
micronutrient
fertilizer
>
1,000
ppm).
Again,
these
qualitative
ratings
are
based
on
a
review
of
the
product
concentration
database
(
TWG
1999c.)

Evaluation
Precedence
As
seen
in
Table
2,
most
of
the
23
metals
on
the
starting
list,
and
all
of
the
MOPC
selected
for
this
health
risk
evaluation,
have
been
identified
and/
or
evaluated
in
previous,
relevant,
reports.
17
Evaluation
precedence
is
considered
an
important
aspect
in
the
final
selection
of
MOPC,
even
when
the
metal
was
not
highly
toxic
or
was
not
found
at
particularly
high
concentrations
in
fertilizer
products.

16
There
is
a
detailed
discussion
of
these
values
in
the
section
of
this
report
entitled
`
Toxicity
Assessment'.
17
The
following
reports
(
or
standards)
have
established
evaluation
precedence
for
the
MOPC:
·
California
based
RBCs
for
arsenic,
cadmium,
and
lead
are
developed
in
CDFA
(
1998).
·
Risks
from
arsenic,
cadmium,
chromium,
copper,
lead,
mercury,
nickel,
vanadium
and
zinc
contained
in
agricultural
fertilizers
was
estimated
in
USEPA
(
1999b).
·
Canada
has
established
metal
limits
in
fertilizers
for
arsenic,
cadmium,
cobalt,
mercury,
molybdenum,
nickel,
lead,
selenium,
and
zinc
as
reported
in
the
Canadian
Fertilizers
Act
R.
S.,
c.
F­
9s.
l.
(
1003).
·
Pollutant
limits
for
arsenic,
cadmium,
chromium,
copper,
lead,
mercury,
molybdenum,
nickel,
selenium,
and
zinc
in
biosolids
applied
to
agricultural
soils
were
developed
by
USEPA
(
1995).
9
DRAFT
Metals
of
Potential
Concern
(
MOPC)
Selected
for
Evaluation
The
following
12
metals
are
selected
as
MOPC.
Note,
the
elemental
symbol
for
each
metal
is
presented
in
parenthesis
next
to
each
MOPC,
however,
for
ease
in
reading
this
document,
the
full
name
is
used
throughout
this
document.
In
addition,
one
radionuclide
(
discussed
in
Section
5.0)
is
selected
for
evaluation.

Arsenic
(
As)
Copper
(
Cu)
Nickel
(
Ni)
Radium
226
(
Ra)
Cadmium
(
Cd)
Lead
(
Pb)
Selenium
(
Se)
Chromium
(
Cr)
Mercury
(
Hg)
Vanadium
(
V)
Cobalt
(
Co)
Molybdenum
(
Mo)
Zinc
(
Zn)

Selection
of
Health
Protective
Exposure
Scenarios
In
a
similar
manner
to
that
used
to
focus
on
which
fertilizer
products
and
MOPC
to
include
in
the
screening
risk
evaluation,
the
exposure
scenario
that
would
be
representative
and
health
protective
of
all
potential
exposure
scenarios
is
identified.
All
of
the
possible
exposure
pathways,
as
well
as
exposure
routes
for
potentially
exposed
populations,
that
occur
postapplication
are
considered.
The
exposure
scenario
with
the
greatest
exposure
and
risk
potential
is
then
identified.

Potential
Exposure
Pathways
The
first
step
in
selecting
the
exposure
scenario
with
the
highest
potential
risk
is
to
determine
all
of
the
possible
exposure
pathways
for
the
MOPC
in
fertilizer,
following
application.
A
complete
exposure
pathway
has
a
transport
pathway,
a
potential
exposure
media,
and
a
likely
exposure
route
(
mode
of
contact
with
the
receptor).
All
of
the
potential
exposure
pathways
are
presented
in
Figure
3.
Each
of
these
exposure
pathways
and
associated
exposure
routes
is
discussed
below.

1.
The
first
pathway
is
runoff
of
the
metals
into
surface
water,
followed
by
incidental
ingestion
and
dermal
contact
by
humans,
as
well
as,
uptake
into
fish
followed
by
ingestion
of
fish
by
humans.
This
exposure
pathway
and
routes
are
eliminated
as
a
major
exposure
pathway
because
(
a)
they
are
not
expected
to
contribute
significantly
to
risk
(
based
on
USEPA's
previous
assessment
of
fertilizers
(
1999b)
and
biosolids
(
1995))
and
(
b)
the
only
MOPC
that
is
expected
to
bioaccumulate
in
fish
is
a
form
of
mercury,
methyl
mercury.
18
The
other
MOPC
are
not
expected
to
bioaccumulate.

2.
Leaching
into
groundwater
followed
by
ingestion
in
drinking
water
is
eliminated
as
a
major
exposure
pathway
based
on
the
elimination
of
this
pathway
in
USEPA
(
1999b,
1995)
and
CDFA
(
1998).
Exposure
from
drinking
water
is
much
less
than
from
crop
consumption.

18
In
soil,
mercury
is
reactive
and
may
form
several
different
complexes.
Although
the
transport
of
mercury
into
a
nearby
water
body,
some
formation
of
methyl
mercury,
and
uptake
into
fish
may
occur,
it
is
expected
that
this
pathway
will
occur
less
frequently,
and
result
in
less
exposure
than
the
complexing
of
mercury
with
chlorine
in
soil
(
especially
since
chlorine
ions
may
be
the
most
persistent
and
available
complexing
agent
for
mercury
in
soil)
(
McLaughlin
et
al.
1996).
10
DRAFT
3.
Volatilization
of
metals
into
air
followed
by
inhalation,
and
wind
blown
dispersion
of
airborne
metals
followed
by
inhalation,
are
eliminated
as
major
exposure
pathways
based
on
USEPA
(
1999b)
and
CDFA
(
1998)
as
well
as
TWG's
applicator
risk
assessment
(
1999a,
b).
Specifically,
this
exposure
pathway
is
eliminated
because
MOPC
are
not
expected
to
volatilize
and
the
inhalation
of
particulates
was
found
to
contribute
minimally
to
risk
in
these
previous
evaluations.
Other
exposure
routes
that
are
selected
for
inclusion
in
the
RBC
equation
(
e.
g.,
unintentional
ingestion
of
fertilized
soil
or
ingestion
crops)
are
the
primary
contributors
to
risk.

4.
The
ingestion
of
MOPC
in
fertilized
soil
and
in
crops
by
foraging
cattle,
followed
by
the
subsequent
ingestion
of
animals
products
(
beef
and
milk)
by
humans,
is
eliminated
as
a
major
exposure
pathway.
19
Instead,
the
direct
exposure
pathways
(
i.
e.,
unintentional
ingestion
of
soil
and
dermal
contact
with
soil,
and
ingestion
of
crops)
are
considered
to
provide
a
much
higher
level
of
exposure,
especially
because
the
MOPC
do
not
bioaccumulate
in
the
terrestrial
food
chain
(
i.
e.,
cattle).

5.
Direct
contact
with
soil
(
i.
e.,
unintentional
ingestion
of
fertilizers
in
soil
and
dermal
contact
with
fertilizers
in
soil)
and
uptake
of
metals
in
the
soil
by
plants
(
crops)
followed
by
ingestion
are
considered
the
most
likely
and
most
substantial
exposure
pathways
and
therefore
are
the
basis
of
the
RBCs.
The
selection
of
these
exposure
pathways
is
based
on
information
presented
in
USEPA
(
1999b
and
1995),
CDFA
(
1998)
and
TWG
(
1999a,
b).

Potential
Populations
and
Exposure
Routes
The
next
step
in
defining
the
exposure
scenario
is
to
identify
all
of
the
potentially
exposed
populations
and
their
associated
exposure
routes.
This
step
is
presented
in
Table
3.
Note,
exposure
pathways
and
routes
eliminated
in
the
previous
step
are
not
included
in
this
table.
There
are
four
potential
populations
considered
for
evaluation
including
a
home
gardener,
the
general
public,
a
farm
worker,
and
a
resident
farmer.

Representative
and
Health
Protective
Exposure
Scenario
Compared
to
the
other
populations,
the
resident
farmer
has
many
more
potential
exposure
routes
and
greater
potential
for
exposure.
The
home
gardener
is
not
selected
because
of
the
lower
exposure
potential
and
low
use
of
fertilizers
compared
to
the
farmer.
The
general
public
is
not
selected
because
of
the
low
relative
exposure
potential
from
the
ingestion
of
soil
compared
to
the
resident
farmer.
The
farm
worker
has
been
evaluated
in
previous
reports
(
TWG
1999a,
b)
and
found
not
to
be
at
risk
from
metals
as
a
result
of
applying
fertilizers.
Clearly,
the
resident
farmer
(
and
family
including
children)
is
the
population
with
the
highest
exposure
potential
and
is
selected
as
the
population
that
the
RBCs
will
be
based
upon.
20
19
These
exposure
routes
are
eliminated
in
CDFA
(
1998)
screening
phase
of
the
assessment
because
they
contribute
much
less
to
risk
than
ingestion
of
crops.
20
The
selection
of
the
resident
farmer
as
the
representative
and
health
protective
population
is
supported
by
the
use
of
this
population
in
developing
RBCs
in
CDFA
(
1998)
and
the
use
of
this
population
to
estimate
risk
from
exposure
to
agricultural
fertilizers
in
USEPA
(
1999b).
11
DRAFT
In
most
risk
evaluations
there
are
populations
that
may
be
considered
"
sensitive
or
high­
end"
populations.
These
populations
are
at
potentially
higher
risk
from
exposure
compared
to
other
populations
either
because
the
population
is
particularly
sensitive
to
the
toxic
effect
of
the
MOPC
(
e.
g.,
children
are
especially
sensitive
to
lead
exposure)
or
because
the
population
is
considered
sensitive
(
e.
g.,
lactating
mother
or
elderly).
In
this
evaluation,
children
are
evaluated.
Elderly
are
not
specifically
evaluated
because
the
adult
farm
resident
scenario
is
considered
health
protective
of
an
elder.
The
exposure
routes
and
associated
exposure
parameters
used
to
evaluate
the
adult
farmer
resident,
represent
greater
exposure
than
an
elder
would
encounter.
The
lactating
mother
is
not
evaluated
because
metals
are
not
typically
fat
soluble,
and
therefore,
are
not
expected
to
be
at
elevated
concentrations
in
mother's
milk.
In
addition,
as
discussed
in
the
toxicity
assessment,
toxicity
values
have
uncertainty
factors
built
into
them
for
different
reasons,
one
of
which
is
to
protect
for
sensitive
subpopulations.

Selection
of
Representative
Crop
Groups
As
indicated
above,
the
ingestion
of
crops
is
a
significant
route
of
exposure.
The
magnitude
of
exposure
from
this
route
varies
depending
on
the
type
of
crop(
s)
evaluated.
Crops
vary
in
how
they
grow
(
e.
g.,
above
or
below
ground,
depth
of
root
system),
how
much
nutrient
they
need
to
grow
(
e.
g.,
higher
or
lower
phosphate
requirement),
and
their
ability
to
take
up
metals
into
edible
portions
of
the
plant.
For
the
purposes
of
this
assessment,
crops
are
therefore
grouped
by
type,
and
these
crop
groups
are
treated
separately
in
the
equation
used
to
derive
the
RBC
values
for
each
MOPC.

In
this
evaluation,
crops
are
grouped
considering
basic
physiology
("
like"
crops
were
grouped
together)
as
well
as
crop
grouping
and
evaluation
in
other
relevant
reports.
21
The
crop
groups
that
are
considered
include:
unexposed
vegetables
(
root
crops),
exposed
vegetables,
grains,
fruit,
forage
crops,
and
field
crops.
Each
of
these
groups
is
further
clarified
and
classified
below:

·
Vegetable
crops
are
also
called
exposed
crops
or
unprotected
crops.
Vegetable
crop
is
a
large,
broad
category
of
many
different
kinds
of
crops.
Examples
of
different
types
of
vegetables
are
leafy
vegetables
(
e.
g.,
endive,
kale,
lettuce,
spinach,
swiss
chard,
and
water
cress),
head
and
stalk
vegetables
(
e.
g.,
artichokes,
asparagus,
broccoli,
brussel
sprouts,
cabbage,
cauliflower,
celery,
and
peppers),
and
legumes
(
e.
g.,
beans
and
peas).
Several
crops
included
in
this
group
are
technically
fruits,
but
are
cultivated
as
vegetables
(
i.
e.,
cucumber,
eggplant,
and
tomato).
All
of
the
above
vegetables
are
considered
in
the
vegetable
crop
group.

·
Unexposed
vegetables
are
also
called
protected
vegetables,
root
crops,
herbage,
tubers,
or
bulbs.
This
report
will
refer
to
this
group
as
root
crops.
Root
crops
have
unique
growing
characteristics
and
are
considered
to
have
"
like"
physiologies;
thus,
they
are
evaluated
together.
Crops
in
this
category
include
beets,
carrots,
fennel,
mangel,
onion,
parsnip,
potatoes,
radish,
rutabaga,
and
turnip.

21
CDFA
(
1998)
evaluated
six
crop
groups:
vegetable,
root,
grain,
tree,
vine,
and
forage
crops.
USEPA
(
1999b)
evaluated
five
crop
groups:
grains,
forage,
fruit,
herbage,
and
roots.
Grain
and
forage
were
evaluated
through
ingestion
of
these
crops
by
cattle
and
subsequent
human
ingestion
of
animal
products.
12
DRAFT
·
Grains
are
also
a
large,
general
crop
group.
Grains
can
be
designated
as
field
grains,
silo
grains,
forage
grains,
or
small
or
large
grains.
The
grains
included
in
this
group
are
all
grains
consumed
by
humans.
Grains
consumed
by
cattle
(
forage
or
silo
grains)
are
not
included
in
this
evaluation
because,
as
discussed,
ingestion
of
animal
products
is
not
evaluated.
Grains
in
this
group
include
corn,
barley,
millet,
oat,
rice,
rye,
and
wheat.

·
Fruit
crops
can
be
grown
on
trees
(
i.
e.,
tree
fruits,
such
as,
limes,
lemons,
and
oranges)
or
as
sweet
fruits.
Examples,
of
sweet
fruits
include
cantaloupe,
apple,
rhubarb,
strawberry,
fig,
grapes,
kiwi,
and
pear.
Vine
crops
(
such
as,
grapes)
are
also
fruits.
The
ingestion
of
fruit
crops
is
not
included
in
this
evaluated
because
they
are
not
expected
to
contribute
significantly
to
exposure.
14
Nuts
are
also
tree
crops,
but
are
not
considered
in
this
evaluation
because
of
low
exposure
potential.
14
·
Field
crop
is
a
general
term
for
crops
grown
on
fields.
Examples
of
field
crops
include
corn,
cotton,
potatoes,
soybeans,
tobacco,
or
wheat
(
USEPA
1999a).
Field
crops
that
are
ingested
by
humans
are
evaluated
in
the
appropriate
crop
groupings
(
grain,
root,
or
vegetable
group).

·
Forage
crops
are
crops
that
are
grown
solely
for
the
purpose
of
feeding
cattle.
Again,
the
ingestion
of
animal
products
by
humans
was
eliminated
from
this
evaluation.
Therefore,
forage
crops
are
not
considered
further.
14
For
consistency,
these
crop
groupings
are
retained
throughout
the
different
components
of
this
evaluation
(
e.
g.,
development
of
plant
uptake
factors,
application
rates,
and
ingestion
rates)
given
available
data.
Crop
groups
expected
to
contribute
significantly
to
exposure
are
selected
for
inclusion
in
the
evaluation.
22
These
are
vegetable,
root
and
grain
crops.
Crop
groups
and
the
rationale
for
inclusion
are
presented
in
Table
4.

Farms
and
their
use
of
fertilizers
vary
by
size,
geography
(
including
soil
and
climate
conditions),
preferred
crop
types,
etc.
USEPA
(
1999a)
recent
report
on
the
use
of
fertilizers
includes
an
overview
of
fertilizer
consumption
and
the
amount
of
crops
produced
in
different
regions
of
the
country.
For
example,
the
following
table
indicates
where
the
use
of
different
fertilizer
types
is
heaviest,
and
those
states
with
the
highest
crop
acreage
(
by
crop).

22
CDFA
(
1998)
eliminated
tree
(
fruit
and
nut)
crops,
vine
crops
(
grapes),
and
forage
crops
from
the
development
of
RBCs
in
the
screening
phase
of
their
assessment
because
their
associated
exposure
to
arsenic,
cadmium,
and
lead
and
subsequent
risk,
were
determined
to
be
considerably
less
than
for
the
other
crop
groupings.
13
DRAFT
FERTILIZER
REGION
STATES
Phosphate
West
North
Central
East
North
Central
Illinois
Indiana
Multiple
Nutrient
South
Atlantic
West
North
Atlantic
Florida
Texas
Secondary
Nutrient
Pacific
South
Atlantic
California
North
Carolina
CROP
STATES
SPECIFIC
CROPS
California
Asparagus,
bell
pepper,
broccoli,
cabbage,
cauliflower,
celery,
lettuce,
tomatoes
Florida
Bell
peppers,
legumes,
snap
peas,
sweet
corn
(
fresh)
Georgia
Snap
peas
Vegetable
Michigan
Cucumbers
(
fresh)
California
Carrots,
onion
Idaho
Potato
Maine
Potato
New
York
Onion
Oregon
Onion
Root
Texas
Potato,
onion
Illinois
Corn
(
for
grain),
wheat
Indiana
Corn
Montana
Corn
Grain
Nebraska
Corn
California
Apples,
citrus
fruits
Fruit
Florida
Citrus
fruits
It
is
also
recognized
that
a
farm
may
grow
one
crop
or
it
may
grow
several
different
kinds
of
crops
(
i.
e.,
multi­
crop
farming).
The
exposure
scenario
for
a
single
crop
farm
could
be
quite
different
from
the
exposure
scenario
for
a
multi­
crop
farm.
For
example,
on
a
single
crop
farm
the
application
rate
would
be
the
same
for
every
parcel
of
the
farm,
because
only
one
crop
is
grown,
and
the
application
rate
is
dependent
on
the
crop
type.
Whereas,
on
a
multi­
crop
farm
the
application
rate
and
crop
acreage
is
proportioned
into
different
crop
groups
(
i.
e.,
grain,
50%,
vegetable,
40%,
and
root,
10%).
Another
parameter
that
is
used
to
quantify
exposure,
and
that
is
crop
specific,
is
the
plant
uptake
factor.
Therefore,
RBCs
for
both
a
single
crop
(
one
for
each
crop
group)
and
a
multi­
crop
(
combines
all
3
crop
groups)
are
developed.
The
lowest
of
these
four
RBCs
is
used
for
the
screening­
level
health
risk
evaluation.
14
DRAFT
Summary
of
Scope
The
scope
of
this
evaluation
is
focused
in
order
to
provide
a
health
protective
screening
evaluation
of
risks
associated
with
post
application
exposure
to
metals
in
inorganic
fertilizers.
Those
fertilizer
types,
metals,
receptors,
and
exposure
routes
that
are
associated
with
the
highest
potential
health
risks
are
identified
for
direct
evaluation.
Those
that
are
not
directly
evaluated
are
represented
because
their
associated
risks
are
even
less
than
those
that
are
evaluated
directly.
Based
on
the
available
data
and
on
analyses
from
existing
reports,
and
consistent
with
accepted
health
risk
assessment
methodology,
this
evaluation
focuses
on:

·
phosphate
fertilizers
and
micronutrient
fertilizers;
·
12
metals
including:
arsenic,
cadmium,
chromium,
cobalt,
copper,
lead,
mercury,
molybdenum,
nickel,
selenium,
vanadium,
zinc,
and
one
radionuclide,
radium
226;
·
exposure
to
the
farm
family
(
including
children);
·
ingestion
of
crops,
unintentional
ingestion
of
fertilized
soil,
and
dermal
contact
with
fertilized
soil;
and
·
single
and
multi­
crop
farming
scenarios
TABLES
TABLE
1
SELECTION
OF
REPRESENTATIVE
FERTILIZER
PRODUCTS:
CONSIDERATION
OF
USE
IN
THE
U.
S.,
APPLICATION
RATE,
PERCENT
NUTRIENT
IN
PRODUCT,
AND
RELATIVE
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
CONCENTRATION
Use
in
US
in
1996
High­
End
Range
of
Rating
of
General
Inorganic
rounded
to
the
(
95th
percentile)
Percent
Relative
Selected
for
Evaluation?

Fertilizer
Category
nearest
million
ton
Application
Rate
Nutrient
in
MOPC
Yes
(
Y)
or
(
purpose)
Nutrient
(
percent
of
total)
(
a)
(
lb/
acre­
year)
(
b)
Product
(
a)
Concentration
(
c)
No
(
N)
Rationale
Macronutrient
N
23
(
38)
206
(
d)
6.3
­
82
Medium
N
Evaluation
of
NPK­
P
and
P
will
be
health
protective
of
NPK­
N
and
N
(
supply
primary
because
of
the
low
relative
MOPC
concentration.

nutrient)
P
7
(
12)
173
(
e)
2.0
­
70.1
High
Y
Primarily
because
of
the
relative
high
MOPC
concentration.
Also
due
to
the
application
rate
and
amount
used
in
the
US.

K
6
(
10)
177
(
f)
9.8
­
62.1
Low
N
Low
relative
MOPC
concentration.

NPK
for
N
19
(
31)
206
3­
46
Medium
N
Evaluation
of
NPK­
P
and
P
will
be
health
protective
of
NPK­
N
and
N
because
of
the
low
relative
MOPC
concentrations.

NPK
for
P
173
11.5
­
27.4
High
Y
Primarily
because
of
the
relative
high
MOPC
concentration.

Also
due
to
the
application
rate
and
amount
used
in
the
US.

Secondary
(
g)
Sulfur
3
(
4.5)
40
14
­
100
N
Low
use
and
low
relative
MOPC
concentration.

(
supply
secondary
Calcium
4,000
NA
Low
(
i)
N
Low
use
and
low
relative
MOPC
concentration.

nutrient)
Magnesium
100
NA
N
Low
use
and
low
relative
MOPC
concentration.

Micronutrients
(
h)
Boron
3
10
­
21
Medium/
Low
(
i)
Y
High
relative
arsenic
concentration.

(
supply
micronutrient)
Iron
20
12
­
15
High
(
i)
Y
High
relative
arsenic
and
cadmium
concentration.

Manganese
10
24.7
­
29.5
Medium/
Low
(
i)
Y
High
relative
arsenic
concentration.

Zinc
10
7
­
58
High
(
i)
Y
High
relative
MOPC
concentration.

Mixes
30
NA
High/
Medium
(
i)
(
j)
N
Appropriate
information
is
not
available.

Notes:
Bold
=
Selected
as
the
representative
and
health
protective
product,
therefore,
evaluated
in
this
assessment.

MOPC
=
Metal
of
Potential
Concern
N
=
Nitrogen.
Examples
of
nitrogen
fertilizers
include:
ammonium
nitrate,
ammonium
sulfate,
ammonium
sulfate­
nitrate­
urea,
calcium
ammonium
nitrate,
calcium
cyanamide,
calcium
nitrate,

calcium
nitrate­
urea,
ferrous
ammonium
sulfate,
magnesium
nitrate,
nitric
acid,
sodium
nitrate,
urea,
urea
formaldehyde,
zinc
manganese
ammonium
sulfate.

P
=
Available
Phosphate
or
Phosphorous
Oxide
(
or
P2O5).
P
is
not
a
fertilizer,
but
is
a
building
block
of
other
fertilizers
(
many
of
which
are
NPKs).
Examples
of
"
phosphate"
fertilizers
include:

ammonium
metaphosphate,
ammonium
phosphate,
ammonium
phosphate
nitrate,
ammonium
phosphate
sulfate,
ammonium
polyphosphate,
basic
lime
phosphate,
basic
slag,

calcium
metaphosphate,
diammonium
phosphate
(
DAP),
magnesium
phosphate,
monoammonium
phosphate
(
MAP),
nitric
phosphate,
phosphate
rock,
phosphoric
acid,

superphosphate
(
SP),
and
triple
SP
(
TSP).

K
=
Potassium
or
Soluble
Potash
(
or
K2O).
Examples
of
potash
fertilizers
include:
lime­
potash
mixtures,
manure
salts,
muriate
potash,
potassium
carbonate,
potassium
nitrate,
potassium
sulfate,

potassium­
magnesium
sulfate,
potassium­
metaphosphate,
and
potassium­
sodium
nitrate.

NPK
=
Nitrogen,
Phosphate,
Potash
blend.
Generally
called
macronutrient
agricultural
blends.
Some
phosphate
fertilizers
are
also
NPs
(
e.
g.,
DAP,
TSP)
or
NPKs.

NA
=
Not
Applicable
TWG
=
The
Weinberg
Group
Inc.

(
a)
Based
on
information
presented
in
USEPA
(
1999a).
Note,
total
percent
does
not
add
up
to
100%
because
liming
agents
(
3.6%)
are
not
included.

(
b)
Based
on
application
to
field
crops
that
are
planted
the
most
(
highest
planting
acreage)
in
the
US
(
USEPA
1999a).

(
c)
Qualitative
rating
of
relative
MOPC
concentrations
among
products.
MOPC
considered
include
arsenic,
cadmium,
chromium,
cobalt,
copper,
lead,
mercury,
molybdenum,
nickel,
selenium,

vanadium,
and
zinc.
Based
on
TWG
fertilizer
database
[(
TWG
1999c)
compilation
of
survey,
literature,
industry
and
state
data],
and
information
presented
in
USEPA
(
1999a),

CDFA
(
1998),
and
USEPA
(
1999b).

(
d)
Based
on
application
to
broccoli
(
USEPA
1999a).

(
e)
Based
on
application
to
potato
(
USEPA
1999a).

(
f)
Based
on
application
to
oranges
(
USEPA
1999a).

(
g)
Examples
of
secondary
nutrient
products
include:
aluminum
sulfate,
calcium
chelate,
calcium
chloride,
Epsom
salt,
and
gypsum.

(
h)
Examples
of
micronutrient
products
include:
borax,
copper
chelate,
magnesia,
manganese
oxide,
ferric
oxide,
non­
chelate,
zinc
oxide,
and
zinc
sulfate.

(
i)
Concentration
of
MOPC
in
the
product
varies
by
MOPC;
these
ratings
are
based
on
the
general
trends
observed.
Considering
all
MOPCs,
zinc
micronutrients
have
the
highest
relative
MOPC
concentrations.
In
addition,
zinc
micronutrient
fertilizers
have
the
most
data
available.
However,
some
MOPCs
are
at
higher
concentrations
(
e.
g.,
arsenic
and
cadmium)

in
micronutrient
fertilizers
other
than
zinc
(
e.
g.,
iron).

(
j)
Mixes
are
not
included
in
the
screening
evaluation,
because
the
necessary
information
(
percent
micronutrient)
is
not
available.
DRAFT
Relative
Ratings
for
Determinants
of
Potential
Health
Risk
MOPC
Concentration
(
b)

Aluminum
N
Not
expected
to
pose
a
health
risk
Antimony
N
Not
expected
to
pose
a
health
risk
Arsenic
CAL,
C,
E,
S
Y
Relative
Toxicity
Barium
N
Not
expected
to
pose
a
health
risk
Beryllium
N
Not
expected
to
pose
a
health
risk
Bismuth
NA
N
Not
expected
to
pose
a
health
risk
Boron
N
Not
expected
to
pose
a
health
risk
Cadmium
CAL,
C,
E,
S
Y
Potential
for
Exposure
(
g)

Chromium
III
(
f)
E,
S
Y
Evaluation
Precedence
Cobalt
C,
S
Y
Evaluation
Precedence
Copper
E,
S
Y
Evaluation
Precedence
Iron
S
N
Not
expected
to
pose
a
health
risk
Lead
CAL,
C,
E,
S
Y
Relative
Toxicity
Manganese
N
Not
expected
to
pose
a
health
risk
Mercury
CAL,
C,
E,
S
Y
Relative
Toxicity
Molybdenum
C,
S
Y
Evaluation
Precedence
Nickel
C,
E,
S
Y
Evaluation
Precedence
Selenium
C,
S
Y
Evaluation
Precedence
Silver
N
Not
expected
to
pose
a
health
risk
Strontium
N
Not
expected
to
pose
a
health
risk
Titanium
N
Not
expected
to
pose
a
health
risk
Vanadium
E
Y
Evaluation
Precedence
Zinc
C,
E,
S
Y
Evaluation
Precedence
Notes:
Bold
=
Selected
for
evaluation.

Italics
=
Micronutrients
(
i.
e.,
essential
to
plant
growth)

=
Relative
High
Toxicity
=
Relative
High
Concentration
=
Relative
Medium
Toxicity
=
Relative
Medium
Concentration
=
Relative
Low
Toxicity
=
Relative
Low
Concentration
NA
=
Not
Available
C
=
Canadian
Standard.
Canadian
Fertilizers
Act
R.
S.,
c.
F­
9s.
1.(
1003).

CAL
=
California
Department
of
Food
and
Agriculture
(
CDFA)
and
the
Heavy
Metal
Task
Force.
1998.
Development
of
Risk
Based
Concentrations
for
Arsenic,
Cadmium,
and
Lead
in
Inorganic
Commercial
Fertilizers.
Foster
Wheeler
Environmental
Corporation,
Sacramento,
CA.

E
=
United
States
Environmental
Protection
Agency
(
USEPA).
1999b.
Estimating
Risks
from
Contaminants
Contained
in
Agricultural
Fertilizers.
Draft.
Washington,
D.
C.:

Office
of
Solid
Waste
and
Center
for
Environmental
Analysis.

S
=
United
States
Environmental
Protection
Agency
(
USEPA).
1995.
A
Guide
to
the
Biosolids
Risk
Assessments
for
the
EPA
Part
503
Rule
.
Washington,
D.
C.:

Office
of
Wastewater
Management.
EPA
832­
B­
93­
005.

(
a)
Toxicity
rating
is
based
on
the
oral
reference
dose
(
RfD),
because,
the
oral
route
of
exposure
is
expected
to
be
the
exposure
route
of
most
concern
(
i.
e.,
incidental
ingestion
of
soil
and
ingestion
of
crops),
and
because
all
of
the
MOPC
have
an
oral
RfD.

(
b)
MOPC
concentration
rating
is
based
on
a
qualitative
evaluation
of
the
MOPC
concentrations
in
products
relative
to
each
other.

(
c)
Phosphate
fertilizers
includes
(
but
are
not
limited
to)
N­
P­
K
blends,
DAP,
MAP,
TSP,
and
SP.

(
d)
Micronutrient
fertilizers
include:
boron,
iron,
manganese,
and
zinc.

(
e)
Evaluation
precedence
identifies
existing,
relevant,
studies
that
have
evaluated
the
MOPC.

(
f)
Based
on
the
assumption
that
chromium
III
(
not
chromium
VI)
is
the
species
that
is
available.

(
g)
Cadmium
is
selected
for
evaluation
because
it
is
easily
taken
up
into
plants
and,
therefore,
has
a
high
exposure
potential.
Relative
toxicity
and
concentration
also
contributed
to
this
selection.
Primary
Reason
Metal
of
Potential
Concern
(
MOPC)
Yes
(
Y)
or
No
(
N)

TABLE
2
SELECTION
OF
METALS
OF
POTENTIAL
CONCERN
(
MOPC):
CONSIDERATION
OF
RELATIVE
TOXICITY,
RELATIVE
PRODUCT
CONCENTRATION,
AND
EVALUATION
PRECEDENCE
Selected
for
Evaluation
?

Toxicity
(
a)
Phosphate
Fertilizer
(
c)
Micronutrient
Fertilizer
(
d)
Evaluation
Precedence
(
e)
DRAFT
TABLE
3
SELECTION
OF
REPRESENTATIVE
AND
HEALTH
PROTECTIVE
EXPOSURE
SCENARIO
Potential
Exposure
Routes
Selected
for
Evaluation?

Soil
Incidental
Dermal
Ingestion
of
Yes
(
Y)
or
Potential
Populations
Ingestion
Contact
Crops
No
(
N)
Rationale
Home
Gardner
Y
Y
Y
N
Lower
exposure
potential
than
resident
farmer.
(
a)

Public
Consumer
N
N
Y
N
Lower
exposure
potential
than
other
scenarios.
(
a)

Lower
exposure
potential
than
a
resident
farmer
and
evaluated
in
Farm
Worker
(
b)
Y
Y
N
N
previous
evaluation.
(
c)

Highest
exposure
potential;
representative
and
health
Resident
Farmer
(
d)
(
e)
Y
Y
Y
Y
protective
of
other
scenarios.

Notes:
Bold
=
Selected
as
the
representative
and
health
protective
exposure
scenario.

RBC
=
Risk
Based
Concentration
Y
=
Yes,
a
plausible
exposure
route
and
expected
to
contribute
significantly
to
exposure.

N
=
No,
not
a
plausible
exposure
route.

(
a)
Each
of
these
populations
has
lower
exposure
potential
compared
to
the
farm
resident
because
exposure
to
fertilized
soil
either
(
1)
does
not
occur
or
(
2)
occurs
less
frequently.

(
b)
Exposure
to
an
applicator,
including
a
farm
worker,
was
evaluated
in
TWG
(
1999a,
b).
No
significant
health
risk
was
found
for
this
exposure
scenario.

(
c)
A
farm
worker
has
a
much
lower
exposure
potential
than
a
farm
resident
because
the
ingestion
of
crops
is
not
applicable
(
or
considered)
for
this
population.

(
d)
Resident
farmer
considers
both
an
adult
and
child
who
lives
on
a
farm.

(
e)
CDFA
(
1998)
focused
on
this
population
in
developing
RBCs
for
arsenic,
cadmium,
and
lead;
USEPA
(
1999b)
also
focused
on
this
population
in
evaluating
risks
from
contaminants
contained
in
agricultural
fertilizers.
DRAFT
TABLE
4
SELECTION
OF
REPRESENTATIVE
AND
HEALTH
PROTECTIVE
CROP
GROUPINGS
Selected
for
Evaluation?

Yes
(
Y)
or
No
(
N)
Rationale
Root
(
a)
Y
Expected
to
contribute
significantly
to
exposure.

Vegetable
(
b)
Y
Expected
to
contribute
significantly
to
exposure.

Grain
(
c)
Y
Expected
to
contribute
significantly
to
exposure.

Fruit
(
d)
N
Much
less
exposure
potential
compared
to
crop
groups
selected
for
evaluation.
(
g)

Forage
(
e)
N
Ingestion
of
animal
products
eliminated
from
further
evaluation
in
scoping
stage.
(
g)

Field
(
f)
N
Field
crops
that
are
ingested
by
humans
are
considered
in
their
appropriate
crop
groups.

Notes:
Bold
=
Selected
as
a
representative
and
health
protective
crop
grouping
and
included
in
the
RBC
equation.

RBC
=
Risk
Based
Concentration
Y
=
Yes,
crop
grouping
expected
to
contribute
significantly
to
exposure
and
included
in
the
RBC
equation.

N
=
No,
crop
grouping
not
expected
to
contribute
significantly
to
exposure
and
not
included
in
the
RBC
equation.

(
a)
Root
crops
are
also
called
unexposed
vegetables
or
protected
vegetables.
Root
crops
include:
beets,

carrots,
fennel,
onions,
parsnip,
potatoes,
radish,
rutabaga,
turnip,
and
mangel.

(
b)
Vegetable
crops
are
also
called
exposed
or
unprotected
vegetables.
Vegetable
is
a
large
broad
category
of
crops.

Examples
of
different
types
of
vegetables
are
leafy
(
e.
g.,
endive,
kale,
lettuce,
swiss
chard,
spinach,
and
water
cress),
head
and
stalk
(
e.
g.,
artichoke,
asparagus,
broccoli,
brussel
sprout,
cabbage,
cauliflower,
celery,
and
peppers).

Several
fruits
are
also
included
in
the
vegetable
category,
because,
they
are
cultivated
as
vegetables
(
i.
e.,
cucumber,

eggplant,
and
tomato).

(
c)
Grain
is
a
large
broad
category
of
crops.
Grains
can
be
designated
as
field
grains,
silo
grains,
forage
grains,
or
small
or
large
grains.
Only
grains
consumed
by
humans
are
included
in
this
group.
These
grains
include
barley,
corn,

millet,
oat,
rice,
rye,
and
wheat.

(
d)
Fruit
crops
can
be
designated
as
vine
crops
(
grape),
tree
crops
(
nuts
or
lemon,
lime,
and
orange)
or
sweet
fruits
(
e.
g.,
apple,
cantaloupe,
fig,
grape,
kiwi,
rhubarb,
pear,
and
strawberry).

(
e)
Forage
crops
are
crops
grown
solely
for
the
purpose
of
feeding
cattle.

(
f)
Field
crop
is
a
general
term
for
crops
grown
on
fields.
Examples
of
field
crops
include
corn,
cotton,
potatoes,

soybeans,
tobacco,
or
wheat.
Field
crops
that
are
ingested
by
humans
are
evaluated
within
their
appropriate
crop
grouping
(
e.
g.,
potatoes
as
root
crops,
wheat
as
grain).

(
g)
CDFA
(
1998)
eliminated
fruit
and
forage
crops
from
the
development
of
RBCs
by
demonstrating
considerably
less
exposure
to
arsenic,
cadmium,
and
lead,
and
therefore
risk,
for
these
crop
groups.

Potential
Crop
Groups
DRAFT
FIGURES
FIGURE
2.
NARROWING
THE
SCOPE
OF
THIS
SCREENING
LEVEL
EVALUATION
­
FOCUSING
ON
THE
FERTILIZER
PRODUCTS,
METALS,
AND
EXPOSURE
SCENARIO
OF
HIGHEST
CONCERN
Nitrogen
Phosphate
Potash
NPK
for
phosphorous
NPK
for
nitrogen
Various
Secondary
and
Micronutrients
Fertilizer
Products
Phosphate
Fertilizers
(
b)

Micronutrient
Fertilizers
METAL
CONCENTRATION
(
a)
Aluminum,
antimony,
arsenic,
barium,

beryllium,
bismuth,
boron,
cadmium,

chromium,
cobalt,
copper,
iron,
mercury,

manganese,
molybdenum,
nickel,
lead,

radium,
selenium,
silver,
strontium,

titanium,
thorium,
uranium,
vanadium,

zinc
Metals
arsenic,
cadmium,
chromium,
cobalt,

copper,
lead,
mercury,
molybdenum,

nickel,
radium226,
selenium,

vanadium,
and
zinc
TOXICITY
(
a)
Exposure
Scenario
Occupational
and
Public
·
Ingestion
soil/
fertilizer
·
Dermal
contact
soil/
fertilizer
·
Inhalation
particulates
·
Ingestion
animal
products
(
beef,
fish,
milk)

·
Ingestion
crops
(
grain,

vegetable,
fruit,
roots,

forage,
vine)

Applicator
(
c):

·
Ingestion
and
dermal
contact
with
fertilizer
·
Inhalation
particulate
Public
­

Farm
Family:

·
Ingestion
crops,

(
grain,
vegetable
and
root)

·
Ingestion
and
dermal
contact
with
soil
EXPOSURE
(
a)

(
a)
This
is
the
primary
factor
considered
when
selecting
the
product.

(
b)
Phosphate
fertilizers
include
phosphate
only
and
NPK­
for­
phosphate
fertilizers.

(
c)
Occupational
exposure
(
i.
e.,
applicator)
was
evaluated
in
TWG
(
1999a,
b).
DRAFT
uptake
leaching
uptake
runoff
SOIL
incidental
ingestion
dermal
contact
uptake
Fish
ingestion
Crops
ingestion
Ground
Water
ingestion
of
drinking
water
Foraging
Cattle
ingestion
of
animal
products
(
beef
and
milk)
volatilization
wind
blown
dispersion
Air
inhalation
Application
of
Inorganic
Fertilizer
Potential
Indirect
Media
of
Exposure
exposure
route
Potential
Direct
Media
of
Exposure
exposure
route
transport
pathway
FIGURE
3.
POTENTIAL
EXPOSURE
PATHWAYS
OF
METALS
OF
POTENTIAL
CONCERN
(
MOPC)
IN
INORGANIC
FERTILIZER
POST
APPLICATION
INCLUDES:
TRANSPORT
PATHWAYS,
MEDIA
OF
POTENTIAL
CONCERN,
AND
ASSOCIATED
EXPOSURE
ROUTES
Surface
Water
incidental
ingestion
dermal
contact
uptake
KEY:
uptake
Crops
ingestion
Indicates:
Excluded
from
further
consideration,
not
a
major
exposure
pathway.

DRAFT
17
DRAFT
SECTION
2.0
¾
DERIVATION
OF
RISK
BASED
CONCENTRATIONS
(
RBCS)

As
noted
in
the
introduction,
this
evaluation
uses
a
standard,
back­
calculation,
risk
based
approach
to
evaluate
potential
health
risks.
RBCs
that
are
nationally
representative
and
health
protective
are
derived.

As
defined
in
Section
1.0,
RBCs
are
derived
to
represent
and
evaluate:

·
2
categories
of
inorganic
fertilizers:
phosphate
fertilizers
and
micronutrient
fertilizers;
·
12
MOPC:
arsenic,
cadmium,
chromium,
cobalt,
copper,
lead,
mercury,
molybdenum,
nickel,
selenium,
vanadium,
and
zinc;
and
1
radionuclide,
radium
226;
·
Farm
resident,
including
adult
and
child;
·
3
routes
of
exposure;
­
Unintentional
ingestion
of
soil
following
fertilizer
application,
­
Dermal
contact
with
soil
following
fertilizer
application,
­
Ingestion
of
crops,
which
are
broken
out
into
3
crop
groups:
root,
vegetable,
and
grain;
and
·
Both
single
crop
and
multi­
crop
farm
scenarios.

Risk
Based
Concentration
(
RBC)
Equation
The
RBC
equation
is
developed
using
standard
USEPA
risk
practices
and
exposure
parameters
(
USEPA
1989).
23
The
standard
equation
to
calculate
risk
combines
3
factors:
estimated
intake
from
exposure,
toxicity
of
the
element
of
interest
(
in
this
case
MOPC),
and
concentration
of
the
MOPC
in
the
media
of
concern
(
i.
e.,
fertilizer
or
product).
In
a
back­
calculation
risk
based
approach,
the
equation
is
arranged
to
solve
for
the
RBC
using
an
estimate
of
potential
exposure,
toxicity,
and
an
acceptable
risk
level.
24
The
RBC
equation
for
the
single
crop
farm
is
presented
below.
The
equation
integrates
the
3
potential
routes
of
exposure.

23
The
standard
USEPA
exposure
(
intake)
and
risk
equations
were
modified
to
fit
the
scenario
evaluated
in
this
report.
24
Standard
USEPA
guidance
presented
in
USEPA
(
1991).
18
DRAFT
Equation
1.
RBC
for
the
Single
Crop
Farm
)]}
*
*
*
*
*
(
THI
or
TR
)
*
*
*
*
*
*
(
)
*
*
*
*
*
*
[(
*
/
1
*
{
*
THI
or
TR
TOX
PUF
AT
RAFc
IRc
EF
ED
TOX
AT
BW
ABS
AF
SA
EF
ED
TOX
AT
BW
CF
RAFs
IRs
EF
ED
FON
AR
SACF
RBC
+
+
=
where:

where:

RBC
=
Risk
Based
Concentration
(
mg
MOPC/
kg
product);
TR/
THI
=
Acceptable
Target
Risk
or
Hazard
Index
(
Unitless);
AR
=
Application
Rate
(
g/
m2­
year);
FON
=
Fraction
of
Nutrient
(
unitless);
SACF
=
Soil
Accumulation
Factor
(
m2­
year/
g);
ED
=
Exposure
Duration
(
years);
EF
=
Exposure
Frequency
(
days/
year);
BW
=
Body
Weight
(
kg);
AT
=
Averaging
Time
(
days);
CF
=
Conversion
Factor
(
1X
10­
6
kg/
mg);
IRs
=
Ingestion
Rate
Soil
(
mg/
day);
SA
=
Surface
Area
(
cm2/
event­
day);
AF
=
Adherence
Factor
(
mg/
cm2);
IRc
=
Ingestion
Rate
Crops
(
kg/
day);
RAF
=
Relative
Absorption
Factor
(
RAF)
(
unitless);
ABS
=
Dermal
Absorption
Factor
(
unitless);
PUF
=
Plant
Uptake
Factor
(
unitless);
and
TOX
=
Toxicity
Values
(
mg/
kg­
day
or
mg/
kg­
day
 
1).

The
RBC
equation
for
the
multi­
crop
farm
scenario
is
more
complicated
than
the
RBC
equation
for
the
single
crop
farm,
because
all
three­
crop
groups
are
integrated
into
one
equation.
Yet,
each
crop
group
has
a
different
AR
and
PUF.
The
RBC
equation
for
the
multi­
crop
farm
scenario
is
presented
below.
Note
the
addition
of
a
new
factor,
Fraction
of
Land
(
FOL),
in
the
equation.
FOL
is
used
to
fractionate
the
addition
of
MOPC
to
soil
by
the
different
application
Fertilizer
Soil
Ingestion
Incidental
SIFsi
Factor
Intake
Summary
AT
BW
CF
RAFs
IRs
EF
ED
/
)
(
*
*
*
*
*
=
Fertilizer
Soil
Contact
Dermal
SIFd
Factor
Intake
Summary
AT
BW
CF
ABS
AF
SA
EF
ED
/
)
(
*
*
*
*
*
*
=
Crop
Ingestion
SIFc
Factor
Intake
Summary
AT
RAFc
IRc
EF
ED
)
(
*
*
*
=
19
DRAFT
rates
for
the
different
crop
groups.
Also
note
the
use
of
SIFs
in
the
equation.
SIFs
are
summary
intake
factors
that
are
derived
for
the
single
crop
farm
in
Equation
1.

Equation
2.
RBC
for
the
Multi­
Crop
Farm
}
*
*
]
*
)
*
*
[(
*
/
1
*
{
THI
or
TR
}
*
*
]
*
)
*
*
[(
*
/
1
*
{
THI
or
TR
}
*
*
]
*
)
*
*
[(
*
/
1
*
{
*
(
THI
or
TR
TOX
SIFg
PUFg
FOLg
TOXd
SIFd
TOX
SIFs
FON
ARg
TOX
SIFr
PUFr
FOLr
TOXd
SIFd
TOX
SIFs
FON
ARr
TOX
SIFv
PUFv
FOLv
TOXd
SIFd
TOX
SIFs
FON
ARv
SACF
RBC
+
+
+
+
+
+
+
+
=
where:

FOL
=
Fraction
of
Land
(
unitless)
(
discussed
below)
v
=
Vegetable
r
=
Root
g
=
Grain
As
discussed
in
Section
1.0,
California
is
the
largest
multi­
crop
farming
state;
so,
the
multi­
crop
RBC
is
based
on
a
multi­
crop
farm
in
this
region.
Gross
estimates
of
the
percentage
of
acreage
dedicated
to
each
crop
group
in
California
were
made
based
on
a
rough
review
of
agricultural
data
(
crop
acreage
harvested)
obtained
from
USDA
(
1999).
In
addition,
CDFA
(
1998)
was
consulted
for
FOLs.
FOLs
of
50%
grain,
40%
vegetable,
and
10%
root
are
used
to
calculate
multi­
crop
RBCs.
24
Acceptable
Target
Risk
(
TR)
or
Hazard
Index
(
THI)

In
keeping
with
standard
USEPA
practices,
a
target
cancer
risk
(
TR)
of
1X
10­
5
and
a
target
hazard
index
(
THI)
of
1
is
used.
25
In
general,
USEPA
uses
an
acceptable
cancer
risk
of
1
X10­
5
(
1
in
10,000)
and
a
hazard
quotient
(
HQ)
of
1
for
noncancer
effects
under
it's
hazardous
waste
programs.
A
HQ
is
the
determination
of
noncancer
risk
for
an
individual
MOPC.
If
the
noncancer
effects
of
the
individual
MOPC
were
all
the
same,
the
THI
(
of
1)
would
need
to
be
reduced
to
account
for
the
additive
noncancer
effects.
However,
since
most
of
the
MOPC
are
associated
with
different
noncancer
effects
(
i.
e.,
different
toxic
endpoints)
the
THI
does
not
need
to
be
reduced
below
1.26
Summary
Intake
Factor
(
SIF)
Parameters
Summary
intake
factors
(
SIFs)
combine
biological
exposure
parameters
and
absorption
factors
to
estimate
intake
from
exposure.
They
are
standard
methods,
intended
to
simplify
the
calculation
24
CDFA
(
1998)
also
uses
these
FOLs
to
develop
RBCs
for
their
multi­
crop
scenario.
25
CDFA
(
1998)
and
USEPA
(
1999b)
use
these
acceptable
risk
and
HQ
levels
in
their
fertilizer
risk
assessment.
26
Associated
target
organs
or
target
effects
for
each
noncarcinogen
are
presented
in
`
Toxicity
Assessment'.
20
DRAFT
of
the
RBC.
Biological
exposure
parameters
are
related
to
behavior
and
are
age
dependent.
They
include:
exposure
duration
(
ED),
exposure
frequency
(
EF),
body
weight
(
BW),
averaging
time
(
AT),
ingestion
rates
(
IR),
skin
surface
area
(
SA),
and
adherence
factor
(
AF).
The
values
for
all
of
these
exposure
parameters
were
developed
from
USEPA
references
and
are
intended
to
represent
the
reasonable
maximum
exposure
(
RME).
They
are
presented
in
Table
5.
As
defined
under
USEPA
(
1989),
RME
is
the
highest
exposure
that
is
reasonably
expected
to
occur
and
that
is
well
above
the
average
case,
but
within
the
bounds
of
the
high­
end
exposure
case.
In
addition,
relative
absorption
factors
(
RAF)
and
dermal
absorption
factors
(
ABS)
are
developed
(
as
appropriate).
The
information
used
to
derive
RAF
and
ABS
are
presented
in
Appendix
A.
RAF
and
ABS
are
presented
in
Appendix
A,
Table
A­
1.

Exposure
Duration
(
ED)

The
exposure
duration
(
ED)
is
the
length
of
time
exposure
occurs
and
is
typically
the
length
of
residence.
The
ED
for
the
farm
adult
is
30
years.
This
ED
is
the
USEPA
recommended
default
ED
at
the
95th
percentile
for
a
family
to
reside
in
a
home.
The
central
default
value
(
50%
percentile)
is
9
years.
There
is
also
a
central
residence
time
estimate
for
a
farm
presented
in
USEPA
(
1997a)
(
about
17
 
18
years),
however;
the
upper­
end
estimate
of
general
residence
time
is
considered
a
better
estimate
for
the
RME
scenario.
The
ED
for
the
farm
child
is
6
years.
This
is
the
standard
age
frame
considered
when
evaluating
risks
to
children.

Exposure
Frequency
(
EF)

Exposure
frequency
(
EF)
represents
how
often
(
days/
year)
the
potential
for
exposure
occurs.
The
exposure
frequency
(
EF)
for
the
farm
adult
and
child
is
350
days/
year
for
all
exposure
routes,
including
dermal
contact
and
incidental
ingestion
of
soil
and
crop
ingestion.
An
EF
of
350
days/
year
is
recommended
when
using
daily
ingestion
rates
(
excluding
time
away
from
home
for
vacation).
In
addition,
an
EF
of
350
days/
year
is
most
representative
of
a
warm
climate.

Averaging
Time
(
AT)

Averaging
time
(
AT)
depends
on
the
toxic
effect
assessed
(
i.
e.,
whether
cancer
or
non­
cancer).
For
non­
carcinogens,
intake
is
averaged
over
ED.
In
the
RBC
equation
for
non­
cancer,
ED
is
in
the
numerator
of
the
intake
equation
and
AT
is
in
the
denominator
(
AT=
ED*
365
days/
yr).
Therefore,
AT
and
ED
cancel
each
other
out.
For
carcinogens,
intake
is
averaged
by
prorating
the
cumulative
dose
over
a
lifetime
(
i.
e.,
70
years
=
25,550
days)
(
USEPA
1989).

Body
Weight
(
BW)

USEPA
standard
default
body
weights
(
BW)
were
used
for
both
the
farm
adult
and
child.
The
BW
values
are
averages;
average
is
the
recommended
statistic
for
BW
when
evaluating
the
RME
scenario
(
USEPA
1989).
The
adult
BW
is
71.8
kg
(
represents
ages
18
 
75
years)
and
the
child
BW
is
15.5
kg
(
average
BW
from
6
months
to
6
years
for
males
and
females)
(
USEPA
1997a).
21
DRAFT
Ingestion
Rate
(
IR)

Ingestion
rate
(
IR)
is
the
amount
of
media
of
interest
(
either
soil
or
crop)
ingested
and
is
presented
as
an
amount
per
day.
IR
correlates
with
BW,
because
IR
correlates
with
age,
which
correlates
with
BW.
Because
IR
correlates
with
BW,
and
the
average
BW
is
suggested
for
the
RME
scenario,
IRs
are
also
central
estimates
(
or
averages).
The
IR
for
soil
is
different
than
the
IR
for
crops
(
and
the
IR
for
each
crop
group
is
different)
as
discussed
below.

·
Soil
The
incidental
soil
IR
for
an
adult
is
50
mg/
day.
This
is
USEPA's
recommended
central
estimate
adult
soil
IR
(
USEPA
1997a).
There
is
no
recommended
high­
end
estimate.
In
the
past,
typical
USEPA
risk
assessments
used
adult
soil
ingestion
rates
of
50
mg/
day
for
an
industrial
setting
and
100
mg/
day
for
a
residential
and
agricultural
setting
(
USEPA
1997a).
USEPA's
most
recent
guidance
(
1997a)
recommends
an
IR
of
50
mg/
day.
Regardless,
whether
using
a
soil
ingestion
rate
of
50
mg/
day
or
100
mg/
day,
the
effect
on
the
RBC
not
significant,
as
discussed
in
the
uncertainty
section.

The
soil
IR
for
a
child
is
200
mg/
day.
This
is
a
conservative
estimate
of
the
mean.
A
high­
end
estimated
soil
IR
of
400
mg/
day
was
considered
too
high
for
this
assessment,
because,
it
is
based
on
a
short
study
period,
and
not
usual
daily
activity
(
USEPA
1997a).
As
with
the
adult
scenario,
the
use
of
a
200
mg/
day
or
400
mg/
day
soil
ingestion
does
not
significantly
influence
the
RBC
(
as
discussed
in
the
uncertainty
section).

·
Crop
IRs
for
each
crop
group
(
i.
e.,
vegetable,
root,
and
grain)
are
developed
from
information
presented
in
USEPA
(
1997a).
Because
the
IR
for
crops
varies
by
age
group,
and
correlates
with
BW,
the
crop
IRs
are
already
averaged
over
BW.
Therefore,
BW
does
not
appear
as
an
independent
parameter
in
the
crop
intake
equation.
In
developing
the
crop
IRs,
the
IRs
for
each
crop
group
consider
all
of
the
data
that
are
appropriate
for
that
crop
group
(
as
listed
in
Section
1.0).
The
crop
IRs
are
weighted
averages
of
the
means,
across
the
age
groups
of
interest,
on
a
per
capita
basis.
Per
capita
intake
rates
are
appropriate
estimates
for
average
intake
of
the
general
population
(
USEPA
1997a).
The
IRs
are
based
on
data
from
the
USEPA
"
key"
and
recommended
study
(
USEPA
1997a).
This
study
is
the
Continuing
Survey
of
Food
Intakes
by
Individuals
(
CSFII)
from
1989­
1991.

These
IRs
are
based
on
"
as
consumed",
which
means
fresh
weight
or
wet
weight.
For
children,
the
age
groups
included
in
the
weighted
average
are
ages
1
 
5.
For
adults,
ages
6­
70+
were
considered.
This
age
group
also
considers
teens
and
young
adults.

Vegetable
Vegetable
IRs
are
developed
from
data
in
Table
9­
9
(
Per
Capita
Intake
of
Exposed
Vegetables)
and
Table
9­
10
(
Per
Capita
Intake
of
Protected
Vegetables)
in
USEPA
(
1997a).
Data
for
exposed
vegetables
considers
all
of
the
vegetables
presented
in
the
22
DRAFT
discussion
of
crop
grouping
in
Section
1.0,
plus
additional
vegetables
not
listed
in
this
group.
Protected
vegetables
in
Table
9­
10
in
USEPA
(
1997a)
are
vegetables
with
a
husk
or
thick
skin
(
not
vegetables
that
grow
underground
or
root
vegetables).
Examples,
of
these
vegetables
include
pumpkin,
squash,
lima
beans,
peas,
and
corn.
Several
of
these
vegetables
do
not
fit
into
the
vegetable
category,
as
defined
for
this
report
(
especially
corn),
however,
all
exposed
vegetables
were
still
included
in
developing
the
IRs
for
vegetables.
The
vegetable
IR
is
the
age
weighted
IR
for
protected
plus
exposed
vegetables.

The
vegetable
IR
for
an
adult
is
1.7
g/
kg­
day.
The
vegetable
IR
for
a
child
is
2.9
g/
kgday

Root
The
IRs
for
root
crops
are
developed
from
data
in
Table
9­
11
(
Per
Capita
Intake
of
Root
Vegetables)
(
USEPA
1997a).
Examples
of
root
vegetables
considered
in
this
table
are
potatoes,
carrots,
beets,
garlic,
onions,
radish,
turnip,
and
leeks.

The
root
IR
for
an
adult
is
1.1
g/
kg­
day
and
the
root
IR
for
a
child
is
2.1
g/
kg­
day.

Grain
The
IRs
for
grain
are
developed
from
data
presented
in
Table
12­
1
(
Per
Capita
Intake
of
Total
Grains
Including
Mixtures)
(
USEPA
1997a).
These
IRs
are
developed
the
same
way
as
the
IRs
for
vegetables
and
roots
(
i.
e.,
time
weighted
averaged,
based
on
the
mean,
and
per
capita).
Total
grains
presented
in
this
table
includes
breads,
sweets
(
cakes,
pie,
and
pastries),
breakfast
foods
with
grains,
pasta,
cereals,
and
rice
and
grain
mixtures.

The
grain
IR
for
an
adult
is
3.4
g/
kg­
day
and
the
grain
IR
for
the
child
is
9.4
g/
kg­
day.

Fraction
Ingested
(
FI)

One
parameter
that
is
not
shown
in
the
RBC
equation,
but
is
factored
in
and
needs
to
be
mentioned
is
fraction
ingested
(
FI).
FI
can
apply
to
any
media
of
interest
(
soil
or
crop)
ingested,
and
is
the
fraction
(
or
portion)
of
the
soil
or
crop
that
originates
from
the
source
(
in
this
case,
soil
following
application
of
fertilizer,
or
crops
grown
on
this
soil).
For
the
purposes
of
this
screening
level
evaluation,
all
(
100%)
of
the
soil
or
crop
is
assumed
to
come
from
the
farm,
therefore,
FI
is
1.
An
FI
of
1
is
the
most
health
protective
(
conservative)
FI
value.
Since
FI
is
1,
for
simplicity,
it
is
not
presented
in
the
RBC
equation.

Skin
Surface
Area
(
SA)

Skin
surface
area
(
SA)
is
the
area
of
skin
that
is
available
for
dermal
contact
with
soil/
fertilizer.
The
skin
SA
is
taken
from
the
most
recent
USEPA
(
1998b)
dermal
guidance.
Similar
to
IR,
skin
SA
correlates
with
BW.
Therefore,
average
or
central
estimates
are
recommended
for
the
RME
scenario.
23
DRAFT
For
soil
exposure,
the
recommended
central
estimate
of
skin
SA
area
for
an
adult
is
5,700
cm2/
day;
the
recommended
central
skin
SA
for
a
child
is
2,900
cm2/
day
(
USEPA
1998b).
The
adult
skin
SA
is
based
on
a
warm
climate
where
more
skin
is
likely
to
be
exposed.
The
adult
skin
SA
is
based
on
the
adult
wearing
short
sleeved
shirt,
shorts,
and
shoes;
the
exposed
areas
are
the
head,
hands,
forearms,
and
lower
legs.
The
child
skin
SA
is
also
based
on
a
warm
climate
scenario
and
a
child
wearing
short
sleeved
shirt
and
shorts,
but
no
shoes.
For
the
child,
the
exposed
SA
area
is
45%
of
the
total
skin
SA
(
USEPA
1998b).

Adherence
Factor
(
AF)

Adherence
factor
(
AF)
is
an
estimate
of
the
amount
of
soil
that
adheres
to
skin.
As
with
the
skin
SA,
the
most
recent
USEPA
dermal
guidance
(
1998b)
was
consulted
for
AFs.
AFs
vary
depending
on
the
exposure
scenario.
For
example,
AFs
are
available
for
a
groundskeeper,
or
nursery
worker,
or
an
archeologist.
The
AF
selected
for
the
adult
is
the
USEPA
recommended
adult,
default
AF,
0.08
mg/
cm2­
event.
This
AF
is
for
the
residential
scenario
and
is
based
on
outdoor
gardening.
The
recommended
default
AF
for
a
child
is
0.3
mg/
cm2­
event
(
USEPA
1998b).

Absorption
Parameters
As
can
be
seen
in
the
RBC
equation,
there
are
two
additional
parameters
in
the
SIF,
relative
absorption
factor
(
RAF)
and
percent
dermal
absorption
(
ABS).
These
parameters
adjust
the
estimated
intake
to
an
actual
absorbed
"
dose."
Absorbed
dose
refers
to
the
amount
of
the
MOPC
that
is
actually
absorbed
into
the
blood
stream
following
exposure
and
intake.
RAF
and
ABS
help
to
develop
a
more
realistic
RBC
by
estimating
the
fraction
of
MOPC
that
is
actually
absorbed
into
the
bloodstream,
not
just
the
amount
of
exposure
(
i.
e.,
ingested
or
contacted).
Absorption
is
representative
of
the
fraction
of
the
MOPC
that
is
available
(
i.
e.,
bioavailable).
Bioavailability
is
the
fraction
of
specific
contaminant
in
a
medium
(
e.
g.,
soil
or
crop)
that
is
absorbed
into
the
bloodstream
across
physiological
barriers.
Without
the
incorporation
of
these
factors,
the
RBCs
may
be
largely
overestimated.
However,
these
parameters
are
only
used,
when
appropriate
and
applicable
data
are
available.
Information
supporting
the
RAFs
is
presented
in
Appendix
A.
For
MOPC
where
data
is
not
available
to
develop
a
RAF,
a
RAF
of
100%
is
assumed.
This
is
the
case
for
most
MOPC.
An
RAF
is
developed
and
incorporated
into
the
RBC
for
arsenic
and
lead,
as
discussed
below.
In
addition,
for
most
MOPC,
a
default
ABS
for
metals
of
1%
is
used
(
USEPA
1998b).

·
Relative
Absorption
Factor
(
RAF)

RAF
is
intended
to
ensure
that
the
toxicity
value
and
estimated
intake
are
based
on
comparable
estimates
of
intake
(
both
based
on
an
absorbed
or
administered
dose,
and
the
same
or
similar
medium).
Therefore,
RAF
depends
on
(
1)
whether
the
toxicity
value
is
an
"
administered"
or
an
actual
absorbed
dose
and
(
2)
the
absorption
from
both
the
medium
of
the
toxicity
study
and
the
medium
of
interest
(
i.
e.,
soil
or
crop).
RAF
is
the
percent
of
the
MOPC
that
is
absorbed
from
the
medium
of
interest
[
following
ingestion,
and
absorption
through
the
gastrointestinal
tract
(
GI)]
divided
by
the
percent
GI
absorption
used
in
the
oral
toxicity
study.
24
DRAFT
The
estimated
intake
and
associated
toxicty
of
arsenic
from
the
ingestion
of
soil
is
adjusted
by
a
RAF.
The
oral
toxicity
value
for
arsenic
is
based
on
an
administered
dose
from
exposure
to
arsenic
in
drinking
water.
An
applicable
and
acceptable
study
on
the
bioavailability
of
arsenic
was
found.
This
study
determined
a
bioavailability
of
arsenic
in
soil
of
42%
(
Rodriquez
et
al.
1999).
The
percent
absorption
of
arsenic
in
drinking
water
is
95%
(
USEPA
1999c).
Therefore,
a
RAF
for
arsenic
in
soil
of
44%
(
42%
¸
95%)
is
incorporated
into
the
RBC.

In
addition,
the
estimated
intake
of
lead
into
the
GI
tract
following
unintentional
ingestion
of
lead
in
soil
and
ingestion
of
lead
in
crops,
and
the
associated
toxicity,
is
adjusted
by
a
RAF.
Since
the
toxicity
of
lead
is
based
on
an
acceptable
blood
lead
level,
which
is
an
absorbed
level
(
or
dose),
the
intake
also
needs
to
be
adjusted
to
an
absorbed
dose.
The
GI
absorption
of
lead
in
soil
and
crop
following
ingestion
is
0.41,
and
0.50,
respectively
(
USDHHS
1997).
The
estimated
intake
from
unintentional
ingestion
of
soil
and
ingestion
of
crops
and
associated
toxicity
is
adjusted
accordingly.

A
default
RAF
of
100%
(
or
1)
is
assumed
for
all
other
MOPC
and
their
associated
exposure
routes.

·
Percent
Dermal
Absorption
(
ABS)

All
of
the
toxicity
values
for
the
dermal
route
of
exposure
are
based
on
an
absorbed
dose
(
as
described
in
the
Toxicity
Assessment
Section).
Therefore,
intake
from
dermal
contact
needs
to
be
in
an
absorbed
dose.
Percent
dermal
absorption
(
ABS)
estimates
the
amount
of
MOPC
that
is
absorbed
across
the
skin
into
the
bloodstream
following
dermal
contact.
Screening
level
ABS
are
used
(
1%
for
all
MOPC,
except
3%
for
arsenic)
and
were
obtained
from
(
USEPA
1998b).

Application
Rate
(
AR)
and
Fraction
of
Nutrient
(
FON)

Application
rate
(
AR)
is
a
very
important
parameter
in
the
RBC
equation
and
can
influence
the
RBC
greatly.
As
defined
in
the
scoping
stage
of
this
evaluation
(
Section
1.0),
RBCs
are
developed
for
phosphate
fertilizers
and
zinc
micronutrient
fertilizers.
Application
rates
(
ARs)
for
phosphate
and
zinc
micronutrient
fertilizers
are
presented
in
Table
6.

Also
discussed
in
Section
1.0,
AR
is
dependent
on
the
plant
nutrient
needs
(
P
or
zinc)
and
the
composition
of
the
product,
specifically,
the
percent
nutrient
(
percent
P
or
percent
zinc).
ARs
vary
for
different
crops
and
different
products.
ARs
for
each
of
the
three
crop
groups
(
vegetable,
root,
and
grain)
are
developed
for
phosphate
and
for
zinc
based
on
information
presented
in
USEPA
(
1999a).
However,
these
ARs
are
based
on
nutrient
needs
of
crops
and
are
not
product
specific
(
i.
e.,
they
do
not
consider
the
percent
nutrient
of
product).
These
ARs
(
or
nutrient
needs)
will
vary
depending
on
the
percent
nutrient
of
the
product.
For
example,
products
with
a
higher
percent
of
P
will
be
applied
less
than
a
product
with
a
low
percent
of
P
in
order
to
meet
the
nutrient
needs
of
the
plant.
The
percent
of
P
for
phosphate
fertilizers
varies
considerably
from
fertilizer
to
fertilizer
(
as
can
be
seen
in
Table
1,
percent
of
P
ranges
from
2.0­
70.1).
25
DRAFT
RBCs
are
intended
for
screening
level
evaluations
and
need
to
be
easy
to
use
and
flexible.
Therefore,
the
RBCs
are
normalized
to
represent
a
1
percent
fraction
of
nutrient
(
FON)
content.
These
RBCs
are
called
unit
RBCs.
Unit
RBCs
can
easily
be
adjusted
to
represent
a
particular
product
with
a
certain
percent
nutrient
content
(
the
concept
of
unit
RBC
and
their
adjustment
is
discussed
in
further
detail
in
Section
4.0).

The
ARs
for
P
(
and
thus
phosphate
fertilizers)
are
based
on
the
appropriate
and
available
crop
data
presented
in
USEPA
(
1999a).
Data
for
all
crops
and
every
state,
regardless
of
geographic
area,
are
compiled
into
the
database
used
to
develop
the
ARs
for
P.
The
data
set
compiled
for
each
crop
group
is
presented
in
Appendix
A.
The
ARs
are
the
95
upper
confidence
limit
(
UCL)
of
the
mean
(
based
on
the
assumption
that
the
data
is
normally
distributed).
Although
this
data
set
may
not
be
normally
distributed,
the
95UCL
of
the
mean
is
considered
an
appropriate
estimate
because
it
is
sufficiently
high­
end.
The
ARs
are
presented
in
USEPA
(
1999a)
in
units
of
1b/
acre­
yr.
These
ARs
are
converted
to
g/
m2­
year
by
0.11
g­
acre/
lb­
m2
(
for
appropriate
units
in
the
RBC)
and
then
adjusted
to
reflect
a
1%
FON.

The
high­
end
ARs
for
phosphate
fertilizers
are:

·
Vegetable
=
119
lb/
acre­
year
(
13
g/
m2­
year);
·
Root
=
157
lb/
acre­
year
(
17
g/
m2­
year);
and
·
Grain
=
63
lb/
acre­
year
(
7
g/
m2­
year).

There
is
limited
information
available
on
the
application
of
micronutrients.
The
information
and
ARs
presented
in
USEPA
(
1999a)
are
based
on
interviews
with
experts.
The
"
high"
AR
for
zinc
micronutrient
presented
in
USEPA
(
1999a)
of
10
lb/
acre
(
1
g/
m2­
year)
is
a
best
estimate.
This
is
the
AR
used
for
all
micronutrient
fertilizers
and
for
all
crop
groups.

Soil
Accumulation
Factor
(
SACF)

The
soil
accumulation
factor
(
SACF)
estimates
how
much
of
an
MOPC
accumulates
in
soil
following
annual
applications
(
over
years
of
farming)
and
takes
into
account
an
estimated
loss
of
MOPC
in
soil
from
transport
of
the
MOPC
into
surrounding
media.
The
accumulation
and
behavior
of
MOPC
in
soil
from
agricultural
application
depends
essentially
on
(
1)
farming
duration
(
years)
(
2)
the
application
rate
(
AR)
of
the
fertilizer
(
3)
the
concentration
of
the
MOPC
in
the
fertilizer
and
(
4)
the
fate
and
transport
of
the
MOPC
in
soil.
Further,
fate
and
transport
depends
on
the
soil
condition,
climatic
conditions
and
MOPC
specific
parameters
(
i.
e.,
MOPC
form,
soil
water
coefficient,
etc.).
USEPA
has
developed
models
that
estimate
the
accumulation
of
MOPC
in
soil
following
application
(
USEPA
1990,
1993).
These
models
were
modified
by
CDFA
(
1998)
for
the
purposes
of
developing
an
RBC
(
Equation
3.0);
the
resulting
equation
is
presented
below.

The
modified
equation
(
Equation
4.0)
is
also
presented
below.
As
can
be
seen
in
Equation
4.0,
SACF
is
related
to
the
duration
of
application,
the
depth
of
soil
that
is
expected
to
accumulate
MOPC,
the
potential
loss
of
the
MOPC
from
soil
through
potential
transport
(
or
now
considered
loss)
pathways,
and
limited
soil
characteristics
(
e.
g.,
bulk
density).
The
fate
and
transport
of
the
MOPC
in
soil,
over
years
of
farming,
depends
on
the
form
of
the
MOPC,
the
type
(
i.
e.,
sandy
or
26
DRAFT
silty
loam)
and
condition
of
soil
(
e.
g.,
the
organic
matter
content
of
the
soil,
the
pH
of
the
soil)
and
the
climatic
conditions
of
the
area.
Because
SACF
depends
on
so
many
different
factors,
which
all
vary
given
any
situation,
not
all
situations
can
be
represented
when
developing
the
RBC.
Instead
and
in
keeping
with
the
intent
of
this
screening
level
evaluation,
a
SACF
is
estimated
that
is
based
on
nationally
representative
high­
end
(
resulting
in
more
protective
RBCs)
assumptions,
and
an
SACF
that
is
based
on
the
most
important
parameters
and
loss
pathways.
The
development
of
SACF
does
not
consider
MOPC
specific
factors
(
except
Kd),
such
as,
the
form
of
the
MOPC
(
speciation
and
complexation),
and
is
based
on
general,
not
site
specific,
assumptions.
All
of
the
parameters
used
to
calculate
the
SACFs
are
presented
in
Table
7.
The
SACFs
are
presented
in
Table
8.

Equation
3.0
Accumulated
Soil
Concentration
s
s
K
BD
Z
T
K
AR
Sc
*
*
*
*
-
-
*
=
100
)]
exp(
1
[

where:
Sc
=
accumulated
soil
concentration
(
mg/
kg);
AR
=
application
rate
(
deposition
rate)
of
metal
(
g/
m2­
yr);
Ks
=
soil
loss
constant
(
yr­
1);
T
=
total
time
period
(
evaluation
time)
over
which
deposition
occurs
(
years);
100
=
conversion
factor
(
mg­
m2/
kg­
cm2);
Z
=
soil
mixing
depth
(
cm);
and
BD
=
soil
bulk
density
(
g/
cm3).

Equation
4.0
Soil
Accumulation
Factor
(
SACF)

SACF
=

s
K
BD
Z
T
K
s
*
*
*
*
-
-
*
-
100
)]
exp(
0
.
1
[
10
6
where:
SACF
=
soil
accumulation
factor
(
m2/
yr­
g);
10­
6
=
conversion
factor
(
kg/
mg);
T
=
total
time
period
over
which
deposition
occurs
(
years);
Z
=
soil
mixing
depth
(
cm);
BD
=
soil
bulk
density
(
g/
cm3);
and
Ks
=
soil
loss
constant
(
yr­
1).

Time
Period
of
Application
(
T)

MOPC
are
added
to
soil
over
years
of
farming.
Because
of
losses
from
the
root
zone,
the
rate
of
accumulation
of
the
MOPC
in
soil
will
slow
over
the
years.
Eventually,
following
application
year
after
year,
on
the
same
soil,
the
concentrations
of
the
MOPC
are
expected
to
reach
a
steady
state.
The
number
of
years
it
takes
the
MOPC
to
reach
steady
state
is
assumed
to
be
50
years,
27
DRAFT
except
for
lead
where
the
application
duration
is
200
years.
These
application
durations
are
developed
in
CDFA
(
1998).

Soil
Mixing
Depth
(
Z)

Soil
mixing
depth
(
Z)
is
the
depth
of
soil
that
is
expected
to
be
tilled.
A
default
Z
of
20
cm
is
used
(
USEPA
1998a).

Soil
Bulk
Density
(
BD)

A
default
BD
of
1.5
g/
cm3
from
USEPA
(
1998a)
is
used.
This
BD
is
based
on
a
loam
soil.

Defining
Potential
Fate
and
Transport
(
Loss
Pathways)
(
Ks)

As
can
be
seen
in
Figure
3,
chemicals
in
soils
can
be
lost
through
four
potential
transport
pathways
including
degradation,
leaching,
erosion,
and
volatilization.
The
loss
of
the
MOPC
through
these
transport
pathways
decreases
the
amount
of
MOPC
that
accumulates
in
soil
and
that
is
available
(
1)
for
exposure
through
direct
contact
with
soil
or
(
2)
uptake
into
crops.
Only
leaching
is
considered
a
mechanism
(
albeit
a
small
amount)
of
metal
loss
from
soil.
25
All
of
the
other
transport
pathways
are
not
considered
in
the
development
of
SACF
because
they
either
are
(
1)
not
plausible
or
(
2)
they
are
inconsequential.
26
The
equation
that
is
used
to
determine
loss
due
to
leaching
is
presented
below
(
Equation
5.0).
This
equation
is
adopted
from
USEPA
(
1993).

Equation
5.0
Metal
Loss
Due
to
Leaching
from
Soil
)
/
0
.
1
(
Q
*
+
*
*
Q
-
+
=
d
K
BD
Z
Ev
I
P
ksl
where:
ksl
=
metal
loss
due
to
leaching
(
yr­
1)
P
=
average
annual
precipitation
(
cm/
yr)
I
=
average
annual
irrigation
(
cm/
yr)
Ev
=
average
annual
evapotranspiration
(
cm/
yr)
Kd
=
soil­
water
partitioning
coefficient
(
mL/
g)
Q
=
soil
volumetric
water
content
(
mL/
cm3)

Equation
5.0
was
further
reduced
because
irrigation
is
designed
to
counter
loss
due
to
evapotranspiration;
therefore,
evapotranspiration
and
irrigation
are
excluded
from
this
equation.

25
Leaching
of
MOPC
into
groundwater,
and
subsequent
ingestion
of
drinking
water,
was
eliminated
as
an
exposure
pathway
(
as
presented
in
Figure
3).
Although
the
amount
of
MOPC
that
leaches
is
expected
to
be
small,
and
is
not
considered
to
contribute
significantly
to
exposure,
the
loss
of
MOPC
through
leaching
is
still
greater
than
the
loss
through
other
transport
pathways.
26
The
other
3
loss
pathways,
degradation,
erosion,
and
volatilization
were
previously
determined
to
(
1)
either
not
occur
or
(
2)
to
be
inconsequential
as
loss
pathways
for
metals
in
agricultural
soils
(
CDFA
1998).
28
DRAFT
Precipitation
(
P)

A
USEPA
(
1998a)
default
precipitation
(
P)
estimate
of
28
cm/
year
is
assumed.
This
precipitation
is
a
relatively
low
precipitation
rate
from
a
national
perspective.
Precipitation
rates
range
across
the
country
from
approximately
18
cm/
year
up
to
165
cm/
year
(
USEPA
1998a).
The
lower
the
precipitation
rate
the
less
potential
for
leaching
and
the
more
MOPC
in
the
soil.

Soil­
Water
Partitioning
(
Kd)

Soil­
water
partitioning
coefficients
(
Kd)
are
used
to
estimate
how
much
of
an
MOPC
is
expected
to
move
from
the
soil
phase
to
the
water
phase.
This
movement
of
an
MOPC
to
the
liquid
phase
makes
the
MOPC
more
bioavailable.
Bioavailable
MOPC
are
available
for
movement
away
from
soil,
for
example,
through
uptake
into
crops
or
leaching
into
groundwater.
Kd
is
best
determined
from
empirical
studies
and
not
modeled.
27
Kd
is
the
ratio
of
the
total
soil
metal
concentration
over
the
dissolved
metal
concentration
(
or
metal
in
the
water
phase).
Kd
is
highly
influenced
by
the
characteristics
of
the
soil
(
e.
g.,
organic
matter
content
and
especially
pH).
Generally,
the
lower
the
pH,
the
higher
the
Kd
(
and
the
more
soluble
and
more
bioavailable
the
MOPC).

The
Kd
values
are
taken
from
an
article
that
compiled
empirically
derived
Kds
from
existing
literature
and
developed
a
distribution
of
these
values.
The
literature
presents
Kds
for
most
of
the
MOPC
over
different
soil
types
(
clays
and
loams)
and
a
pH
range
of
4.5
 
9.0
(
Baes
and
Sharp
1983).
The
Kd
selected
for
use
in
the
SACF
is
the
mean
value.
Because
there
were
no
Kd
values
for
mercury,
nickel,
and
vanadium
in
Baes
and
Sharp
(
1983),
Kds
for
these
MOPC
are
adopted
from
USEPA
(
1995)
and
Gerriste
et
al.
(
1982).
These
values
are
also
mean
estimates.
The
soil
type
in
Gerriste
et
al.
(
1982)
is
sandy
soil
and
sandy
loam
with
pH's
of
5.0
and
8.0,
respectively.

Soil
Volumetric
Water
Content
(
Q
)

A
default
soil
volumetric
water
content
(
Q
)
of
0.2
mL/
cm3
is
used
(
USEPA
1998b).

Plant
Uptake
Factors
(
PUFs)

Like
AR,
plant
uptake
factor
(
PUF)
is
a
critical
parameter
in
the
RBC
equation.
28
PUF
estimates
the
amount
of
MOPC
present
in
soil
that
is
taken
up
by
the
crop.
29
PUF
is
MOPC
specific
and
is
determined
through
experimental
studies
that
measure
the
concentration
of
MOPC
in
soil
and
then
MOPC
in
plant
tissue
of
plants
grown
on
this
soil.
Basically,
PUF
is
the
ratio
of
total
(
not
extractable,
as
discussed
below)
MOPC
concentration
in
plant
over
the
MOPC
concentration
in
soil.
In
addition
to
the
influence
of
crop
type
and
MOPC,
there
are
many
other
factors
that
influence
PUF.
These
factors
include
study
design
(
e.
g.,
greenhouse
or
pot
or
field
study),
form
of
the
MOPC,
and
the
soil
types
and
conditions
of
the
study.
Each
of
these
factors
is
considered
27
As
discussed
in
USEPA
(
1999b).
28
In
CDFA
(
1998)
sensitivity
analysis,
PUF
was
determined
to
be
one
of
the
most
sensitive
parameters
for
most
of
the
RBCs.
29
PUF
is
also
called
transfer
coefficient
or
transfer
ratio.
29
DRAFT
when
selecting
studies
that
are
used
to
develop
PUFs.
A
presentation
of
the
study
selection
criteria
are
presented
in
Appendix
B,
along
with
the
summary
statistics
for
each
PUF
data
set.
PUFs
that
are
used
to
calculate
the
RBCs
are
presented
in
Table
9.

Green
House,
Pot,
and
Field
Studies
Study
design
(
i.
e.,
green
house
or
pot
or
field)
will
influence
the
PUF.
Generally,
when
both
the
plant
root
system
and
soil
are
confined,
as
in
a
green
house
or
pot
study,
the
opportunity
for
uptake
of
the
MOPC
by
the
plant
is
increased.
The
higher
uptake
could
result
from
increased
soil
temperature
and
differences
in
evapotranspiration
(
Chaney
et
al.
1999),
and
in
comparison,
in
field
studies,
the
root
system
has
a
greater
space,
and
more
dilute
soil
system,
allowing
less
potential
for
MOPC
uptake.
Nevertheless,
because
of
the
sometimes
limited
information
from
field
studies,
greenhouse
and
pot
studies
are
included
in
the
PUF
database.
30
Type
of
Fertilizer
The
chemical
form
of
the
MOPC
in
the
fertilizer
influences
the
PUF
and
the
MOPC
form
is
likely
to
be
different
for
different
types
of
fertilizers.
In
general,
the
form
of
the
MOPC
in
fertilizer
is
different
in
organic
fertilizer
compared
to
inorganic
fertilizer.
Given
that
this
evaluation
is
focused
on
inorganic
fertilizers,
studies
using
inorganic
fertilizers
are
of
most
interest.

MOPC
in
inorganic
fertilizers
are
generally
impurities
and
are
usually
part
of
a
relatively
immobile
complex.
The
plant
uptake
of
MOPC
in
phosphate
fertilizers
is
generally
lower
than
some
other
fertilizers,
like
soluble
chloride
or
sulfate
salts.
MOPC
in
these
fertilizers,
which
are
extremely
soluble,
are
much
more
available
for
plant
uptake.
MOPC
in
inorganic
fertilizers
usually
have
higher
plant
uptake
than
MOPC
in
organic
fertilizer.
MOPC
in
organic
fertilizers
tend
to
have
an
increased
capacity
to
sorb
to
soil
because
of
the
presence
of
several
hydrous
metal
oxides
(
aluminum,
iron,
and
manganese)
(
Chaney
et
al.
1999).
In
general,
studies
using
organic
fertilizers
are
not
appropriate
for
developing
PUFs
for
inorganic
fertilizer
application.
However,
studies
using
organic
fertilizer
(
sewage
sludge)
are
included
in
the
database
if
the
addition
of
an
organic
fertilizer
was
more
like
the
addition
of
an
inorganic
fertilizer.
These
studies
were
used
only
if:

1.
The
experiment
included
an
untreated
(
control)
plot
with
typical
plant
yields.
Control
plots
with
atypically
low
plant
yields
were
assessed
to
be
inadequately
fertilized
and,
therefore,
inappropriate
for
evaluating
PUFs.
2.
Sludge
had
been
added
many
years
ago
and
MOPC
concentrations
in
soil
had
reached
steady
state.
3.
Flyash
was
added
to
soil
at
nontoxic
levels,
and
like
sludge,
was
allowed
to
reach
steady
state
with
the
surrounding
soil.

30
USEPA
(
1999b)
conducted
a
sensitivity
analysis
on
the
use
of
field
versus
pot
studies
for
estimating
fertilizer
risks
and
found
data
from
field
studies
to
be
the
most
appropriate
information
to
use
for
this
scenario.
More
specifically,
the
PUFs
developed
from
pot
studies
are
much
higher
than
the
PUFs
from
field
studies;
therefore,
field
studies
are
more
appropriate
for
the
exposure
scenario.
30
DRAFT
Soil
Type
and
Condition
PUF
is
also
influenced
by
soil
type
(
e.
g.,
sandy­
silty
loam,
sand)
and
soil
conditions
(
e.
g.,
pH,
cation
exchange
capacity,
temperature,
and
moisture
content),
because,
these
factors
will
affect
the
form
and
behavior
of
the
MOPC
in
soil.
The
studies
included
in
the
PUF
database
represent
a
wide
variety
of
soils
and
soil
conditions
covering
a
large
range
of
chemical
and
physical
soil
properties.
The
database
included
information
obtained
throughout
the
US
and
some
information
from
Canada,
Europe,
Australia
and
elsewhere.
An
evaluation
of
the
variability
of
these
specific
soil
factors
was
not
conducted
on
the
PUF
database,
however,
the
database
is
considered
large
enough
to
average
out
the
affects
of
these
variables.
In
addition,
a
high­
end
estimate
of
the
PUF
was
used
in
developing
the
RBC
to
represent
conditions
where
high
plant
uptake
may
occur.

Studies
Excluded
from
Consideration
Studies
were
excluded
from
the
PUF
database
because
insufficient
information
was
presented
to
be
useful.
In
particular,
studies
that
did
not
report
total
metal
soil
concentrations
(
or
at
least
sufficient
data
to
calculate
total
metal
soil
concentration)
were
excluded
from
the
database.
These
studies
typically
report
an
extractable
(
or
plant
available)
soil
concentration.
Plant
available
(
i.
e.,
extractable)
MOPC
concentration
in
soil
does
not
correlate
well
with
total
MOPC
soil
concentration
because
of
the
different
methods
of
extraction
and
is
not
considered
a
good
value
for
estimating
PUFs.
31
In
general,
PUFs
developed
using
extractable
MOPC
concentrations
are
lower
than
PUFs
using
total
MOPC
concentrations.

In
addition,
studies
where
the
methods
were
deemed
to
be
inappropriate
or
not
applicable
for
this
scenario,
were
excluded.
For
example,
studies
where
the
application
rates
of
the
fertilizer
were
exaggerated,
in
comparison
with
practical
application
rates,
were
excluded
from
the
database.

Presentation
of
PUFs
The
PUFs
for
each
MOPC
and
crop
group
are
presented
in
Table
9.
The
PUFs
are
presented
in
both
dry
and
wet
(
or
fresh)
weight.
Most
studies
present
plant
and
soil
concentrations
in
dry
weight;
dry
weights
are
generally
more
constant
than
fresh
weight.
However,
PUFs
need
to
be
in
the
same
units
as
the
ingestion
rates
(
IR).
IRs
are
presented
in
"
as
consumed
basis"
(
as
consumed
equals
wet
weight),
therefore,
the
PUFs
are
converted
from
dry
to
weight
wet.
This
conversion
is
done
by
multiplying
the
PUF
in
dry
weight
by
a
dry
weight
fraction
for
the
crop
over
the
dry
weight
fraction
of
the
soil.
The
percent
(
or
fraction)
of
dry
weight
is
derived
from
the
percent
of
wet
weight
(
or
moisture
values)
(
i.
e.,
100%
weight
­
%
wet
weight
=
%
dry
weight).
The
fraction
of
dry
weight
for
vegetable,
root,
and
grains
are
10%,
11%,
90%,
respectively.
These
values
are
based
on
standard
USEPA
data
(
USEPA
1997a).
The
fraction
dry
weight
for
soil
is
90%.
This
fraction
is
based
on
sandy
loam
soil
because
this
is
the
type
of
soil
used
in
most
of
the
studies.
Regardless
of
soil
type,
the
percent
moisture
content
of
soil
is
typically
low;
therefore,
the
dry
weight
fraction
is
usually
high.
The
PUFs
in
Table
9
are
the
90%
upper
confidence
limit
(
UCL)
of
the
geometric
mean,
which
is
a
high­
end
estimate.
Generally,
the
data
for
PUFs
are
log
normally
distributed.

31
Expert
opinion
from
Dr.
Roland
Hauck
of
Florence,
AL.
Personal
Communications.
1999
31
DRAFT
Toxicity
Assessment
In
developing
the
RBCs,
the
toxicity
of
the
MOPC
are
evaluated
for
both
cancer
and
non­
cancer
endpoints
(
note
the
exceptions
for
lead,
as
discussed
below).
Toxicity
values
were
obtained
from
USEPA's
online
Integrated
Risk
Information
System
(
IRIS)
(
USEPA
1999c),
USEPA's
Health
Effects
Assessment
Summary
Tables
(
HEAST)
(
USEPA
1997b)
and
USEPA
Region
III
risk
based
concentration
toxicity
values
(
USEPA
1999c).
The
oral
and
dermal
toxicity
values
are
presented
in
Table
10.

For
several
MOPC
(
i.
e.,
chromium
and
mercury)
the
toxicity
values
depend
on
the
form
of
the
MOPC.
For
example,
toxicity
values
are
available
for
chromium
III
and
chromium
VI.
For
mercury,
toxicity
values
are
available
for
elemental
mercury,
mercuric
chloride,
and
methyl
mercury.
Assumptions
about
the
form
of
the
MOPC
that
is
likely
to
be
found
in
soil
following
years
of
application
of
inorganic
fertilizer
are
made
and
the
appropriate
toxicity
values
are
used
to
calculate
the
RBC.
In
summary,
chromium
III
and
mercuric
chloride
(
or
divalent
mercury)
are
more
likely
to
be
found
in
soil
and
be
available
for
uptake
and
potential
exposure,
compared
to
the
other
forms
of
these
MOPC.

Carcinogenic
Effects
For
MOPC
exhibiting
carcinogenic
potential,
cancer
slope
factors
(
SF)
are
developed
by
USEPA's
Carcinogen
Risk
Assessment
Verification
Endeavor
Work
Group
(
CRAVE).
These
slope
factors
are
developed
from
chronic
animal
studies
or,
where
possible,
human
epidemiological
data,
and
represent
the
excess
lifetime
cancer
risk
associated
with
various
levels
of
exposure.
Cancer
slope
factors
(
SFs)
are
expressed
as
in
terms
of
dose
in
units
of
(
mg
chemical/
kg
body
weight/
day)­
1.
They
describe
the
upper
bound
increase
in
an
individual's
risk
of
developing
cancer
over
a
70­
year
lifetime
per
unit
of
exposure
or
dose,
where
the
unit
of
acceptable
exposure
is
expressed
as
mg
chemical/
kg
body
weight/
day
(
mg/
kg/
day).
In
addition
to
developing
the
SF,
USEPA
assigns
a
weight
of
evidence
classification
for
each
carcinogen,
which
are
also
provided
in
Table
10.

Non­
Carcinogenic
Effects
Toxicity
criteria
for
chemicals
potentially
causing
noncarcinogenic
effects
are
expressed
as
references
doses
(
RfDs).
The
RfD
is
a
threshold
level
of
beyond
which
toxic
effects
may
result.
RfDs
are
expressed
in
units
of
dose
(
mg
chemical/
kg
body
weight/
day).
Chronic
oral
RfDs
are
developed
to
be
protective
for
long­
term
exposure
to
a
chemical.
To
derive
a
RfD,
a
series
of
professional
judgements
are
made
to
assess
the
quality
and
relevance
of
the
human
or
animal
data
and
to
identify
the
critical
study
and
the
toxic
effect.
A
toxicity
level
from
the
critical
study,
preferably
the
highest
no­
observable­
adverse­
effect
level
(
NOAEL),
is
used.
For
each
uncertainty
associated
with
the
NOAEL,
a
standardized
factor
is
applied
to
establish
a
margin
of
safety.
For
example,
uncertainty
factors
are
used
to
account
for
sensitive
subpopulations
or
the
extrapolation
of
animal
data
to
humans.
An
oral
RfD
for
cadmium
in
both
food
and
water
is
available.
The
toxicity
value
for
food
is
used
in
this
evaluation.
32
DRAFT
Dermal
Toxicity
Values
Toxicity
values
are
available
from
USEPA
for
the
oral
(
i.
e.,
ingestion)
route
of
exposure,
but
are
not
available
for
the
dermal
route
of
exposure.
Dermal
toxicity
values
are
developed
by
converting
the
oral
toxicity
values
from
an
administered
dose
to
an
absorbed
dose,
following
USEPA
standard
guidance
(
USEPA
1989).
For
RfDs,
the
oral
value
is
adjusted
to
a
dermal
toxicity
value
by
multiplying
the
oral
RfD
by
the
fraction
of
MOPC
that
is
absorbed
in
the
gastrointestinal
tract
(
GI
ABS).
The
oral
SFs
are
converted
to
dermal
SFs
by
dividing
by
the
GI
ABS.
GI
ABS
values
are
also
presented
in
Table
10.
Note,
if
the
oral
toxicity
value
is
already
based
on
an
absorbed
dose
(
e.
g.,
cadmium),
then
no
adjustment
is
necessary.
The
GI
ABS
values
are
from
the
chemical
specific
Agency
for
Toxic
Substance
Disease
Registry
(
ATSDR)
toxicological
profiles.

Toxicity
Value
for
Lead
No
RfD
or
CSF
has
been
established
for
lead
(
USDHHS
1997).
The
general
consensus
on
evaluating
lead
exposure
and
toxicity
is
through
measuring
blood
lead
levels
(
NAS
1980).
USEPA
and
ATSDR
recommend
a
fetal
acceptable
blood
lead
concentration
of
10
m
g/
dL
(
PbB
fetal,
0.95,
goal).
This
level
is
as
an
upper
limit
indicator
below
which
no
adverse
effects
would
be
expected.
The
USEPA
approach
for
developing
acceptable
concentrations
for
blood
lead
was
used
in
developing
the
acceptable
blood
lead
concentration.
The
acceptable
fetal
blood
lead
level
of
10
m
g/
dL
is
used
to
develop
a
target
blood
lead
concentration
(
PbB
a,
c,
g).
In
addition,
biokinetic
slope
factors
(
BKSF)
for
the
different
exposure
routes
and
the
child
and
adult
are
used
to
convert
the
estimated
intake
to
a
blood
lead
level
(
DTSC
1992).
32
32
CDFA
(
1998)
used
the
same
biokinetic
slope
factors.
TABLES
TABLE
5
VALUES,
DESCRIPTIONS,
AND
REFERENCES
FOR
BIOLOGICAL
EXPOSURE
PARAMETERS
(
a)

Parameter
Units
Adult
Descriptor
Child
Descriptor
Reference
Exposure
Duration
(
ED)
years
30
RME
default,
95th
percentile
length
of
residence
6
typical
RME
default
USEPA
(
1997a)

Exposure
Frequency
(
EF)
days/
year
350
daily
contact;
days/
year
at
home
350
daily
contact;
days/
year
at
home
USEPA
(
1989)

Averaging
Time
(
AT)
days
Cancer
25,550
prorated
over
a
lifetime
of
70
yrs
25,550
prorated
over
a
lifetime
of
70
yrs
USEPA
(
1989)

Non­
cancer
10,950
averaged
over
ED
2,190
averaged
over
ED
USEPA
(
1989)

Body
Weight
(
BW)
kg
71.8
default,
mean
15.5
mean
(
b)
USEPA
(
1997a)

Ingestion
Rates
(
IR)
default,
conservative
Soil
estimate
of
the
mean
Crop
Vegetable
1.7
mean
(
c)
2.9
mean
(
d)
USEPA
(
1997a)

Root
1.1
mean
(
c)
2.1
mean
(
d)
USEPA
(
1997a)

Grain
3.4
mean
(
c)
9.4
mean
(
d)
USEPA
(
1997a)

Fraction
Ingested
(
FI)
unitless
1
NA
1
NA
NA
Skin
Surface
Area
(
SA)
cm
2­
day
5,700
RME
default
(
f)
2,900
RME
default
(
f)
USEPA
(
1998b)

Adherence
Factor
(
AF)
mg/
cm
2­
day
0.08
RME
default
(
f)
0.3
RME
default
(
f)
USEPA
(
1998b)

Notes:
NA
=
Not
Applicable
RBC
=
Risk
Based
Concentration
RME
=
Reasonable
Maximum
Exposure
USEPA
=
United
States
Environmental
Protection
Agency
(
a)
All
values
are
intended
to
result
in
an
RBC
representative
of
an
RME
scenario.

(
b)
Calculated
average
for
ages
6
months
to
6
years
for
male
and
female.

(
c)
Calculated
time
weighted
mean
developed
from
key
study.
Represents
per
capita
intake,
ages
18­
70+.

(
d)
Calculated
time
weighted
mean
developed
from
key
study.
Represents
per
capita
intake,
ages
1­
5.

(
f)
Skin
SA
and
AF
values
are
central
estimates.
USEPA
(
1997a)

mg/
day
g/
kg­
day
50
default,
mean
200
DRAFT
TABLE
6
APPLICATION
RATES
(
ARs)
FOR
PHOSPHATE
FERTILIZERS
AND
ZINC
MICRONUTRIENT
FERTILIZERS
Fertilizer
Application
Rate
(
AR)
(
a)

lb/
acre­
year
(
b)
g/
m2­
year
(
c)
lb/
acre
­
year
(
d)
g/
m2­
year
(
c)

Vegetable
119
13
10
1.1
Root
157
17
10
1.1
Grain
63
6.9
10
1.1
(
a)
Developed
from
information
presented
in
USEPA
(
1999a).
Rounded
to
the
nearest
whole
number.
(
b)
High­
end
estimate
of
data
set
compiled
for
each
crop
group,
including
all
states,
presented
in
Appendix
B.
The
high­
end
estimate
is
the
95%
upper
confidence
limit
(
UCL)
of
the
mean,
assuming
a
normal
distribution.

(
c)
Converted
to
appropriate
units
for
the
RBC
equation
(
g/
m
2­
year)
by
multiplying
by
the
conversion
0.11
g­
acre/
lb­
m
2.
(
d)
Limited
data
is
available
on
the
application
of
micronutrient
fertilizers,
therefore,
this
is
a
high­
end
best
estimate
based
on
industry
experts,
as
presented
in
USEPA
(
1999a).
Crop
Group
Phosphate
Zinc
Micronutrient
DRAFT
TABLE
7
PARAMETERS
USED
TO
CALCULATE
SOIL
ACCUMULATION
FACTORS
(
SACFs)

Parameter
Value
Application
Time
Period
(
T)
(
yrs)
50
(
a)
Soil
Depth
(
Z)
(
cm/
yr)
20
(
b)

Bulk
Density
(
BD)
(
g/
cm
3)
1.5
(
b)

Soil
Loss
(
Ks)
(
yr­
1)
(
c)
Arsenic
0.14
Cadmium
0.14
Chromium
0.00042
Cobalt
0.017
Copper
0.042
Lead
0.0094
Mercury
0.0028
Molybdenum
0.046
Nickel
0.015
Selenium
0.33
Vanadium
0.084
Zinc
0.058
Precipitation
(
P)
(
cm/
year)
28
Soil
Volumetric
Water
Content
(
mL/
cm
3)
0.20
Soil
Water
Partition
Coefficient
(
Kd)
(
L/
kg)
Arsenic
6.7
(
d)
Cadmium
6.7
(
d)
Chromium
2200
(
d)
Cobalt
55
(
d)
Copper
22
(
d)
Lead
99
(
d)
Mercury
330
(
e)
Molybdenum
20
(
d)
Nickel
63
(
e)
Selenium
2.7
(
d)
Vanadium
11
(
e)
Zinc
16
(
d)

(
a)
Reasonable
assumption
for
T
developed
in
CDFA
(
1998).
A
T
of
200
yrs
is
used
for
lead.
(
b)
Obtained
from
USEPA
(
1998a).
(
c)
Calculated.
(
d)
Obtained
from
Baes
and
Sharp
(
1983).
(
e)
Obtained
from
Gerritse
et
al.
(
1982)
and
USEPA
(
1995).

DRAFT
TABLE
8
SOIL
ACCUMULATION
FACTORS
(
SACFs)

MOPC
SACF
(
a)
m2/
yr­
g
Arsenic
2.4E­
05
Cadmium
2.4E­
05
Chromium
1.6E­
04
Cobalt
1.1E­
04
Copper
6.9E­
05
Lead
3.0E­
04
Mercury
1.6E­
04
Molybdenum
6.5E­
05
Nickel
1.2E­
04
Selenium
1.0E­
05
Vanadium
3.9E­
05
Zinc
5.4E­
05
Notes:
MOPC
=
Metal
of
Potential
Concern
(
a)
Calculated.

DRAFT
TABLE
9
PLANT
UPTAKE
FACTORS
(
PUFs)
FOR
EACH
CROP
GROUP
Metal
PUF
(
mg
MOPC/
kg
plant/
mg
MOPC/
kg
soil)
(
unitless)
(
a)
of
Potential
Dry
Weight
(
b)
Wet
Weight
Concern
(
MOPC)
Vegetable
(
c)
Root
(
d)
Grain
(
e)
Vegetable
Root
Grain
Arsenic
0.3
0.05
0.03
0.03
0.0061
0.03
Cadmium
(
f)
1.7
0.93
0.12
0.17
0.11
0.12
Chromium
(
g)
0.0014
0.0014
0.037
0.00014
0.00018
0.037
Cobalt
0.05
0.03
0.02
0.005
0.0037
0.02
Copper
0.034
0.22
0.31
0.0034
0.027
0.31
Lead
0.08
0.05
0.05
0.008
0.0061
0.05
Mercury
0.61
0.67
0.26
0.061
0.082
0.26
Molybdenum
1.1
0.15
0.22
0.11
0.018
0.22
Nickel
0.15
0.07
0.05
0.015
0.0086
0.05
Selenium
0.88
0.76
0.57
0.088
0.093
0.57
Vanadium
(
h)
0.007
0.007
0.007
0.0007
0.00086
0.007
Zinc
1.7
0.46
0.58
0.17
0.056
0.58
(
a)
PUFs
are
the
90%
upper
confidence
limit
(
UCL)
of
the
geometric
mean,
which
is
considered
a
high­
end
estimate.
(
b)
Converted
to
wet
weight
(
ww)
using
the
dry
weight
(
dw)
fraction.
Dry
Weight
Fractions
are:
vegetable
=
91%
moisture,
9%
dry;
root
=
89%
moisture,
11%
dry;
grain
=
10%
moisture,
90%
dry;
and
soil
(
based
on
sandy
loam)
=
10
%
moisture,
90%
dry
(
USEPA
1997a).
Example
of
dw
to
ww
conversion:
PUF
arsenic,
vegetable
dw
*
dw
fraction
vegetable/
dw
fraction
soil
=
0.3
*
0.09/
0.90
=
0.03
(
c)
Vegetable
database
consists
of
data
for
broccoli,
brussel
sprouts,
cabbage,
cauliflower,
cucumber,
eggplant,
kale,
lettuce,
pepper,
spinach,
swiss
chard,
and
tomato.
(
d)
Root
crop
database
consists
of
data
for
beet,
carrot,
fennel,
mangel,
onion,
parsnip,
potato,
radish,
and
rutabaga.
(
e)
Grains
database
consists
of
data
for
barley,
corn,
millet,
oats,
rice,
and
wheat.
(
f)
Cadmium
PUF
does
not
consider
the
presence
of
zinc,
which
can
decrease
the
cadmium
PUF.
(
g)
The
PUFs
for
chromium
(
vegetable
and
root)
were
adopted
from
(
USEPA
1999b).
(
h)
Very
limited
data
were
found
that
could
be
used
to
develop
a
PUF
for
vanadium.
This
PUF
is
based
on
data
for
forage
crops
(
obtained
from
USEPA
(
1999b)).

DRAFT
TABLE
10
ORAL
AND
DERMAL
TOXICITY
VALUES
Noncancer
Toxicity
Value
Cancer
Toxicity
Value
GI
ABS
Fraction
Oral
Dermal
Oral
Dermal
Metal
of
Potential
RfD
RfD
(
a)
Safety
Target
Organ
SF
SF
(
a)
Target
Concern
(
MOPC)
Value
Source
(
mg/
kg­
day)
(
mg/
kg­
day)
Factor
or
Effect
Source
(
mg/
kg­
day)­
1
(
mg/
kg­
day)­
1
Tissue
WOEC
Source
Arsenic
0.95
IRIS
3.0E­
04
2.9E­
04
3
skin
IRIS
1.5E+
00
1.5E+
00
skin
A
IRIS
Cadmium
(
b)
­­
­­
1.0E­
03
1.0E­
03
10
kidney
IRIS
­­
­­
­­
­­
­­

Chromium
(
III)
(
c)
0.02
USDHHS
1993
1.5E+
00
3.0E­
02
1,000
none
observed
IRIS
­­
­­
­­
D
IRIS
Cobalt
0.44
USDHHS
1992
6.0E­
02
2.6E­
02
10
blood
RBC
­­
­­
­­
­­
­­

Copper
0.97
USDHHS
1989
4.0E­
02
3.9E­
02
­­
­­
RBC
­­
­­
­­
D
IRIS
Lead
­­
­­
10
ug/
dL
acceptable
fetal
blood
lead
level
and
biokinetic
slope
factors
specific
to
age
group
and
exposure
route.
B2
USEPA
1996
Mercury
(
d)
0.07
IRIS
3.0E­
04
2.1E­
05
1,000
autoimmune,
kidney
IRIS
­­
­­
­­
C
IRIS
Molybdenum
1
(
f)
5.0E­
03
5.0E­
03
30
joints,
blood
IRIS
­­
­­
­­
­­
­­

Nickel
(
e)
0.007
USDHHS
1995
2.0E­
02
1.4E­
04
300
decreased
organ
weight
IRIS
­­
­­
­­
­­
­­

Selenium
­­
­­
5.0E­
03
5.0E­
03
3
liver,
CNS
(
selenosis)
IRIS
­­
­­
­­
D
IRIS
Vanadium
0.03
USDHHS
1990
7.0E­
03
2.1E­
04
100
­­
HEAST
­­
­­
­­
­­
­­

Zinc
0.81
USDHHS
1994
3.0E­
01
2.4E­
01
3
blood
IRIS
­­
­­
­­
D
IRIS
Notes:
­­
=
Not
Applicable
or
Not
Available
CNS
=
Central
Nervous
System
GI
ABS
=
Gastrointestinal
Absorption
Fraction
HEAST
=
Health
Effects
Assessment
Summary
Tables
(
USEPA
1997b)

IRIS
=
Integrated
Risk
Information
System
(
USEPA
1999c)

RfD
=
Reference
Dose
SF
=
Slope
Factor
USDHHS
=
United
States
Department
of
Health
and
Human
Services
WOEC
=
Weight
of
Evidence
Classification
(
A
=
human
carcinogen,
B
=
probable
human
carcinogen,
C
=
possible
human
carcinogen,
D
=
not
classifiable
as
to
human
carcinogenicity)

(
a)
Dermal
toxicity
values
are
not
developed
by
the
USEPA,
so,
the
oral
toxicity
values
are
used.
In
most
cases,
the
oral
toxicity
value
is
an
administered
dose
and
is
not
an
absorbed
dose
(
note
the
incorporation
of
a
percent
dermal
absorption
value),
therefore,
the
toxicity
value
also
needs
to
be
in
an
absorbed
dose.
Oral
toxicity
values
that
are
administered
are
converted
to
absorbed
dose
by
multiplying
the
oral
RfD
by
the
GI
ABS
or
dividing
the
SF
by
the
GI
ABS
(
USEPA
1989).

(
b)
Toxicity
values
are
based
on
cadmium
in
food,
which
is
based
on
an
absorbed
dose.

(
c)
Toxicity
values
are
based
on
insoluble
salts.
As
discussed
in
the
Toxicity
Assessment
Section,
chromium
(
Cr)
is
expected
to
be
primarily
in
the
form
of
CrIII
(
rather
than
CrVI)
in
soil
and
available
for
uptake.

(
d)
Toxicity
values
are
based
on
mercuric
chloride.
As
discussed
in
the
Toxicity
Assessment
Section,
mercuric
chloride
(
or
divalent
mercury)
is
assumed
to
be
the
most
likely
form
of
mercury
found
in
soil.
Based
on
oral
administration
of
mercuric
chloride
in
mice.
A
1%
GI
ABS
value
was
also
reported.

(
e)
Toxicity
values
are
based
on
soluble
nickel
salts.

(
f)
No
GI
ABS
information
was
found
for
molybdenum;
therefore,
a
GI
ABS
fraction
of
1
was
assumed.
DRAFT
33
DRAFT
SECTION
3.0
¾
PRESENTATION
OF
RISK
BASED
CONCENTRATIONS
(
RBCS)
FOR
METALS
OF
POTENTIAL
CONCERN
(
MOPC)

A
summary
of
all
of
the
parameters
that
go
into
deriving
the
risk
based
concentrations
(
RBCs)
are
presented
in
Tables
11,
12,
and
13.
Table
11
summarizes
the
parameters
used
to
calculate
the
summary
intake
factors
(
SIFs);
Table
12
presents
the
SIFs
for
each
exposure
pathway;
and
Table
13
provides
the
remaining
parameters
used
to
calculate
the
RBCs.
The
unit
RBCs,
based
on
a
one
percent
fraction
of
nutrient
(
FON),
are
presented
in
Table
14
for
phosphate
fertilizers
and
micronutrient
fertilizers.

As
seen
in
the
tables,
unit
RBCs
are
calculated
for
a
single
crop
farm
and
a
multi­
crop
farm
for
both
an
adult
and
a
child.
The
lowest
RBC
for
each
MOPC
is
selected
for
screening
human
health
risks
and
is
presented
in
the
last
two
columns
of
Table
14.

Note
that
for
arsenic
the
adult
farm
resident
has
the
lowest
RBC
because
arsenic
is
a
carcinogen
and
the
exposure
duration
is
much
longer
for
an
adult.
The
lowest
RBCs
for
the
remainder
of
the
MOPC
are
for
the
child
farm
resident.
The
multi­
crop
scenario
always
has
the
lowest
RBC
value
because
exposure
is
coming
from
all
crop
types
not
just
one
of
the
crop
types.
TABLES
TABLE
11
SUMMARY
OF
ALL
OF
THE
PARAMETERS
AND
ASSUMPTIONS
USED
TO
CALCULATE
THE
SUMMARY
INTAKE
FACTORS
(
SIFs)
(
a)

Parameter
(
b)
Units
Parameter
Values
Target
Cancer
Risk
and
Hard
Quotient
unitless
­­
TR
Target
Cancer
Risk
1.0E­
05
THQ
Target
Hazard
Quotient
1
Biological
Exposure
Parameters
Adult
Child
EF
Exposure
Frequency
days/
year
350
350
ED
Exposure
Duration
years
30
6
AT
Averaging
Time
days
Cancer
25,550
25,550
Noncancer
10,950
2190
BW
Body
Weight
kg
71.8
15.5
IRs
Soil
Ingestion
Rate
mg/
day
50
200
IRc
Ingestion
Rate
g/
kg­
day
Vegetables
1.7
2.9
Roots
1.1
2.1
Grains
3.4
9.4
AF
Adherence
Factor
mg/
cm
2
0.08
0.3
SA
Exposed
Skin
Surface
Area
cm
2/
day
5,700
RAF
Relative
Absorption
Factor
unitless
Arsenic
0.42
1
Cadmium
1
1
Chromium
1
1
Cobalt
1
1
Copper
1
1
Lead
0.41
0.5
Mercury
1
1
Molybdenum
1
1
Nickel
1
1
Selenium
1
1
Vanadium
1
1
Zinc
1
1
ABS
Dermal
Absorption
Factor
unitless
­­
Arsenic
0.03
Cadmium
0.01
Chromium
0.01
Cobalt
0.01
Copper
0.01
Lead
1
Mercury
0.01
Molybdenum
0.01
Nickel
0.01
Selenium
0.01
Vanadium
0.01
Zinc
0.01
Notes:

­­
Not
Applicable
(
a)
The
equations
used
to
calculate
the
SIFs
are
presented
below.

SIFs
are
calculated
to
simplify
the
calculation
of
the
RBC,
and
are
presented
in
Table
12.

(
b)
The
development
of
all
of
these
parameters
is
presented
in
Section
2.0.

SIF
Calculations:

Unintentional
Ingestion
of
Fertilized
Soil
Summary
Intake
Factor
(
SIFsi)
=
(
ED*
EF*
IRs*
RAFs*
CF)/(
BW*
AT)

Dermal
Contact
with
Fertilized
Soil
Summary
Intake
Factor
(
SIFd)
=
(
ED*
EF*
SA*
AF*
ABS*
CF)/(
BW*
AT)

Crop
Ingestion
Summary
Intake
Factor
(
SIFc)
=
(
ED*
EF*
IRc*
RAFc)/(
AT)
Soil
(
s)
Crop
(
c)
2,900
DRAFT
TABLE
12
SUMMARY
INTAKE
FACTORS
(
SIFs)
(
a)

Summary
SIF
Value
Intake
Factors
(
SIF)
Units
Adult
Child
Unintentional
Ingestion
of
Fertilized
Soil
(
SIF)
si
day­
1
Cancer
Arsenic
(
a)
1.2E­
07
4.5E­
07
Noncancer
Arsenic
2.8E­
07
5.2E­
06
Lead
(
b)
2.7E­
07
5.1E­
06
All
Other
MOPC
(
c)
6.7E­
07
1.2E­
05
Dermal
Contact
with
Fertilized
Soil
(
SIF)
d
Cancer
Arsenic
7.8E­
08
1.4E­
07
Noncancer
Arsenic
1.8E­
07
1.6E­
06
All
Other
MOPC
(
c)
6.1E­
08
5.4E­
07
Crop
Ingestion
Vegetable
(
SIF)
v
Cancer
Arsenic
7.0E­
04
2.4E­
04
Noncancer
Lead
(
b)
8.2E­
04
1.4E­
03
All
Other
MOPC
(
c)
1.6E­
03
2.8E­
03
Root
(
SIF)
r
Cancer
Arsenic
4.5E­
04
1.7E­
04
Noncancer
Lead
(
b)
5.3E­
04
1.0E­
03
All
Other
MOPC
(
c)
1.1E­
03
2.0E­
03
Grain
(
SIF)
g
Cancer
Arsenic
1.4E­
03
7.7E­
04
Noncancer
Lead
(
b)
1.6E­
03
4.5E­
03
All
Other
MOPC
(
c)
3.3E­
03
9.0E­
03
(
a)
Arsenic
is
the
only
MOPC
that
is
evaluated
for
potential
carcinogenicity.

(
b)
Lead
SIFs
are
adjusted
appropriately
by
biokinetic
slope
factors
specific
to
age
group
and
exposure
route.

(
c)
The
only
parameters
in
the
SIF
equations
(
presented
below)
that
are
MOPC
specific,
and
therefore,
can
change
the
SIF
to
be
MOPC
specific,
are
RAF
or
ABS.
If
a
MOPC
specific
RAF
or
ABS
is
not
found,
a
default
value
is
used;
then
the
SIF
is
not
specific
MOPC,
and
therefore,
is
generic,
and
presented
in
the
All
Other
MOPC
row.

SIF
Calculations:

Unintentional
Ingestion
of
Fertilized
Soil
Summary
Intake
Factor
(
SIFsi)
=
(
ED*
EF*
IRs*
RAFs*
CF)/(
BW*
AT)
Dermal
Contact
with
Fertilized
Soil
Summary
Intake
Factor
(
SIFd)
=
(
ED*
EF*
SA*
AF*
ABS*
CF)/(
BW*
AT)
Crop
Ingestion
Summary
Intake
Factor
(
SIFc)
=
(
ED*
EF*
IRc*
RAFc)/(
AT)

DRAFT
TABLE
13
PARAMETERS
(
SACF,
AR,
PUF,
FOL,
AND
TOXICITY
VALUES)
USED
TO
CALCULATE
THE
RISK
BASED
CONCENTRATIONS
(
RBCs)
(
a,
b)

Parameter
(
c)
Units
Parameter
Values
SACF
Soil
Accumulation
Factor
m
2­
yr/
g
­­
Arsenic
2.4E­
05
Cadmium
2.4E­
05
Chromium
1.6E­
04
Cobalt
1.1E­
04
Copper
6.9E­
05
Lead
3.0E­
04
Mercury
1.6E­
04
Molybdenum
6.5E­
05
Nickel
1.2E­
04
Selenium
1.0E­
05
Vanadium
3.9E­
05
Zinc
5.4E­
05
AR
(
d)
Application
Rate
g/
m
2­
yr
Vegetable
(
v)
Root
(
r)
Grain
(
g)
Phosphate
13
17
6.9
Zinc
Micronutrient
1.1
1.1
1.1
PUF
Plant
Uptake
Factor
unitless
Vegetable
Root
Grain
Arsenic
0.03
0.0061
0.03
Cadmium
0.17
0.11
0.12
Chromium
0.00014
0.00018
0.037
Cobalt
0.005
0.0037
0.02
Copper
0.0034
0.027
0.31
Lead
0.008
0.0061
0.05
Mercury
0.061
0.082
0.26
Molybdenum
0.11
0.018
0.22
Nickel
0.015
0.0086
0.05
Selenium
0.088
0.093
0.57
Vanadium
0.0007
0.00086
0.007
Zinc
0.17
0.056
0.58
FOL
(
e)
Fraction
of
Land
unitless
Vegetable
Root
Grain
0.4
0.1
0.5
Toxicity
Value
Oral
(
o)
Dermal
(
d)

SF
Slope
Factor
(
mg/
kg­
day)­
1
Arsenic
1.5E+
00
1.5E+
00
RfD
Reference
Dose
mg/
kg­
day
Arsenic
3.0E­
04
2.9E­
04
Cadmium
1.0E­
03
1.0E­
03
Chromium
1.5E+
00
3.0E­
02
Cobalt
6.0E­
02
2.6E­
02
Copper
4.0E­
02
3.9E­
02
Lead
­­
­­
Mercury
3.0E­
04
2.1E­
05
Molybdenum
5.0E­
03
5.0E­
03
Nickel
2.0E­
02
1.4E­
04
Selenium
5.0E­
03
5.0E­
03
Vanadium
7.0E­
03
2.1E­
04
Zinc
3.0E­
01
2.4E­
01
Notes:

­­
Not
Applicable
(
a)
The
equations
used
to
calculate
the
RBCs
are
presented
below.

(
b)
Summary
Intake
Factors
(
SIFs)
are
presented
in
Table
12.

(
c)
All
of
the
parameters
are
presented
in
Section
2.0.

(
d)
AR
is
adjusted
so
that
the
RBC
is
based
on
1%
fraction
of
nutrient
(
FON),
resulting
in
unit
RBCs.

The
AR
is
inversely
proportionate
to
the
FON,
therefore,
AR
is
adjusted
to
1%
FON
by
dividing
by
1%.

(
e)
FOL
is
only
needed
for
the
calculation
of
the
multiple
crop
RBCs.

RBC
Calculations
for
Single
Crop
Farm
(
equations
adopted
from
CDFA
1998):

Cancer
RBC
=
TR/{
SACF*[
AR*(
SIFsi*
SFo*
RAFs+
SIFd*
SFd+
PUF*
SIFc*
SFo*
RAFc)]}

Noncancer
RBC
=
THI/{
SACF*[
AR*(
SIFsi*
1/
RfDo*
RAFs+
SIFd*
1/
RfDd+
PUF*
SIFc*
1/
RfDo*
RAFc)]}

RBC
Calculations
for
Multiple
Crop
Farm
(
equations
adopted
from
CDFA
1998):

Cancer
RBC
=

TR/(
SACF*{
ARv*[((
SIFsi*
SFo+
SIFd*
SFd)*
FOLv)+
PUFv*
SIFv*
SFo]}+{
ARr*[((
SIFsi*
SFo+

SIFsd*
SFd)*
FOLr)+
PUFr*
SIFr*
SFo]}+{
ARg*[((
SIFsi*
SFo+
SIFd*
SFd)*
FOLg)+
PUFg*
SIFg*
SFo]})

Noncancer
RBC
=

THI/(
SACF*{
ARv*[((
SIFsi*
1/
RfDo+
SIFd*
1/
RfDd)*
FOLv)+
PUFv*
SIFv*
1/
RfDo]}+{
ARr*[((
SIFsi
*
1/
RfDo+
SIFd*
1/
RfDd)*
FOLr)+
PUFr*
SIFr*
1/
RfDo]}+{
ARg*[((
SIFsi*
1/
RfDo+
SIFd*
1/
RfDd)*
FOLg)+

PUFg*
SIFg*
1/
RfDo]})

DRAFT
TABLE
14
UNIT
RISK
BASED
CONCENTRATIONS
(
RBCs)
(
a)
FOR
ALL
SCENARIOS
Adult
Farm
Resident
RBC
Child
Farm
Resident
RBC
Lowest
Unit
RBC
(
b)

MOPC
Vegetable
Roots
Grains
Multi­
crop
Vegetable
Roots
Grains
Multi­
crop
Scientific
Notation
Standard
Notation
Phosphate
Fertilizer
Arsenic
(
c)
9.9E+
00
5.4E+
01
9.4E+
00
4.5E+
00
2.7E+
01
9.7E+
01
1.7E+
01
9.8E+
00
4.5E+
00
4.5
Cadmium
1.1E+
02
2.0E+
02
1.5E+
02
4.9E+
01
6.4E+
01
9.8E+
01
5.4E+
01
2.3E+
01
2.3E+
01
23
Chromium
(
III)
1.8E+
06
1.4E+
06
1.1E+
05
1.0E+
05
1.7E+
05
1.3E+
05
3.6E+
04
3.4E+
04
3.4E+
04
34,000
Cobalt
4.5E+
04
6.6E+
04
1.2E+
04
8.4E+
03
1.5E+
04
1.5E+
04
4.0E+
03
3.1E+
03
3.1E+
03
3,100
Copper
7.0E+
04
1.1E+
04
8.2E+
02
7.6E+
02
2.0E+
04
5.0E+
03
3.0E+
02
2.8E+
02
2.8E+
02
280
Lead
1.3E+
03
2.0E+
03
2.1E+
02
1.6E+
02
7.7E+
02
9.3E+
02
8.5E+
01
7.3E+
01
7.3E+
01
73
Mercury
1.5E+
01
1.3E+
01
3.3E+
00
2.2E+
00
7.8E+
00
6.1E+
00
1.2E+
00
9.0E­
01
9.0E­
01
0.9
Molybdenum
3.3E+
02
2.2E+
03
1.6E+
02
1.0E+
02
1.8E+
02
9.0E+
02
5.6E+
01
4.2E+
01
4.2E+
01
42
Nickel
3.8E+
03
5.4E+
03
1.4E+
03
1.0E+
03
9.9E+
02
9.3E+
02
4.5E+
02
3.5E+
02
3.5E+
02
350
Selenium
2.6E+
03
2.9E+
03
3.8E+
02
3.0E+
02
1.5E+
03
1.4E+
03
1.4E+
02
1.2E+
02
1.2E+
02
120
Vanadium
3.6E+
04
2.9E+
04
1.0E+
04
8.3E+
03
4.2E+
03
3.2E+
03
2.8E+
03
2.2E+
03
2.2E+
03
2,200
Zinc
1.5E+
04
5.3E+
04
4.2E+
03
3.1E+
03
8.8E+
03
2.5E+
04
1.5E+
03
1.2E+
03
1.2E+
03
1,200
Micronutrient
Fertilizer
Arsenic
(
c)
1.2E+
02
8.4E+
02
5.9E+
01
3.8E+
01
3.2E+
02
1.5E+
03
1.0E+
02
7.4E+
01
3.8E+
01
38
Cadmium
1.3E+
03
3.1E+
03
9.5E+
02
4.7E+
02
7.6E+
02
1.5E+
03
3.4E+
02
2.1E+
02
2.1E+
02
210
Chromium
(
III)
2.1E+
07
2.1E+
07
6.7E+
05
6.7E+
05
2.1E+
06
2.1E+
06
2.2E+
05
2.2E+
05
2.2E+
05
220,000
Cobalt
5.4E+
05
1.0E+
06
7.3E+
04
6.2E+
04
1.8E+
05
2.3E+
05
2.5E+
04
2.3E+
04
2.3E+
04
23,000
Copper
8.3E+
05
1.8E+
05
5.2E+
03
5.0E+
03
2.3E+
05
7.8E+
04
1.9E+
03
1.8E+
03
1.8E+
03
1,800
Lead
1.6E+
04
3.1E+
04
1.3E+
03
1.2E+
03
9.1E+
03
1.5E+
04
5.4E+
02
5.0E+
02
5.0E+
02
500
Mercury
1.7E+
02
2.0E+
02
2.1E+
01
1.7E+
01
9.3E+
01
9.5E+
01
7.4E+
00
6.5E+
00
6.5E+
00
6.5
Molybdenum
3.9E+
03
3.5E+
04
9.8E+
02
7.6E+
02
2.2E+
03
1.4E+
04
3.5E+
02
3.0E+
02
3.0E+
02
300
Nickel
4.6E+
04
8.4E+
04
9.0E+
03
7.5E+
03
1.2E+
04
1.4E+
04
2.9E+
03
2.6E+
03
2.6E+
03
2,600
Selenium
3.1E+
04
4.6E+
04
2.4E+
03
2.1E+
03
1.7E+
04
2.2E+
04
8.7E+
02
8.0E+
02
8.0E+
02
800
Vanadium
4.2E+
05
4.5E+
05
6.4E+
04
5.9E+
04
5.0E+
04
5.1E+
04
1.7E+
04
1.7E+
04
1.7E+
04
17,000
Zinc
1.8E+
05
8.3E+
05
2.6E+
04
2.3E+
04
1.0E+
05
4.0E+
05
9.6E+
03
8.6E+
03
8.6E+
03
8,600
Notes:
Bold
=
Lowest
RBC
MOPC
=
Metal
of
Potential
Concern
(
a)
The
units
for
all
RBCs
are
mg
MOPC/
kg
product
(
i.
e.,
ppm).
The
lowest
unit
RBC
for
each
metal
is
shown
in
the
two
far
right
columns.

This
is
the
value
used
for
screening
(
presented
in
Section
4.0).

(
b)
The
lowest
unit
RBC
is
the
lowest
for
child
and
adult
farm
residents.

(
c)
The
RBCs
presented
for
arsenic
are
based
on
cancer.
All
other
RBCs
are
based
on
non­
cancer.
DRAFT
34
DRAFT
SECTION
4.0
¾
SCREENING
HEALTH
EVALUATION:
COMPARISON
OF
THE
RISK
BASED
CONCENTRATIONS
(
RBC)
WITH
THE
CONCENTRATION
OF
THE
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
IN
FERTILIZER
PRODUCTS
A
screening­
level
determination
of
whether
a
particular
fertilizer
product
poses
a
potential
health
risk
is
accomplished
by
comparing
the
measured
concentration
of
a
MOPC
(
e.
g.
arsenic)
in
the
product
to
the
RBC
for
that
same
MOPC.
The
RBCs
for
this
assessment
are
derived
in
this
report
and
presented
in
Table
14.
The
lowest
RBCs
are
the
most
appropriate
to
use
in
a
screening­
level
health
risk
evaluation.
The
measured
concentrations
of
MOPC
are
obtained
from
the
published
literature,
from
a
survey
of
fertilizer
manufacturers,
and
from
monitoring
programs
being
conducted
by
a
number
of
states.
This
database
has
been
compiled
by
TWG.
33
The
concentrations
of
the
MOPC
in
products
must
be
in
the
same
units
as
the
RBCs
to
make
a
direct
comparison.
The
RBCs
and
the
product
concentration
database
are
reported
in
mg
MOPC/
kg
product
(
i.
e.,
part
per
million
or
ppm).
Comparisons
can
be
made
on
a
product­
byproduct
basis,
or
if
there
are
multiple
reported
concentrations
of
a
MOPC
for
the
same
fertilizer
(
e.
g.,
samples
from
different
batches
or
from
different
manufacturers),
the
maximum
MOPC
concentration
can
be
compared
to
the
RBC
as
an
initial
screen.
Comparing
the
lowest
RBC
to
the
maximum
MOPC
concentration
provides
the
most
health
protective
estimate
of
health
risk.
If
the
concentration
of
the
MOPC
in
the
fertilizer
is
below
the
RBC,
there
is
no
health
risk.
If
the
concentration
of
the
MOPC
in
the
fertilizer
is
above
the
RBC,
further
evaluation
is
warranted.
An
exceedence
of
a
screening­
level
RBC
does
not
necessarily
indicate
there
is
a
health
risk
because
the
RBCs
are
health
protective
derived
to
ensure
that
health
risks
are
not
underestimated
(
but
they
may
be
overestimated).
A
firm
conclusion
regarding
health
risks,
in
the
case
of
a
RBC
exceedence,
therefore,
requires
a
closer
evaluation.

Before
the
RBCs
can
be
compared
to
the
measured
levels
of
MOPC
in
a
product,
however,
the
unit
RBCs
(
i.
e.,
RBCs
derived
for
1%
of
the
nutrient
in
a
product;
reported
in
Table
14)
need
to
be
adjusted
for
the
actual
fraction
of
nutrient
(
FON)
in
the
product.
The
unit
RBC
is
adjusted
by
multiplying
the
RBC
by
the
percent
FON.
For
phosphate
fertilizers,
the
FON
is
the
phosphate
(
or
P2O5)
component;
for
micronutrient
fertilizers,
it
is
the
principal
micronutrient
component
(
e.
g.
zinc
or
iron).
The
representative
FON
is
determined
using
both
the
TWG
fertilizer
database
and
information
reported
in
USEPA
(
1999a).
The
FONs
for
each
product
category
are
best
estimates
and
are
presented
in
Table
15
(
for
phosphate)
and
Table
16
(
for
micronutrients).

The
comparisons
of
FON
adjusted
RBCs
to
maximum
measured
concentrations
of
MOPC
in
products
(
by
fertilizer
type
or
product
category)
are
presented
in
Tables
17
and
18
for
phosphate
and
micronutrient
fertilizers,
respectively.
Phosphate
product
categories
include,
for
example,
diammonium
phosphate
or
urea­
ammonium
phosphate.
There
are
also
a
number
of
product
samples
that
were
reported
as
`
agricultural
blends';
they
contain
N,
P
and
K
but
with
no
micronutrients
added.
The
micronutrient
product
categories
are
boron,
iron,
manganese,
and
zinc
micronutrient
fertilizers.

33
TWG
fertilizer
database
consists
of
state,
literature,
and
industry
data
on
inorganic
fertilizers.
A
summary
of
this
database
is
presented
in
TWG
(
1999c).
This
database
is
updated
as
new
data
become
available.
35
DRAFT
Results
There
were
no
RBC
exceedances
for
any
of
the
12
MOPC
in
phosphate
fertilizers
(
see
Table
17).
There
were
comparisons
made
for
15
categories
of
phosphate
fertilizers
(
including
the
agricultural
blends)
and
for
a
total
of
approximately
925
individual
fertilizer
samples.

There
were
RBC
exceedances
among
the
four
categories
of
micronutrient
fertilizers,
primarily
for
the
MOPC
arsenic
and
lead.
A
total
of
approximately
140
individual
fertilizer
samples
were
evaluated.
The
exceedances
include:

·
2
for
arsenic
in
boron
micronutrient
fertilizers;
·
8
for
arsenic
in
iron
micronutrients;
·
2
for
arsenic
in
manganese
micronutrient
fertilizers;
·
1
for
lead
in
iron
micronutrient
fertilizers;
·
1
for
lead
in
manganese
micronutrient
fertilizers;
·
6
for
lead
in
zinc
micronutrient
fertilizers;
·
and
2
for
zinc
in
zinc
micronutrient
fertilizers.

A
closer
evaluation
of
the
exceedances,
to
determine
if
these
fertilizers
pose
a
health
risk,
would
involve
several
steps,
including:
(
1)
replacing
the
default
FON
developed
for
the
fertilizer
category
with
the
FON
for
the
individual
fertilizer
sample
(
not
always
reported
in
the
database)
34,
(
2)
confirmation
that
the
product
is
still
on
the
market
(
a
number
of
the
samples
reported
in
the
database
are
years
old),
and
(
3)
determine
the
exact
usage
(
including
application
rate,
crop
types,
etc.)
for
the
product
of
interest,
then
adjust
the
RBC
value
to
more
closely
reflect
the
actual
exposure
scenario
conditions.

34
Six
of
these
22
exceedances
become
non­
exceedances
when
the
unit
RBC
is
adjusted
by
a
sample­
specific
FON
in
place
of
the
default
FON
for
the
product
category.
FONs
were
reported
for
most
of
the
samples.
TABLES
TABLE
15
PERCENT
FRACTION
OF
NUTRIENT
(
FON)
ESTIMATES
FOR
PHOSPHATE
FERTILIZER
PRODUCT
CATEGORIES
TWG
Database
(
a)
USEPA
(
b)

Product
Reported
Best
Category
N
(
c)
Minimum
Maximum
Median
Mean
%
P2O5
Estimate
(
d)

Agricultural
Blends
59
2
60
15
18
­­
18
Ammonium
Phosphate
Sulfate
1
20
20
­­
­­
20.0
20
Ammonium
Polyphosphate
1
34
34
­­
­­
60.0
34
Diammonium
Phosphate
4
46
53
46
48
46.0
46
Monoammonium
Phosphate
8
50
52
52
51
51.8
52
Nitrophosphate
1
20
20
­­
­­
­­
20
Orthophosphate
1
30
30
­­
­­
­­
30
Phosphate
5
15
37
30
27
­­
30
Phosphoric
Acid
2
52
60
56
56
53.3
56
Superphosphate
2
18
20
19
19
20.7
20
Superphosphoric
acid
4
61
70
69
67
70.1
70
Triple
Superphosphate
7
44
46
46
45
45.7
46
Urea
Ammonium
Polyphosphate
­
KCl
1
19
19
­­
­­
­­
19
Urea­
Ammonium
Phosphate
1
45
45
­­
­­
­­
45
Urea­
Diammonium
Phosphate
­
KCl
1
15
15
­­
­­
­­
15
Notes:
­­
=
Not
Applicable
N
=
Number
of
Samples
%
P2O5
=
Phosphate
(
Phosphorous)

TWG
=
The
Weinberg
Group
Inc.

USEPA
=
United
States
Environmental
Protection
Agency
(
a)
All
values
are
the
%
P2O5
of
the
product
category.
TWG
database
is
compiled
from
industry,
literature,
and
states'

monitoring
data
(
TWG
1999c).

(
b)
Numbers
are
from
Table
3­
4
of
USEPA
(
1999a).

(
c)
Reflects
the
number
of
samples
of
a
product
with
a
reported
%
P2O5.

(
d)
The
best
estimate
is
the
%
FON
that
is
used
to
adjust
the
unit
RBC.
DRAFT
TABLE
16
PERCENT
FRACTION
OF
NUTRIENT
(
FON)
ESTIMATES
FOR
MICRONUTRIENT
FERTILIZER
PRODUCT
CATEGORIES
TWG
Database(
a)
USEPA
(
1999a)
(
b)

Product
Best
Category
N
(
c)
Minimum
Maximum
Median
Mean
N
Minimum
Maximum
Mean
Estimate
(
d)

Boron
5
10
21
15
15
2
10
21
15.5
15
Iron
16
2
58
20
24
3
12
15
14
24
Manganese
7
28
40
12
12
2
24.7
29.5
27.1
12
Zinc
29
7
89
25
27
63
7
89
26.5
27
Notes:
`

­­
=
Not
Applicable
N
=
Number
of
Samples
TWG
=
The
Weinberg
Group
Inc.

USEPA
=
United
States
Environmental
Protection
Agency
(
a)
TWG
database
is
compiled
from
industry,
literature,
and
states'
monitoring
data
(
TWG
1999c).

(
b)
All
values
are
the
%
micronutrient
of
the
product
category.
Statistics
are
calculated
from
the
data
set
found
in
Appendix
G
of
USEPA
(
1999a).

(
c)
Reflects
the
number
of
products
for
which
a
%
micronutrient
is
reported.

(
d)
The
best
estimate
is
the
%
FON
that
is
used
to
adjust
the
unit
RBC.
DRAFT
TABLE
17
SCREENING
LEVEL
EVALUATION:

COMPARISON
OF
THE
CONCENTRATION
OF
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
IN
PHOSPHATE
FERTILIZERS
TO
THE
ADJUSTED
RISK
BASED
CONCENTRATION
(
RBC)

Statistical
Summary
of
Concentration
Data
(
a)
Comparison
Exceed?

Product
90%
Unit
Adjusted
Maximum
Yes
or
Category
N
Minimum
Maximum
GM
GSD
UCL
(
b)
RBC
(
c,
d)
RBC
(
e)
Concentration
No
(
f)
N
(
g)

Agricultural
Blends
Arsenic
84
0.15
42
2.6
3.6
3.2
4.5
81
42
No
­­

Cadmium
83
0.015
160
3.2
7.1
4.6
23
410
160
No
­­

Chromium
84
0.25
5,100
49
4.2
64
34,000
610,000
5,100
No
­­

Cobalt
35
0.65
22
3.3
2.9
4.5
3,100
56,000
22
No
­­

Copper
55
0.14
540
15
5.1
22
280
5,000
540
No
­­

Lead
79
0.1(
h)
650
4.8
9.3
7.3
73
1,300
650
No
­­

Mercury
46
0.0025
1.1
0.036
6.5
0.058
0.9
16
1.1
No
­­

Molybdenum
10
0.69
6
3.4
1.9
4.9
42
760
6
No
­­

Nickel
52
0.54
54
8.6
3
11
350
6,300
54
No
­­

Selenium
26
0.025
5.7
0.22
2.9
0.32
120
2,200
5.7
No
­­

Vanadium
52
0.28
350
42
3.7
56
2,200
40,000
350
No
­­

Zinc
57
0.85
6,300
107
7.8
130
1,200
22,000
6,300
No
­­

Ammonium
Phosphate
Sulfate
Arsenic
2
4.1
4.2
4.1
1
­­
4.5
90
4.2
No
­­

Cadmium
2
150
150
150
1
­­
23
460
150
No
­­

Chromium
2
210
250
230
1.1
­­
34,000
680,000
250
No
­­

Cobalt
2
2.5
3.2
2.8
1.2
­­
3,100
62,000
3.2
No
­­

Copper
2
11
16
13
1.3
­­
280
5,600
16
No
­­

Lead
2
2.1
4.4
3
1.7
­­
73
1,500
4.4
No
­­

Mercury
2
0.01
0.024
0.015
1.9
­­
0.9
18
0.024
No
­­

Molybdenum
2
5
5.7
5.3
1.1
­­
42
840
5.7
No
­­

Nickel
2
200
220
208
1.1
­­
350
7,000
220
No
­­

Selenium
2
0.13
2
0.5
7.1
­­
120
2,400
2
No
­­

Vanadium
1
400
400
­­
­­
­­
2,200
44,000
400
No
­­

Zinc
2
1,500
2,400
1,900
1.4
­­
1,200
24,000
2,400
No
­­

Foot
notes
are
presented
at
the
end
of
the
table.
DRAFT
TABLE
17
(
continued)

Statistical
Summary
of
Concentration
Data
(
a)
Comparison
Exceed?

Product
90%
Unit
Adjusted
Maximum
Yes
or
Category
N
Minimum
Maximum
GM
GSD
UCL
(
b)
RBC
(
c,
d)
RBC
(
e)
Concentration
No
(
f)
N
(
g)

Ammonium
Polyphosphate
Arsenic
7
0.6
21
7.7
3.5
19
4.5
150
21
No
­­

Cadmium
11
4
56
15
2.2
23
23
780
56
No
­­

Chromium
9
57
400
150
2
240
34,000
1,200,000
400
No
­­

Cobalt
3
0.15
1.4
0.53
3.1
­­
3,100
110,000
1.4
No
­­

Copper
10
0.5
14
3
3.6
6.4
280
9,500
14
No
­­

Lead
10
0.17
150
2.7
10
10
73
2,500
150
No
­­

Mercury
1
0.0025
0.0025
­­
­­
­­
0.9
31
0.0025
No
­­

Molybdenum
2
3.1
6.5
4.5
1.7
­­
42
1,400
6.5
No
­­

Nickel
5
0.5
14
5.9
4.1
­­
350
12,000
14
No
­­

Selenium
2
2
2.1
2
1
­­
120
4,100
2.1
No
­­

Vanadium
5
49
230
94
1.8
­­
2,200
75,000
230
No
­­

Zinc
10
46
820
180
2.3
290
1,200
41,000
820
No
­­

Diammonium
Phosphate
Arsenic
114
0.05
21
10
1.9
11
4.5
210
21
No
­­

Cadmium
347
0.25
190
5.1
1.8
5.3
23
1,100
190
No
­­

Chromium
117
1
620
69
1.8
76
34,000
1,600,000
620
No
­­

Cobalt
106
0.25
10
3.8
1.8
4.1
3,100
140,000
10
No
­­

Copper
115
0.45
98
1.8
2.9
2.1
280
13,000
98
No
­­

Lead
344
0.5
150
3.4
2.5
3.7
73
3,400
150
No
­­

Mercury
167
0.001
0.5
0.046
6.4
0.058
0.9
41
0.5
No
­­

Molybdenum
103
2.5
47
11
1.4
11
42
1,900
47
No
­­

Nickel
127
1.1
160
17
1.8
18
350
16,000
160
No
­­

Selenium
103
0.025
5
1.2
5
1.6
120
5,500
5
No
­­

Vanadium
78
11
280
130
1.4
130
2,200
100,000
280
No
­­

Zinc
115
0.83
2,300
82
2.9
96
1,200
55,000
2,300
No
­­

Foot
notes
are
presented
at
the
end
of
the
table.
DRAFT
TABLE
17
(
continued)

Statistical
Summary
of
Concentration
Data
(
a)
Comparison
Exceed?

Product
90%
Unit
Adjusted
Maximum
Yes
or
Category
N
Minimum
Maximum
GM
GSD
UCL
(
b)
RBC
(
c,
d)
RBC
(
e)
Concentration
No
(
f)
N
(
g)

Monoammonium
Phosphate
Arsenic
84
0.05
25
10
2.6
12
4.5
230
25
No
­­

Cadmium
233
0.15
210
6.2
2
6.6
23
1,200
210
No
­­

Chromium
83
0.5
730
69
2.5
82
34,000
1,800,000
730
No
­­

Cobalt
79
0.78
12
4.3
1.9
4.8
3,100
160,000
12
No
­­

Copper
80
0.44
76
1.8
2.9
2.2
280
15,000
76
No
­­

Lead
231
0.05
150
4.9
2.5
5.4
73
3,800
150
No
­­

Mercury
98
0.002
1.5
0.044
6.5
0.061
0.9
47
1.5
No
­­

Molybdenum
75
4
38
12
1.4
13
42
2,200
38
No
­­

Nickel
82
1.3
240
17
1.7
19
350
18,000
240
No
­­

Selenium
74
0.05
20
1.1
4.4
1.4
120
6,200
20
No
­­

Vanadium
52
35
1,100
160
1.6
170
2,200
110,000
1,100
No
­­

Zinc
80
10
3,400
75
2.1
86
1,200
62,000
3,400
No
­­

Nitrophosphate
(
i)

Arsenic
5
3.6
7.4
6.1
1.3
­­
4.5
90
7.4
No
­­

Cadmium
5
2.6
4.3
3.2
1.2
­­
23
460
4.3
No
­­

Chromium
5
39
200
66
1.9
­­
34,000
680,000
200
No
­­

Cobalt
5
2.7
12
6.4
1.7
­­
3,100
62,000
12
No
­­

Copper
5
11
71
21
2.1
­­
280
5,600
71
No
­­

Lead
5
2.5
20
4.5
2.3
­­
73
1,100
20
No
­­

Mercury
1
0.38
0.38
­­
­­
­­
0.9
18
0.38
No
­­

Nickel
5
5.7
86
15
2.9
­­
350
7,000
86
No
­­

Vanadium
4
65
83
71
1.1
­­
2,200
44,000
83
No
­­

Zinc
5
0.48
140
19
8.8
­­
1,200
24,000
140
No
­­

Foot
notes
are
presented
at
the
end
of
the
table.
DRAFT
TABLE
17
(
continued)

Statistical
Summary
of
Concentration
Data
(
a)
Comparison
Exceed?

Product
90%
Unit
Adjusted
Maximum
Yes
or
Category
N
Minimum
Maximum
GM
GSD
UCL
(
b)
RBC
(
c,
d)
RBC
(
e)
Concentration
No
(
f)
N
(
g)

Orthophosphate
(
i)

Arsenic
2
21
21
21
­­
­­
4.5
140
21
No
­­

Cadmium
2
20
20
19
­­
­­
23
690
20
No
­­

Lead
2
150
150
150
­­
­­
73
2,200
150
No
­­

Phosphate
(
i)
­­

Arsenic
5
0.2
25
2.1
10
­­
4.5
130
25
No
­­

Cadmium
4
3
69
10
4.6
­­
23
690
69
No
­­

Lead
3
1
110
11
10
­­
73
2,200
110
No
­­

Phosphoric
Acid
Arsenic
14
0.5
19
7.5
3.3
13
4.5
250
19
No
­­

Cadmium
10
0.15
160
18
11
75
23
1,300
160
No
­­

Chromium
3
62
900
160
4.4
­­
34,000
1,900,000
900
No
­­

Cobalt
3
0.15
4
1.2
6.2
­­
3,100
170,000
4
No
­­

Copper
3
0.2
0.5
0.37
1.7
­­
280
16,000
0.5
No
­­

Lead
10
0.5
10
1.6
2.4
2.7
73
4,100
10
No
­­

Mercury
3
0.0025
0.25
0.054
14
­­
0.9
50
0.25
No
­­

Molybdenum
3
5.9
11
8.7
1.4
­­
42
2,400
11
No
­­

Nickel
3
0.5
15
4.6
6.8
­­
350
20,000
15
No
­­

Selenium
3
2
2.5
2.3
1.1
­­
120
6,700
2.5
No
­­

Vanadium
3
57
140
97
1.6
­­
2,200
120,000
140
No
­­

Zinc
3
31
63
45
1.4
­­
1,200
67,000
63
No
­­

Superphosphate
Arsenic
4
7
21
11
1.7
­­
4.5
90
21
No
­­

Cadmium
4
2
4.9
3.8
1.5
­­
23
460
4.9
No
­­

Chromium
3
32
40
34
1.1
­­
34,000
680,000
40
No
­­

Cobalt
1
2.5
2.5
­­
­­
­­
3,100
62,000
2.5
No
­­

Copper
1
6.9
6.9
­­
­­
­­
280
5,600
6.9
No
­­

Lead
4
1
17
6.2
3.5
­­
73
1,500
17
No
­­

Mercury
1
0.0025
0.0025
­­
­­
­­
0.9
18
0.0025
No
­­

Molybdenum
2
3.9
27
10
3.9
­­
42
840
27
No
­­

Nickel
4
8.8
14
11
1.2
­­
350
7,000
14
No
­­

Selenium
1
2
2
­­
­­
­­
120
2,400
2
No
­­

Vanadium
2
49
190
97
2.7
­­
2,200
44,000
190
No
­­

Zinc
2
43
56
49
1.2
­­
1,200
24,000
56
No
­­

Foot
notes
are
presented
at
the
end
of
the
table.
DRAFT
TABLE
17
(
continued)

Statistical
Summary
of
Concentration
Data
(
a)
Comparison
Exceed?

Product
90%
Unit
Adjusted
Maximum
Yes
or
Category
N
Minimum
Maximum
GM
GSD
UCL
(
b)
RBC
(
c,
d)
RBC
(
e)
Concentration
No
(
f)
N
(
g)

Superphosphoric
Acid
(
i)

Arsenic
9
0.2
31
6.9
4.7
18
4.5
320
31
No
­­

Cadmium
9
0.5
160
33
8.3
120
23
1,600
160
No
­­

Chromium
2
300
840
500
2.1
­­
34,000
2,400,000
840
No
­­

Copper
2
2.5
30
8.6
5.8
­­
280
20,000
30
No
­­

Lead
5
0.05
8.5
1.3
7.3
­­
73
5,100
8.5
No
­­

Molybdenum
2
6
6.8
6.4
1.1
­­
42
2,900
6.8
No
­­

Nickel
2
22
27
24
1.2
­­
350
25,000
27
No
­­

Selenium
1
4.3
4.3
­­
­­
­­
120
8,400
4.3
No
­­

Vanadium
2
52
200
100
2.6
­­
2,200
150,000
200
No
­­

Zinc
2
30
240
85
4.4
­­
1,200
84,000
240
No
­­

Triple
Superphosphate
Arsenic
68
0.05
21
9.8
2.4
10
4.5
210
21
No
­­

Cadmium
204
1.8
180
8
2
8.6
23
1,100
180
No
­­

Chromium
63
3.5
550
84
1.9
96
34,000
1,200,000
550
No
­­

Cobalt
56
1.8
15
6.1
2
7.1
3,100
140,000
15
No
­­

Copper
58
1
55
4.2
2.2
5
280
13,000
55
No
­­

Lead
201
1
1,900
8.4
2
9.1
73
3,400
1,900
No
­­

Mercury
85
0.0025
1.3
0.056
4.8
0.074
0.9
41
1.3
No
­­

Molybdenum
53
6
72
12
1.4
13
42
1,900
72
No
­­

Nickel
64
10
150
19
1.6
21
350
16,000
150
No
­­

Selenium
54
0.025
21
2
3.2
2.6
120
5,500
21
No
­­

Vanadium
33
87
720
140
1.4
160
2,200
100,000
720
No
­­

Zinc
57
42
1,600
100
2
120
1,200
55,000
1,600
No
­­

Urea­
Ammonium
Polyphosphate­
KCl
(
i)

Arsenic
4
5.2
7.8
6.7
1.2
­­
4.5
86
7.8
No
­­

Cadmium
5
1.6
24
4.1
2.9
­­
23
440
24
No
­­

Chromium
5
44
160
63
1.7
­­
34,000
650,000
160
No
­­

Cobalt
2
3.5
3.9
3.7
1.1
­­
3,100
59,000
3.9
No
­­

Copper
4
3.9
26
10
2.2
­­
280
5,300
26
No
­­

Lead
5
1.1
3.8
2.2
1.7
­­
73
1,400
3.8
No
­­

Nickel
4
9.2
27
13
1.6
­­
350
6,700
27
No
­­

Vanadium
5
47
98
76
1.3
­­
2,200
42,000
98
No
­­

Zinc
4
6.9
75
28
2.7
­­
1,200
23,000
75
No
­­

Foot
notes
are
presented
at
the
end
of
the
table.
DRAFT
TABLE
17
(
continued)

Statistical
Summary
of
Concentration
Data
(
a)
Comparison
Exceed?

Product
90%
Unit
Adjusted
Maximum
Yes
or
Category
N
Minimum
Maximum
GM
GSD
UCL
(
b)
RBC
(
c,
d)
RBC
(
e)
Concentration
No
(
f)
N
(
g)

Urea­
Ammonium
Phosphate
(
i)

Arsenic
1
1
1
­­
­­
­­
4.5
200
1
No
­­

Cadmium
1
110
110
­­
­­
­­
23
1,000
110
No
­­

Chromium
1
380
380
­­
­­
­­
34,000
1,500,000
380
No
­­

Lead
1
3.2
3.2
­­
­­
­­
73
3,300
3.2
No
­­

Mercury
1
0.0025
0.0025
­­
­­
­­
0.9
41
0.0025
No
­­

Selenium
1
0.15
0.15
­­
­­
­­
120
5,400
0.15
No
­­

Urea­
Diammonium
Phosphate­
KCl
(
i)

Arsenic
2
4.7
4.9
4.8
1
­­
4.5
68
4.9
No
­­

Cadmium
2
2
2.1
2
1
­­
23
350
2.1
No
­­

Chromium
2
28
43
34
1.3
­­
34,000
510,000
43
No
­­

Cobalt
1
7.2
7.2
­­
­­
­­
3,100
47,000
7.2
No
­­

Copper
2
3.9
7.2
5.3
1.5
­­
280
4,200
7.2
No
­­

Lead
2
1.8
2.1
1.9
1.1
­­
73
1,100
2.1
No
­­

Nickel
2
6.2
11
8.4
1.5
­­
350
5,300
11
No
­­

Vanadium
2
49
73
60
1.3
­­
2,200
33,000
73
No
­­

Zinc
2
0.3
0.55
0.41
1.5
­­
1,200
18,000
0.55
No
­­

Notes:
­­
=
Not
Applicable
GM
=
Geometric
Mean
GSD
=
Geometric
Standard
Deviation
N
=
Number
of
Samples
(
or
Exceedances)

90%
UCL
=
90%
Upper
Confidence
Limit
(
a)
All
concentrations
are
in
mg
MOPC/
kg
product
(
or
ppm).
Data
is
from
industry,
literature,
and
states'
monitoring
data
[
compiled
and
maintained
by
The
Weinberg
Group
Inc.
(
TWG
1999c)].

(
b)
A
90
%
UCL
is
provided
when
the
number
of
samples
for
the
MOPC
is
greater
than
five.
The
90%
UCL
is
considered
a
good
upper
end
estimate
of
the
mean.

(
c)
Unit
RBC
is
based
on
a
1%
fraction
of
nutrient
(
FON).
All
RBCs
are
in
mg
MOPC/
kg
product.

(
d)
%
FON
for
each
product
category
is
a
best
estimate.
The
determination
of
FON
is
presented
in
Table
15.

%
FON
for
each
product
category
is:

agricultural
blends
=
18;
ammonium
phosphate
sulfate
=
20;
ammonium
polyphosphate
=
34;
diammonium
phosphate
=
46;
monoammonium
phosphate
=
52;

nitrophosphate
=
20;
orthophosphate
=
30;
phosphate
=
30;
phosphoric
acid
=
56;
superphosphate
=
20;
superphosphoric
acid
=
70;

triple
superphosphate
=
46;
urea
ammonium
polyphosphate
­
KCl
=
19;
urea
ammonium
phosphate
=
45;
and
urea
­
diammonium
phosphate
­
KCl
=
15.

(
e)
Adjusted
RBC
equals
the
unit
RBC
multiplied
by
the
%
FON.

For
example,
arsenic
unit
RBC
for
agricultural
blends
=
4.5
and
the
%
FON
for
agricultural
blends
is
18.
Therefore,
the
adjusted
RBC
for
arsenic
in
agricultural
blends
=
4.5*
18
=
81
mg
of
arsenic/
kg
product.

(
f)
If
the
maximum
concentration
is
greater
than
the
adjusted
RBC,
there
is
an
exceedance.

(
g)
The
number
of
exceedances
is
the
number
of
samples
(
within
each
product
category)
with
a
concentration
greater
than
the
adjusted
RBC.

(
h)
All
numbers
have
two
significant
figures.
When
only
one
digit
is
presented,
a
zero
(
to
the
right
of
the
decimal)
is
the
last
digit.
For
example,
6
=
6.0
and
0.05
=
0.050.

(
i)
TWG
(
1999c)
does
not
have
data
for
all
MOPC
for
the
following
product
categories:
nitrophosphate,
orthophosphate,
phosphate,
superphosphoric
acid,

urea­
ammonium
polyphosphate
­
KCl,
urea­
ammonium
phosphate,
and
urea­
diammonium
phosphate.
DRAFT
TABLE
18
SCREENING
LEVEL
EVALUATION:

COMPARISON
OF
THE
CONCENTRATION
OF
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
IN
MICRONUTRIENT
FERTILIZERS
TO
THE
ADJUSTED
RISK
BASED
CONCENTRATION
(
RBC)

Statistical
Summary
of
Concentration
Data
(
a)
Comparison
Exceed?

Product
90%
Unit
Adjusted
Maximum
Yes
or
Category
N
Minimum
Maximum
GM
GSD
UCL
(
b)
RBC
(
c,
d)
RBC
(
e)
Concentration
No
(
f)
N
(
g)

Boron
Micronutrient
Arsenic
8
1.8
1,000
42
8.6
180
38
570
1,000
Yes
2
Cadmium
5
0.75
20
10
4.3
­­
210
3,200
20
No
­­

Chromium
1
1.3
1.3
­­
­­
­­
220,000
3,300,000
1.3
No
­­

Cobalt
1
1.8
1.8
­­
­­
­­
23,000
350,000
1.8
No
­­

Copper
1
0.5
(
h)
0.5
­­
­­
­­
1,800
27,000
0.5
No
­­

Lead
7
1
150
21
12
130
500
7,500
150
No
­­

Mercury
1
0.0025
0.0025
­­
­­
­­
6.5
98
0.0025
No
­­

Molybdenum
1
0.25
0.25
­­
­­
­­
300
4,500
0.25
No
­­

Nickel
3
0.5
4
1.8
3
­­
2,600
39,000
4
No
­­

Selenium
1
2
2
­­
­­
­­
800
12,000
2
No
­­

Vanadium
1
17
17
­­
­­
­­
17,000
260,000
17
No
­­

Zinc
1
7.7
7.7
­­
­­
­­
8,600
130,000
7.7
No
­­

Iron
Micronutrient
(
i)

Arsenic
35
0.6
6,200
67
13
140
38
910
6,200
Yes
8
Cadmium
31
0.3
3,900
17
5.4
28
210
5,000
3,900
No
­­

Chromium
10
2
120
8.9
3.9
20
220,000
5,300,000
120
No
­­

Lead
37
0.37
18,000
330
12
660
500
12,000
18,000
Yes
1
Nickel
10
3.4
210
31
4.2
71
2,600
6,200
210
No
­­

Manganese
Micronutrient
Arsenic
14
0.1
2,000
19
16
70
38
460
2,000
Yes
2
Cadmium
13
0.16
55
3.1
6
7.4
210
2,500
55
No
­­

Chromium
8
3.1
460
17
5.8
57
220,000
2,600,000
460
No
­­

Cobalt
5
11
290
74
3.4
­­
23,000
280,000
290
No
­­

Copper
3
21
40,000
2,500
65
­­
18,000
220,000
40,000
No
­­

Lead
14
0.55
13,000
62
30
310
500
6,000
13,000
Yes
1
Mercury
5
0.0025
0.23
0.01
7.6
­­
6.5
78
0.23
No
­­

Molybdenum
5
2.5
850
15
12
­­
300
3,600
850
No
­­

Nickel
11
1.5
560
43
5.4
110
2,600
31,000
560
No
­­

Selenium
5
2
20
6.2
2.9
­­
800
9,600
20
No
­­

Vanadium
3
0.55
33
3
8.4
­­
17,000
200,000
33
No
­­

Zinc
5
61
94,000
4,700
25
­­
8,600
100,000
94,000
No
­­

Foot
notes
are
presented
at
the
end
of
the
table.
DRAFT
TABLE
18
(
continued)

Statistical
Summary
of
Concentration
Data
(
a)
Comparison
Exceed?

Product
N
of
90%
Unit
Adjusted
Maximum
Yes
or
Category
Samples
Minimum
Maximum
GM
GSD
UCL
(
b)
RBC
(
c,
d)
RBC
(
e)
Concentration
No
(
f)
N
(
g)

Zinc
Micronutrient
Arsenic
56
0.1
130
4.5
8.8
7.4
38
1,000
130
No
­­

Cadmium
74
0.095
2,300
24
8.5
36
210
5,700
2,300
No
­­

Chromium
24
0.25
8,100
24
17
65
1,800,000
49,000,000
8,100
No
­­

Cobalt
6
0.25
790
17
36
330
23,000
620,000
790
No
­­

Copper
4
4.4
1,700
170
14
­­
1,800
49,000
1,700
No
­­

Lead
72
0.32
28,000
180
23
320
500
14,000
28,000
Yes
6
Mercury
16
0.0025
12
0.03
31
0.14
6.5
180
12
No
­­

Molybdenum
5
0.25
14
1.2
5.6
­­
300
8,100
14
No
­­

Nickel
14
4.3
450
47
4.4
96
2,600
70,000
450
No
­­

Selenium
15
0.013
25
0.77
9.1
2.1
800
22,000
25
No
­­

Vanadium
4
0.5
47
14
9.3
­­
17,000
460,000
47
No
­­

Zinc
6
22,000
350,000
160,000
2.8
380,000
8,600
230,000
350,000
Yes
2
Notes:
­­
=
Not
Applicable
GM
=
Geometric
Mean
GSD
=
Geometric
Standard
Deviation
N
=
Number
of
Samples
(
or
Exceedances)

90%
UCL
=
90
percent
Upper
Confidence
Limit
(
a)
All
concentrations
are
in
mg
MOPC/
kg
product
(
or
ppm).
Data
is
from
industry,
literature,
and
states'
monitoring
data
[
compiled
and
maintained
by
The
Weinberg
Group
Inc.
(
TWG
1999c)].

(
b)
A
90
%
UCL
is
provided
when
the
number
of
samples
for
the
MOPC
is
greater
than
five.
The
90%
UCL
is
considered
a
good
upper
end
estimate
of
the
mean.

(
c)
Unit
RBC
is
based
on
a
1%
fraction
of
nutrient
(
FON).
All
RBCs
are
in
mg
MOPC/
kg
product.

(
d)
%
FON
for
each
product
category
is
a
best
estimate.
The
determination
of
FON
is
present
in
Table
16.

%
FON
for
each
product
category
is:

boron
micronutrient
=
15;
iron
micronutrient
=
24;
manganese
micronutrient
=
12;
and
zinc
micronutrient
=
27.

(
e)
Adjusted
RBC
equals
the
unit
RBC
multiplied
by
the
%
FON.

For
example,
arsenic
unit
RBC
for
micronutrient
=
38,
%
FON
for
boron
miconutrient
=
15,
therefore,
the
adjusted
RBC
for
arsenic
in
boron
micronutrient
=
38*
15
=
570
mg
arsenic/
kg
product.

(
f)
If
the
maximum
concentration
is
greater
than
the
adjusted
RBC,
there
is
an
exceedance.

(
g)
The
number
of
exceedances
is
the
number
of
samples
(
within
each
product
category)
with
a
concentration
greater
than
the
adjusted
RBC.

(
h)
All
numbers
have
two
significant
figures.
When
only
one
number
is
presented,
a
zero
(
to
the
right
of
the
decimal)
is
the
last
digit.

For
example,
6
=
6.0
and
0.05
=
0.050.

(
i)
TWG
(
1999c)
does
not
have
data
for
all
MOPC
for
the
iron
micronutrient
category.
DRAFT
36
DRAFT
SECTION
5.0
¾
DERIVATION
OF
THE
RISK
BASED
CONCENTRATION
(
RBC)
FOR
RADIONUCLUDE
(
RADIUM226)
AND
SCREENING
LEVEL
HEALTH
EVALUATION:
COMPARISON
OF
THE
RBC
WITH
PRODUCT
DATA
Several
radionuclides
have
been
detected
in
phosphate
fertilizers,
namely
uranium238,
radium226,
and
thorium232.
This
section
derives
a
RBC
for
one
of
the
radionuclides,
radium226.
Radium226
is
selected
as
the
radionuclide
to
develop
a
RBC
based
on
relative
toxicity,
relative
product
concentration,
and
evaluation
precedence.
The
RBC
for
radium226
is
used
to
conduct
a
screening
level
health
evaluation.

Relative
Toxicity
A
radionuclide
is
the
radioactive
species
of
a
specific
element.
Radionuclides
exert
a
toxic
effect
by
transferring
energy
from
the
electric
field
of
their
nucleus
thereby
destroying
surrounding
cells
and
producing
free
radicals.
Toxicity
is
measured
as
activity.
Radionuclides
are
classified
by
USEPA
as
Group
A
carcinogens
(
USEPA
1999d),
and
as
such,
the
RBCs
are
developed
based
on
carcinogenic
risk.
Radium226
has
higher
relative
toxicity,
based
on
the
ingestion
slope
factors
(
USEPA
1999d),
compared
to
the
other
radionuclides
under
consideration.
The
ingestion
slope
factors
for
radium226,
thorium232,
and
uranium238
are
2.96E­
10
(
for
radium
and
its
shortlived
decay
products),
3.28E­
11,
and
4.27E­
11,
respectively.
The
slope
factors
are
expressed
as
age­
average
lifetime
oral
radiation
cancer
incidence
risk
per
unit
intake
or
exposure;
the
units
are
risk/
pCi
(
picoCurie,
discussed
below).

Relative
Concentration
in
Product
The
amount
(
or
concentration)
of
a
radionuclide
is
also
measured
as
activity.
Typically,
the
unit
of
activity
is
expressed
as
becqueral
(
Bq).
Bq
is
the
quantity
of
a
radionuclide
where
one
atom
is
transferred
per
second.
In
the
derivation
of
the
RBC,
Bq
are
converted
to
more
conventional
units,
picoCurie
(
pCi),
in
order
to
match
the
units
of
the
toxicity
value.
There
is
limited
data
on
the
concentration
of
radionuclides
in
phosphate
fertilizers.
During
processing,
the
concentration
of
uranium238
and
thorium232
will
generally
remain
in
the
phosphate
component
of
the
fertilizer
(
USEPA
1999a).
Uranium238
decays
to
form
radium226
(
USEPA
1999e).
The
halflife
for
radium226
is
1,600
years.
Radium226
then
decays
to
form
radon­
222
gas,
which
has
a
half­
life
of
3.8
days
(
USEPA
1999e).
Radium226
in
phosphate
ore
will
be
contained
in
the
phosphogypsum
by­
product
(
USEPA
1999a).
Thorium232
is
at
lower
levels
in
phosphate
fertilizer
than
uranium238
and
radium226
(
USEPA
1999a
and
TWG
1999c).
The
level
of
uranium238
and
radium226
measured
in
various
phosphate
fertilizers
varies.

Evaluation
Precedence
Radium226
is
selected
as
a
good
example
radionuclide
to
develop
a
RBC.
This
selection
is
based
largely
on
evaluation
precedence.
Currently,
the
USEPA
(
1999e)
has
established
strict
regulatory
limits
on
phosphogypsum,
including
a
ban
on
its
use
in
building
roads
in
Florida
due
to
radium
content.
The
ban
is
based
on
the
potential
risk
to
a
resident
if
the
road
is
abandoned
and
a
house
is
built
on
the
road.
Under
USEPA
regulation,
the
agricultural
use
of
phosphogypsum
is
permitted
if
a
stack
(
pile)
has
less
than
10
pCi/
g
of
radium226.
37
DRAFT
Derivation
of
the
Risk
Based
Concentration
(
RBC)

A
RBC
is
derived
for
radium226
for
the
exposure
scenario
defined
in
Section
1.0,
the
farm
family
and
unintentional
ingestion
of
fertilized
soil
and
ingestion
of
crops.
35
The
dermal
contact
exposure
route
is
not
included
in
the
RBC
because
of
the
low
risk
potential
from
dermal
exposure.

The
RBC
is
calculated
using
a
similar
approach
and
many
of
the
same
parameters
that
are
used
to
derive
the
MOPC
RBCs.
However,
because
of
the
difference
in
toxicity
(
e.
g.,
slope
factors
are
expressed
as
activity
other
than
concentration)
of
radionuclides,
the
RBC
for
radium226
is
calculated
in
a
slightly
different
way
than
the
RBCs
for
the
MOPC.
In
addition,
radium
specific
parameters
are
needed
for
several
parameters.
Deviations
from
the
derivation
of
the
RBCs
for
the
MOPC
are:

(
1)
radionuclide
slope
factors
are
not
expressed
as
a
function
of
body
weight
and
time,
therefore,
these
parameters
are
not
included
in
the
intake
equation;
(
2)
radium226
specific
parameters
for
PUF
and
Kd;
and
(
3)
radionuclide
slope
factors
are
expressed
as
an
activity.

Radium226
specific
parameters
are:

·
Kd
of
214
­
470
mL/
g
(
USDHHS
1989b);
·
PUF
(
unitless)
for
vegetable
crops
is
0.012,
root
crops
is
0.012,
and
for
grain
is
0.001
 
0.6
(
Post,
Buckley,
Schuh,
&
Jernigan,
Inc.
[
PBS&
J]
1990,
Watson
et
al.,
1983);
and
·
Oral
Slope
Factor
2.96E­
10
risk/
pCi
(
USEPA
1999d).

The
PUFs
values
for
vegetable
and
root
crops
are
consistent.
However,
there
is
a
wide
range
of
PUFs
for
grain
(
Watson
et
al.,
1983).
In
a
report
by
PBS&
J
(
1990)
the
authors
suggest
that
the
0.6
PUF
for
grain
is
too
high;
they
suggest
a
more
realistic
PUF
for
grain
(
0.01
for
"
control"
soils
or
0.001
for
grain
grown
on
phosphate
clay
settling
areas).
The
grain
PUF
value
that
is
similar
to
the
PUFs
for
vegetable
and
root
is
used
to
calculate
the
RBC
(
0.01).

In
addition,
given
the
consideration
of
only
one
loss
pathway,
the
low
end
Kd
value
is
used
to
calculate
the
RBC.

The
amount
of
radium226
that
is
taken
into
the
body
through
unintentional
ingestion
of
fertilized
soil
and
ingestion
of
crops
is
adjusted
by
the
percent
of
radium226
that
is
expected
to
be
absorbed
in
the
gastrointestinal
tract
(
GI),
which
is
20%
(
USDHSS
1989b).

35
The
decay
of
radium226
to
radon­
222
gas
and
potential
for
inhalation
exposure
is
recognized.
However,
under
the
farm
family
exposure
scenario,
the
contribution
of
exposure
from
inhalation
is
expected
to
be
much
lower
than
the
other
routes
of
exposure.
The
exposure
for
this
route
is
expected
to
be
low
because
(
1)
the
limited
time
of
exposure
(
time
spent
in
the
filed)
and
(
2)
because
the
exposure
is
not
in
a
confined
space
but
in
open
field,
which
will
allow
the
radionuclide
to
dissipate.
38
DRAFT
Presentation
of
the
Risk
Based
Concentration
(
RBC)
and
Health
Screening
Evaluation
The
unit
RBCs
for
radium226
are
presented
below,
the
lowest
unit
RBC
is
21
pCi/
g
and
is
based
on
the
multi­
crop
farm
and
the
adult.

RBC
(
pCi/
g)
Vegetable
Root
Grain
Multiple
Crop
Adult
55
70
64
21
Child
540
520
460
200
The
unit
RBC
is
adjusted
by
the
appropriate
FON
for
screening
and
compared
with
the
activity
measured
in
select
phosphate
products.
The
screening
evaluation
is
presented
below.
There
are
no
exceedances
of
the
radium226
RBC
by
measured
activity
levels
of
radium
226
in
phosphate
fertilizers.

Activity
Level
in
Product
(
pCi/
g)
(
a)
Product
FON
Adjusted
RBC
Minimum
Maximum
Exceedances
DAP
46
966
0.7
­­
None
MAP
52
1,100
0.6
12.8
None
TSP
46
970
84
­­
None
SP
20
420
92
­­
None
NPK
18
380
0.4
124
None
­­
Indicates
one
sample.
(
a)
Activity
level
in
phosphate
products
is
from
TWG
(
1999c)
and
several
world
wide
samples
from
USEPA
(
1999a).
39
DRAFT
SECTION
6.0
¾
DISCUSSION
OF
UNCERTAINTY
Each
step
in
establishing
the
scope
of
the
evaluation
and
in
developing
the
RBCs
has
some
inherent
uncertainty
associated
with
it.
The
major
uncertainties
in
this
evaluation
of
fertilizers
are
described
in
this
section
in
order
to
provide
an
indication
of
the
relative
degree
to
which
the
uncertainty
may
underestimate
or
overestimate
exposure,
the
RBCs,
and/
or
the
conclusions
of
the
screening
evaluation.
Note,
an
overestimate
of
exposure
will
result
in
a
RBC
that
is
lower,
a
lower
RBC
is
more
health
protective.
An
assessment
of
the
major
uncertainties
associated
with
establishing
the
scope
of
the
evaluation
and
developing
the
RBCs
is
presented
in
Table
19.
In
addition,
an
assessment
of
the
magnitude
of
relative
impact
in
the
RBC
equation
associated
with
each
parameter
is
presented
in
Table
20.

The
purpose
of
this
document
is
to
provide
fertilizer
manufacturers
and
interested
regulators
with
an
easy
tool
to
evaluate
whether
the
concentrations
of
select
elements
(
MOPC),
in
a
particular
commercial
inorganic
fertilizer,
may
pose
a
health
risk
to
the
humans
following
its
application
to
agricultural
soil.
The
tool
is
a
screening­
level
RBC
that
defines
a
health
protective
exposure
limit.
RBCs
are
calculated
based
on
a
reasonable
maximum
exposure
(
RME)
and
"
high­
end
values"
purposely
selected
to
account
for
the
inherent
uncertainty
associated
with
each
parameter.
RBCs
are
intended
to
be
an
evaluation
tool.
More
specifically,
the
RBC
is
an
evaluation
threshold
above
which
further
evaluation
(
more
product
specific)
are
necessary
to
determine
if
there
is,
in
fact,
a
risk.
The
RBCs
are
therefore,
more
likely
to
be
over­
rather
than
under­
protective
of
human
health,
and
the
uncertainty
analysis
supports
this
conclusion.

The
information
presented
in
Tables
19
and
20
follow
the
organization
of
the
information
as
presented
in
the
report
and
are
discussed
below
by
major
category.

Scope
of
the
Evaluation
The
scope
of
the
evaluation
is
narrowed
to
focus
on
the
products,
MOPC,
exposed
population,
and
exposure
pathways
of
greatest
concern.
As
a
result,
the
RBCs
are
focused
on
the
highest
potential
exposure
and
are
intended
to
be
health
protective
of
all
other
exposure
scenarios.
The
RBCs
may
result
in
an
overestimate
of
potential
risk
but
are
not
likely
to
underestimate
risk.

Based
on
(
1)
the
available
MOPC
concentration
data
in
a
wide
range
of
inorganic
fertilizer
products,
(
2)
the
relative
toxicity
of
the
MOPC,
and
(
3)
the
precedence
for
health
risk
evaluation,
the
selection
of
phosphate
fertilizers
and
micronutrient
fertilizers
and
the
12
metals
(
plus
radium
226)
there
is
very
little
uncertainty
that
there
are
higher
risks
for
other
products
or
metals.

Fertilizer
applicators
are
at
minimal
risk
from
MOPC
in
inorganic
fertilizers
(
TWG
1999a,
b).
Ingestion
is
the
major
exposure
pathway
and
therefore
a
crop
consumer
who
lives
on
a
farm
(
i.
e.,
farm
adult
and
child)
has
the
highest
expected
exposure
to
MOPC
(
USEPA
1999b,
CDFA
1998).
Exposure
is
from
both
ingestion
of
crops
plus
incidental
dermal
and
soil
ingestion.
The
added
exposure
from
applying
fertilizer
is
not
expected
to
add
significantly
to
the
risk
to
the
farm
adult.

Several
exposure
pathways
(
transport
pathways
and
exposure
routes)
are
not
major
exposure
pathways
and
are
excluded
from
the
development
of
the
RBCs.
The
exclusion
of
these
exposure
40
DRAFT
pathways
is
not
likely
to
significantly
underestimate
risk,
since
the
exposure
pathways
and
exposure
routes
of
greatest
concern
(
the
primary
drivers
of
the
RBC)
are
the
basis
of
the
RBC
(
USEPA
1999b,
CDFA
1998).
In
particular,
the
ingestion
of
animal
products
is
not
considered
in
the
RBC.
The
exclusion
of
this
exposure
route
is
not
likely
to
underestimate
risk
because
all
of
the
MOPC
that
is
taken
up
into
grains
is
assumed
to
be
directly
consumed
by
humans
(
rather
than
splitting
the
MOPC
exposure
into
direct
consumption
of
crops
and
indirect
consumption
of
animals
that
ate
the
crops).
Similarly,
the
assumption
that
the
form
of
mercury
is
mercuric
chloride
(
that
accumulates
in
soil),
and
not
methyl
mercury
(
that
bioaccumulates
in
fish),
is
very
unlikely
to
significantly
change
the
final
evaluation
of
risk.
36
Again,
it
is
a
matter
of
splitting
the
total
MOPC
added
to
soil
into
two
exposure
pathways
versus
considering
the
total
MOPC
added
to
soil
in
a
single
exposure
pathway.

Several
exposure
routes
that
are
not
considered
"
environmental
acceptable
end
points"
(
Chaney
et
al.,
1999)
for
specific
MOPC
were
included
in
the
RBC.
For
example,
several
MOPC
may
be
toxic
(
phytotoxic)
to
the
plant
(
e.
g.
zinc)
before
reaching
levels
that
could
be
toxic
to
humans
that
ingest
the
plant
(
or
crop).
The
inclusion
of
the
ingestion
of
crops
in
the
RBC
for
these
MOPC
may
overestimate
risk.

Derivation
of
the
Risk
Based
Concentration
(
RBC)

The
RBCs
are
intended
to
represent
a
RME
scenario;
therefore,
they
are
expected
to
be
reasonably
and
maximally
health
protective.
The
lower
RBC
is
the
more
health
protective.
Many
of
the
parameters
are
statistical
estimates
recommended
by
USEPA
for
the
RME
scenario.
An
assessment
of
the
magnitude
of
relative
impact
in
the
RBC
equation
for
each
of
these
parameters
is
presented
in
Table
20.
The
magnitude
of
impact
considers
(
1)
the
possible
range
of
values
(
e.
g.,
EF
of
350
days/
year
 
1
day
/
year,
or
soil
ingestion
for
a
child
of
100
mg/
day
 
400
mg/
day)
and
(
2)
the
weight
that
each
of
the
parameters
has
on
the
RBC
(
e.
g.,
SACF,
AR,
and
PUF
can
significantly
influence
the
RBC).
Two
parameters
in
particular,
AR
and
PUF,
that
have
upper
end
estimates,
are
particularly
influential
on
the
RBC
derivation.
The
use
of
an
RME
scenario
and
upper
end
estimates
for
AR
and
PUF
is
more
likely
to
underestimate
rather
than
overestimate
the
RBCs
(
i.
e.,
overestimate
rather
than
underestimate
risk),
as
discussed
below.
Several
additional
assumptions
are
made
that
may
further
underestimate
the
RBC
(
overestimate
risk);
these
assumptions
are
also
discussed
below.

The
biological
exposure
parameters
(
e.
g.,
BW
[
body
weight],
IR
[
ingestion
rate],
and
SA
[
exposed
skin
surface
area])
are
recommended
RME
estimates.
These
parameters
may
underestimate
the
RBC,
but
are
considered
reasonable
for
a
screening­
level
evaluation.
In
addition,
they
have
a
low
relative
impact
on
the
RBC
equation.
The
use
of
an
FI
of
1
assumes
that
100%
of
the
crops
that
a
person
consumes
is
from
the
farm.
This
is
the
highest
FI
and
assumes
that
all
of
the
crops
that
are
ingested
are
fertilized.
Also,
the
effect
of
preparing
and/
or
cooking
crops
for
consumption
is
not
evaluated
in
the
RBC.
The
exclusion
of
this
factor
may
36
In
soil,
mercury
is
reactive
and
may
form
several
different
complexes.
Although
the
transport
of
mercury
into
a
nearby
water
body,
formation
of
methyl
mercury,
and
uptake
into
fish
may
occur,
it
is
expected
that
this
pathway
will
occur
less
frequently,
and
result
in
less
exposure
than
the
complexing
of
mercury
with
chlorine
in
soil
(
especially
since
chlorine
ions
may
be
the
most
persistent
complexing
agent
for
mercury
in
soil)
(
McLaughlin
et
al.
1996).
41
DRAFT
overestimate
risk
and
underestimate
the
RBC
because
it
is
likely
that
cooking
will
result
in
less
concentration
of
a
MOPC
in
the
crop
by
causing
the
release
of
some
of
the
MOPC.

The
use
of
high­
end
estimates
for
AR
and
PUF
may
result
in
RBCs
that
are
underestimated
for
a
"
typical"
scenario.
However,
the
use
of
high­
end
estimates
for
these
parameters
ensures
that
the
RBCs
are
health
protective
of
possible
high­
end
exposures.
For
example,
plant
uptake
of
an
MOPC
is
generally
higher
in
acidic
soil.
The
use
of
an
upper
end
estimate
of
PUF
results
in
RBCs
that
are
health
protective
of
this
potential
scenario.
In
addition,
the
PUFs
may
be
further
overestimated
by
the
inclusion
of
greenhouse
or
pot
studies.
MOPC
uptake
is
typically
greater
in
pot
studies
than
field
studies;
still
pot
studies
were
included
in
the
database.
Conversely,
the
PUFs
may
be
underestimated
by
the
use
of
total
compared
to
extractable
MOPC
soil
concentration
in
the
denominator
of
the
PUF.
Lastly,
the
PUFs
are
based
on
all
of
the
plant
parts,
not
just
the
edible
portion.
The
magnitude
of
uncertainty
on
the
use
of
data
from
the
whole
plant
in
developing
the
PUFs
is
unknown.
In
general,
the
PUFs
are
probably
overestimates
of
MOPC
plant
uptake
rather
than
underestimates.

Another
parameter
that
may
further
underestimate
rather
than
overestimate
the
RBC
is
the
assumption
of
100%
relative
absorption
factor
(
RAF)
from
the
ingestion
of
MOPC
in
soil
and
crops
for
most
of
the
MOPC.
Again,
this
is
selected
as
a
conservative
parameter
for
a
screeninglevel
evaluation.
RAF
adjusts
the
estimated
intake
and
toxicity
value
to
an
absorbed
dose
resulting
in
a
RBC
that
is
more
realistic
and
representative
of
actual
exposure,
intake,
and
absorption.
The
absorbed
dose
is
likely
to
be
less
than
the
administered
dose,
especially
when
the
MOPC
is
sorbed
to
soil
or
in
plant
tissue.
For
all
MOPC,
except
arsenic,
RAF
is
assumed
to
be
1.
In
addition,
lead
intake
is
adjusted
by
percent
absorption
values.
A
RAF
of
1
can
have
different
magnitudes
of
effect
on
the
RBC
depending
on
the
MOPC
and
the
basis
of
the
toxicity
value.
For
example,
most
of
the
toxicity
values
are
based
on
an
administered
dose
in
the
diet
or
food.
The
absorbed
dose
may
be
lower
than
the
administered
dose.
In
this
case
toxicity
would
occur
at
a
lower
dose,
resulting
in
a
lower
toxicity
value.
Therefore,
a
toxicity
value
based
on
an
administered
dose
may
be
greater
than
the
a
toxicity
value
based
on
an
absorbed
dose.
Conversely,
an
estimated
intake
that
is
also
based
on
an
administered
intake,
rather
than
an
absorbed
intake,
may
be
over
estimated,
especially
depending
on
the
medium
of
exposure.
Therefore,
if
possible
toxicity
values
and
intake
should
both
be
based
on
administered
dose
or
an
absorbed
dose
and
the
same
(
or
similar)
medium
of
exposure.

When
the
toxicity
value
is
based
on
an
absorbed
dose
and
the
estimated
intake
is
based
on
administered
dose,
as
is
the
case
for
cadmium,
the
RBC
may
be
underestimated.
The
toxicity
value
for
cadmium
is
based
on
food
and
is
derived
using
a
pharmacokinetic
model
that
considers
the
percent
of
cadmium
that
is
absorbed
into
the
blood
stream
from
the
diet.
Yet,
the
estimated
intake
of
cadmium
from
the
crop
and
incidental
soil
ingestion
is
based
on
the
amount
of
food
or
soil
ingested
and
not
the
actual
amount
of
cadmium
absorbed
into
the
bloodstream.
The
absorption
of
cadmium
in
these
media
is
assumed
to
be
100%,
whereas,
cadmium
absorption
from
food
or
soil
in
the
gut
is
expected
to
be
much
lower
(
less
than
5%).

The
magnitude
of
the
effect
of
soil
accumulation
factor
(
SACF)
on
the
RBC
is
unknown.
SACF
may
overestimate
or
underestimate
accumulation
and
bioavailability
of
the
MOPC
in
soil
following
application.
The
consideration
of
MOPC
loss
through
leaching
as
the
only
loss
42
DRAFT
pathway
is
likely
to
underestimate
the
RBC
because
it
is
likely
that
loss
of
MOPC
through
other
loss
pathways
could
occur.
Conversely
however,
the
Kd
values
used
in
the
development
of
the
RBC
may
overestimate
the
leaching
of
the
MOPC
into
groundwater
and
underestimate
the
exposure
in
soil.
The
lower
the
Kd,
the
more
available
the
MOPC
is
for
leaching
into
groundwater
and
the
less
remains
in
the
soil.
There
is
a
very
wide
range
of
Kd
values
(
both
measured
and
estimated)
in
the
literature.
The
Kds
selected
for
this
evaluation
are
based
on
measured
data
and
come
from
a
single
literature
source,
but
are
on
the
lower
end
of
the
Kd
range.

The
USEPA
toxicity
values
used
in
the
development
of
the
RBCs
are
purposely
conservative.
For
instance,
the
toxicity
value
for
arsenic
is
based
on
a
nutrient
deficient
population.
The
agency
has
built
in
considerable
safety
factors.
In
addition,
for
this
evaluation
in
particular,
the
use
of
the
oral
cancer
slope
factor
for
arsenic
may
overestimate
risk
since
the
cancer
toxicity
value
for
arsenic
is
based
on
(
1)
inhalation
and
lung
cancer
and
(
2)
drinking
water
and
skin
cancer,
neither
being
directly
related
to
the
ingestion
of
food.

Also,
toxicity
values
for
several
forms
of
chromium
are
available.
In
order
to
select
the
most
appropriate
toxicity
value
to
use
in
developing
the
RBCs,
assumptions
are
made
about
the
form
of
the
MOPC
that
is
likely
to
accumulate
in
soil
and
be
available
for
uptake
into
crop
and
human
exposure.
In
particular,
chromium
III
is
assumed
to
accumulate
in
soil
and
be
available
for
uptake,
not
chromium
VI.
This
assumption
about
the
form
of
chromium
may
underestimate
risk
from
exposure
because
chromium
III
is
less
toxic
than
chromium
VI.
However,
chromium
III
is
the
form
expected
to
accumulate
in
soil
over
a
long
period
of
time.

The
presence
and
effect
of
other
MOPC
on
toxicity
(
synergism,
antagonism)
or
uptake
(
e.
g.,
cadmium
and
zinc)
are
not
considered
and
may
underestimate
or
overestimate
risks.
More
than
one
MOPC
is
often
present
in
a
fertilizer.
In
addition,
the
contribution
of
MOPC
in
soil
from
natural
background
levels
is
also
not
accounted
for
in
the
RBC.
The
exclusion
of
contribution
from
background
may
overestimate
the
RBC
and
underestimate
exposure
and
risk.
The
potential
for
underestimating
exposure
and
risk
from
these
factors
is
assumed
to
be
offset
by
the
overall
high
end
parameters
and
assumptions
used
in
the
derivation
of
the
RBCs.

Overall
Assessment
of
Uncertainty
on
the
RBC
and
Health
Risk
Screening
Evaluation
The
approach
used
in
this
evaluation
is
consistent
with
the
generally
accepted
practice
in
screening­
level
health
risk
assessments.
To
this
end,
the
products,
MOPC,
exposed
population,
and
exposure
scenario
are
selected
and
the
RBCs
are
derived
to
ensure
they
are
sufficiently
health
protective.
Despite
several
uncertainties
that
may
overestimate
the
RBC
(
underestimate
risk),
the
scope,
the
RBCs
and
the
health
screening
evaluation
(
comparison
of
RBCs
to
measured
MOPC
concentrations
in
products)
are
considered
to
be
health
protective.
In
addition,
most
of
the
parameters,
in
particular
parameters
that
have
a
relative
high
impact
on
the
RBC
equation
(
e.
g.,
AR,
PUF),
are
high
end
estimates.
TABLES
TABLE
19
MAJOR
ASSUMPTIONS
AND
UNCERTAINTIES
ASSOCIATED
WITH
THE
RISK
BASED
CONCENTRATIONS
(
RBCs)
AND
THE
SCREENING
LEVEL
HEALTH
RISK
EVALUATION
DRAFT
Assumption
Magnitude
of
Uncertainty
and
Effect
on
the
Risk
Based
Concentration
(
RBC)
and
Estimate
of
Risk
Rationale
Scope
of
the
Evaluation
Focuses
on
phosphate
and
select
micronutrient
fertilizers.
Low
 
may
underestimate
risk
(
overestimate
RBC)
if
other
classes
had
higher
metal
levels,
but
not
likely.
These
classes
of
inorganic
fertilizers
tend
to
contain
higher
levels
of
the
metals
of
potential
concern
(
MOPC).
Phosphate
fertilizers
have
the
highest
levels
of
metals
compared
to
other
macronutrient
fertilizers.
Also,
micronutrient
fertilizers
that
are
evaluated
have
the
highest
metal
concentrations.

Focuses
on
twelve
metals
of
potential
concern
(
MOPC)
and
one
radionuclide
(
radium
226)
considered
to
have
toxicological
significance
compared
to
other
metals
found
in
inorganic
fertilizers.
Low
 
may
underestimate
risk
and
overestimate
the
RBC
if
the
other
metals
are
more
toxic
or
were
at
significantly
higher
levels,
but
not
likely.
Other
metals
found
in
inorganic
fertilizers
have
lower
comparative
toxicity.
Also,
since
the
metals
with
high
toxicity
are
generally
not
found
to
a
health
concern
(
arsenic,
mercury
and
lead),
then
the
other
metals
are
not
expected
to
be
a
health
concern.

Focuses
on
farmer
family
and
select
exposure
pathways
 
unintentional
ingestion
of
fertilized
soil,
dermal
contact
fertilized
soil
and
ingestion
of
crops.
Low
 
may
overestimate
risk
and
underestimate
the
RBC.
Health
protective
of
all
other
scenarios
because
considered
the
scenario
with
highest
exposure,
and
therefore,
expected
to
have
the
lowest
RBC.

Exclusion
of
several
exposure
pathways
and
routes,
such
as,
ingestion
of
animal
products
that
have
taken
up
MOPC,
and
bioaccumulation
of
methyl
mercury
in
fish.
Low
 
may
underestimate
risk
and
overestimate
the
RBC.
Not
likely
to
underestimate
risk
because
the
highest
exposure
routes
are
the
basis
of
the
RBC.
In
particular,
the
RBC
for
grains
is
based
on
the
assumption
that
all
of
the
MOPC
that
is
taken
up
into
grain
is
directly
consumed
by
humans.

Lack
of
the
consideration
of
environmentally
acceptable
endpoints.
For
example,
MOPC
may
be
toxic
to
the
plant
before
reaching
levels
that
could
toxic
to
humans.
Low
 
Medium
 
may
overestimate
risk
and
underestimate
RBC.
Plant
toxicity
is
not
considered
in
this
evaluation.
The
RBCs
are
intended
to
be
health
protective
of
the
ingestion
of
MOPC
in
crops
for
any
scenario.

Derivation
of
the
Risk
Based
Concentration
(
RBC)

Development
of
a
RME
scenario.
Low
 
Medium
 
may
overestimate
risk
and
underestimate
the
RBC.
Standard
screening
level
guidance
to
ensure
the
RBCs
are
sufficiently
health
protective.

Exposures
are
based
on
granular
fertilizer.
Low
 
may
under
or
overestimate
risk
and
RBC.
Exposure
to
fertilizer
in
the
granular
form
is
assumed
to
be
similar
to
soil
and
exposure
to
liquid
fertilizer
is
assumed
to
result
in
similar
exposure
as
to
granular
fertilizer.
Sufficiently
health
protective.

Upper
 
end
estimates
for
AR
and
PUF.
Low
 
Medium
 
may
overestimate
risk
and
underestimate
the
RBC.
Ensures
the
RBCs
are
health
protective
of
scenario
were
high
accumulation,
uptake,
and
exposure
may
occur.
TABLE
19
(
continued)

DRAFT
Assumption
Magnitude
of
Uncertainty
and
Effect
on
the
Risk
Based
Concentration
(
RBC)
and
Estimate
of
Risk
Rationale
Development
of
PUFs
(
1)
includes
greenhouse
and
pot
studies
and
(
2)
is
based
on
total
MOPC
concentration
in
soil.
Low
 
Medium
 
may
under
or
overestimate
risk
and
RBC.
Uptake
of
MOPC
by
plants
in
greenhouse
and
pot
studies
is
greater
than
in
filed
studies.
PUFs
based
on
total
MOPC
concentration
in
soil
are
lower
than
PUFs
based
on
extractable
MOPC
concentration
in
soil.

RAF
of
1
(
or
100%).
Low
 
Medium
 
may
overestimate
exposure
and
risk
and
underestimate
the
RBC.
Conservative
assumption
given
the
lack
of
information
needed
to
develop
appropriate
and
applicable
RAF.
RAF
is
probably
lower
than
100%.

Development
of
SACF
 
consideration
of
limited
loss
pathways
and
use
of
low
end
Kds.
Low
 
Medium
 
may
over
or
underestimate
risk
and
RBC.
An
SACF
based
on
limited
loss
pathways
may
result
in
more
MOPC
accumulating
in
soil.
Conversely,
low
end
Kds
may
overestimate
the
availability
of
MOPC
to
transport
and
leach
into
groundwater.

Conservatively
derived
USEPA
cancer
slope
factors,
chronic
reference
doses,
and
lead
biokinetic
slope
factor
are
used
to
evaluate
risk.
Medium
 
may
overestimate
risk
and
underestimate
RBC.
For
noncancer
effects,
combinations
of
uncertainty
factors
along
with
doseresponse
data,
often
from
laboratory
animals,
are
used
to
derive
criteria
to
protect
the
most
sensitive
human
receptors.
For
cancer
effects,
doseresponse
data
are
used
to
derive
slope
factors
that
estimate
an
upper
limit
on
risk
associated
with
a
given
exposure.
Actual
risk
could
be
much
lower
(
especially
for
arsenic).

Toxicity
criteria
for
the
dermal
exposure
of
exposure
were
derived
using
route­
to­
route
extrapolation
and
an
adjustment
to
an
absorbed
dose.
Medium
 
may
over
or
underestimate
risk
and
RBC.
Depending
on
the
MOPC,
the
route
of
administration
or
exposure
may
change
the
toxicity.

Toxicity
value
for
chromium
III,
not
chromium
VI
is
used.
Low
 
may
underestimate
risk
and
overestimate
the
RBC.
Chromium
VI
is
more
toxic
than
chromium,
however,
chromium
III
is
expected
to
accumulate
in
soil
over
a
long
time
period.

Factors
not
considered
when
developing
the
RBC
·
Contribution
of
MOPC
from
background
·
The
presence
and
effect
of
other
MOPC
on
toxicity
(
synergism
antagonism)
or
uptake
(
e.
g.
cadmium
and
zinc)
Low
 
Medium
 
may
over
or
underestimate
risk
and
RBC.
Impossible
to
assess
each
of
the
factors
because
of
lack
of
information
that
is
needed.
Overall
conservative
approach
is
considered
health
protective.
TABLE
20
MAGNITUDE
OF
RELATIVE
IMPACT
ASSOCIATED
WITH
EACH
PARAMETER
IN
THE
RISK
EQUATION
DRAFT
Parameter
Statistical
Descriptor
Magnitude
of
Relative
Impact
(
High,
Low)
in
Risk
Equation
(
a)

Biological
Exposure
Parameters
Exposure
Duration
(
ED)
95th
percentile,
upper
end
estimate
High
(
for
arsenic,
the
only
carcinogen)

Exposure
Frequency
(
EF)
Very
high
end,
assumes
exposure
every
day
of
the
year
except
for
2
weeks
away
from
home
High
Averaging
Time
(
AT)
Standard
default,
but
high
end,
based
on
lifetime
exposure
for
cancer
and
length
of
exposure
(
exposure
duration)
for
noncancer
High
Body
Weight
(
BW)
Mean
estimate
Low
Ingestion
Rates
for
Soil
and
Crops
(
IR)
Mean
estimates
Low
Fraction
Ingested
(
FI)
Highest
possible
percent
High
Skin
Surface
Area
(
SA)
Central
tendency
Low
Adherence
Factor
(
AF)
Central
tendency
Low
Crops
Specific
Parameters
Application
Rate
(
AR)
95%
upper
confidence
limit
of
the
arithmetic
mean
 
upper
end
estimate
High
Plant
Uptake
Factors
(
PUFs)
90%
confidence
limit
of
the
geometric
mean
 
upper
end
estimate
High
Fraction
of
Land
(
FOL)
Reasonable
estimates
Low
Soil
Accumulation
Factor
(
SACF)
Reasonable
estimate,
combination
of
high,
central
and
low­
end
values
High
Metal
of
Potential
Concern
(
MOPC)
Specific
Parameters
Toxicity
Values
(
Tox)
High
end,
standard
health
protective
values
High
Relative
Absorption
Factor
(
RAF)
Mostly
100%,
high
end
percent
(
except
for
arsenic
and
lead)
Low
 
High
(
MOPC
dependent)

(
a)
The
magnitude
of
impact
considers
(
1)
the
possible
range
of
values
(
e.
g.,
EF
of
350
days/
year
 
1
day
/
year
or
soil
ingestion
for
a
child
of
100
mg/
day
 
400
mg/
day)
and
(
2)
the
weight
that
each
of
the
parameters
has
in
the
RBC
equation
(
e.
g.,
SACF,
AR,
and
PUF
have
significant
weight).
43
DRAFT
SECTION
7.0
¾
CONCLUSIONS
OF
EVALUATION
The
screening
evaluation
indicates
there
are
no
exceedances
for
any
of
the
phosphate
fertilizer
RBCs
and
therefore
no
post
application
health
risks
from
exposure
to
metals
in
NPK
types
of
fertilizers.
With
regard
to
micronutrient
fertilizers,
there
are
exceedances
of
arsenic
and
lead
RBCs
for
several
micronutrient
fertilizer
products.
These
products
contain
relatively
high
levels
of
arsenic
and
lead
in
some
samples.
Because
of
the
health
protective
nature
of
screening
level
evaluations,
and
because
exceedances
occur
only
at
the
maximum
metal
concentration
in
some
of
the
samples,
a
firm
conclusion
regarding
health
risks
from
micronutrient
products
or
product
categories
requires
a
closer,
product­
by­
product
evaluation.
A
refined
evaluation
would
take
into
account
the
exact
uses
and
use
conditions
of
the
specific
products,
as
well
as
monitoring
data
for
arsenic
and
lead
concentrations
in
additional
samples
of
these
products.

As
with
all
risk
assessments
there
is
some
level
of
uncertainty
associated
with
this
evaluation.
The
major
uncertainties
are
identified
and
described
in
the
report.
The
uncertainty
is
more
likely
to
err
on
the
side
of
overestimating
the
potential
for
risk
rather
than
underestimating
the
potential
risk
for
both
the
NPK
and
micronutrient
fertilizer
products.
44
DRAFT
SECTION
8.0
¾
COMPARISON
TO
OTHER
EVALUATIONS
In
addition
to
this
evaluation,
evaluations
of
inorganic
fertilizers
have
been
conducted
and
are
presented
in
two
previous
reports:
CDFA
(
1998)
and
USEPA
(
1999b).
37
These
reports
are
used
throughout
this
evaluation
to
assist
in
establishing
health
protective
assumptions
and
in
focusing
the
scope
of
this
evaluation.
A
comparison
of
the
(
1)
purpose
and
general
approach
(
2)
scope
(
3)
specific
key
parameters
and
(
4)
the
conclusions
among
these
three
evaluations
is
made
in
this
section.

Purpose
and
General
Approach
The
purpose
and
general
approach
of
each
of
the
evaluations
is
presented
in
Table
21.
All
three
evaluations
are
intended
to
assist
in
answering
the
question:
are
inorganic
fertilizers
safe,
or
more
specifically,
does
the
use
of
inorganic
fertilizer
on
agricultural
soils
pose
a
health
risk?
Each
of
these
evaluations
provides
valuable
information
to
answer
this
question.
However,
each
assessment
has
a
somewhat
different
approach
and
thus
provides
unique
as
well
as
complimentary
information
and
conclusions.

The
purpose
of
this
evaluation
is
to
develop
a
flexible
screening
tool
that
can
be
used
to
evaluate
inorganic
fertilizer
products.
In
addition,
this
assessment
evaluates
a
fairly
comprehensive
fertilizer
product
database
(
TWG
1999c).
Because
the
purpose
of
this
evaluation
is
to
provide
a
flexible
screening
tool,
that
can
be
used
to
evaluate
many
products
now
and
in
the
future,
this
evaluation
uses
a
back­
calculation,
risk
based
approach
and
develops
RBCs.
This
evaluation
uses
a
deterministic
and
high­
end
exposure
estimate
approach
to
develop
health
protective
RBCs,
or
levels
of
metals
in
products.
In
addition,
this
evaluation
is
intended
to
be
nationwide
in
its
application.

As
stated
in
USEPA
(
1999b),
the
purpose
of
USEPA's
assessment
is
to
estimate
potential
risks
posed
to
human
health
and
the
environment
by
contaminants
in
(
23)
fertilizer
products.
Such
a
determination
of
risk
requires
a
forward
risk
assessment
approach.
That
is,
USEPA
determines
risks
for
a
range
of
product
types
that
are
currently
in
commerce.
A
summary
of
this
product
database
is
presented
in
USEPA
(
1999a).
USEPA
uses
a
probabilistic
approach
to
estimate
the
distribution
of
individual
lifetime
risk
from
exposure
to
metals
in
inorganic
fertilizer
following
application.
USEPA's
evaluation
has
nationwide
application.

The
purpose
of
the
CDFA
(
1998)
evaluation
is
to
develop
RBCs
for
three
metals
in
inorganic
fertilizers,
arsenic,
mercury,
and
lead,
that
are
based
on
application
and
exposure
in
California.
Of
all
the
metals
that
are
present
in
inorganic
fertilizers,
these
three
were
chosen
(
based
on
a
screening
evaluation)
because
they
are
considered
to
pose
the
highest
risk.
CDFA
(
1998)
offers
a
method
but
does
not
evaluate
actual
product
data
and
therefore
does
not
make
conclusions
with
regard
to
health
risks.
California
uses
a
probabilistic
approach
to
develop
the
RBCs.

37
The
USEPA
fertilizer
risk
assessment
relies
on
the
information
provided
in
a
companion
report,
USEPA
1999a.
45
DRAFT
Scope
The
scope
of
each
of
these
evaluations
varies;
a
comparison
of
the
scope
is
also
presented
in
Table
21.

The
scope
of
this
evaluation
is
narrowed
to
focus
on
the
products,
MOPC,
populations
and
exposure
pathways
of
greatest
concern.
The
products
evaluated
are
phosphate
fertilizers
and
select
micronutrient
fertilizers
(
boron,
iron,
manganese,
and
zinc).
The
MOPC
for
which
RBCs
are
developed
and
products
are
evaluated
are:
arsenic,
cadmium,
chromium,
cobalt,
copper,
lead,
mercury,
molybdenum,
nickel,
selenium,
vanadium,
and
zinc
and
one
radionuclide,
radium
226.
The
exposure
scenario
is
the
farm
family,
including
adults
and
children,
and
exposure
pathways
that
contribute
the
most
to
risk
including
direct
contact
with
fertilized
soil
(
i.
e.,
unintentional
ingestion
and
dermal
contact)
and
uptake
of
MOPC
into
crops
and
subsequent
ingestion
of
crops.
The
RBCs
are
intended
to
be
nationally
representative.
The
crops
are
grouped
into
like
physiological
groups
(
vegetable,
root,
and
grain);
each
of
these
groups
is
evaluated
independently.

USEPA
(
1999b)
evaluates
all
of
the
general
categories
of
inorganic
fertilizer
products
(
e.
g.,
NPK
for
P,
NPK
for
N,
phosphate
fertilizers,
nitrogen
fertilizers,
potash
fertilizers,
etc.),
farm
workers
and
farm
residents
(
both
adults
and
children),
most
of
the
potential
exposure
pathways
(
all
three
evaluations
exclude
drinking
water),
and
29
geographic
locations.
Crops
are
grouped
as
ingested
by
animals
(
grain
and
forage)
and
crops
ingested
by
humans
(
fruit,
herb
or
above
ground
vegetables,
and
root).
USEPA
(
1999b)
evaluates
nine
MOPC:
arsenic,
cadmium,
cobalt,
copper,
lead,
mercury,
nickel,
vanadium,
and
zinc,
as
well
as
dioxin.
USEPA
(
1999b)
also
evaluates
risk
to
the
environment.

The
scope
of
CDFA
(
1998)
is
focused
on
the
development
of
RBCs
for
phosphate
and
zinc
micronutrient
fertilizers
and
three
MOPC:
arsenic,
cadmium,
and
lead.
In
addition,
as
mentioned
above,
the
CDFA
(
1998)
evaluation
focuses
on
California.
The
exposure
scenario
that
the
RBCs
are
based
on
is
narrowed
to
focus
on
the
exposure
scenario
of
greatest
concern
through
a
deterministic,
forward
risk
assessment
screening
evaluation.
The
focused
exposure
scenario
consists
of
the
farm
family
(
adults
and
children)
and
direct
contact
with
fertilized
soil
(
i.
e.,
unintentional
ingestion
and
dermal
contact)
and
the
uptake
of
the
MOPC
through
the
ingestion
of
crops.
Crops
are
grouped
and
evaluated
similar
to
this
evaluation.

Key
Parameters
Whether
the
assessment
uses
a
forward
risk
based
approach
(
determination
of
risk
for
a
specific
group
of
products)
or
a
back­
calculation
risk
based
approach
(
development
of
RBCs
and
a
screening
evaluation
of
current
and
future
products),
there
are
"
key"
parameters
in
common.
Key
parameters
are
those
that
can
significantly
influence
the
estimation
of
the
RBC
or
risk;
they
are
also
called
sensitive
parameters.
A
comparison
of
the
parameters
used
in
each
of
the
three
evaluations
is
presented
in
Table
22.
The
key
parameters
include
application
rate
(
AR),
soil
accumulation
factor
(
specifically
related
to
loss
and
bioavailability),
plant
uptake
factor
(
PUF),
46
DRAFT
and
representative
MOPC
concentration
in
product.
Other
parameters
are
also
presented
in
Table
22
(
i.
e.,
biological
exposure
parameters
and
toxicity
values);
however,
these
parameters
are
generally
similar
among
the
three
evaluations
and
therefore
do
not
influence
the
estimation
of
the
RBC
or
risk
as
much
as
the
key
parameters.

Application
Rate
(
AR)

The
application
rates
used
in
this
evaluation
are
developed
from
information
presented
in
USEPA
(
1999a).
ARs
for
each
of
the
three
crop
groups
are
developed
for
both
phosphate
fertilizers
and
zinc
micronutrient
fertilizers.
The
ARs
are
upper­
end
estimates
of
the
data
set
for
each
crop
group
(
they
are
the
95
percent
upper
confidence
limit,
95UCL
of
the
mean,
based
on
a
normal
distribution).
The
ARs
for
phosphate
fertilizers
are
118,
154,
and
63
lbs/
acre­
year
for
vegetable,
root,
and
grain
crops,
respectively.
The
AR
for
zinc
micronutrient
fertilizer
is
10
lbs/
acre
for
all
3
crop
groups,
and
is
an
estimate
from
industry
experts
(
USEPA
1999a).

The
ARs
used
in
USEPA
(
1999b)
are
taken
directly
from
USEPA
report
(
1999a)
where
the
consumption
and
use
of
inorganic
fertilizers
is
presented.
The
ARs
for
each
generic
fertilizer
category
are
based
on
a
distribution
of
percentile
(
50th,
85th,
and
95th)
ARs.
For
the
purposes
of
comparing,
the
high­
end
(
85%)
estimate
from
USEPA
(
1999a)
for
phosphate
fertilizer
is
173
lbs/
acre
and
the
maximum
AR
(
95%)
is
252
lbs/
acre­
year.
The
high­
end
ARs
for
micronutrient
fertilizers
are
10
lbs/
acre­
year
for
zinc
and
20
lbs/
acre­
year
for
iron
micronutrient
fertilizers
(
USEPA
1999a).
The
distribution
of
ARs
is
combined
with
varying
FONs
in
determining
the
distribution
of
risk.

ARs
used
in
developing
the
RBC
in
CDFA
(
1998)
are
also
represented
as
a
distribution.
For
comparison
purposes,
phosphate
fertilizer
ARs
values
(
mean)
reported
in
CDFA
(
1998)
are
60.0,
67.4,
and
38.2
lb/
acre­
year
for
vegetable,
root,
and
grain
crop
groups,
respectively
(
CDFA
1998).
The
AR
for
micronutrient
fertilizers
is
6.1
lb/
acre­
year
for
all
crop
groups.

Soil
Accumulation
The
accumulation
of
MOPC
soil
following
application
is
estimated
in
each
of
the
three
evaluations
using
similar
models.
However,
assumptions
that
are
made
regarding
soil
accumulation,
loss
from
soil,
and
the
Kd
values
are
different.

In
this
evaluation,
SACF
considers
only
the
loss
of
MOPC
through
leaching,
thereby,
most
of
the
MOPC
that
is
applied
is
assumed
to
accumulate
in
soil.
SACF
is
primarily
based
on
generic
USEPA
default
parameters.
The
Kd
values
are
measured
values
published
in
the
literature.
These
Kd
values
are
on
the
lower
end
of
the
Kd
range.

The
accumulation
of
MOPC
in
soil
in
USEPA's
evaluation
is
more
complex
because
it
considers
the
loss
of
MOPC
through
several
loss
pathways.
Also,
accumulation
and
loss
is
determined
for
each
of
the
29
geographic
locations
using
geographic
specific
parameters.
The
Kd
distributions
in
USEPA
(
1999b)
are
from
derived
from
a
database
of
Kds
compiled
by
USEPA.
47
DRAFT
The
accumulation
of
MOPC
in
soil
in
CDFA
(
1998)
considers
several
loss
pathways
however
only
leaching
is
determined
to
contribute
substantially
to
loss.
The
other
loss
pathways
are
determined
to
be
negligible.
The
Kd
values
used
in
CDFA
(
1998)
are
the
same
as
the
Kd
values
used
in
this
evaluation.

Plant
Uptake
Factor
(
PUF)

The
plant
uptake
factors
(
PUFs)
used
in
this
evaluation
are
based
primarily
on
field
studies,
however,
some
data
are
from
greenhouse
or
pot
studies
(
in
the
instance
of
insufficient
field
data).
Also,
any
studies
that
applied
organic
fertilizer
are
generally
excluded
from
the
PUF
database.
The
PUF
data
are
grouped
by
crop:
vegetable,
root,
and
grain.
PUF
estimates
are
the
90
percent
upper
confidence
limit
(
UCL)
assuming
a
log
normal
distribution
(
or
the
95%
UCL,
based
on
a
normal
distribution).
PUFs
are
presented
in
Table
23.

The
plant
uptake
factors
(
defined
as
Br
in
USEPA's
evaluation)
in
USEPA
(
1999b)
are
presented
as
distributions
and
are
developed
from
a
comprehensive
literature
search.
All
of
the
PUF
data
used
in
CDFA
(
1998)
is
included
in
this
database
as
well
as
additional
data.
The
majority
of
PUF
data
is
from
field
studies;
however,
some
data
is
from
greenhouse
studies
(
used
to
supplement
data
set
in
the
instance
of
insufficient
field
data).
Studies
that
use
organic
fertilizer
are
not
included
in
the
database.
PUFs
are
developed
for
herbs
(
exposed
vegetables
consumed
by
humans),
roots,
grains,
fruits,
and
forage
crops.
The
mean
value
of
the
distribution
is
presented
in
Table
23
for
comparison
purposes.

The
PUF
distributions
developed
in
CDFA
(
1998)
also
exclude
studies
that
apply
organic
fertilizer,
however,
unlike
the
data
in
USEPA
or
this
report,
most
of
the
data
in
CDFA
(
1998)
is
from
greenhouse
and
pot
studies.
The
mean
PUF
is
also
presented
in
Table
23
for
comparison
purposes.

Other
parameters,
biological
exposure
parameters
(
e.
g.,
IRs,
BW,
and
SA),
absorption
values,
and
toxicity
values,
are
generally
developed
from
standard
USEPA
resources.
Some
of
these
parameters
are
represented
as
distributions
and
not
point
estimates
in
USEPA
(
1999b)
and
CDFA
(
1998).
Nevertheless,
these
parameters
are
generally
similar.

MOPC
Concentration
in
Product
MOPC
concentration
in
product
is
only
considered
in
this
evaluation
and
in
USEPA
(
1999b).
A
comparison
of
MOPC
concentrations
is
presented
in
Table
24.
CDFA
(
1998)
does
not
conduct
a
health
evaluation
of
products
and
therefore
does
not
consider
product
information.

The
product
database
used
in
this
evaluation
is
a
fairly
comprehensive
database
and
consists
of
industry,
state,
and
literature
data
(
TWG
1999c).
Products
for
which
there
are
reported
MOPC
concentrations
are
evaluated
as
product
groups
or
types,
but
can
also
be
evaluated
separately.

The
product
database
for
USEPA's
risk
assessment
(
1999b)
is
based
on
a
recent
USEPA
report
on
inorganic
fertilizers
(
USEPA
1999a)
that
summarizes
the
literature
data.
MOPC
concentrations
for
a
product
type
(
e.
g.
diammonium
phosphate)
are
evaluated
as
a
distribution.
48
DRAFT
However,
for
several
products,
limited
product
data
are
available
and
distributions
could
not
be
developed.

Conclusion
Regarding
Determination
of
Risk
Only
this
evaluation
and
USEPA
(
1999b)
evaluate
potential
risk
from
exposure
to
MOPC
following
application.
However,
the
RBC
values
for
arsenic,
cadmium
and
lead
are
similar
for
this
evaluation
and
the
CDFA
(
1998)
evaluation.
Both
this
evaluation
and
USEPA
(
1999b)
evaluation
conclude
that
there
is
no
significant
post­
application
human
health
risk
from
exposure
to
NPK
types
of
inorganic
fertilizers.
The
CDFA
(
1998)
evaluation
would
give
the
same
conclusion
if
its
RBC
values
were
compared
to
MOPC
concentrations
in
the
fertilizer
product
database.
With
regard
to
micronutrient
fertilizers,
both
this
evaluation
and
USEPA
(
1999b)
identified
several
micronutrient
fertilizers
that
contain
levels
of
certain
MOPC,
in
particular
arsenic,
that
pose
a
possible
health
risk.
While
it
is
a
basic
tenant
of
health
risk
assessment
that
exposure
to
a
high
enough
concentration
of
a
chemical
can
pose
an
unacceptable
risk,
a
closer
look
at
these
relatively
few
micronutrient
product
samples
is
warranted
before
a
firm
conclusion
of
risk
for
these
specific
samples,
and
even
more
so
for
product
types
or
categories,
can
be
made.
USEPA
(
1999b)
concluded
that
hazardous
constituents
in
fertilizers
generally
do
not
pose
harm
to
human
health
or
the
environment.
38
This
evaluation,
and
by
similarity
in
RBCs,
the
CDFA
(
1998)
evaluation
are
in
general
agreement
with
this
conclusion.

38
Based
on
a
screening
level
ecological
risk
evaluation
of
metals
in
fertilizer
runoff
into
streams,
USEPA
(
1999b)
concluded
that
no
exceedances
of
water
quality
criteria
are
projected.
TABLES
DRAFT
TABLE
21
COMPARISON
OF
THE
PURPOSE,
GENERAL
APPROACH,
AND
SCOPE
OF
THIS
EVALUATION
TO
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
AND
CDFA
(
1998)
DEVELOPMENT
OF
RISK
BASED
CONCENTRATIONS
(
RBCs)
FOR
ARSENIC,
CADMIUM,
AND
LEAD
Factor
This
Evaluation
USEPA
CDFA
General
Purpose
Develop
flexible
risk
based
screening
tool
and
to
evaluate
available
product
data.
Estimate
distribution
of
individual
lifetime
risk
based
on
available
product
information.
Develop
RBCs
for
arsenic,
cadmium
and
lead.

Back
calculation,
risk
based
approach
 
development
of
risk
based
concentrations
(
RBCs)
Forward
risk
assessment
Back
calculation,
risk
based
approach
 
development
of
RBCs
Approach
Deterministic
based
on
a
reasonable
maximum
exposure
(
RME)
scenario
Probabilistic
presents
risks
at
50,
90,
95,
and
99
percentile
Probabilistic
develop
RBCs
(
protective
of
90
percentile
risks)

Perspective
National
(
health
protective)
National
(
29
geographic
locations)
California
Scope
Fertilizers
Œ
Phosphate
(
blends
and
phosphate)

Œ
Select
micronutrients
(
boron,
iron,

manganese,
and
zinc)
Œ
Macronutrient
(
phosphate,
NPK
for
phosphate,

NPK
for
nitrogen,
potash)

Œ
Amendments
(
sulfur
for
nutrient,
sulfur
for
pH,

lime,
and
gypsum)

Œ
Micronutrient
(
boron,
iron,
manganese,
zinc,

and
mixes)
Œ
Phosphate
Œ
Zinc
micronutrients
Metals
of
Potential
Concern
(
MOPC)
Arsenic,
Cadmium,
Chromium,
Cobalt,

Copper,
Lead,
Mercury,
Molybdenum,

Nickel,
Selenium,
Vanadium,
and
Zinc
(
radium
226
is
also
evaluated)
Arsenic,
Cadmium,
Chromium,
Copper,
Lead,

Mercury,
Nickel,
Vanadium,
and
Zinc
(
dioxin
is
also
evaluated)
Arsenic,
Cadmium,
and
Lead
Populations
and
Exposure
Routes
Farm
family
­
adult
and
child
Œ
unintentional
ingestion
of
fertilized
soil
Œ
dermal
contact
with
fertilized
soil
Œ
crop
ingestion
on
a
single
and
multicrop
farm
(
vegetable,
root,
and
grains)

note:
a
worker
is
evaluated
in
previous
reports
(
TWG
1999a,
b)
Farm
family
­
adult
and
child
Œ
inhalation
Œ
ingestion
of
animal
products
(
milk
and
beef)

following
ingestion
of
forage
crops
and
grain
Œ
ingestion
of
crops
(
fruit,
vegetable,
and
root)

(
multiple
only)

Œ
unintentional
ingestion
of
fertilized
soil
(
not
added
to
indirect
pathways)

Œ
ingestion
fish
Œ
direct
ingestion
fertilizer
(
adult
worker
only)
Farm
family
­
adult
and
child
Œ
unintentional
ingestion
of
fertilized
soil
Œ
dermal
contact
with
fertilized
soil
Œ
crop
ingestion
on
a
single
and
multi­
crop
farm
(
vegetable,
root,

and
grain)

note:
focused
on
this
exposure
scenario
through
a
deterministic
risk
based
forward
screen
DRAFT
TABLE
22
COMPARISON
OF
KEY
PARAMETERS
USED
IN
THIS
EVALUATION
TO
THESE
PARAMETERS
IN
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
AND
CDFA
(
1998)
DEVELOPMENT
OF
RISK
BASED
CONCENTRATIONS
(
RBCs)
FOR
ARSENIC,

CADMIUM,
AND
LEAD
Key
Parameters
This
Evaluation
USEPA
CDFA
Application
Rate
(
AR)
Upper
end
point
estimates
based
on
information
from
USEPA
(
1999a)
(
a)

Phosphate
118
lb/
acre
 
yr
 
vegetable
154
lb/
acre
 
yr
 
root
63
lb/
acre
 
yr
 
grain
Micronutrient
10
lbs/
acre
 
yr
Distribution
based
on
information
from
USEPA
(
1999a)
(
a)

High­
end
estimates:

Phosphate
173
lb/
acre
 
yr
 
all
crops
Micronutrient
10
lb/
acre
 
yr
(
for
zinc)

20
lb/
acre
 
yr
(
for
iron)
Based
on
California
data
and
distribution
based
Representative
value:

Phosphate
60.1
lb/
acre
 
yr
 
vegetable
66.2
lb/
acre
 
yr
 
root
37.4
lb/
acre
 
yr
 
grain
Micronutrient
6
lbs/
acre
 
yr
Soil
Accumulation
Factor
(
SACF)
Œ
Based
on
national
default
values
and
only
one
loss
pathway
(
leaching)

Œ
50
yrs
application
duration
(
200
for
lead)

Œ
Low
end
Kd
values
Œ
Based
on
regional
information
and
several
default
values
and
several
loss
pathways
Œ
100
yrs
application
duration
(
followed
by
40
years
of
inactive
use)

Œ
Distribution
of
Kd
values
that
includes
high­
end
values
Œ
California
specific
and
several
loss
pathways
Œ
50
yrs
application
duration
(
200
for
lead)

Œ
Low
end
Kd
values
Plant
Uptake
Factors
(
PUFs)
(
a)
Œ
Upper
end
point
estimate
Œ
Database
consists
of
field
studies
and
limited
greenhouse
and
potted
Œ
Represented
as
a
distribution
Œ
Database
consists
of
all
data
in
CDFA
plus
additional
data
Œ
Primarily
field
studies,
except
when
insufficient
field
data,
then
greenhouse
and
potted
studies
Œ
Represented
as
a
distribution
Œ
Mostly
pot
and
greenhouse
studies;
few
field
studies
Toxicity
Values
Standard
USEPA
Standard
USEPA
Standard
USEPA
and
DTSC
General
Exposure
Parameters
(
e.
g.,
ingestion
rates,
exposure
duration,
exposed
skin
surface
area,
and
body
weight
and
relative
absorption
factors
and
fraction
ingested)
Œ
Based
on
USEPA
default,
RME
recommended
point
estimates
Œ
100%
fraction
ingested
Œ
100%
(
or
1)
relative
absorption
factor
(
except
for
arsenic
and
lead)
Œ
Generally
based
on
USEPA
standard
default,

several
represented
as
a
distribution
Œ
IRs
developed
differently
considers
a
fraction
ingested
of
less
than
100%

Œ
Relative
absorption
of
100%
Œ
Generally
based
on
USEPA
default,
some
California,
Department
of
Toxic
Substance
Control
(
DTSC)
specific
information
Œ
100%
fraction
ingested
Œ
Similar
relative
absorption
factor
as
this
evaluation
MOPC
Concentration
in
Product
(
b)
Œ
Comprehensive
product
database
Œ
Maximum
product
concentration
used
for
screening
Œ
Concentration
data
obtained
from
USEPA
(
1999a)

Œ
Represented
as
a
distribution
except
for
when
limited
number
of
samples
available
(
e.
g.,
iron
micronutrient)
NA
Notes:
NA
Not
Applicable
(
a)
PUFs
are
presented
in
Table
23.

(
b)
MOPC
concentrations
in
product
are
presented
in
Table
24
and
Table
25.
DRAFT
TABLE
23
COMPARISON
OF
PLANT
UPTAKE
FACTORS
(
PUFs)
USED
IN
THIS
EVALUATION
TO
THE
PUFs
DEVELOPED
IN
USEPA
(
1999b)

INORGANIC
FERTILIZER
RISK
ASSESSMENT
AND
CDFA
(
1998)
DEVELOPMENT
OF
RISK
BASED
CONCENTRATIONS
(
RBCs)
FOR
ARSENIC,
CADMIUM,
AND
LEAD
PUFs
(
a)

This
Evaluation
(
upper
end
estimate,
95
UCL)
USEPA
(
mean,
although
estimated
as
a
distribution)
CDFA
(
mean,
although
estimated
as
a
distribution)

Metal
of
Potential
Concern
(
MOPC)
Vegetable
Root
Grain
Herbage
Root
Grain
Vegetable
Root
Grain
Arsenic
0.30
0.05
0.03
0.065
0.099
0.005
0.024
0.011
0.02
Cadmium
1.7
0.93
0.12
0.81
0.75
0.54
0.68
0.31
0.092
Chromium
0.0014
0.0014
0.0037
0.032
0.0011
0.000093
­­
­­
­­

Cobalt
0.05
0.03
0.02
­­
­­
­­
­­
­­
­­

Copper
0.034
0.22
0.31
0.28
0.45
1.7
­­
­­
­­

Lead
0.08
0.05
0.05
0.12
0.046
0.11
0.014
0.026
0.0096
Mercury
0.61
0.67
0.26
0.52
0.036
0.57
­­
­­
­­

Molybdenum
1.1
0.15
0.22
­­
­­
­­
­­
­­
­­

Nickel
0.15
0.07
0.05
0.0086
­­
­­
­­
­­
­­

Selenium
0.88
0.76
0.57
­­
­­
­­
­­
­­
­­

Vanadium
0.007
0.007
0.007
­­
­­
­­
­­
­­
­­

Zinc
1.7
0.46
0.58
0.77
0.13
0.97
­­
­­
­­

Notes:
­­
Not
applicable
or
not
available
(
a)
PUFs
are
based
on
dry
weight
and
are
unitless.
TABLE
24
COMPARISON
OF
THE
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
CONCENTRATIONS
IN
PHOSPHATE
FERTILIZER
PRODUCTS
USED
IN
THIS
EVALUATION
TO
THE
MOPC
CONCENTRATIONS
USED
IN
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
Concentrations
(
a)
This
Evaluation
USEPA
MOPC
Minimum
Maximum
Mean
(
b)
Minimum
Maximum
Mean
Arsenic
0.05
42
10
0.05
155
12
Cadmium
0.015
205
13
0.03
250
44
Chromium
0.25
5,060
120
4.3
896
110
Cobalt
0.04
58
5.6
NE
NE
NE
Copper
0.14
544
14
0.2
1,170
41
Lead
0.05
1,860
13
0.1
5,425
140
Mercury
0.001
1.5
0.16
0.003
0.2
0.1
Molybdenum
0.69
72
12
NE
NE
NE
Nickel
0.5
351
22
0.5
195
28
Selenium
0.03
27
2.6
NE
NE
NE
Vanadium
0.28
1,106
128
25
721
180
Zinc
0.30
6,270
260
1
2,193
240
Notes:

NE
Not
Evaluated
(
a)
Concentrations
are
presented
as
ppm
(
or
mg
MOPC/
kg
product).

(
b)
For
comparison
purposes,
the
mean
values
assume
a
normal
distribution,
the
mean
values
presented
in
Section
4.0
assume
a
log
normal
distribution.

DRAFT
TABLE
25
COMPARISON
OF
THE
METAL
OF
POTENTIAL
CONCERN
(
MOPC)
CONCENTRATIONS
IN
MICRONUTRIENT
FERTILIZER
PRODUCTS
USED
IN
THIS
EVALUATION
TO
THE
MOPC
CONCENTRATIONS
USED
IN
USEPA
(
1999b)
INORGANIC
FERTILIZER
RISK
ASSESSMENT
Concentrations
(
a)
This
Evaluation
(
b)
USEPA
MOPC
Minimum
Maximum
Mean
Minimum
Maximum
Mean
Arsenic
0.1
6,200
400
0.5
4,950
560
Cadmium
0.095
3,900
120
0.75
2,165
340
Chromium
0.25
8,100
290
1.3
580
170
Cobalt
0.25
790
200
NE
NE
NE
Copper
0.5
40,000
7,700
1.5
2,050
640
Lead
0.32
28,000
2,400
5
52,000
9,400
Mercury
0.0025
12
1
0.01
3.36
1.3
Molybdenum
0.25
850
83
NE
NE
NE
Nickel
0.5
560
88
2.5
8,950
760
Selenium
0.013
25
6
NE
NE
NE
Vanadium
0.5
47
23
0.5
41
15
Zinc
8
350,000
120,000
6
60.8
33
Notes:
NE
Not
Evaluated
(
a)
Concentrations
are
presented
as
ppm
(
or
mg
MOPC/
kg
product).
(
b)
For
comparison
purposes,
the
mean
values
assume
a
normal
distribution,
the
mean
values
presented
in
Section
4.0
assume
a
log
normal
distribution.

DRAFT
49
DRAFT
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