A bioaccumulation factor (BAF) is used to relate the
concentration of a substance in an aquatic organism to the concentration of the
substance in the waters in which the organism resides when all routes of
exposure (ambient water and food) are included. A BAF is used in the derivation
of water quality criteria to protect wildlife and criteria and values to
protect human health.
a) Selection of
Data. BAFs can be obtained or developed from one of the following methods,
listed in order of preference.
1)
Field-measured BAF.
2)
Field-measured biota-sediment accumulation factor (BSAF).
3) Laboratory-measured
bioconcentration
factor (
BCF).
The concentration of particulate organic carbon (POC) and
dissolved organic carbon (DOC) in the test solution must be either measured or
reliably estimated.
4)
Predicted
BCF.
Predicted baseline BCF = Kow.
b) Calculation of Baseline BAFs for Organic
Chemicals
The most preferred BAF or BCF from above is used to calculate
a baseline BAF which in turn is utilized to derive a human health or wildlife
specific BAF.
1) Procedures for
Determining the Necessary Elements of Baseline Calculation
A) Lipid Normalization. The lipid-normalized
concentration, C
1, of a chemical in tissue is defined
using the following equation:
C1 = Cb /
f1
Where:
|
Cb
|
=
|
concentration of the organic chemical in the tissue
of aquatic biota (either whole organism or specified tissue)
(µg/g)
|
|
f1
|
=
|
fraction of the tissue that is lipid
|
B)
Bioavailability.
The fraction of the total chemical in the ambient water that
is freely dissolved, ffd, must be calculated using the
following equation:
ffd = 1 / {1 + [(DOC)(Kow)/10] +
[(POC)(Kow)]}
Where:
|
DOC
|
=
|
concentration of dissolved organic carbon, kg of
dissolved organic carbon/L of water
|
|
Kow
|
=
|
octanol-water partition coefficient of the
chemical
|
|
POC
|
=
|
concentration of particulate organic carbon, kg of
particulate organic carbon/L of water
|
C)
Food Chain Multiplier (
FCM). For an organic chemical, the
FCM used must be
taken from Table B-1 in Appendix B of 40 CFR
132, incorporated by reference at
35 Ill. Adm. Code
301.106.
2) Calculation of Baseline BAFs
A) From Field-Measured BAFs
Baseline BAF = {[measured BAFtT /
ffd] - 1}{1 / f1}
Where:
|
BAFtT
|
=
|
BAF based on total concentration in tissue and water
of study organism and site
|
|
f1
|
=
|
fraction of the tissue of study organism that is
lipid
|
|
ffd
|
=
|
fraction of the total chemical that is freely
dissolved in the ambient water
|
B)
From a Field-Measured
Biota-Sediment Accumulation Factor (
BSAF)
(Baseline BAF)i = (baseline
BAF)r (BSAF)i
(Kow)i / (BSAF) r
(Kow)r
Where:
|
(BSAF)i
|
=
|
BSAF for chemical "i"
|
|
(BSAF)r
|
=
|
BSAF for the reference chemical
"r"
|
|
(KOW)i
|
=
|
octanol-water partition coefficient for chemical
"i"
|
|
(KOW)r
|
=
|
octanol-water partition coefficient for the reference
chemical "r"
|
i) A
BSAF must
be calculated using the following equation:
BSAF = C1 /
Csoc
Where:
|
C1
|
=
|
the lipid-normalized concentration of the chemical in
tissue
|
|
Csoc
|
=
|
the organic carbon-normalized concentration of the
chemical in sediment
|
ii)
The organic carbon-normalized concentration of a chemical in sediment,
C
soc, must be calculated using the following equation:
Csoc = Cs /
foc
Where:
|
Cs
|
=
|
concentration of chemical in sediment (µg/g
sediment)
|
|
foc
|
=
|
fraction of the sediment that is organic
carbon
|
C) From a Laboratory-Measured
BCF
baseline BAF = (FCM) {[measured BCFtT
/ ffd] - 1} {1 /f1}
Where:
|
BCFtT
|
=
|
BCF based on total concentration in tissue and
water.
|
|
f1
|
=
|
fraction of the tissue that is lipid
|
|
ffd
|
=
|
fraction of the total chemical in the test water that
is freely dissolved
|
|
FCM
|
=
|
the food-chain multiplier obtained from Table B-1 in
Appendix B to 40 CFR 132,, incorporated by reference at 35 Ill. Adm. Code
301.106, by linear interpolation for trophic level 3 or 4, as necessary
|
D)
From a Predicted
BCF
baseline BAF = (FCM) (predicted baseline BCF) =
(FCM)(Kow)
Where:
|
FCM
|
=
|
the food-chain multiplier obtained from Table B-1 in
Appendix B to 40 CFR 132, incorporated by reference at 35 Ill. Adm. Code
301.106, by linear interpolation for trophic level 3 or 4, as necessary
|
|
Kow
|
=
|
octanol-water partition coefficient
|
c) Human Health and Wildlife BAFs for Organic
Chemicals
1) Fraction freely dissolved
(f
fd). By using the equation in subsection (b)(1)(B),
the f
fd to be used to calculate human health and
wildlife BAFs for an organic chemical must be calculated using a standard
POC
concentration of 0.00000004 kg/L and a standard
DOC concentration of 0.000002
kg/L:
ffd = 1 / [1+ (0.00000024
kg/L)(Kow)]
2) Human health
BAF. The human health BAFs for an organic chemical must be calculated using the
following equations:
A) For
Trophic Level 3
Human Health BAFHHTL3 = [(baseline
BAF)(0.0182) + 1] (ffd)
B) For
Trophic Level 4
Human Health BAFHHTL4 = [(baseline
BAF) (0.0310) + 1] (ffd)
Where:
0.0182 and 0.0310 are the standardized fraction lipid values
for trophic levels 3 and 4, respectively, that are used to derive human health
criteria and values
3)
Wildlife
BAF. The wildlife BAFs for an organic chemical must be calculated
using the following equations:
A) For
Trophic
Level 3
Wildlife BAFWLTL3 = [(baseline
BAF)(0.0646) +1] (ffd)
B) For
Trophic Level 4
Wildlife BAFWLTL4 = [(baseline
BAF)(0.1031) + 1] (ffd)
Where:
0.0646 and 0.1031 are the standardized fraction lipid values
for trophic levels 3 and 4, respectively, that are used to derive wildlife
criteria
d) Human Health and Wildlife BAFs for
Inorganic Chemicals. For inorganic chemicals, the baseline BAFs for trophic
levels 3 and 4 are both assumed to equal the
BCF determined for the chemical
with fish.
1) Human Health. Measured BAFs and
BCFs used to determine human health BAFs for inorganic chemicals must be based
on concentration in edible tissue (e.g., muscle) of freshwater fish.
2) Wildlife. Measured BAFs and BCFs used to
determine wildlife BAFs for inorganic chemicals must be based on concentration
in the whole body of freshwater fish and invertebrates.
