Authority: IC 13-14-8; IC 13-14-9; IC 13-18-3

Affected: IC 13-18-4

Sec. 13. (a) This section describes procedures for deriving BAFs to be used in the calculation of human health Tier I criteria and Tier II values, and criteria documents issued after January 1, 1980, and wildlife Tier I criteria. A subset of the human health BAFs is also used to identify the chemicals that are considered BCCs. BAFs are derived as follows:

1. (1) Bioaccumulation reflects uptake of a substance by aquatic organisms exposed to the substance through all routes, such as ambient water and food, as would occur in nature. Bioconcentration reflects uptake of a substance by aquatic organisms exposed to the substance only through the ambient water. Both BAFs and BCFs are proportionality constants that describe the relationship between the concentration of a substance in aquatic organisms and its concentration in the ambient water. In this section, BAFs, rather than BCFs, are used to calculate Tier I criteria for human health and wildlife, and Tier II values for human health, because they better account for the total exposure of aquatic organisms to chemicals.

2. (2) For organic chemicals, the lipid content of the aquatic organisms is used to account for partitioning of organic chemicals within organisms, so that data from different tissues and species can be integrated. The baseline BAF is based on the concentration of freely dissolved organic chemicals in the ambient water to facilitate extrapolation from one (1) water to another. Baseline BAFs must be derived using one (1) of the following four (4) methods:

   1. (A) Measured baseline BAFs are derived from field-measured BAFs.
   2. (B) Predicted baseline BAFs are derived using BSAFs.
   3. (C) Predicted baseline BAFs are derived by multiplying a laboratory-measured BCF by a FCM.
   4. (D) Predicted baseline BAFs are derived by multiplying a predicted BCF by a FCM.

3. (3) For inorganic chemicals, BAFs are assumed to equal BCFs (that is, the FCM is one (1.0)), unless chemical-specific biomagnification data support using a FCM other than one (1.0). The baseline BAFs are derived using either of the following two (2) methods:

   1. (A) Field-measured BAFs.
   2. (B) By multiplying laboratory-measured BCFs by a FCM.
4. (4) Because both humans and wildlife consume fish from both trophic levels three (3) and four (4), two (2) baseline BAFs are needed to calculate either a human health criterion or value, or a wildlife criterion, for a chemical. When appropriate, ingestion through consumption of invertebrates, plants, mammals, and birds in the diet of wildlife species to be protected may be taken into account.

(b) The following procedures must be used to review and select the data necessary to determine BAFs, BSAFs, and BCFs:

1. (1) Measured BAFs, BSAFs, and BCFs are assembled from available sources, including the following:

   1. (A) U.S. EPA Ambient Water Quality Criteria* documents issued after January 1, 1980.
   2. (B) Published scientific literature.
   3. (C) Reports issued by U.S. EPA or other reliable sources.
   4. (D) Unpublished data.
   5. (E) Sources referenced in the Aquatic Toxicity Information Retrieval (AQUIRE) database*.

2. (2) The following procedural and quality assurance requirements must be met for field-measured BAFs:

   1. (A) The field studies used must be limited to those conducted in the Great Lakes system, with fish at or near the top of the aquatic food chain such as in trophic levels three (3) or four (4).
   2. (B) The trophic level of the fish species must be determined.
   3. (C) The site of the field study should not be so unique that the BAF cannot be extrapolated to other locations where the criteria and values will apply.
   4. (D) For organic chemicals, the percent lipid must be either measured or reliably estimated for the tissue used in the determination of the BAF.
   5. (E) The concentration of the chemical in the water must be measured in a way that can be related to particulate organic carbon (POC) or dissolved organic carbon (DOC), and should be relatively constant during the steady-state time period.
   6. (F) For organic chemicals with log KOW greater than four (4), the concentrations of POC and DOC in the ambient water must be either measured or reliably estimated.
   7. (G) For inorganic and organic chemicals, BAFs must be used only if they are expressed on a wet weight basis. BAFs reported on a dry weight basis cannot be converted to wet weight unless a conversion factor is measured or reliably estimated for the tissue used in the determination of the BAF.

3. (3) The following procedural and quality assurance requirements must be met for field-measured BSAFs:

   1. (A) The field studies used must be limited to those conducted in the Great Lakes system, with fish at or near the top of the aquatic food chain such as in trophic levels three (3) or four (4).
   2. (B) Samples of surface sediments (zero (0) to one (1) centimeter is ideal) must be from locations where there are net depositions of fine sediment, and that are representative of average surface sediment in the vicinity of the organism.
   3. (C) The KOWs used must be of acceptable quality as described in subdivision (6).
   4. (D) The site of the field study should not be so unique that the resulting BAF cannot be extrapolated to other locations where the criteria and values will apply.
   5. (E) The trophic level of the fish species must be determined.
   6. (F) The percent lipid must either be measured, or reliably estimated, for the tissue used in the determination of the BAF.

4. (4) The following procedural and quality assurance requirements must be met for laboratory-measured BCFs:

   1. (A) The test organism must not be diseased, unhealthy, or adversely affected by the concentration of the chemical.
   2. (B) The total concentration of the chemical in the water must be measured, and should be relatively constant during the steady-state time period.
   3. (C) The organisms must be exposed to the chemical using a flow-through or renewal procedure.
   4. (D) For organic chemicals, the percent lipid must either be measured or reliably estimated for the tissue used in the determination of the BCF.
   5. (E) For organic chemicals with log KOW greater than four (4), the concentrations of POC and DOC in the test solution must either be measured or reliably estimated.
   6. (F) Laboratory-measured BCFs should be determined using fish species, but BCFs determined with molluscs and other invertebrates may be used with caution. For example, because invertebrates metabolize some chemicals less efficiently than vertebrates, a baseline BCF determined for a chemical using invertebrates is expected to be higher than a comparable baseline BCF determined using fish.

   7. (G) If laboratory-measured BCFs increase or decrease as the concentration of the chemical increases in the test solutions in a bioconcentration test, the BCF measured at the lowest test concentration that is above concentrations existing in the control water must be used. For example, a BCF should not be calculated from a control treatment. The concentrations of an inorganic chemical in a bioconcentration test should be:

      1. (i) greater than normal background levels; and
      2. (ii) greater than levels required for normal nutrition of the test species if the chemical is a micronutrient;
   8. but below levels that adversely affect the species. Bioaccumulation of an inorganic chemical might be overestimated if concentrations are at or below normal background levels due to nutritional requirements of the test organisms, for example.
   9. (H) For inorganic and organic chemicals, BCFs must be used only if they are expressed on a wet weight basis. BCFs reported on a dry weight basis cannot be converted to wet weight unless a conversion factor is measured, or reliably estimated, for the tissue used in the determination of the BAF.
   10. (I) BCFs for organic chemicals may be based on measurement of radioactivity only when the BCF is intended to include metabolites, or when there is confidence that there is no interference due to metabolites.
   11. (J) The calculation of the BCF must appropriately address growth dilution.
   12. (K) Other aspects of the methodology used must be similar to those described by ASTM, 2013, Standard Practice for Conducting Bioconcentration Tests with Fishes and Saltwater Bivalve Molluscs, Standard E 1022**.

5. (5) The following procedural and quality assurance requirements must be met for predicted BCFs:

   1. (A) The KOW used must be of acceptable quality as described in subdivision (6).

   2. (B) The predicted baseline BCF must be calculated using the equation:

      predicted baseline BCF = KOW
      Where:	KOW	=	octanol-water partition coefficient.

6. (6) The value of KOW must be determined as follows:

   1. (A) The value of KOW used for an organic chemical must be determined by giving priority to the experimental and computational techniques used as follows:

      1. (i) Where the Log KOW is less than four (4) (Log KOW < 4):

         	Priority	Technique
         	1	Slow-stir
         	1	Generator-column
         	1	Shake-flask
         	2	Reverse-phase liquid chromatography on C18 chromatography packing with extrapolation to zero percent solvent
         	3	Reverse-phase liquid chromatography on C18 chromatography packing without extrapolation to zero percent solvent
         	4	Calculated by the CLOGP program

      2. (ii) Where the Log KOW is greater than four (4) (Log KOW > 4):

         	Priority	Technique
         	1	Slow-stir
         	1	Generator-column
         	2	Reverse-phase liquid chromatography on C18 chromatography packing with extrapolation to zero percent solvent
         	3	Reverse-phase liquid chromatography on C18 chromatography packing without extrapolation to zero percent solvent
         	4	Shake-flask
         	5	Calculated by the CLOGP program

   2. (B) The CLOGP program is a computer program available from Pomona College. A value of KOW that seems to be different from the others should be considered an outlier and not used. The value of KOW used for an organic chemical must be the geometric mean of the available KOWs with highest priority, or can be calculated from the arithmetic mean of the available log KOWs with the highest priority. Because it is an intermediate value in the derivation of a BAF, the value used for the KOW of a chemical should not be rounded to fewer than three (3) significant digits, and a value for log KOW should not be rounded to fewer than three (3) significant digits after the decimal point.
7. (7) This section provides overall guidance for the derivation of BAFs, but it cannot cover all the decisions that must be made in the review and selection of acceptable data. Professional judgment is required throughout the process. A degree of uncertainty is associated with the determination of any BAF, BSAF, BCF, or KOW. The amount of uncertainty in a baseline BAF depends on both the quality of data available and the method used to derive the BAF.
8. (8) In subsections (c) through (g), "BAF", "BSAF", "BCF", and "KOW" refer to the "BAF", "BSAF", "BCF", and "KOW" that are consistent with the procedural and quality assurance requirements given in this subsection.

(c) For comparative purposes, baseline BAFs should be derived for each chemical by as many of the four (4) methods as available data allow. Baseline BAFs must be derived using the following four (4) methods, which are listed from most preferred to least preferred:

1. (1) A measured baseline BAF for an organic or inorganic chemical derived from a field study of acceptable quality.
2. (2) A predicted baseline BAF for an organic chemical derived using field-measured BSAFs of acceptable quality.
3. (3) A predicted baseline BAF for an organic or inorganic chemical derived from a BCF measured in a laboratory study of acceptable quality and an FCM.
4. (4) A predicted baseline BAF for an organic chemical derived from a KOW of acceptable quality and an FCM.

(d) The following procedures must be used to calculate baseline BAFs for organic chemicals:

1. (1) The following procedures must be used to determine the lipid-normalized concentration:

   1. (A) It is assumed that BAFs and BCFs for organic chemicals can be extrapolated on the basis of percent lipid from one (1) tissue to another and from one (1) aquatic species to another in most cases.
   2. (B) Because BAFs and BCFs for organic chemicals are related to the percent lipid, it does not make any difference whether the tissue sample is whole body or edible portion, but both the BAF (or BCF) and the percent lipid must be determined for the same tissue. The percent lipid of the tissue should be measured during the BAF or BCF study, but in some cases it can be reliably estimated from measurements on tissue from other organisms. If percent lipid is not reported for the test organisms in the original study, it may be obtained from the author; or, in the case of a laboratory study, lipid data for the same or a comparable laboratory population of test organisms that were used in the original study may be used.

   3. (C) The lipid-normalized concentration, Cl, of a chemical in tissue is defined using the following equation:

      Cl =	CB
      	fl

      Where:	CB =	concentration of the organic chemical in the tissue of aquatic biota (either whole organism or specified tissue) (micrograms per gram).
      	fl =	fraction of the tissue that is lipid.

2. (2) By definition, baseline BAFs and BCFs for organic chemicals, whether measured or predicted, are based on the concentration of the chemical that is freely dissolved in the ambient water in order to account for bioavailability. The following procedures must be used to determine this freely dissolved concentration:

   1. (A) For the purposes of this subsection, the relationship between the total concentration of the chemical in the water (that which is freely dissolved plus that which is sorbed to particulate organic carbon or to dissolved organic carbon), to the freely dissolved concentration of the chemical in the ambient water, must be calculated using the following equation:

      Where:	=	freely dissolved concentration of the organic chemical in the ambient water.
      	=	total concentration of the organic chemical in the ambient water.
      	ffd =	fraction of the total chemical in the ambient water that is freely dissolved.

   2. (B) 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)	+ (POC) (KOW)
      10

(3) In the absence of a field-measured BAF or a predicted BAF derived from a BSAF, a FCM must be used to calculate the baseline BAF for trophic levels three (3) and four (4) from a laboratory-measured or predicted BCF. For an organic chemical, the FCM used must be derived from Table 13-1 in subsection (h), using the chemical's log K_OW and linear interpolation. An FCM greater than one (1.0) applies to most organic chemicals with a log K_OW of four (4) or more. The trophic level used must take into account the age or size of the fish species consumed by the human, avian, or mammalian predator because, for some species of fish, the young are in trophic level three (3), whereas the adults are in trophic level four (4).

(4) A baseline BAF must be calculated from a field-measured BAF of acceptable quality using the following equation: Where:  =  based on total concentration in tissue and water.    =  fraction of the tissue that is lipid.    f_fd =  fraction of the total chemical that is freely dissolved in the ambient water.

The trophic level to which the baseline BAF applies is the same as the trophic level of the organisms used in the determination of the field-measured BAF. For each trophic level, a species mean measured baseline BAF must be calculated as the geometric mean if more than one (1) measured baseline BAF is available for a given species. For each trophic level, the geometric mean of the species mean measured baseline BAFs must be calculated. If a baseline BAF based on a measured BAF is available for either trophic level three (3) or four (4), but not both, a measured baseline BAF for the other trophic level must be calculated using the ratio of the FCMs that are obtained by linear interpolation from Table 13-1 in subsection (h) for the chemical.

(5) A baseline BAF must be calculated from a field-measured BAF in accordance with the following: (A) A baseline BAF for organic chemical "i" must be calculated from a field-measured BSAF of acceptable quality using the following equation: (Baseline BAF)_i = (Baseline BAF)_r   (BSAF)_i (K_OW)_i    (BSAF)_r (K_OW)_r    Where:  (BSAF)_i =  BSAF for chemical "i".    (BSAF)_r =  BSAF for the reference chemical "r".    (K_OW)_i =  octanol-water partition coefficient for chemical "i".    (K_OW)_r =  octanol-water partition coefficient for the reference chemical "r".  (B) A BSAF must be calculated using the following equation: Where:  =  the lipid-normalized concentration of the chemical in tissue.    C_SOC =  the organic carbon-normalized concentration of the chemical in sediment.  (C) The organic carbon-normalized concentration of a chemical in sediment, C_SOC, must be calculated using the following equation: C_SOC =  C_S    f_OC    Where:  C_S =  concentration of chemical in sediment (micrograms per gram of sediment).    f_OC =  fraction of the sediment that is organic carbon.  (D) Predicting BAFs from BSAFs requires data from a steady-state (or near steady-state) condition between sediment and ambient water for both a reference chemical "r" with a field-measured BAF^d, and other chemicals "n = i" for which BSAFs are to be determined. (E) The trophic level to which the baseline BAF applies is the same as the trophic level of the organisms used in the determination of the BSAF. For each trophic level, a species mean baseline BAF must be calculated as the geometric mean if more than one (1) baseline BAF is predicted from BSAFs for a given species. For each trophic level, the geometric mean of the species mean baseline BAFs derived using BSAFs must be calculated. (F) If a baseline BAF based on a measured BSAF is available for either trophic level three (3) or four (4), but not both, a baseline BAF for the other trophic level must be calculated using the ratio of the FCMs that are obtained by linear interpolation from Table 13-1 in subsection (h) for the chemical.

(6) A baseline BAF for trophic level three (3), and a baseline BAF for trophic level four (4), must be calculated from a laboratory-measured BCF of acceptable quality and a FCM using the following equation: Where:  =  BCF based on total concentration in tissue and water.    =  fraction of the tissue that is lipid.    f_fd =  fraction of the total chemical in the test water that is freely dissolved.    FCM =  the food-chain multiplier obtained from Table 13-1 in subsection (h) by linear interpolation for trophic level three (3) or four (4), as necessary.

For each trophic level, a species mean baseline BAF must be calculated as the geometric mean if more than one (1) baseline BAF is predicted from laboratory-measured BCFs for a given species. For each trophic level, the geometric mean of the species mean baseline BAFs based on laboratory-measured BCFs must be calculated.

(7) A baseline BAF for trophic level three (3), and a baseline BAF for trophic level four (4), must be calculated from a K_OW of acceptable quality and a FCM using the following equation: Baseline BAF = (FCM)(predicted baseline BCF) = (FCM)(K_OW)  Where:  FCM =  the food-chain multiplier obtained from Table 13-1 in subsection (h) by linear interpolation for trophic level three (3) or four (4) as necessary.    K_OW =  octanol-water partition coefficient.

(e) The following procedures must be used to calculate human health and wildlife BAFs for organic chemicals:

1. (1) To calculate human health and wildlife BAFs for an organic chemical, the KOW of the chemical must be used with a POC concentration of 0.00000004 kilograms per liter and a DOC concentration of 0.000002 kilograms per liter to yield the fraction freely dissolved:

2. (2) The human health BAFs for an organic chemical must be calculated using the following equations:

   1. (A) For trophic level three (3):

      Where:

      0.0182 is the standardized fraction lipid value for trophic level three (3) that is used to derive human health criteria and values.

   2. (B) For trophic level four (4):

      Where:

      0.0310 is the standardized fraction lipid value for trophic level four (4) that is used to derive human health criteria and values.

3. (3) The wildlife BAFs for an organic chemical must be calculated using the following equations:

   1. (A) For trophic level three (3):

      Where:

      0.0646 is the standardized fraction lipid value for trophic level three (3) that is used to derive wildlife criteria.

   2. (B) For trophic level four (4):

      Where:

      0.1031 is the standardized fraction lipid value for trophic level four (4) that is used to derive wildlife criteria.

(f) The following procedures must be used to calculate human health and wildlife BAFs for inorganic chemicals:

1. (1) For inorganic chemicals, the baseline BAFs for trophic levels three (3) and four (4) are both assumed to equal the BCF determined for the chemical with fish; for example, the FCM is assumed to be one (1) for both trophic levels three (3) and four (4). However, an FCM greater than one (1) might be applicable to some metals, such as mercury, if an organometallic form of the metal biomagnifies, for example.

2. (2) The following procedures must be used to calculate human health BAFs for inorganic chemicals:

   1. (A) Measured BAFs and BCFs used to determine human health BAFs for inorganic chemicals must be based on the edible tissue, such as muscle, of freshwater fish, unless it is demonstrated that whole body BAFs or BCFs are similar to edible tissue BAFs or BCFs. BCFs and BAFs based on measurements of aquatic plants and invertebrates should not be used in the derivation of human health criteria and values.

   2. (B) If one (1) or more field-measured baseline BAFs for an inorganic chemical are available from studies conducted in the Great Lakes system with the muscle of fish:

      1. (i) for each trophic level, a species mean measured baseline BAF must be calculated as the geometric mean if more than one (1) measured BAF is available for a given species; and
      2. (ii) for each trophic level, the geometric mean of the species mean measured baseline BAFs must be used as the human health BAF for that chemical.
   3. (C) If an acceptable measured baseline BAF is not available for an inorganic chemical and one (1) or more acceptable edible portion laboratory measured BCFs are available for the chemical, a predicted baseline BAF must be calculated by multiplying the geometric mean of the BCFs times a FCM. The FCM will be one (1.0) unless chemical-specific biomagnification data support using a multiplier other than one (1.0). The predicted baseline BAF must be used as the human health BAF for that chemical.

3. (3) The following procedures must be used to calculate wildlife BAFs for inorganic chemicals:

   1. (A) Measured BAFs and BCFs used to determine wildlife BAFs for inorganic chemicals must be based on whole body freshwater fish and invertebrate data, unless it is demonstrated that edible tissue BAFs or BCFs are similar to whole body BAFs or BCFs.

   2. (B) If one (1) or more field-measured baseline BAFs for an inorganic chemical are available from studies conducted in the Great Lakes system with whole body of fish or invertebrates:

      1. (i) for each trophic level, a species mean measured baseline BAF must be calculated as the geometric mean if more than one (1) measured BAF is available for a given species; and
      2. (ii) for each trophic level, the geometric mean of the species mean measured baseline BAFs must be used as the wildlife BAF for that chemical.
   3. (C) If an acceptable measured baseline BAF is not available for an inorganic chemical, and one (1) or more acceptable whole body laboratory measured BCFs are available for the chemical, a predicted baseline BAF must be calculated by multiplying the geometric mean of the BCFs times a FCM. The FCM will be one (1.0) unless chemical-specific biomagnification data support using a multiplier other than one (1.0). The predicted baseline BAF must be used as the wildlife BAF for that chemical.

(g) For both organic and inorganic chemicals, human health and wildlife BAFs for both trophic levels must be reviewed for consistency with all available data concerning the bioaccumulation, bioconcentration, and metabolism of the chemical. For example, information concerning octanol-water partitioning, molecular size, or other physicochemical properties that might enhance or inhibit bioaccumulation should be considered for organic chemicals. BAFs derived in accordance with this methodology should be modified if changes are justified by available data.

(h) The following must be used to obtain food-chain multipliers:

*Copies of these documents and access to the AQUIRE database may be obtained from U.S. EPA, 1200 Pennsylvania Avenue, N.W., Washington, D.C. 20460, www.epa.gov, or are available for review at the Indiana Department of Environmental Management, Office of Legal Counsel, Indiana Government Center North, 100 North Senate Avenue, Thirteenth Floor, Indianapolis, Indiana 46204.

**Copies of this document may be obtained from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428, www.astm.org, or are available for review at the Indiana Department of Environmental Management, Office of Legal Counsel, Indiana Government Center North, 100 North Senate Avenue, Thirteenth Floor, Indianapolis, Indiana 46204.

(Water Pollution Control Division; 327 IAC 2-1.5-13; filed Jan 14, 1997, 12:00 p.m.: 20 IR 1392; errata filed Aug 11, 1997, 4:15 p.m.: 20 IR 3377; filed Sep 6, 2018, 11:50 a.m.: 20181003-IR-327170278FRA; readopted filed Oct 18, 2024, 1:57 p.m.: 20241113-IR-327230810RFA)