Minnesota Legislature
Office of the Revisor of Statutes
Minnesota Administrative Rules
7050.0218 FOR TOXIC POLLUTANTS: DEFINITIONS AND METHODS FOR DETERMINING HUMAN HEALTH-BASED NUMERIC STANDARDS AND SITE-SPECIFIC NUMERIC CRITERIA FOR AQUATIC LIFE, HUMAN HEALTH, AND FISH-EATING WILDLIFE.
Subpart 1.
Purpose.
The methods in this part and part 7050.0219 meet the objectives in part 7050.0217 and provide the basis for developing human health-based numeric chronic standards and site-specific numeric criteria for aquatic toxicity, human health, and fish-eating wildlife. The agency may also adopt new standards according to Minnesota Statutes, chapter 14, to replace those listed in parts 7050.0220 to 7050.0227 and 7052.0100 that are more stringent or less stringent if new scientific evidence shows that a change in the standard is justified.
Subp. 2.
Site-specific criteria.
The class 2 and class 7 numeric water quality standards for toxic pollutants in parts 7050.0220, 7050.0222, 7050.0227, and 7052.0100 do not address all pollutants that may be discharged to surface waters and cause toxic effects. Therefore, methods are established in this part and part 7050.0219 to address on a site-specific basis the discharge into surface waters of toxic pollutants not listed in parts 7050.0220, 7050.0222, 7050.0227, 7052.0100. Class 2 and class 7 site-specific numeric criteria for toxic pollutants shall be derived by the commissioner using the procedures in this part.
A.
A site-specific criterion so derived is specific to the point source being addressed. Any effluent limitation derived from a site-specific criterion under this subpart shall only be required after the discharger has been given notice of the specific proposed effluent limitations and an opportunity to request a hearing as provided in part 7000.1800.
B.
A site-specific criterion so derived for remedial action cleanup activities is specific to the affected surface water body.
Subp. 3.
Definitions.
For the purposes of parts 7050.0217 to 7050.0227, the following terms have the meanings given them.
A.
"Acute-chronic ratio" or "ACR" means the ratio of the acute toxicity, expressed as a LC50 or EC50, of a toxicant to its chronic toxicity expressed as the chronic value. The ACR is used as a factor for estimating chronic toxicity on the basis of acute toxicity.
B.
"Acute toxicity" means a stimulus severe enough to rapidly induce a response. In toxicity tests, a response is normally observed in 96 hours or less. Acute effects are often measured in terms of mortality or other debilitating effects, represented as LC50s or EC50s, and expressed as concentrations of mass per unit volume, percent effluent, or toxic units.
C.
"Adjustment factor, lifetime" or "AFlifetime" means the numeric multiplier used to modify the adult-based cancer slope factor for lifetime (70 years standard in risk characterization) exposure based on chemical-specific data.
D.
"Adverse effect" means a biochemical change, functional impairment, or pathologic lesion that affects the performance of the whole organism or reduces an organism's ability to respond to an additional environmental challenge.
E.
"Age-dependent adjustment factor" or "ADAF" means the default numeric modifiers to the cancer slope factor that account for the increased susceptibility to cancer from early-life exposures to linear carcinogens in the absence of chemical-specific data. For default use, there are three ADAF:
F.
"Available and reliable scientific data" means information derived from scientific literature including: published literature in peer reviewed scientific journals, USEPA ambient water quality criteria documents, and other reports or documents published by the USEPA or other governmental agencies.
G.
"Bioaccumulation factor" or "BAF" means the concentration of a pollutant in one or more tissues of an aquatic organism, exposed from any source of the pollutant but primarily from the water column, diet, and bottom sediments, divided by the average concentration in the solution in which the organism had been living, under steady state conditions.
H.
"Bioaccumulative chemical of concern" or "BCC" has the meaning given in part 7052.0010, subpart 4.
I.
"Bioconcentration factor" or "BCF" means the concentration of a pollutant in one or more tissues of an aquatic organism, exposed only to the water as the source of the pollutant, divided by the average concentration in the solution in which the organism had been living, under steady state conditions.
J.
"Biomagnification" means the increase in tissue concentration of a pollutant in aquatic organisms at successive trophic levels through a series of predator-prey associations, primarily occurring through dietary accumulation. The expression used to quantify this increase is the biomagnification factor or "BMF." For a given water body, the BMF is calculated as:
(1)
the ratio of the tissue concentration of a pollutant in a predator at a particular trophic level to the tissue concentration in its prey at the next lower trophic level; or
K.
"Biota-sediment accumulation factor" or "BSAF" means the ratio (in kilogram of organic carbon/kilogram of lipid) of a pollutant's lipid-normalized concentration in tissue of an aquatic organism to its organic carbon-normalized concentration in surface sediment, where:
(3)
the surface sediment is representative of average surface sediment in the vicinity of the organism.
L.
"Cancer potency slope factor" or "CSF" means a factor indicative of a chemical's human cancer causing potential and an upper-bound estimate of cancer risk per increment of dose that can be used to estimate cancer risk probabilities for different exposure levels. CSF is expressed in units of cancer incidence per milligram of pollutant per kilogram of body weight-day (mg/kg-day)-1.
M.
"Cancer risk level" or "CR" means the probability that daily exposure to a carcinogen over a lifetime may induce cancer. CR refers to an incremental or additional excess cancer risk equal to 1 x 10-5 (1 in 100,000) and is applied with the cancer potency slope factor for single chemicals and for mixtures.
N.
"Carcinogen, linear" or "C" means a chemical agent for which, either by a known mode of action or a conservative assumption, the associated cancer risk varies in direct proportion to the extent of exposure and for which there is no risk-free level of exposure. The toxicological value for a C is the cancer potency slope factor. Seventy years is the standard lifetime duration used by United States Environmental Protection Agency in the characterization of lifetime cancer risk.
O.
"Carcinogen, nonlinear" or "NLC" means a chemical agent for which, particularly at low doses, the associated cancer risk does not rise in direct proportion to the extent of exposure and for which a threshold level of exposure exists below which there is no cancer risk. For NLC, the reference dose is the toxicological value used as the threshold for cancer risk.
P.
"Chronic toxicity" means a stimulus that lingers or continues for a long period of time, often one-tenth the life span or more. A chronic effect can be mortality, reduced growth, reproduction impairment, harmful changes in behavior, and other nonlethal effects.
Q.
"Chronic criterion" or "CC" and "chronic standard" or "CS" mean the highest water concentration or fish tissue concentration of a toxicant or effluent to which aquatic life, humans, or wildlife can be exposed indefinitely without causing chronic toxicity. CC represents a site-specific chronic criterion developed under this part and part 7050.0219 or part 7052.0110. CS represents a chronic standard listed in parts 7050.0220 and 7050.0222 or in part 7052.0100. CC and CS are further distinguished by the organisms they are developed to protect and medium in which they apply:
(1)
CCtox or CStox represent values applied in surface water developed to protect aquatic life from chronic toxicity;
(2)
CCdfr or CSdfr represent values applied in surface water based on protecting humans from exposure to the pollutant from drinking water, eating fish, and aquatic recreation;
(3)
CCfr or CSfr represent values applied in surface water based on protecting humans from exposure to the pollutant from eating fish and aquatic recreation;
(4)
CCft or CSft represent values applied in fish tissue based on protecting humans from exposure to the pollutant from eating fish; and
(5)
CCw represents values applied in surface water based on protecting wildlife from exposure to the pollutant from eating aquatic organisms.
R.
"Chronic value" means the geometric mean of the highest tested concentration that did not cause an unacceptable adverse effect and the lowest tested concentration that did cause an unacceptable adverse effect, and in which all higher test values cause an effect, in an approved chronic test.
S.
"Criterion" means a number or numbers established for a pollutant derived under this part or part 7050.0219 or 7052.0110, or issued by the USEPA, to protect aquatic life, humans, or wildlife.
T.
"Developmental health endpoint" or "developmental toxicity" means an adverse effect on the developing organism that may result from parental exposure prior to conception, maternal exposure during prenatal development, or direct exposure postnatally until the time of sexual maturation. Developmental toxicity may be detected at any point in the lifespan of the organism. The major manifestations of developmental toxicity include:
U.
"Duration" means the time over which the instream concentration of a pollutant is averaged for comparison with the standard or criterion.
V.
"Durations for human health-based algorithms" or "D" means the length of the exposure period under consideration for noncancer and linear cancer algorithms.
(1)
The four default D used in developing reference doses and corresponding intake rates are:
(c)
subchronic: a period of more than 30 days, up to eight years based on application of the less than ten percent standard life expectancy of 70 years for humans; or
(2)
The default durations for use in the linear cancer algorithms with age dependent adjustment factors are:
(c)
54 years for the 16- up to 70-year age group.
For any algorithm, use of chemical-specific data to define durations for noncancer or linear cancer algorithms are preferred when acceptable data are available.
W.
"Effect concentration" or "EC50" means the toxicant concentration that causes equilibrium loss, immobilization, mortality, or other debilitating effects in 50 percent of the exposed organisms during a specific time of observation.
X.
"Endocrine" or "E" means a change in circulating hormone levels or interactions with hormone receptors, regardless of the organ or organ system affected. Health endpoints with or without the E designation are deemed equivalent, for example, thyroid (E) = thyroid, and must be included in the same health risk index equation.
Y.
"Final acute value" or "FAV" means an estimate of the concentration of a pollutant corresponding to the cumulative probability of 0.05 in the distribution of all the acute toxicity values for the genera or species from the acceptable acute toxicity tests conducted on a pollutant. The FAV is the acute toxicity limitation applied to mixing zones in part 7050.0210, subpart 5; and to dischargers in parts 7053.0215, subpart 1; 7053.0225, subpart 6; and 7053.0245, subpart 1.
Z.
"Food chain multiplier" or "FCM" means the ratio of a bioaccumulation factor by trophic level to an appropriate bioconcentration factor. FCM refers to values developed using USEPA models or from available and reliable field studies.
AA.
"Frequency" means the number of times a standard can be exceeded in a specified period of time without causing acute or chronic toxic effects on the aquatic community, human health, or fish-eating wildlife.
BB.
"Genus mean acute value" or "GMAV" means the geometric mean of the SMAVs available for the genus.
CC.
"Health risk index" means the sum of the quotients calculated by identifying all chemicals that share a common health endpoint or are based on linear carcinogenicity and dividing the water or fish tissue concentration for each chemical (measured or statistically derived) by its applicable chronic standard or chronic criterion. To meet the objectives in part 7050.0217, the health risk index must not exceed a value of one. The equations for the risk indices are found in part 7050.0222, subpart 7, items D and E.
DD.
"Health risk index endpoint" or "health endpoint" means the general description of toxic effects used to group chemicals for the purpose of calculating a health risk index.
EE.
"Intake rate" or "IR" means rate of ingestion, inhalation, or dermal contact, depending on the route of exposure, expressed as the amount of a media taken in, on a per body weight and daily basis, for a specified duration.
FF.
"Lethal concentration" or "LC50" means the toxicant concentration killing 50 percent of the exposed organisms in a specific time of observation.
GG.
"Lowest observable adverse effect level" or "LOAEL" means the lowest exposure level that caused a statistically or biologically significant increase in the frequency or severity of adverse effects observed between the exposed population and its appropriate control group.
HH.
"Magnitude" means the acceptable amount of a toxic pollutant in water or fish tissue expressed as a concentration.
II.
"Maximum criterion" or "MC" means the highest concentration of a toxicant in water to which aquatic organisms can be exposed for a brief time with zero to slight mortality. The MC equals the FAV divided by two.
JJ.
"Maximum standard" or "MS" means the highest concentration of a toxicant in water to which aquatic organisms can be exposed for a brief time with zero to slight mortality. The MS equals the FAV divided by two. Maximum standards are listed in part 7050.0222.
LL.
"Mode of action" or "MOA" means the sequence of key events following pollutant or chemical exposure upon which the toxic outcome depends.
MM.
"National methods" means the methods the USEPA uses to develop aquatic life criteria as described in Stephan, C.E., D.J. Mount, D.J. Hansen, J.H. Gentile, G.A. Chapman, and W.A. Brungs, 1985, "Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses," USEPA, Office of Research and Development, Environmental Research Laboratories, Duluth MN; Narragansett, RI, Corvallis, OR. 98 p; available through the National Technical Information Service, Springfield, VA. (Publication PB85-227049).
NN.
"No observable adverse effect level" or "NOAEL" means the highest exposure level at which there is no statistically or biologically significant increase in the frequency or severity of adverse effects between the exposed population and its appropriate control group.
OO.
"Octanol to water partition coefficient" or "Kow" means the ratio of the concentration of a chemical in the octanol phase to its concentration in the aqueous phase of a two-phase octanol to water system after equilibrium of the chemical between the two phases has been achieved. The base 10 logarithm of the Kow or log Kow is used in the calculation of bioaccumulation factors. The log Kow has been shown to be proportional to the bioconcentration potential of lipophilic organic chemicals.
PP.
"Percent effluent" means the representation of acute or chronic toxicity of an effluent as a percent of whole effluent mixed in dilution water, where acute toxicity is expressed by LC50s or EC50s and chronic toxicity is expressed by NOAEL.
QQ.
"Reference dose" or "RfD" means an estimate of a dose for a given duration to the human population, including susceptible subgroups such as infants, that is likely to be without an appreciable risk of adverse effects during a lifetime. It is derived from a suitable dose level at which there are few or no statistically or biologically significant increases in the frequency or severity of an adverse effect between the dosed population and its associated control group. The RfD includes one or more divisors, applied to the suitable dose level, accounting for:
(3)
uncertainty in extrapolating from effects observed in a short-term study to effects of long-term exposure;
(5)
uncertainty associated with deficiencies in the available data.
The product of the divisors is not to exceed 3,000 in an RfD used for a chronic standard. The RfD is expressed in units of daily dose as milligrams of chemical per kilogram of body weight-day or mg/kg-day.
RR.
"Relative source contribution factor" or "RSC" means the percentage or apportioned amount (subtraction method) of the reference dose for a pollutant allocated to surface water exposures from drinking or incidental water ingestion and fish consumption. In the absence of sufficient data to establish a pollutant- or chemical-specific RSC value, the default RSC is 0.2 or 0.5 as described in part 7050.0219, subpart 5.
SS.
"Species mean acute value" or "SMAV" means the geometric mean of all the available and acceptable acute values for a species.
TT.
"Standard" means a number or numbers established for a pollutant or water quality characteristic to protect a specified beneficial use as listed in parts 7050.0221 to 7050.0227. The standard for a toxic pollutant includes the CS, MS, and FAV. Some pollutants do not have an MS or an FAV due to insufficient data. For these pollutants, the CS alone is the standard.
UU.
"Toxic effect" means an observable or measurable adverse biological event in an organ, tissue, or system. The designation of health endpoints does not exclude other possible observable or measurable biological events. For the purpose of grouping chemicals and creating a health risk index when multiple chemicals are present, toxic effects may be ascribed to more general health risk index endpoints or health endpoints.
VV.
"Toxic pollutant" means a pollutant listed as toxic under section 307(a)(1) of the Clean Water Act, United States Code, title 33, section 1317(a)(1), or as defined by Minnesota Statutes, section 115.01, subdivision 20. Toxic pollutant is used interchangeably in this part and parts 7050.0217, 7050.0219, and 7050.0222, subpart 7, items B to G, with the terms "pollutant" and "chemical."
WW.
"Toxic unit" means a measure of acute or chronic toxicity in an effluent. One acute toxic unit (TUa) is the reciprocal of the effluent concentration that causes 50 percent effect or mortality to organisms for acute exposures (100/LC50); one chronic toxic unit (TUc) is the reciprocal of the effluent concentration that causes no observable adverse effect level on test organisms for chronic exposures (100/NOAEL).
XX.
"Trophic level" or "TL" means the food web level in an ecosystem that is occupied by an organism or group of organisms because of what they eat and how they are related to the rest of the food web. For example, trophic level 3 in an aquatic ecosystem consists of small fish such as bluegills, crappies, and smelt and trophic level 4 consists of larger carnivorous fish such as walleye, northern pike, and most trout species.
ZZ.
"Water quality characteristic" means a characteristic of natural waters, such as total hardness or pH. Some water quality characteristics can affect the toxicity of pollutants to aquatic organisms.
AAA.
"Whole effluent toxicity test" means the aggregate toxic effect of an effluent measured directly by a toxicity test. Effects on tested organisms are measured and expressed as toxic units or percent effluent for both acute and chronic whole effluent toxicity tests.
Subp. 4.
Adoption of USEPA national criteria.
The USEPA establishes aquatic life and human health-based criteria under section 304(a)(1) of the Clean Water Act, United States Code, title 33, section 1314. The USEPA criteria, subject to modification as described in this subpart, are applicable to class 2 waters of the state. The USEPA has described the national methods for developing aquatic life criteria in "Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses."
USEPA criteria that vary with an ambient water quality characteristic such as total hardness or pH will be established for specific waters or reaches using data available to the commissioner. Central values such as the means or medians for the characteristic will be used unless there is evidence to support using different values. Values for water quality characteristics can be estimated for specific waters or reaches that have no data by using data from a nearby watershed with similar chemical properties.
A.
The USEPA aquatic life criteria are adopted unchanged by the agency, unless modified under item C, as the criteria applicable to designated class 2A waters in parts 7050.0420 and 7050.0470.
B.
The USEPA criteria are adopted, subject to modification as described in this item or item C, for application to cool and warm water habitats and wetlands. Cool and warm water habitats (class 2Bd and 2B) are defined in part 7050.0415 or listed in part 7050.0470. Wetlands (class 2D) waters are defined in part 7050.0415 or listed in part 7050.0470.
(1)
Acute data, in the form of the ranked genus mean acute values used by the USEPA to determine the national criteria, are the data used to determine the class 2Bd, 2B, and 2D criteria.
(2)
GMAVs for fish in the family Salmonidae are deleted from the lowest of the ranked GMAVs so that all of the lowest four GMAVs in the USEPA data set are for nonsalmonid species. Following these deletions, no other salmonid GMAVs are deleted. If none of the lowest four GMAVs in the USEPA data set are for salmonid species, no GMAVs are deleted. The minimum of eight GMAVs specified in the national methods must be met, except that nonsalmonid fish can take the place of the salmonid requirement if the prescribed deletions eliminate all salmonids from the national data set.
(3)
The number of GMAVs in the USEPA criteria data set is reduced by the number of salmonid GMAVs deleted.
(4)
The FAV is determined according to the national methods as follows:
(a)
for each species for which one or more acute value is available, a SMAV is calculated as the geometric mean of all the acceptable acute values;
(b)
for each genus for which one or more SMAV is available, a GMAV is calculated as the geometric mean of all the SMAVs;
(d)
a rank is assigned to the GMAVs from "1" for the lowest to "N" for the highest, and if two or more GMAVs are identical, successive ranks are arbitrarily assigned;
(f)
the four GMAVs that have cumulative probabilities closest to 0.05 are selected, and if there are less than 59 GMAVs, these will always be the lowest four GMAVs; and
(g)
using the selected GMAVs and their respective cumulative probabilities, calculate:
| Σ((ln GMAV)2)-((Σ(ln GMAV))2/4) |
| S2 = ___________________________________ |
| Σ(P)-((Σ(square root of P))2/4) |
| Σ(ln GMAV)-S(Σ(square root of P)) |
| L = ___________________________________ |
| 4 |
| A = S(square root of 0.05) + L |
| FAV = eA |
| where: | FAV = final acute value |
| N = number of GMAVs | |
| P = rank/N+1 | |
| ln = natural logarithm to base e S,L, and A are intermediate steps |
(5)
If, as a result of the recalculation of the USEPA criterion for application to class 2Bd, 2B, and 2D waters, the FAV for these water classes is lower than the FAV for class 2A waters, the class 2Bd, 2B, or 2D FAV will be changed to equal the class 2A FAV, unless the lower class 2Bd, 2B, or 2D FAV is justified based on the available toxicological data.
(7)
The CC is determined using the national methods. If sufficient chronic data is available to determine the CC directly from chronic values, salmonid chronic values will be deleted from the national data set following the same procedures used for acute data in this item. If sufficient chronic data is not available, the USEPA ACR, subject to modification under item C, is divided into the FAV to determine the CC.
C.
If the commissioner finds that the information that supports a USEPA criterion is no longer current or complete for reasons including, but not limited to, changes to the relationship between a water quality characteristic and toxicity; the ACR; the weight given to toxicity data for a commercially or recreationally important species; or the human health-based methods; then the commissioner shall evaluate all available information and modify the criterion according to the information and with the objectives in part 7050.0217 and the methods in this part and part 7050.0219. Any effluent limitation determined to be necessary based on site-specific criteria derived under this item shall only be required after the discharger has been given notice to the specific proposed effluent limitations and an opportunity to request a hearing as provided in part 7000.1800.
Subp. 5.
Toxicity-based criteria.
Toxicity-based aquatic life criteria shall be determined using the methods in this subpart when no USEPA criterion is available.
A.
Criteria shall be determined using the USEPA national method if the minimum data required in this item and item B are met. Data for saltwater organisms can be used for nonionizable organic chemicals. Data for saltwater organisms cannot be used for ionizable organic or inorganic chemicals. Data for all North American species can be used. A minimum of eight GMAVs representing the following groups must be available:
B.
The additional acute data requirements in subitems (1) and (2) apply when developing criteria for pesticides.
(1)
If the chemical is an insecticide, one of the eight GMAVs required in item A, subitem (5), must be for an insect.
(2)
If the chemical is a herbicide, the eight GMAVs required in item A must be supplemented with acute data for two plant species, one of which is an algal species.
C.
The FAV is calculated as described in subpart 4, item B, subitem (4). No more than two of the lowest four GMAVs may be for a saltwater species.
E.
The CCtox is the FAV divided by an ACR. Available chronic data are used to determine ACRs as described in item F and measured chronic values are compared to the CCtox. If an approved chronic value for a commercially, recreationally, or ecologically important freshwater species is lower than the CCtox, the CCtox will be set to equal that chronic value.
F.
The ACR is determined according to subitems (1) to (3).
(1)
A measured ACR is determined by dividing the acute value by the chronic value for the same species from tests that meet the requirements for determining ACRs in the national method. If more than one ACR is available for a species, a species mean ACR is calculated as the geometric mean of the available ACRs.
(2)
A minimum of three measured ACRs, each for a different species, must be available to determine a final measured ACR. The final measured ACR is the geometric mean of all the available species mean ACRs.
(3)
If no measured ACRs are available, the following default ACRs shall be used:
(a)
an ACR of 20 is used with nonpesticide, nonbioaccumulative organic chemicals with log Kow values of three or less; and
(b)
an ACR of 55 is used with pesticides, inorganic chemicals, or bioaccumulative organic chemicals with log Kow values greater than three.
(4)
If two or fewer measured ACRs are available, the default ACRs in subitem (3) are incorporated into the calculation of the final ACR as follows:
(a)
if two measured ACRs are available, the final ACR is the geometric mean of the two measured ACRs and the appropriate default ACR; and
(b)
if one measured ACR is available, the final ACR is the geometric mean of the measured ACR and two appropriate default ACRs.
G.
If the acute data available do not meet the requirements in items A and B, toxicity-based criteria can be determined by the method in this item. This method is not applicable to ionizable organic chemicals, or to bioaccumulative organic chemicals and pesticides with BCF greater than 5,000 or log Kow values greater than 5.19.
(1)
Acute data are assembled. A minimum of two acute values in the following groups must be available:
(b)
a member of one of the following genera in the family Daphnidae: Daphnia, Ceriodaphnia, Simocephalus.
(2)
For insecticides, a third acute value must be available for an insect species in addition to the acute values required in subitem (1).
(3)
For herbicides, two acute values for plant species, one of which is an algal species, must be available in addition to the acute values required in subitem (1).
(8)
The FAV is calculated by dividing the lowest GMAV by the appropriate factor listed below, depending on the number of GMAVs available that meet the minimum data requirements in subitems (2) and (3) and in item A.
| Number of GMAVs | Factor | |
| 2 | 13.0 | |
| 3 | 8.0 | |
| 4 | 7.0 | |
| 5 | 6.1 | |
| 6 | 5.2 | |
| 7 | 4.3 |
(10)
A final ACR is determined as described in item F, except that the default ACR shall be 18 for all chemicals for which this method is applicable as specified in this item.
(12)
If chronic data are available, they are used to determine measured ACR as described in item F, and chronic data are compared to the CCtox.
Subp. 8.
Taste and odor criteria.
The agency shall limit the addition of pollutants to surface waters to the extent necessary to protect fish and other edible freshwater organisms from acquiring objectionable tastes and odors. The agency will use the USEPA national organoleptic criteria, established under section 304(a)(1) of the Clean Water Act, United States Code, title 33, section 1314, when establishing concentrations above which unacceptable tastes and odors could be imparted to aquatic organisms.
Subp. 9.
Wildlife-based criteria.
The agency shall use the procedures in this subpart to establish wildlife-based criteria. Wildlife criteria shall protect wildlife consumers of freshwater aquatic organisms from adverse effects of toxic pollutants. Wildlife criteria are applicable to all surface waters, subject to the exceptions in subpart 10, item B, subitem (1).
A.
Wildlife-based criteria shall be determined using toxicological information from available sources of scientific data for wildlife or domestic animal species, exposed to toxic pollutants through ingestion including gavage.
B.
Wildlife-based criteria are calculated using the following formula:
| NOAEL x BWt x SSF | ||
| CCw mg/L = | _ | |
| DW + (F x BAF) |
| where: | CCw = wildlife chronic criterion in mg/L |
| NOAEL = no observable adverse effect level in mg of substance per kg of body weight per day (mg/kg BWt/day) as derived from mammalian or avian toxicity studies. If the NOAEL is in mg/L, the NOAEL will be multiplied by the average daily volume of water consumed by the test animals in liters per day and divided by the average weight of the test animals in kg. If the NOAEL is in mg/kg of food consumed, the NOAEL will be multiplied by the average amount of food consumed daily by the test animals and divided by the average weight of the test animals in kg | |
| BWt = average body weight of test organisms in kg | |
| SSF = species sensitivity factor to account for difference in the sensitivity in test species. This factor will vary between 1 and 0.1. The appropriate factor will be determined by the commissioner based on available and reliable scientific data on the relative sensitivity of the test organism compared to other wildlife species | |
| DW = average volume of water consumed per day by the test animals in liters | |
| F = average amount of food consumed per day by test animals in kg | |
| BAF = BAF in liters per kg |
C.
Drinking (DW) and feeding (F) rates for test organisms can be estimated using the following equations if these rates are not available from the original study:
D.
A final BAF for calculating a wildlife chronic criterion (CCw) is determined as in subpart 7, except that the BCFs and BAFs are adjusted to represent whole body BCFs and BAFs.
(1)
Normalized BCFs and BAFs are multiplied by 12 percent lipid for CCw applicable to class 2A waters.
(2)
Normalized BCFs and BAFs are multiplied by five percent lipid for CCw applicable to class 2Bd and 2B waters.
(4)
BCFs estimated using the relationship between BCFs and the log Kow are normalized by dividing the estimated BCF by 7.6 and then multiplying by 12 for class 2A waters or by five for class 2Bd and 2B waters.
(5)
Measured or estimated BCFs for lipophilic organic chemicals with log Kow values in the range of three or more are multiplied by the factor from subpart 7, item B, subitem (8).
Subp. 10.
Applicable criteria or human health-based standard.
The final criteria or chronic standard for human health for toxic pollutants for surface waters must be the lowest of the applicable criteria or standards for human health derived under this part and part 7050.0219.
A.
Applicable criteria or standards for human health by use for class 2A, 2Bd, 2B, and 2D surface waters are listed for each applicable population protected (aquatic life, humans, and fish-eating wildlife). The applicable criteria or standards for human health must be the lowest of the CC or CS as described in subitems (1) to (3):
(1)
for aquatic life toxicity: a CCtox and MC based on toxicity to aquatic organisms from subpart 4 or 5 or a CCtox based on plant toxicity from subpart 4 or 5;
B.
Applicable criteria for class 7 waters must be the lowest of the following:
(1)
a CCw from subpart 9, if aquatic organisms can be sustained in the class 7 water so that they are subject to predation by wildlife; or
C.
If the site-specific application of criteria developed in this subpart is used to establish an effluent limitation for national pollutant discharge elimination system and state disposal system permits or to establish the degree of remedial action cleanup activities, the provisions of part 7050.0222, subpart 7, items B to G, apply.
History:
15 SR 1057; 18 SR 2195; 19 SR 1310; 24 SR 1105; 32 SR 1699; 39 SR 1344; 41 SR 545; 42 SR 441; 46 SR 5
Published Electronically:
August 25, 2021
Official Publication of the State of Minnesota
Revisor of Statutes