Chapter NR 105

NR 105.07(3)(a) (a) If the NOAEL is given in milligrams of toxicant per liter of water consumed (mg/L), the NOAEL shall be multiplied by the daily average volume of water consumed by the test animals in liters per day (L/d) and divided by the average weight of the test animals in kilograms (kg).

NR 105.07(3)(b) (b) If the NOAEL is given in milligrams of toxicant per kilogram of food consumed (mg/kg), the NOAEL shall be multiplied by the average amount of food in kilograms consumed daily by the test animals (kg/d) and divided by the average weight of the test animals in kilograms (kg).

NR 105.07(4) (4) In those cases in which a NOAEL is unavailable and a lowest observed adverse effect level (LOAEL) is available from studies of animal species exposed repeatedly to the substance via oral routes including gavage, the LOAEL may be substituted with proper adjustment to estimate the NOAEL. An uncertainty factor of between one and 10 may be applied to the LOAEL, depending on the sensitivity of the adverse effect, to reduce the LOAEL into the range of a NOAEL. If the LOAEL is available in units other than mg/kg-d, the LOAEL shall be expressed in the same manner as that specified for the NOAEL in sub. (3).

NR 105.07(5) (5) In instances where a NOAEL is based on subchronic data, an uncertainty factor may be applied to extrapolate from subchronic to chronic levels. The value of the uncertainty factor may not be less than 0.1 and may not exceed 1.0. This factor is to be used when assessing highly bioaccumulative substances where toxicokinetic considerations suggest that a bioassay of limited length underestimates chronic effects.

NR 105.07(6) (6) If drinking or feeding rates are not available for representative species, drinking (W) and feeding rates (FTLi) shall be calculated for representative mammalian or avian species by using the allometric equations given in pars. (a) and (b).

NR 105.07(6)(a) (a) For mammalian species the allometric equations are as follows:

NR 105.07(6)(b) (b) For avian species the allometric equations are as follows:

NR 105.07 Note Note: Criteria to protect domestic animals will be considered on an as needed basis using a model that accounts for domestic animal exposure through drinking water. Because domestic animals do not regularly consume aquatic organisms, the wildlife exposure model is not appropriate.

NR 105.07 History History: Cr. Register, February, 1989, No. 398, eff. 3-1-89; am. table 7, Register, July, 1991, No. 427, eff. 8-1-91; am. (1), (2) (a), (b), (3) (intro.), (6) (intro.), r. and recr. (2) (c), (5), cr. (2) (d), (e), r. (6) (a), renum. (6) (b) and (c) to be (6) (a) and (b) and am., Register, August, 1997, No. 500, eff. 9-1-97.

NR 105.08 NR 105.08 Human threshold criteria.

NR 105.08(1) (1) The human threshold criterion (HTC) is the maximum concentration of a substance established to protect humans from adverse effects resulting from contact with or ingestion of surface waters of the state and from ingestion of aquatic organisms taken from surface waters of the state. Human threshold criteria are derived for those toxic substances for which a threshold dosage or concentration can be estimated below which no adverse effect or response is likely to occur.

NR 105.08(2) (2) For noncarcinogenic components of mixtures in effluents, interactions among substances may be additive, antagonistic or synergistic and may be accounted for by a model that is supported by credible scientific evidence. The risks are assumed to be additive when substances are members of the same structural class and cause potential adverse effects via the same mechanism of action, influencing the same kind of endpoint, and shall be accounted for by a model that is supported by credible scientific evidence.

NR 105.08(3) (3) Human threshold criteria are listed in Table 8. Criteria for the same substance may be different depending on the surface water classification, due to the lipid value of representative fish, a component of the BAF, and whether or not the water may be a source of drinking water. Further application of these criteria to protect drinking water and downstream uses in the Great Lakes system shall be according to s. NR 106.06 (1)

NR 105.08(4) (4) To derive human threshold criteria for substances not included in Table 8 the following methods shall be used:

NR 105.08(4)(a) (a) The human threshold criterion shall be calculated as follows:

NR 105.08(4)(b) (b) For surface waters classified as public water supplies, if the human threshold criterion for a toxic substance as calculated in par. (a) exceeds the maximum contaminant level (MCL) for that substance as specified in ch. NR 809 or the July 8, 1987 Federal Register (52 FR 25690), the MCL shall be used as the human threshold criterion.

NR 105.08(5) (5) The acceptable daily exposure (ADE) referenced in sub. (4) represents the maximum amount of a substance which if ingested daily for a lifetime results in no adverse effects to humans. Paragraphs (a) to (c) list methods for determining the acceptable daily exposure.

NR 105.08(5)(a) (a) The department shall review available references for acceptable daily exposure or equivalent values, such as a reference dose (RfD) as used by the U.S. environmental protection agency, and for human or animal toxicological data from which an acceptable daily exposure can be derived. Suitable references for review include, but are not limited to, those presented in s. NR 105.04 (5).

NR 105.08(5)(b) (b) When human or animal toxicological data are available, the department may derive an acceptable daily exposure by using as guidance procedures presented by the U.S. environmental protection agency in “Water Quality Criteria Documents; Availability” (45 FR 79318, November 28, 1986). Additional guidance for deriving acceptable daily exposures from toxicological data are given in subds. 1. to 4. Alternate procedures may be used if supported by credible scientific evidence.

NR 105.08(5)(b)1. 1. No observable adverse effect levels (NOAELs) and lowest observable adverse effect levels (LOAELs) from studies of humans or mammalian test species shall be divided by an uncertainty factor to derive an acceptable daily exposure. Uncertainty factors reflect uncertainties in predicting acceptable exposure levels for the general human population based upon experimental animal data or limited human data. Factors to be considered when selecting an uncertainty factor include, but are not limited to, interspecies and individual variations in response and susceptibility to a toxicant, and the quality and quantity of the available data. The following guidelines shall be considered when selecting an uncertainty factor:

NR 105.08(5)(b)1.a. a. Use an uncertainty factor of 10 when extrapolating from valid experimental results from studies on prolonged ingestion by humans. This 10-fold factor protects sensitive members of the human population.

NR 105.08(5)(b)1.b. b. Use an uncertainty factor of 100 when extrapolating from valid results of long-term feeding studies on experimental animals with results of studies of human ingestion not available or insufficient (e.g., acute exposure only). This represents an additional 10-fold uncertainty factor in extrapolating data from the average animal to the average human.

NR 105.08(5)(b)1.c. c. Use an uncertainty factor of 1000 when extrapolating from less than chronic results on experimental animals with no useful long-term or acute human data. This represents an additional 10-fold uncertainty factor in extrapolating from less than chronic to chronic exposures.

NR 105.08(5)(b)1.d. d. Use an additional uncertainty factor of between 1 and 10 depending on the severity of the adverse effect when deriving an acceptable daily exposure from a lowest observable adverse effect level (LOAEL). This uncertainty factor reduces the LOAEL into the range of a no observable adverse effect level (NOAEL).

NR 105.08(5)(b)1.e. e. Use an additional uncertainty factor of 10 when deriving an acceptable daily exposure for a substance which the U.S. environmental protection agency classifies as a “group C” carcinogen, but which is not defined as a carcinogen in s. NR 105.03 (13).

NR 105.08(5)(b)2. 2. Results from studies of humans or mammalian test species used to derive acceptable daily exposures shall have units of milligrams of toxicant per kilogram of body weight per day (mg/kg-d). When converting study results to the required units, a water consumption of 2 liters per day (L/d) and a body weight of 70 kilograms (kg) is assumed for humans. The following examples and procedures illustrate the conversion of units:

NR 105.08(5)(b)2.a. a. Results from human studies which are expressed in milligrams of toxicant per liter of water consumed (mg/L) are converted to mg/kg-d by multiplying the results by 2 L/d and dividing by 70 kg.

NR 105.08(5)(b)2.b. b. Results from animal studies which are expressed in milligrams of toxicant per liter of water consumed (mg/L) are converted to mg/kg-d by multiplying the results by the daily average volume of water consumed by the test animals in liters per day (L/d) and dividing by the average weight of the test animals in kilograms (kg).

NR 105.08(5)(b)2.c. c. Results from animal studies which are expressed in milligrams of toxicant per kilogram of food consumed (mg/kg) are converted to mg/kg-d by multiplying the results by the average amount of food consumed daily by the test animals in kilograms per day (kg/d) and dividing by the average weight of the test animals in kilograms (kg).

NR 105.08(5)(b)2.d. d. If a study does not specify water or food consumption rates, or body weight of the test animals, standard values taken from appropriate references, such as the National Institute of Occupational Safety and Health, 1980, Registry of Toxic Effects of Chemical Substances, may be used to convert units.

NR 105.08(5)(b)2.e. e. Results from animal studies in which test animals were not exposed to the toxicant each day of the test period shall be multiplied by the ratio of days that the test animals were dosed to the total days of the test period. For the purposes of this adjustment, the test period is defined as the interval beginning with the administration of the first dose and ending with the administration of the last dose, inclusive.

NR 105.08(5)(b)3. 3. When assessing the acceptability and quality of human or animal toxicological data from which an acceptable daily exposure can be derived, the department may use the following documents as guidance:

NR 105.08(5)(b)3.a. a. “Guidelines for Mutagenicity Risk Assessment”, (51 FR 34006, September 24, 1986).

NR 105.08(5)(b)3.b. b. “Guidelines for the Health Risk Assessment of Chemical Mixtures”, (51 FR 34014, September 24, 1986).

NR 105.08(5)(b)3.c. c. “Guidelines for the Health Assessment of Suspect Development Toxicants”, (51 FR 34028, September 24, 1986).

NR 105.08(5)(b)3.d. d. “Guidelines for Exposure Assessment”, (51 FR 34042, September 24, 1986).

NR 105.08(5)(b)3.e. e. Any other documents that the department deems reliable.

NR 105.08(5)(b)4. 4. When the available human or animal toxicological data contains conflicting information, the department may consult with experts outside of the department for guidance in the selection of the appropriate data.

NR 105.08(5)(c) (c) Using sound scientific judgment, the department shall select an acceptable daily exposure as derived in pars. (a) and (b) for calculation of the human threshold criterion. When selecting an acceptable daily exposure, the department shall adhere to the following guidelines unless a more appropriate procedure is supported by credible scientific evidence:

NR 105.08(5)(c)1. 1. Acceptable daily exposures based on human studies are given preference to those based on animal studies.

NR 105.08(5)(c)2. 2. When deriving an acceptable daily exposure from animal studies preference is given to chronic studies involving oral routes of exposure, including gavage, over a significant portion of the animals’ life span. If acceptable studies using oral exposure routes are not available, acceptable daily exposures derived from studies using alternate exposure routes, such as inhalation, may be used.

NR 105.08(5)(c)3. 3. When 2 or more acceptable daily exposure values are available and have been derived from studies having equal preference as defined in subds. 1. and 2., the lowest acceptable daily exposure is generally selected. If the acceptable daily exposure values differ significantly, the department may consult with experts outside of the department for guidance in the selection of the more appropriate acceptable daily exposure.

NR 105.08 History History: Cr. Register, February, 1989, No. 398, eff. 3-1-89; correction in (3) (b) made under s. 13.93 (2m) (b) 7., Stats., Register, September, 1995, No. 477; renum. (2) to (4) to be (3) to (5) and am., cr. (2), r. and recr. Table 8, am. (5) (intro.), 1. (intro.), d., e., 2 (intro.) and (c) and am., Register, August, 1997, No. 500, eff. 9-1-97; CR 03-050: am. Table 8 Register February 2004 No. 578, eff. 3-1-04; CR 07-110: am. Table 8 Register November 2008 No. 635, eff. 12-1-08; CR 09-123: am Table 8 Register July 2010 No. 655, eff. 8-1-10.

NR 105.09 NR 105.09 Human cancer criteria.

NR 105.09(1) (1) The human cancer criterion (HCC) is the maximum concentration of a substance or mixture of substances established to protect humans from an unreasonable incremental risk of cancer resulting from contact with or ingestion of surface waters of the state and from ingestion of aquatic organisms taken from surface waters of the state. Human cancer criteria are derived for those toxic substances which are carcinogens as defined in s. NR 105.03 (13).

NR 105.09(2) (2) For any single carcinogen or any mixture of carcinogens the incremental cancer risk from exposure to surface waters and aquatic organisms taken from surface waters may not exceed one in 100,000. The combined cancer risk of individual carcinogens in a mixture is assumed to be additive unless an alternate model is supported by credible scientific evidence.

NR 105.09(3) (3) Human cancer criteria are listed in Table 9. Criteria for the same substance may be different depending on the surface water classification, due to the lipid value of representative fish, a component of the BAF, and whether or not the water may be a source of drinking water. Further application of these criteria to protect drinking water and downstream uses in the Great Lakes system shall be according to s. NR 106.06 (1).

NR 105.09(4) (4) To derive human cancer criteria for substances not included in Table 9 the following methods shall be used:

NR 105.09(4)(a) (a) The human cancer criterion shall be calculated as follows:

HCC= RAD x 70 kg
WH + (FH x BAF)

NR 105.09(4)(b) (b) For surface waters classified as public water supplies, if the human cancer criterion for a toxic substance as calculated in par. (a) exceeds the maximum contaminant level (MCL) for that substance as specified in ch. NR 809 or the July 8, 1987 Federal Register (52 FR 25690), the MCL shall be used as the human cancer criterion.

NR 105.09(5) (5) The risk associated dose (RAD) referenced in sub. (4) represents the maximum amount of a substance which if ingested daily for a lifetime of 70 years has an incremental cancer risk equal to one case of human cancer in a population of 100,000. Methods for deriving the risk associated dose are specified in pars. (a) to (d).

NR 105.09(5)(a) (a) The department shall review available references for acceptable human and animal studies from which the risk associated dose can be derived. The department shall use sound scientific judgment when determining the acceptability of a study and may use the U.S. environmental protection agency’s “Guidelines for Carcinogen Risk Assessment” (FR 51 33992, September 24, 1986) as guidance for judging acceptability. Suitable references for review include, but are not limited to, those presented in s. NR 105.04 (5).

NR 105.09(5)(b) (b) If an acceptable human epidemiologic study is available, contains usable exposure data, and indicates a carcinogenic effect, the risk associated dose shall be set equal to the lifetime average exposure which would produce an incremental cancer risk of one in 100,000 based on the exposure information from the study and assuming the excess cancer risk is proportional to the lifetime average exposure. If more than one human epidemiologic study is judged to be acceptable, the most protective risk associated dose derived from the studies is generally used to calculate the human cancer criterion. If the risk associated dose values differ significantly, the department may consult with experts outside of the department for guidance in the selection of the more appropriate value.

NR 105.09(5)(c) (c) In the absence of an acceptable human epidemiologic study, the risk associated dose shall be derived from available studies which use mammalian test species and which are judged acceptable. Methods for deriving the risk associated dose are specified in subds. 1. to 4.

NR 105.09(5)(c)1. 1. A linear, non-threshold dose-response relationship as applied by the U.S. environmental protection agency in “Water Quality Criteria Documents; Availability” (45 FR 79318, November 28, 1980) shall be assumed unless a more appropriate dose-response relationship or extrapolation model is supported by credible scientific evidence.

NR 105.09 Note Note: The linear non-threshold dose-response model used by the U.S. environmental protection agency provides an upper-bound estimate (i.e., the one-sided 95% upper confidence limit) of incremental cancer risk. The true cancer risk is unknown. While the true cancer risk is not likely to be greater than the upper bound estimate, it may be lower.

NR 105.09(5)(c)2. 2. When a linear, non-threshold dose-response relationship is assumed, the risk associated dose shall be calculated using the following equation:

RAD= 1 x 0.00001
q1*

NR 105.09(5)(c)3. 3. The department shall adhere to the following guidance for deriving carcinogenic potency factors, or corresponding values if an alternate dose-response relationship or extrapolation model is used, unless more appropriate procedures are supported by credible scientific evidence:

NR 105.09(5)(c)3.a. a. If 2 or more mammalian studies are judged acceptable, but vary in either species, strain or sex of the test animals, or in tumor type or site, the study giving the greatest carcinogenic potency factor shall be used. Studies which produce a spuriously high carcinogenic potency factor due to the use of a small number of test animals may be excluded.

NR 105.09(5)(c)3.b. b. If 2 or more mammalian studies are judged acceptable, are comparable in size and are identical in regard to species, strain and sex of the test animals and to tumor sites, the geometric mean of the carcinogenic potency factors derived from each study shall be used.

NR 105.09(5)(c)3.c. c. If in an acceptable study, tumors were induced at more than one site, the number of animals with tumors at one or more of the sites shall be used as incidence data when deriving the cancer potency factor.

NR 105.09(5)(c)3.d. d. The combination of benign and malignant tumors shall be used as incidence data when deriving the cancer potency factor.

NR 105.09(5)(c)3.e. e. Calculation of an equivalent dose between animal species and humans using a surface area conversion, and conversion of units of exposure to milligrams of toxicant per day (mg/d) shall be performed as specified by the U.S. environmental protection agency in “Water Quality Criteria Documents; Availability” (45 FR 79318, November 28, 1980).

NR 105.09(5)(c)3.f. f. If the duration of the mammalian study (D) is less than the natural life span of the test animal (LS), the carcinogenicity potency factor is multiplied by the factor (D/LS)3.

NR 105.09(5)(c)4. 4. When available mammalian studies contain conflicting information, the department shall consult with the department of health services and may consult with experts outside of the department for guidance in the selection of the appropriate study.

NR 105.09(5)(d) (d) If both a human epidemiologic study and a study of mammalian test species are judged reliable but only the animal study indicates a carcinogenic effect, it is assumed that a risk of cancer to humans exists but that it is less than could have been detected in the epidemiologic study. An upper limit of cancer incidence may be calculated assuming that the true incidence is just below the level of detection in the cohort of the epidemiologic study. The department may consult with experts outside of the department for guidance in the selection of the appropriate study.

NR 105.09 History History: Cr. Register, February, 1989, No. 398, eff. 3-1-89; am. table 9 and (6), Register, July, 1991, No. 427, eff. 8-1-91; correction in (4) (b) made under s. 13.93 (2m) (b) 7., Stats., Register, September, 1995, No. 477; am. (1), (3), r. and recr. Table 9, am. (4) (a), (b), (5) (intro.), (a) (b), (c) (intro.) and 2., r. (6), Register, August, 1997, No. 500, eff. 9-1-97; CR 03-050: am. Table 9 Register February 2004 No. 578, eff. 3-1-04; CR 07-110: am. Table 9 Register November 2008 No. 635, eff. 12-1-08; CR 09-123: am. Table 9 Register July 2010 No. 655, eff. 8-1-10; correction in (5) (c) 4. made under s. 13.92 (4) (b) 6., Stats., Register April 2023 No. 808.

NR 105.10 NR 105.10 Bioaccumulation factor.

NR 105.10(1) (1) The bioaccumulation factor used to derive wildlife, human threshold, human cancer and taste and odor criteria or secondary values is determined from a baseline BAF using the methodology provided in Appendix B to 40 CFR part 132. 40 CFR part 132, Appendix B as stated on September 1, 1997, is incorporated by reference. BAFs shall be used to calculate criteria and secondary values for human health and wildlife. Use of a BAF greater than 1000, as determined from either of the methods referred to in sub. (2) (c) or (d) for organic substances, will result in the calculation of a secondary value. The baseline BAF is based on the concentration of freely dissolved substances in the ambient water to facilitate extrapolation from one water to another.

NR 105.10(2) (2) Baseline BAFs shall be derived using one of the following 4 methods, which are listed from most preferred to least preferred.

NR 105.10(2)(a) (a) A measured baseline BAF for an organic or inorganic substance derived from a field study of acceptable quality;

NR 105.10(2)(b) (b) A predicted baseline BAF for an organic substance derived using field-measured BSAFs of acceptable quality;

NR 105.10(2)(c) (c) A predicted baseline BAF for an organic or inorganic substance derived from a BCF measured in a laboratory study of acceptable quality and a food-chain multiplier. Food-chain multipliers are provided in 40 CFR part 132, Appendix B; or

NR 105.10(2)(d) (d) A predicted baseline BAF for an organic substance derived from a KOW of acceptable quality and a food-chain multiplier.

NR 105.10(3) (3) Review and selection of data. Measured BAFs, BSAFs and BCFs shall meet the quality assurance requirements provided in 40 CFR part 132, Appendix B and shall be obtained from available sources including the following:

NR 105.10(3)(a) (a) EPA Ambient Water Quality Criteria documents issued after January 1, 1980.

NR 105.10(3)(b) (b) Published scientific literature.

NR 105.10(3)(c) (c) Reports issued by EPA or other reliable sources.

NR 105.10(3)(d) (d) Unpublished data.

NR 105.10(4) (4) Human health and wildlife BAFs for organic substances.

NR 105.10(4)(a) (a) To calculate human health and wildlife BAFs for organic substances, the KOW of the substance shall be used with a POC concentration of 0.00000004 kg/L and a DOC concentration of 0.000002 kg/L to yield the fraction freely dissolved:

ffd   = 1 .

1 + (DOC)(Kow) + (POC)(Kow)

  10

  =   1 ..

    1 + (0.000002 kg/L)(Kow) + (0.00000004 kg/L)(Kow)