Illinois Administrative Code › Title 35 - ENVIRONMENTAL PROTECTION › Part 302 - WATER QUALITY STANDARDS › Subpart F - PROCEDURES FOR DETERMINING WATER QUALITY CRITERIA › Section 302.654 - Determining the Risk Associated Intake

Current through Register Vol. 48, No. 28, July 12, 2024
The Risk Associated Intake (RAI) is the maximum amount of a
				  substance that if ingested daily for a lifetime, is expected to result in the
				  risk of one additional case of human cancer in a population of one million.
				  Where more than one carcinogenic chemical is present, the RAI must be based on
				  an allowed additive risk of one additional case of cancer in a population of
				  one hundred thousand. The RAI must be derived as specified in subsections (a)
				  through (c).
a) For those substances
				for which a human epidemiologic study has been performed, the RAI equals the
				product of the dose from exposure in units of milligrams of toxicant per
				kilogram body weight per day (mg/kg-d) that results in a 70-year lifetime
				cancer probability of one in one million, times the average weight of an adult
				human of 70 kilograms (kg). The resulting RAI is expressed in milligrams
				toxicant per day (mg/d). If more than one human epidemiologic study is
				available, the lowest exposure level resulting in a 70-year lifetime
				probability of cancer equal to a ratio of one in one hundred thousand must be
				used in calculating the RAI.
b) In
				the absence of an epidemiologic study, for those toxic substances for which a
				carcinogenic potency factor (CPF) has been derived from studies of mammalian
				test species, the risk associated intake is calculated from the equation:
RAI = K/CPF
Where:
RAI
=
Risk associated intake in milligrams per day
							 (mg/d);
K
=
A constant consisting of the product of the average
							 weight of an adult human, assumed to be 70 kg, and the allowed cancer risk
							 level of one in one million (1/1,000,000); and
CPF
=
Carcinogenic Potency Factor is the risk of one
							 additional cancer per unit dose from exposure. The CPF is expressed in units of
							 inverse milligrams per kilogram - day (l/mg/kg-d) as derived in subsections
							 (b)(1) through (b)(7).
1) Only those
				studies that fulfill the data requirement criteria of Section
				302.606 must be used in
				calculating the CPF.
2) The linear
				no-threshold dose-response relationship developed in the same manner as in the
				USEPA document "Mutagenicity and Carcinogenicity Assessment of 1,3-butadiene",
				incorporated by reference in 35 Ill. Adm. Code
				301.106, must be used in
				obtaining the unit risk, defined as the 95th percentile upper bound risk of one
				additional cancer resulting from a lifetime exposure to a unit concentration of
				the substance being considered. The CPF must be estimated from the unit risk in
				compliance with subsection (b)(7). In calculating a CPF, the Agency must review
				alternate scientifically valid protocols if so requested.
3) If in a study of a single species more
				than one type of tumor is induced by exposure to the toxic substance, the
				highest of the CPFs is used.
4) If
				two or more studies vary in either species, strain, or sex of the test animal,
				or tumor type, the highest CPF is used.
5) If more than one tumor of the same type is
				found in some of the test animals, these should be pooled so that the
				dose-response relationship is dose versus number of tumors per animal. The
				potency estimate for this dose-response relationship is used if it is higher
				than estimates resulting from other methods.
6) If two or more studies are identical
				regarding species, strain, and sex of the test animal, and tumor type, the
				highest of the CPFs is used.
7)
				Calculation of an equivalent dose between animal species and humans using a
				surface area conversion, and conversion of units of exposure to dose in
				milligrams of toxicant per kilogram of body weight per day (mg/kg-d), must be
				performed as specified in the USEPA document "Mutagenicity and Carcinogenicity
				Assessment of 1,3-butadiene", incorporated by reference in 35 Ill. Adm. Code
				301.106.