New Mexico Administrative Code › Title 20 - ENVIRONMENTAL PROTECTION › Chapter 3 - RADIATION PROTECTION › Part 4 - STANDARDS FOR PROTECTION AGAINST RADIATION › Section 20.3.4.461 - APPENDIX B - ANNUAL LIMITS ON INTAKE (ALI) AND DERIVED AIR CONCENTRATIONS (DAC) OF RADIONUCLIDES FOR OCCUPATIONAL EXPOSURE; EFFLUENT CONCENTRATIONS; CONCENTRATIONS FOR RELEASE TO SANITARY SEWERAGE

Current through Register Vol. 35, No. 13, July 16, 2024
A. Introduction.
				For each radionuclide, table I of this section indicates the chemical form
				which is to be used for selecting the appropriate ALI or DAC value. The ALIs
				and DACs for inhalation are given for an aerosol with an activity median
				aerodynamic diameter (AMAD) of 1 micrometer, and for three classes (D, W and Y)
				of radioactive material, which refer to their retention (approximately days,
				weeks or years) in the pulmonary region of the lung. This classification
				applies to a range of clearance half-times for D if less than 10 days, for W
				from 10 to 100 days and for Y greater than 100 days. The class (D, W or Y)
				given in the column headed "Class" applies only to the inhalation ALIs and DACs
				given in columns 2 and 3 of table I of this section. Table II of this section
				provides concentration limits for airborne and liquid effluents released to the
				general environment. Table III of this section provides concentration limits
				for discharges to sanitary sewerage.
B. Note. The values in tables I, II and III
				of this section are presented in the E-notation. In this notation a value of
				6E-02 represents a value of 6x10-2 or 0.06, 6E+2
				represents 6x102 or 600, and 6E+0 represents
				6x100 or 6.
C. Table I "Occupational Values".
(1) Note that the columns in table I of this
				section titled "Oral Ingestion ALI," "Inhalation ALI" and "DAC," are applicable
				to occupational exposure to radioactive material.
(2) The ALI's in this section are the annual
				intakes of given radionuclide by "reference man" which would result in either a
				committed effective dose equivalent of 5 rems (0.05 sievert) (stochastic ALI),
				or a committed dose equivalent of 50 rems (0.5 sievert) to an organ or tissue
				(non-stochastic ALI). The stochastic ALIs were derived to result in a risk, due
				to irradiation of organs and tissues, comparable to the risk associated with
				deep dose equivalent to the whole body of 5 rems (0.05 sievert). The derivation
				includes multiplying the committed dose equivalent to an organ or tissue by a
				weighting factor, wT. This weighting factor is the
				proportion of the risk of stochastic effects resulting from irradiation of the
				organ or tissue, T, to the total risk of stochastic effects when the whole body
				is irradiated uniformly. The values of wT are listed
				under the definition of weighting factor in 20.3.4.7 NMAC. The non-stochastic
				ALI's were derived to avoid non-stochastic effects, such as prompt damage to
				tissue or reduction in organ function.
(3) A value of wT =
				0.06 is applicable to each of the five organs or tissues in the "remainder"
				category receiving the highest dose equivalents, and the dose equivalents of
				all other remaining tissues may be disregarded. The following portions of the
				gastro-intestinal (GI) tract - stomach, small intestine, upper large intestine
				and lower large intestine - are to be treated as four separate
				organs.
(4) Note that the dose
				equivalents for an extremity, skin and lens of the eye are not considered in
				computing the committed effective dose equivalent, but are subject to limits
				that must be met separately.
(5)
				When an ALI is defined by the stochastic dose limit, this value alone is given.
				When an ALI is determined by the non-stochastic dose limit to an organ, the
				organ or tissue to which the limit applies is shown, and the ALI for the
				stochastic limit is shown in parentheses. Abbreviated organ or tissue
				designations are used:
(a) LLI wall = lower
				large intestine wall;
(b) St wall =
				stomach wall;
(c) Blad wall =
				bladder wall; and
(d) Bone surf =
				bone surface.
(6) The
				use of the ALI's listed first, the more limiting of the stochastic and
				non-stochastic ALI's, will ensure that non-stochastic effects are avoided and
				that the risk of stochastic effects is limited to an acceptably low value. If,
				in a particular situation involving a radionuclide for which the non-stochastic
				ALI is limiting, use of that non-stochastic ALI is considered unduly
				conservative, the licensee may use the stochastic ALI to determine the
				committed effective dose equivalent. However, the licensee shall also ensure
				that the 50 rems (0.5 sievert) dose equivalent limit for any organ or tissue is
				not exceeded by the sum of the external deep dose equivalent plus the internal
				committed dose equivalent to that organ, not the effective dose. For the case
				where there is no external dose contribution, this would be demonstrated if the
				sum of the fractions of the non-stochastic ALI's (ALIns)
				that contribute to the committed dose equivalent to the organ receiving the
				highest dose does not exceed unity, that is, the sum (intake in microcuries of
				each radionuclide/ALIns) is less than or equal to 1.0.
				If there is an external deep dose equivalent contribution of
				Hd, then this sum must be less than 1 -
				(Hd/50), instead of less than or equal to 1.0. Note that
				the dose equivalents for an extremity, skin and lens of the eye are not
				considered in computing the committed effective dose equivalent, but are
				subject to limits that must be met separately.
(7) The derived air concentration (DAC)
				values are derived limits intended to control chronic occupational exposures.
				The relationship between the DAC and the ALI is given by:
DAC = ALI (in microcuries) / (2000 hours per working year x
				  60 minutes/hour x 20000 milliliter per minute) = (ALI / 2.4 x
				  109 ml) microcuries/milliliter, where 20000
				  milliliter is the volume of air breathed per minute at work by reference man
				  under working conditions of light work.
(8) The DAC values relate to one of two modes
				of exposure: either external submersion or the internal committed dose
				equivalents resulting from inhalation of radioactive materials. DACs based upon
				submersion are for immersion in a semi-infinite cloud of uniform concentration
				and apply to each radionuclide separately.
(9) The ALI and DAC values include
				contributions to exposure by the single radionuclide named and any in-growth of
				daughter radionuclides produced in the body by decay of the parent. However,
				intakes that include both the parent and daughter radionuclides should be
				treated by the general method appropriate for mixtures.
(10) The values of ALI and DAC do not apply
				directly when the individual both ingests and inhales a radionuclide, when the
				individual is exposed to a mixture of radionuclides by either inhalation or
				ingestion or both, or when the individual is exposed to both internal and
				external irradiation (see 20.3.4.406 NMAC). When an individual is exposed to
				radioactive materials which fall under several of the translocation
				classifications of the same radionuclide, such as class D, class W or class Y,
				the exposure may be evaluated as if it were a mixture of different
				radionuclides.
(11) It should be
				noted that the classification of a compound as class D, W or Y is based on the
				chemical form of the compound and does not take into account the radiological
				half-life of different radionuclides. For this reason, values are given for
				class D, W and Y compounds, even for very short-lived radionuclides.