Maximum Permissible Exposure Limits

PURPOSE: This rule establishes maximum permissible exposure limits. Maximum permissible doses are established for both external and internal exposures for persons within or outside controlled areas. (1) Except as provided in subsections (1)(A)–(C) of this rule, the maximum permissible dose (MPD) from all external sources of ionizing radiation for persons within a controlled area shall be as listed in Table I. Table I A dose to the whole body, head and trunk, in addition to that listed in Table I, shall be permitted for a calendar year, provided that all three (3) of the following conditions are met: Maximum dose Maximum dose permitted in any permitted in any Part of Body calendar year calendar quarter Whole body, head 5 rems 3 rems and trunk, major portion of the bone marrow, gonads or lens of eye. Skin of large body 30 rems 10 rems area. Hands and forearms, 75 rems 25 rems feet and ankles (A) During any calendar quarter, the maximum dose of three (3) rems, listed in Column B of Table I, is not exceeded; (B) The user has determined the individual’s previous accumulated occupational dose; and (C) The dose, when added to the previously accumulated occupational dose, does not exceed the maximum permissible accumulated dose (MPAD) calculated according to the formula: MPAD = (N–18) × 5 rems, where N is the individual’s age in full years. (2) For persons within a controlled area, the radiation dose to the tissues of the body from radioactive materials within the body shall be controlled by limiting the average rates at which these materials are taken into the body. Where this intake results from breathing contaminated air, the concentrations of the radionuclides in the air, averaged over any calendar quarter, shall not exceed the concentrations listed in Appendix I, Table 2,Column 1 of this chapter. The values in this table are for a workweek of forty (40) hours. For longer workweeks, the values must be adjusted downward accordingly. Where this intake results from the occurrence of radioactive material in drinking water and foodstuffs, the permissible concentrations shall be the same as in section (3) of this rule. (3) For persons outside a controlled area, the MPD to the whole body due to sources within the controlled area or to radioactive materials escaping from the controlled area, shall be two (2) millirems in any one (1) hour, 0.1 rem in any seven (7) consecutive days and 0.5 rem in any year. In meeting this requirement, the user may take reasonable advantage of operational factors such as the amount of time that the radiation is present or that the area is occupied by any one (1) person. (4) For persons outside a controlled area, the radiation dose to tissues of the body from radioactive materials within the body shall be controlled by limiting the average rates at which the materials are taken into the body. Where this intake results from the occurrence of radioactive materials in the air, drinking water or foodstuffs, the average concentrations of the radionuclides in the air or drinking water or foodstuffs, averaged over any calendar quarter, shall not exceed the concentrations listed in Appendix I, Table 2, Columns 2 and 3 of this chapter. AUTHORITY: section 192.420, RSMo 1986.* This rule was previously filed as 13 CSR 5090.040. Original rule filed Nov. 9, 1964, effective Dec. 9, 1964. *Original authority: 192.420, RSMo 1963.