§179.21 Sources of radiation used for inspection of food, for inspection of packaged food, and for controlling food processing.
Sources of radiation for the purposes of inspection of foods, for inspection of packaged food, and for controlling food processing may be safely used under the following conditions:
（a） The radiation source is one of the following:
（1） X-ray tubes producing X-radiation from operation of the tube source at a voltage of 500 kilovolt peak or lower.
（2） Sealed units producing radiations at energy levels of not more than 2.2 million electron volts from one of the following isotopes: Americium-241, cesium-137, cobalt-60, iodine-125, krypton-85, radium-226, and strontium-90.
（3） Sealed units producing neutron radiation from the isotope Californium-252 （CAS Reg. No. 13981-17-4） to measure moisture in food.
（4） Machine sources producing X-radiation at energies no greater than 10 million electron volts （MeV）.
（5） Monoenergetic neutron sources producing neutrons at energies not less than 1 MeV but no greater than 14 MeV.
（b） To assure safe use of these radiation sources:
（1） The label of the sources shall bear, in addition to the other information required by the Act:
（i） Appropriate and accurate information identifying the source of radiation.
（ii） The maximum energy of radiation emitted by X-ray tube sources.
（iii） The maximum energy of X-radiation emitted by machine source.
（iv） The minimum and maximum energy of radiation emitted by neutron source.
（2） The label or accompanying labeling shall bear:
（i） Adequate directions for installation and use.
（ii） A statement that no food shall be exposed to radiation sources listed in paragraph （a） （1） and （2） of this section so as to receive an absorbed dose in excess of 10 grays.
（iii） A statement that no food shall be exposed to a radiation source listed in paragraph （a）（3） of this section so as to receive an absorbed dose in excess of 2 milligrays.
（iv） A statement that no food shall be exposed to a radiation source listed in paragraph （a）（4） of this section so as to receive a dose in excess of 0.5 gray （Gy）.
（v） A statement that no food shall be exposed to a radiation source listed in paragraph （a）（5） of this section so as to receive a dose in excess of 0.01 gray （Gy）.
Code of Federal Regulations
[42 FR 14635, Mar. 15, 1977, as amended at 48 FR 46022, Oct. 11, 1983; 61 FR 14246, Apr. 1, 1996; 64 FR 69191, Dec. 10, 1999; 66 FR 18539, Apr. 10, 2001; 69 FR 76404, Dec. 21, 2004]