4. Definitions and Workplace Standards

4.1 Laboratory Procedures

1. To prevent accidental entry of radioactive materials into the body, high standards of cleanliness and good housekeeping must be maintained in all laboratories where radioactive material is present.
2. Visitors are not allowed without approval of the laboratory supervisor.
3. Wash hands and arms thoroughly before handling any object which goes to the mouth, nose, or eyes (e.g., cigarettes, cosmetics, foods).
4. Smoking and eating in radioisotope laboratories is prohibited. Refrigerators are not to be used jointly for foods and radioactive materials.
5. One or more trial runs beforehand with non-radioactive materials are recommended for new procedures and with new personnel to test the effectiveness of procedures and equipment and to shorten the possible exposure period.
6. Use shielding when desirable.
7. Do not work with radioactive materials if there is a break in the skin below the wrist.
8. Always use latex gloves when handling more than a few hundred counts per minute. Wear protective clothing: lab coats, safety glasses.
9. Never pipette by mouth. Use rubber bulbs, syringes, or mechanical devices.
10. Clean up minor spills immediately. For major spills follow emergency procedures.
11. Whenever possible, operations with radioactive materials should be conducted in a hood or some other type of closed system. Operations with materials susceptible to atmospheric distribution, such as boiling, evaporating, distilling or ashing must be done in a hood with an air flow of approximately 120 linear feet per minute. Work with finely divided powder must be done in a hood.
12. Table and bench tops should be of a non-porous, chemical-resistant material. Working surfaces shall be covered with absorbent diaper.
13. When work is completed, each person will clean up his own work area and arrange for disposal or proper storage of all radioactive materials and equipment. Monitor yourself, wash and monitor again.
14. Laboratories shall provide special radioactive waste containers. These shall bear the words "Caution, Radioactive Waste".
15. Repairs such as plumbing should not be undertaken unless a representative of the Radiation Safety Section is present.
16. When use and storage of radioactive materials is to be terminated at a facility, notify the Radiation Safety Section, which must make a terminal survey before an area can be released for other uses.

4.2 Classification of Radionuclides According to Relative Hazard Potential

The following classifications are according to the State of Israel Pharmacists Law of 1980.

Class 1 (very high toxicity)

Pb-210, Po-210, Ra-223, Ra-226, Ra-228, Ac-227, Th-227, Th-228, Th-230, Pa-231, U-230, U-232, U-233, U-234, Np-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Am-241, Am-243, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246, Cf-249, Cf-250, Cf-252.

Class 2 (high toxicity)

Na-22, Cl-36, Ca-45, Sc-46, Mn-54, Co-56, C0-60, Sr-89, Sr-90, Y-91, Zr-95, Ru-106,Ag-110m, In-114m, Cd-115, Sb-124, Sb-125, Te-127m, Te-129m, I-124, I-125, I-126, I-131, I-133, Cs-134, Cs-137, Ba-140, Ce-144, Eu-152, Eu-154, Tb-160, Tm-170, Hf-181, Ta-182, Ir-192, Tl-204, Bi-207, Bi-210, At-211, Pb-212, Ra-224, Ac-228, Pa-230, Th-234, U-236, Bk-249.

Class 3 (moderate toxicity)

Be-7, C-14, Fe-18, Na-24, Cl-38, Si-31, P-32, P-33, S-35, A-41, K-42, K-43, Ca-47, Sc-47, Sc-48, V-48, Cr-51, Mn-52, Mn-56, Fe-52, Fe-55, Fe-59, Co-57, Co-58, Ni-63, Ni-65, Cu-64, Zn-65, Zn-69m, Ga-72, As-73, As-74, As-76, As-77, Se-75, Br-82, Kr-85, Kr-87, Rb-86, Sr-85, Sr-91, Y-90, Y-92, Y-93, Zr-97, Nb-93m, Nb-95, Mo-99, Tc-96, Tc-97m, Tc-97, Tc-99, Ru-97, Ru-103, Ru-106, Rh-105, Pd-103, Pd-109, Ag-105, Ag-111, Cd-109, Cd-115, In-115m, Sn-113, Sn-125, Sb-122, Te-125m, Te-127, Te-129, Te-131m, Te-132, I-130, I-132, I-134, I-135, Xe-135, Cs-131, Cs-136, Ba-131, La-140, Ce-141, Ce-143, Pr-142, Pr-143, Nd-147, Nd-149, Pm-147, Pm-149, Sm-151, Sm-153, E-152, Eu-155, Gd-153, Gd-159, Dy-165, Dy-166, Ho-166, Er-169, Er-171, Tm-171, Yb-175, Lu-177, W-185, W-187, W-181, Re-183, Re-186, Re-188, Os-185, Os-191, Os-193, Ir-190, Ir-192, Pt-191, Pt-193, Pt-197, Au-196, Au-198, Au-199, Hg-197, Hg-197m, Hg-203, TI-200, TI-201, TI-202, Pb-203, Bi-206, Bi-212, Rn-220, Rn-222, Th-231, Pa-233, Np-239.

Class 4 (slight toxicity)

H-3, O-15, A-37, C-58m, Ni-59, Zn-69, Ge-71, Kr-85, Sr-85m, Rb-87, Y-91m, Zr-93, Nb-97, Tc-96m, Tc-99m, Rh-103m, In-113m, I-129, Xe-131m, Xe-133, Cs-134m, Cs-135, Sm-147, Re-187, Os-191m, Pt-193m, Pt-197m, Th-132, U-236, U-238, Natural U.

4.3 Workplace Standards for Operations with Unsealed Radioactive Materials

Category "C" laboratory must be equiped with washable surfaces: floor covered with PVC, tables and benches should be of a non-porous, chemical resistant material, chairs of vinyl, stainless-steel sink, elbow (or electronic) operated faucet, liquid-soap dispenser, fume-hood for volatile materials.

Category "B" laboratory (part of the Radiation Safety). Special radioactivity lab planned for high activities. On top of the above specifications has hoods with Stronger air flow, double shielding, emergency shower and all work is supervised by the radiation inspector.

4.4 Activity Limitations of Radioisotopes in the different types of Laboratories

Category "B"	Category "C"	Toxicity class
10-104Ci or less	10 Ci or less	very high
102-105 Ci or less	102 Ci or less	high
103-106 Ci or less	103 Ci or less	medium
104-107 Ci or less	104 Ci or less	low

Ammendments to the above activity limitations:

Storage	x 100
Simple wet procedure (dilution)	x 10
Simple procedure	x 1
Complex procedure with spill hazard	/10
Procedure involving use of powders	/100

4.5 Radioisotopes - Definitions and Units

4.5.1 Atomic Structure

• Atomic number (Z) - the number of protons in the nucleus of the atom
• Mass number (A) - the number of protons+neutrons in the nucleus of the atom
• Isotopes - atoms with the same atomic number but different mass numbers
• Radioactivity - the property of certain nuclides of emitting radiation by the spontaneous transformation of their nuclei
• Radionuclides - nuclei of radioactive isotopes
  ^A_ZX is the general symbol for element X with Z protons and A-Z neutrons in its nucleus.
  For example ¹³⁵₅₃I has 53 protons and 78 neutrons.
• Energy Unit - a measure of the energy of nuclear particles and photons:
  1eV=1.610^-12 ergs = 1.6 x 10^-19 Joul
  1 MeV = 10⁶ eV
• Radioactivity - the property of certain nuclides of emitting radiation by the spontaneous transformation of their nuclei
• Alpha emission - Particulate radiation consisting of fast moving helium nuclei (2 protons; 2 neutrons) produced by the disintegration of heavy nuclei; atomic number > 52
• Beta emission - An electron ejected from a nucleus during radioactive transformation. Beta particles produced by a given nuclide have a range of initial energies from a maximum, which is a characteristic of the nuclide, down to zero
• Gamma and X-rays - Electromagnetic radiation emitted by atomic nuclei; the wavelength is generally in the range 1 x 10^-10 to 2 x 10^-13 meters
• Neutron - One of the particles of which nuclei consist; it is of zero charge and slightly heavier than a proton

4.5.2 Activity Units

• Activity of a quantity of radioactive material - the number of nuclear transformations (radioactive decay) which occur in this quantity in unit time.

  Curie -	the unit of activity
  	One curie (1Ci) = 3.7 x 1010 disintegrations per second (dps)
  	1 Ci = 3.7 x 1010 Bq (Becquerel)
  	mCi = 3.7 x 107 dps
  	Ci = 3.7 x 104 dps

• dps x counter efficiency = cps (counts per second)

• Radioactive concentration - the activity per unit quantity of any material in which a radionuclide occurs; normally expressed as activity per unit volume, i.e., mCi/ml.

• Specific activity - activity per gram or per mole

4.5.3 Ionizing Radiation Units

• Exposure unit - roentgen (r)
  The amount of X or gamma radiation that produces 1 electric charge as a result of interactions in 1 cubic centimeter of dry air.
  1mR = 10^-3R

• Absorbed dose unit - rad
  Rad is a measure of the dose of any ionizing radiation to body tissues in terms of the energy absorbed per unit of mass of tissue. One rad is the dose corresponding to the absorption of 100 ergs per gram tissue.
  1 rad = 0.01 Gy (Gray); 1 Gy = 1 J/Kg.

• Dose equivalent unit - REM (Roentgen equivalent man)
  Rem is a measure of the dose of any ionizing radiation to body tissue in terms of its estimated biological effect, relative to a dose of 1 roentgen (r) of X-rays [1 millirem (mrem) =0.001 rem]. The relation of the rem to other dose units depends upon the biological effect under consideration and upon the conditions for irradiation. Each of the following is considered to be equivalent to a dose of 1 rem:
  1. A dose of 1 roentgen due to X- or gamma radiation
  2. A dose of 1 rad due to X-, gamma, or beta radiation
  3. A dose of 0.1 rad due to neutrons or high energy protons
  4. A dose of 0.05 rad due to particles heavier that protons and with sufficient energy to reach the lens of the eye

  Sievert (Sv); 1 Sv = 100 rem
  1 rem = 0.01 Sv

• External exposure is determined by activity and distance
  Absorbed dose rate in rem/hr produced by gamma rays from 1 mCi at a distance of 1 cm from the point source (specific gamma ray constant or k factor).

• Inverse Square of Distance law
  Doubling the distance from the source quarters the radiation dose.

  Example: Cr-51 k factor = 0.16
  The Exposure rate from 1 mCi at 1 cm distance from the source is 0.16 r/h (160 mr/hr).
  Increasing the distance to 20 cm (estimated working distance) will reduce the exposure to 160/400 = 0.4 mr/hr.

4.6 Properties of Commonly Used Isotopes

Radio-isotope	Phys. half life	Biol. half life	Energy MeV (max.)	Gamma Exposure rate R/h 1cm from 1mc	Range in air	Critical organ	Quant. in "C" lab (mCi)	Notes
S-35	87 d	90 d	0.17	n/a	24 cm	whole body	1	1,5
P-32	14 d	19 d	1.7	n/a	6 m	bone	1	4
Ca-45	165d	var.	0.257	n/a	48 cm	bone	0.1	1
H-3	12 y	10 d	0.018	n/a	5 mm	whole body	10	1,2
C-14	5760y	25 d	0.159	n/a	22 cm	body fat	10	1,3
Cr-51	28 d	616d	0.322	0.16	n/a	lower large intestine	1	6
I-125	60 d	138d	0.035		n/a	thyroid	0.1	6,7

Notes

1. Millicurie amounts do not pose a significant external exposure hazard.
2. Notes on H-3: after use of >10 mCi open bench or >100 mCi in a fume hood, radiotoxicology assay by the Radiation Safety personnel is required.
3. Because of the long halflife of C-14, take care not to contaminate items which are difficult to decontaminate.
4. Notes on P-32: users handling > 5 mCi must work in the central radioactivity laboratory. Work behind shielding when possible; shield with perspex, NOT LEAD; wear eye protection.
5. Some compounds, such as S-35 methionine, may vaporize on opening of container. When doing metabolic labelling of cells with S-35 methionine, place active charcoal in the incubator.
6. Shield large (mCi) quantities with lead.
7. Notes for I-125: users handling > 0.1 mCi carrier-free iodine must work in the central radioactivity laboratory.

4.7 Handling Precautions of Commonly Used Isotopes

The files below are in PDF format:

1. Calcium-45
2. Carbon-14
3. Chromium-51
4. Iodine-125
5. Phosphorus-32
6. Rubidium-86
7. Sulfur-35
8. Tritium
9. Phosphorus-33