taken to ensure that the test instrument used is reasonably responsive to radiations emitted by the available isotopes (for example, if C14 is used, rather specialized search equipment may be necessary).

The amount of activity in the form of gas, vapor, dust, or spray in the air must be determined routinely in the laboratory if the activities used are compatible with the production of an inhalation hazard.

3. Inspection of Protective Clothing

The first inspection of protective clothing should be made by the wearer prior to removal. Very active items should be discarded as active solid waste, in closed containers. The remaining items should be washed and monitored under controlled conditions. Special laundry facilities should be used by all groups regularly engaged in radioisotope work. Preferred solvents for laundry rinses depend on the chemistry of the isotopes used. Where miscellaneous isotopes may be present, dilute acetic or citric acid is recommended. Dilute nitric acid may be used on rubber items. Before contaminated garments are considered for release to public laundry service, the extent of hazard shall be very carefully evaluated.

4. Inspection of Wastes

Laboratory personnel is responsible for the inspection of the disposable containers for solid waste. Tests for emitted beta and gamma radiation, and in some cases for radioactive contamination of surrounding air, are required. Radiation monitoring of the assembly of these containers at a central depot may be necessary.

Monitoring and segregation of active liquid waste is similarly required. The inspection of gaseous and dust effluents, etc., is mandatory in the larger installations where such effluents may be hazardous. Tests for possible deposition and accumulation beyond the confines of the laboratory may be required. Detection methods sufficiently sensitive to give large-scale deflections when subjected to natural radioactive contamination in air, water, or soil, are required, because the maximum permissible additional contamination is of this same order of magnitude.

5. Management of Radiation Accidents

(a) External Radiation

A person presumed significantly overexposed to external radiation should be removed promptly from the hazardous area. Such a person should not be allowed to return to work involving radiation unless it is evident that radiation damage will not result. If investigation indicates that the overexposure may be serious, the exposed person should be referred to a physician qualified to ascertain the extent of the radiation injury, if any.

(b) Ingestion

Persons swallowing radioactive solutions should be treated as for poisoning. The material should be removed by an emetic or by stomach pump, and the residue rendered insoluble to reduce absorption. Addition of carrier element may be indicated. Blood samples and subsequent urine samples should be analyzed to compute the body content of contaminant. Where this approximates the maximum permissible load, radical corrective procedures are indicated. Similar protocol applies to other forms of potential intake described below.

(c) Surface Contamination

Persons splashed with active solutions should wash the affected parts immediately, and if still contaminated, apply recognized decontaminating agents. Where the chemistry of the active solution is not immediately known, an application of titanium dioxide paste, or a saturated solution of potassium permanganate followed by a 5-percent sodium bisulfite solution rinse, is frequently effective. Care should be taken to ensure that no activity is left under the fingernails.

When the hand is known to be contaminated with a small spot of high specific activity, it is better not to wash the hand, as this unnecessarily spreads the contamination. Such spots are removed by masking off the surrounding areas, and by cleaning the affected part with cotton applicators dipped in suitable decontaminants. Care should be taken not to scratch or erode through the epidermal skin layer when scrubbing the body to remove surface contamination.

(d) Minor Injuries

Persons cut by glassware, injured by hypodermic needles, etc., should wash the injured part under a strong stream of water immediately following the injury. A venous-return tourniquet may be applied if the material is unusually toxic. If it is ascertained that the injury was caused by an item bearing a hazardous amount of material, a biopsy section of the wound should be analyzed. Excision of the part to reduce further body absorption may be indicated in extreme cases.

(e) Inhalation

Persons inhaling radiotoxic fume, spray, or dust, should be treated to stimulate removal of the toxic material from the lung.

VI. Transportation

1. Shipment of Isotopes

The shipment of radioisotopes should be made in accordance with the regulations of the Interstate Commerce Commission, and with any further specific restrictions of authorized distributors of radioactive material (see appendix 3). The formal regulations cover interstate rail, truck, and water transportation. Transportation by air operates under an interim arrangement (see appendix 3).

2. Movements in the Laboratory

Each laboratory or institution should have a central controlled storage location for incoming isotope shipments. The minimum amounts of active material necessary for the intended processing should be withdrawn from this store, and any excess returned promptly after the operation. Movements of millicurie or greater amounts should be governed by written transfers. Each laboratory supervisor is then aware of the total activity problem in his group. Transfers from the central store to each laboratory should be made in properly shielded containers, and liquid shipments should be protected against spills. Within the laboratory, the active material shall be kept in a specified safe work place. Transfers from one place to another should be reduced to a minimum, and, when necessary, should be made with shielding adequate to protect all personnel in the laboratory. The general rules for such shielding may be deduced from the regulations prescribed for the shipment of isotopes outside the laboratory (see appendices 2 and 3).

FIGURE 1.-Thickness, T mm, of typical materials required to stop completely beta-rays of maximum energy, E MEV.

Appendix 2. Gamma-Ray Shielding

1. Required Shield Thickness

The table given below may be used to determine the required thicknesses for shielding from gamma-ray sources in the laboratory.

Select column for energy required (use next higher if exact value is not given). Entry gives thickness in centimeters of lead for different source strengths at 1 m for 8 hr/day to give 50 mr. Add algebraically the correction terms for other

1

working ranges or times, and multiply by factor for shield material.

Example: An iron shield is required for the manipulation of 500 mc of radioactive material emitting 1.8-Mev gamma rays at a minimum working distance of 50 cm, and for 4 hr/day.

Shield thickness=(8.60+2.77-1.39) X 1.43 14.3 cm of Fe, in which (a) (b) (c)

a=basic entry.

(d)

b=correction for danger range=50 cm.
c=correction for 4 hr/day.

d=conversion from Pb to Fe.